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Title: The life of Isambard Kingdom Brunel, Civil Engineer

Author: Isambard Brunel

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Language: English

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THE   LIFE
OF
ISAMBARD   KINGDOM   BRUNEL,
CIVIL ENGINEER.

BY

I S A M B A R D   B R U N E L,   B.C.L.,
OF LINCOLN’S INN;
CHANCELLOR OF THE DIOCESE OF ELY.


LONDON:
LONGMANS, GREEN, AND CO.
1870.

PREFACE.

I HAVE NOT attempted to describe the events of my father’s life in chronological order beyond the end of Chapter III., which brings down the narrative to the close of 1835, the year in which the Act was obtained for the Great Western Railway.

Chapter IV. contains a general account of my father’s railway works, with the exception of the Bridges, which are described in Chapter VII. The history of the Broad Gauge and of the trial of the Atmospheric System on the South Devon Railway is given in Chapters V. and VI.

Chapters VIII.—XIII. contain an account of my father’s labours for the advancement of Ocean Steam Navigation. It will be noted that these chapters cover the same period as Chapters IV.—VII., namely, from 1835, the year of the commencement of the Great Western Railway and the ‘Great Western’ Steam-ship, to 1859, the year of his death, in which the Saltash Bridge and the ‘Great Eastern’ were both completed.

Chapters VII. (on the Bridges) and XIV. (on the Docks) have been written by Mr. William Bell, for many years a member of my father’s engineering staff; and in regard to Chapter V. (on the Broad Gauge), I have to acknowledge assistance rendered me by Mr. William Pole, F.R.S.

For the Note on the Carbonic Acid Gas Engine which follows Chapter I., I am indebted to Mr. William Hawes; and for Chapter VI. (on the Atmospheric System) to Mr. Froude, F.R.S.

I have also printed letters, written to me at my request, relating to various incidents in my father’s life.

The assistance I received in the preparation of the chapters on Steam Navigation from my friend the late Captain Claxton, R.N., has been referred to in the note to p. 234.

I have throughout availed myself of my brother’s professional knowledge.

I have been compelled, in order to bring the work within the compass of a single volume, to omit much that would otherwise have been inserted, and I must therefore be held responsible for the general arrangement of those parts which have been contributed by others, as well as for the chapters which I have written myself.

Lastly, I desire gratefully to thank those friends who, by supplying me with materials and revising the proof sheets, have helped me in my endeavour to make this book, as far as possible, an accurate record of my father’s life, written in the spirit of which he would have approved.

I. B.

18 Duke Street, Westminster:
November, 1870.

CONTENTS

LIST

OF

REPORTS AND OTHER ORIGINAL DOCUMENTS.

LIST

OF

ILLUSTRATIONS.

LIFE

OF

ISAMBARD KINGDOM BRUNEL.

CHAPTER I.

EARLY LIFE.

A.D. 1806—1828.

Isambard Kingdom Brunel was born on the ninth day of April, 1806, at Portsmouth, and was the only son of Sir Marc Isambard Brunel.[1]

Most biographies commence with an account of the parentage of the person whose life is about to be written. If this be permitted in any case, no apology can be needed for prefixing to a Life of Mr. Brunel some particulars of his father’s career, since he was indebted to him, not only for the inheritance of many natural gifts, and for a professional education such as few have been able to procure, but also for a bright example of the cultivation of those habits of forethought and perseverance, which alone can ensure the successful accomplishment of great designs.

Sir Marc Isambard Brunel was a native of Hacqueville, a village in Normandy, where his family had been settled for several generations. He was originally intended for the priesthood; but, as he showed no inclination for that calling, and a very decided talent for mechanical pursuits, he was permitted to enter the French Navy; and he served in the West Indies for six years, namely, from 1786 to 1792. On his return home, at the expiration of his term of service, his strong Royalist sympathies made it unsafe for him to remain in France, and with great difficulty he managed to escape to America. He landed at New York in September 1793, and soon obtained employment as a civil engineer. A few years afterwards he was appointed engineer to the State of New York; and, while holding that office, he designed a cannon foundry and other important public works.

In January 1799, when Sir Isambard was in his thirtieth year, he came over to England, and shortly after his arrival married Miss Sophia Kingdom, a lady for whom he had formed an attachment some years before.[2]

The first great work undertaken by him in this country was the machinery for making blocks, which he designed and erected for Government at Portsmouth.

The history of the invention and construction of this system of machinery (for it consisted of forty-three separate machines) need not be given at length; but it may be permitted to extract the following passage from Mr. Beamish’s ‘Life of Sir Isambard Brunel’ (pp. 97, 99, 2nd edition), in which he points out the benefits which have resulted from its introduction, and the position its inventor is entitled to hold among those who have contributed to the progress of mechanical science.

On the completion of the block machinery Sir Isambard Brunel removed to London, and took a house in Lindsay Row, Chelsea, where he remained until he was obliged to live nearer the works of the Thames Tunnel.

Mr. Brunel’s first recollections were of the house at Chelsea; and in 1814, when he was eight years old, he commenced his school life under the Rev. Weeden Butler, who resided in the neighbourhood. Previously to his going to Mr. Butler, he had been taught Euclid by Sir Isambard; and he had also a great talent for drawing, for which he had been remarkable even from four years old. His drawings were beautifully precise and neat, but, when the subject admitted of it, full of vigour and picturesque effect.

After some time he was sent to Dr. Morell’s school at Hove, near Brighton. The following extract is taken from one of his letters home in 1820:—

In the intervals of his classical studies he seems to have employed himself, not only in making a survey of Hove in its existing state, but also in a critical examination of the works in progress for its enlargement. It is told of him that one evening he predicted the fall, before the next morning, of some houses which were building opposite the school, and laid a bet on the subject, which his companions readily accepted. He had noticed the bad way in which the work was done, and that the stormy weather, which appeared to be setting in for the night, would probably blow the walls down. In the morning he claimed the wager, for the buildings had fallen in the night.

Except from November 1820 to August 1822, when he was at the Collége Henri Quatre at Paris,[3] Mr. Brunel was so very little absent from home that he became thoroughly acquainted with all his father’s undertakings. Among these was the veneering machinery at Battersea, remarkable for the great diameter of the saw, the steadiness of its motion, and the mechanical arrangements for clearing the veneer from the saw; also the works at the Government establishments at Woolwich and Chatham, and the machinery for making shoes. They have been fully described by Mr. Beamish; but the mere mention of their names is enough to show how great were the advantages enjoyed by Mr. Brunel in receiving from his father his early professional education.

From the year 1823 Mr. Brunel was regularly employed in his father’s office. It was in the early part of this year that the project of the Thames Tunnel first began to occupy Sir Isambard’s attention; but he was also engaged at that time in other works of great importance, among them the suspension bridges for the Ile de Bourbon, and designs for bridges of the same character over the Serpentine, and over the Thames at Kingston.[4] Some account of the Bourbon bridges, and also of experiments with carbonic acid gas, on which Mr. Brunel was engaged, will be found in the notes to this chapter.

The history of the Thames Tunnel will be told, as far as possible, in Sir Isambard Brunel’s own words, as given in his journals.[5] Although these extracts do not relate to works for which Mr. Brunel was personally responsible, they have been inserted in the belief that they are valuable, not only as showing the nature and extent of his duties as his father’s assistant, but also as displaying, in the most interesting and authentic form, Sir Isambard’s character and genius at a time when his son was brought into hourly contact with him, and under circumstances which would cause the influence of his example to make a deep and lasting impression.

Previously to the year 1823 there had been several plans suggested for the construction of a tunnel under the Thames; and it would seem that a great demand was supposed to exist for some such means of communication between the two sides of the river eastward of London Bridge; for after the failure of the operations undertaken by Mr. Vasie in 1805, and Mr. Trevethick in 1807,[6] a high level suspension bridge was proposed, although it was not intended to be used for heavy traffic.[7]

The first reference to the Tunnel in Sir Isambard’s journals is dated February 12, 1823. ‘Engaged on drawings connected with Tunnel;’ and on the 17th and following days of the same month, ‘Isambard was engaged on Tunnel.’ These entries become more and more frequent in the pages of his diary, until it is evident that Sir Isambard’s whole time and thoughts were absorbed in this work.

The spring of 1823 was occupied in preparing drawings and models of his plans, and in enlisting the sympathy and assistance of various influential persons. By the close of the year the designs were matured sufficiently to enable the promoters of the scheme to commence the task of organising a company for carrying it out; and in January 1824 they resolved to call a general meeting of their friends, and invite public subscriptions.

On February 17, Sir Isambard explained his plans at the Institution of Civil Engineers, and on the next day a meeting was held at the City of London Tavern, under the presidency of Mr. William Smith, M.P., more than a hundred persons being present. Resolutions authorising the formation of a company were passed unanimously, and the share list was opened. In the course of an hour one-third of the subscriptions was filled up, namely, 1250 shares; and before the end of the day the number of shares taken was 1381.

Borings were then commenced in order to ascertain the nature of the strata through which the Tunnel would pass. A bed of gravel was found over the clay, which gave Sir Isambard great anxiety. A large pipe or shaft was sunk on the side of the river, and in it the water rose to within three feet of the surface of the ground, and fell about eighteen inches with the tide. ‘It is manifest (Sir Isambard writes) from this that unless the Tunnel is enclosed in the stratum of clay, it would be unsafe to drive through the bed of gravel. The Tunnel must, therefore, begin with the substantial clay.’

However, the result of thirty-nine borings in two parallel lines across the river, to the depth of from 23 to 37½ feet, seemed to prove that there was below the gravel a stratum of strong blue clay of sufficient depth to ensure the safety of the Tunnel.[8]

A report to this effect was made to the shareholders at their first general meeting in July, and it was also stated that the works would be completed in three years.

The first operation connected with the works, was the constriction of a shaft; and for this purpose land was bought on the Rotherhithe bank, about fifty yards from the river. On March 2, 1825, the ceremony of laying the first stone of the shaft was performed.

The mode in which Sir Isambard decided to construct the shaft was one not uncommonly adopted in the construction of wells; but to apply it to sinking a shaft fifty feet in diameter was a novel and bold undertaking. The brickwork intended to form the lining of the shaft was built on the surface of the ground, and the earth being excavated from within and underneath the structure, it sank gradually down to its final position.

The brickwork was 3 feet thick, bound together by iron and timber ties, and there were built into it 48 perpendicular iron rods, one inch in diameter, fastened to a wooden curb at the bottom, and to another curb at the top of the wall, by nuts and screws.

When the shaft or tower of brickwork was completed up to the top, 42 feet in height, the next step was to remove the blockings on which it rested, and this being done the gravel was excavated and hoisted up, and the shaft descended by its own weight.

The Rotherhithe shaft was only sunk forty feet in this manner; the remaining twenty feet, in order to leave the opening for the Tunnel, was constructed by under-pinning, or underlaying, as it was then termed. The underlaying was commenced in the beginning of June.[10]

By July 4 they had got down to the level of the intended foundation of the shaft, having passed into a stratum of gravel, black pebbles embedded in greenish sand, with little or no water; from which circumstance Sir Isambard was of opinion that it was unconnected with the stratum of gravel above.

On the 28th Sir Isambard enters in his journal the following additional observations upon the success of his plans for sinking the shaft:—

On August 11 the underlaying was completed, and preparations were made for constructing a reservoir in the bottom of the shaft for receiving the permanent pumps. This was finished on October 11, with great difficulty, owing to the nature of the ground, which consisted of loose sand containing a large quantity of water.

Thus at last the shaft was completed, and Sir Isambard was able to commence the Tunnel itself, which he ultimately determined to construct in the form of a rectangular mass of brickwork, 37½ feet wide and 22 feet high, pierced by two parallel horseshoe archways, each 14 feet wide and 17 feet high.

Before entering upon the history of this undertaking, some account must be given of the machine which Sir Isambard Brunel devised for effecting its accomplishment.

In order to avoid a quicksand of considerable depth and extent, the Tunnel had to be carried but a short distance below the bed of the river; and, as in all tunnelling through soft soil,[11] the top and sides of the excavation had to be supported until the brickwork was built in; and the front or face had also to be held up as the miners advanced. This support was given by means of a machine called ‘the shield,’ described on one occasion by Sir Isambard as ‘an ambulating cofferdam, travelling horizontally.’[12]

The main body of the shield consisted of twelve independent structures or ‘frames’ made of cast and wrought iron. They were each 22 feet high, and rather more than 3 feet wide; and, when placed side by side, like books on a shelf, against the face of the excavation, they occupied the whole area of the face, and also the top, bottom, and sides for 9 feet in advance of the brickwork. Each frame stood on two feet resting on the ground, and was divided in its height into three cells by cast-iron floors. In these cells, of which there were thus thirty-six in all, the miners stood, and worked at the ground in front of them.

The duty which the shield had to perform was to support the ground until the brickwork was built within the excavation; but it was essential that this should be done in such a manner as to allow of the mining operations being carried on; and it was also necessary that the machine itself should be capable of being moved forward.

The first point, therefore, which has to be explained in the action of the shield is the manner in which the earth was supported by it.

It has been already stated that each frame rested upon two feet, or large iron plates. These two feet together covered the ground under the frame to which they belonged, and thus the whole of the earth beneath the frames was pressed down by the feet.

The earth above was supported by narrow iron plates, called staves, laid on the heads of the frames parallel to the line of the Tunnel, the ends resting on the completed brickwork behind it. The earth at the sides was kept up by staves resting against the outermost frames.

The arrangement for holding up the earth at the face of the excavation was necessarily of a more complicated character. Each frame supported a series of boards called poling-boards, by means of small screw-jacks or poling-screws, two to each poling-board, which abutted against the frames, and pressed the boards against the earth. The boards were 3 feet long, 6 inches wide, and 3 inches thick, and were arranged horizontally. These poling-boards, more than five hundred in number, covered the whole surface in front of the frames.

To resist the backward thrust of the poling-screws against the frames, each frame was held forward by two large screws, one at the top of the frame, and the other at the bottom, abutting against the brickwork of the Tunnel. The brickwork was completed close up behind the shield as it advanced.

The way in which the earth was excavated, and the shield moved forward, has now to be explained.

The plates or staves which supported the ground at the top and sides of the shield were pushed forward separately by screw-jacks; but in order to advance the poling-boards in front, it was necessary that that portion of the ground against which they pressed should be removed.

The miner, standing in his cell, took down one, or, at the most, two of the poling-boards, commencing at the top of the cell, and having excavated the earth a few inches in advance, replaced the poling-boards against the newly-formed face, pressing them against it with the poling-screws. Thus the excavation was carried on without depriving the ground of the support it received from the shield, except at the point where the miner was actually at work.

The operation of advancing the frames was effected in the following way. When everything was ready for a move, one of the feet which carried the frames on jointed legs was lifted up, and advanced forward a few inches, and then pressed down on to the ground, until in its new position it again bore the weight of the frame. This done, the other foot was lifted, moved forward, and screwed down in the same manner, and then the frame itself was pushed ahead by means of the large abutting screws, which kept it top and bottom from being forced back on the brickwork.

It is, however, evident that these abutting screws would have been unable to push on the frame, while the ground in front was pressing back the poling-boards against it; therefore, during the process of moving a frame, it had to be relieved from the thrust of its poling-screws. Accordingly, when it was desired to advance any one of the frames, the butts of the poling-screws of the tier of boards in front of it were shifted sideways, so as to rest, not against the frame to which they belonged, but against the frames next it on either side. This done, the frame itself was advanced, and was then ready to receive again its own poling-screws, and also those belonging to the adjoining frames, so that they might in their turn be moved forward. It will thus be seen that the whole shield was not moved forward at one time, but that the frames were advanced alternately.

There were many other ingenious arrangements in the design of the shield, which need not be referred to in a description intended only to give such a general idea of the machine as may make the history of its operation intelligible.[13]

When the frames had been completed in Messrs. Maudslay’s factory, they were conveyed to Rotherhithe, and lowered down the shaft. An opening had been left at the bottom of the wall, about 37 feet wide by 22 feet high, and against this the shield was erected. It was then ready to commence its progress through the ground below the river.

On November 25, 1825, the shield made its first start. Sir Isambard was unfortunately unable to witness what was in fact the actual commencement of the Tunnel, as he had three days before been seized with a sudden and alarming attack of illness, which kept him at home till December 6. The works were left under the direction of Mr. Brunel.

On March 6 the proprietors paid a visit to the Tunnel, and were highly satisfied with what they saw. On that evening Sir Isambard writes:—

Sir Isambard’s journal continues:—

On the 30th a raft was sunk over the shield, and the water in the shaft was brought so low that the last flight of steps was visible. However, on the next day the river broke in again; and as it was found that the raft was open at the west side, it was raised and towed on shore.

On June 19, a general meeting of the proprietors was held, to consider the position of the company. Sir Isambard addressed the meeting, and also presented a long report, in which he entered very fully into the circumstances of the recent accident and the causes which led to it. He then described the means he had taken to restore the works by sinking bags of clay and gravel. He adds: ‘I have already succeeded in closing the hole through which the water first penetrated, and feel confident that the second opening which afterwards appeared is also stopped, but a short time is necessary to elapse for the new ground over the shield to settle and consolidate. It has already supported a head of water of thirty-five feet.’

A small tarpaulin was now spread over the frames, and operations commenced for cleaning them. This was a most difficult and dangerous work, especially as the water was still so high that the frames could only be approached by boats. The men, even the best hands, were at first greatly alarmed at the danger they were in; but the example set by Mr. Brunel and Mr. Beamish produced, as Sir Isambard notes, the best effect, and they soon became reconciled to their situation.

On July 11, Sir Isambard thought that matters had so far advanced that a large tarpaulin, which it was proposed to sink over the frames, ‘would have its full effect.’ It was accordingly sunk on the following day, under the superintendence of Mr. Brunel. Sir Isambard adds to his account of the operation—‘This reflects great credit on Isambard, and the apparent facility with which it was effected evinces his presence of mind, for a single faux pas would have spoilt the whole.’[21]

As the year drew to a close, the difficulty of working the silt increased, and with this difficulty increased also the expense of maintaining the staff of men required. On December 18, Mr. Brunel, writing for his father, who was absent from town for a few days, thus describes the nature of the soil through which they were then passing.

On January 1, 1828, Sir Isambard returned to London; and on the 12th, when about 600 feet of the Tunnel had been completed, a second irruption occurred, which put a stop to the works for seven years.

The particulars of this accident are thus described by Mr. Brunel, in a letter to the Directors of the Company:—

This statement Sir Isambard embodied in a report to the Directors of January 28, which was circulated among the proprietors.

As soon as the first excitement caused by the irruption had ceased, Mr. Brunel directed the diving-bell to be prepared in order to ascertain the state of the shield and the extent of the disturbance of the bed of the river caused by the rush of water into the Tunnel.

He was, however, so seriously injured that he could not actively superintend the preparations, but his orders were given with his usual clearness, calmness, and decision; and as soon as the barge containing the diving-bell was properly moored over the Tunnel, he was carried out and laid upon a mattress on the deck of the barge, that he might direct what was to be done.

As evening came on he became so much worse that he was taken into the cabin; but everything which took place was reported to him.

At length, the bell being ready, it was lowered early on the Sunday morning, but the chain not being long enough, proceedings were delayed until a longer chain could be obtained.

As, however, a chain of the right size and length could not be obtained, the strongest cable which could be procured in the neighbourhood was substituted for the chain. A controversy then arose between the assistant engineers and the foremen as to the sufficiency of the strength of the cable; and it was agreed to consult and to abide by the opinion of Mr. Brunel, who was then lying in great pain in the cabin.

No answer could be obtained from him for some minutes, and then he only said, ‘Don’t go down.’ This not being satisfactory to the advocates of the sufficiency of the cable, it was agreed to lower the bell empty, which was done, and it was brought up safely; but just as it was swung over the barge, the rope broke and the bell fell on to the stage.

The next day Mr. Brunel was taken home, when it was found that, besides the injury to his knee which he received while endeavouring to save the lives of the three men who were with him,[22] he had received serious internal injuries, which kept him under medical treatment for several months.

When he was able to return to Rotherhithe all hope of continuing the works was for the time abandoned. When they were resumed, in 1835, he was entirely engrossed in the independent pursuit of his profession; and, with the exception of a few occasions when he acted for his father, he had no further connection with the Tunnel.

It is not, therefore, necessary to continue the narrative in detail; but a brief summary of the subsequent history of the enterprise may be interesting to those who are unacquainted with it.

The Tunnel was cleared of water, and efforts were made, unfortunately without success, to raise funds for the completion of the undertaking. Great enthusiasm was exhibited by the general public and by many eminent persons, including the Duke of Wellington; but the money was not forthcoming, and nothing was left but to brick in the shield, and wait for more favourable times.

It was not till the beginning of 1835 that the Company was able, by the aid of a loan from Government, to recommence the works. The old shield was removed and a new one substituted, in which considerable improvements were introduced. Slings connecting the frames were added, which enabled each frame to support its neighbours when necessary, and important alterations were also made in the arrangements for keeping the frames at the right distance from one another, and for giving greater facility of adjustment to the various parts.

Before the Wapping side was reached there were three more irruptions of the river, namely, August 23, November 3, 1837, and March 21, 1838; but in October 1840 the shaft on the Wapping shore was commenced. It differed from the Rotherhithe shaft, in being sunk the whole depth without underpinning, and was made of a slightly conical form, to reduce the friction in sinking, and had a larger quantity of iron hoops introduced into the brickwork, in order to increase its strength. When this structure had been sunk to the required depth (70 feet), the excavation of the Tunnel was resumed, and at last the shield was brought up to the brickwork of the shaft. The operation of making the junction between the Tunnel and the shaft was one of much difficulty, but it was at length satisfactorily accomplished, and the Tunnel was opened to the public on March 25, 1843—eighteen years and twenty-three days after the commencement of the work.[23]

Sir Isambard Brunel, whose health had for some time been failing, now retired altogether from his professional labours. After passing a few years in peaceful and happy seclusion, surrounded by those he loved, and watched over by their affectionate care, he died on December 12, 1849, in his 81st year, having been spared to carry to completion his greatest work, and to see his son following in his footsteps with a success which must have exceeded his most sanguine expectations.

The education Mr. Brunel received from his father was well calculated to form the foundation of his future career. During the later and more arduous part of the contest, which was ended by the irruption of January 1828, he held both the nominal and actual post of Resident Engineer of the Thames Tunnel; but from the commencement of the works, when he was only nineteen years old, he had been, as stated by Sir Isambard, ‘a most valuable coadjutor in the undertaking.’ While placed in this responsible position he acquired habits of endurance and of self-reliance, and learnt to act with promptitude and decision in the application of those measures which experience had shown to be effective in each particular class of emergency. But beyond all other advantages, he had before him the example of his father’s character, in which a rare degree of gentleness and modesty of disposition was joined to unflinching energy, and a determination to overcome all difficulties.

NOTE A (p. 5).

The Bourbon Suspension Bridges.[24]

The suspension bridges designed by Sir Isambard Brunel for crossing rivers in the Ile de Bourbon were two in number. One of them had two spans of 122 feet each in the clear, and 131 feet 9 inches between the points of suspension of the chains. The second had but one span of the same dimensions as those of the larger bridge. In the design of these bridges one of the most important points to be attended to, was to render them secure against hurricanes, which are both frequent and severe in the Ile de Bourbon.

In the larger bridge there was a pier of masonry, built in the middle of the river up to the level of the roadway of the bridge. The suspension chains of the bridge were in three groups, 9 feet 8 inches apart, so as to leave room for two roadways, each about 8 feet 9 inches wide. Each of these groups of chains consisted of two chains side by side. Each chain was made with long links like those of the chain cables used for moorings.

These links, which were made of iron 1·36 inch in diameter, were 4 feet 8 inches long, inside measure, and were each connected together by two short coupling links, 8¾ inches long, inside measure, of iron 1·36 inch by 1 inch, and two pins, each two inches in diameter.

The two chains of each group were placed side by side, with the links upright; one of the pins at each joint was made long enough to serve for both chains, and, in the middle of its length between the two chains, was passed through an eye at the upper end of one of the suspending rods of the bridge. Thus to every joint in each group of the main chains, or at intervals of about 5 feet, there was a suspending rod. These rods were 1¼ inch in diameter.

The pins of the joints of the main chains had half heads at each end of them. They could thus be easily inserted in erecting the bridge, but once in place were quite secure. At every fourth joint in the main chains one of the joint pins was made in two halves, with wedges inserted between them for adjusting the length of the main chains.

Thus there were six chains, and as the links of these had each two parts of iron 1·36 inch in diameter, the total sectional area of the six chains was 17·4 inches.

Each group of the main chains was supported at a height of 25 feet 6 inches above the roadway at the centre pier, and at a height of 5 feet 3 inches at each of the side piers, the lowest portion of the curve of the chain being about 1 foot below the points of suspension of the side piers.

The upright standards, carrying the chains both at the centre pier and at the side piers, consisted for each group of chains of a triangular framework of cast iron, strengthened by long bolts of wrought iron. There were thus three of these triangular frames parallel to each other at each of the piers, and those at the centre pier were braced together over the carriage road. The main chains were not bolted to the standards, but were slung from them by a vertical suspension link, which thus allowed them to move a little lengthways. This link, in fact, performed the function of the rollers now generally put under the saddles of suspension bridges.

The ends of the main chains were held by back stays, formed of bars 3 inches broad by 1¼ inch thick, and 10 feet long, with joints made with short links, and 2⅜ inch pins. The ends of those back stays were secured to holding down plates 3 feet in diameter, sunk deep in the ground and well loaded.

As there was a vertical suspension rod at each joint of the main chains, there was a suspension rod hanging from each of the three groups of chains at about every five feet of the length of the bridge. To each set of these rods was attached a cross girder of cast iron of a T section, with a large rounded bead at the lower edge of the upright web; and connecting these under each of the main chains was a longitudinal timber beam about 8 inches square.

The cast-iron cross girders carried longitudinal teak planking, the planks on which the carriage wheels ran being 12 inches wide and 4 inches thick, protected at the top by wrought-iron plates running longitudinally. The horse-path was protected by iron plates arranged crosswise.

Under each span of the bridge were four chains curved upwards and also sideways. These chains were fastened at their ends into the piers, and were connected to the roadway by ties drawn up tight and attached to the main longitudinal bearers of the platform; the object being to stiffen the platform.

These under tie chains were made each of a set of rods 1¼ inch in diameter with eyes at their ends, the ends being connected by short joint links and 1¼ inch pins; and to these joint links were attached the tie rods which connect these inverted chains with the platform of the bridge, and so prevented its being lifted or blown sideways by the force of the wind.

In the smaller bridge, which, as has been said, consisted of one span of 131 feet 9 inches between the points of suspension, these points were 15 feet 5 inches above the roadway, and the lowest part of the chain was 9 feet 7 inches below the points of suspension. The details of this bridge were similar to those of the larger one.

NOTE B (p. 5).

Experiments with Carbonic Acid Gas.

In 1823 Mr. Faraday made the important discovery that under certain conditions of temperature and pressure many gases could be liquefied, and that these liquids exerted great expansive force by slight additions of temperature, returning quickly with regularity and certainty to their original state upon the application of cold.

The discovery of this new force appeared of such importance, that Mr. Faraday lost no time in publishing it to the world; and Sir Isambard Brunel very soon afterwards commenced a series of experiments to determine the value of the liquid gas as a mechanical agent.

The first experiments were made at Chelsea; but the prosecution of them was soon transferred to the care of Mr. Brunel at Rotherhithe, where he devoted all his spare time to the construction of his father’s proposed ‘Differential Power Engine.’

That the progress of this discovery, and of the experiments made with a view to the application of the liquid gas, as a motive power, may be understood, it is necessary to state that in March 1823 Mr. Faraday communicated to the Royal Society the results of his first experiments on the liquefaction of gases.

The fluid was then produced by the decomposition of the hydrate of chlorine by heat in a closed tube, the amount of gas evolved being so great as to produce a pressure in the tube sufficient to condense the gas into a fluid of the same volume.

This interesting experiment was followed by others with that rapidity and success so remarkable in everything undertaken at that time in the laboratory of the Royal Institution; and within a month another paper was read before the Royal Society, in which the degrees of pressure and temperature at which several gases could be liquefied were recorded, and the means employed to produce and liquefy each gas accurately described.

On April 17 a third paper was communicated by Mr. Faraday, ‘On the Application of Liquids produced by the Condensation of Gases as Mechanical Agents.’

The question is thus stated: ‘The ratio of the elastic force dependent upon pressure is to be combined with that of the expansive force dependent on temperature; and the development of latent heat on compression and the necessity of its reabsorption in expansion must awaken doubts as to the economical results to be obtained by employing the steam of water under very great pressures and very elevated temperatures.

No such doubt can arise respecting liquids, which require for their existence even a compression equal to thirty or forty atmospheres, and where slight elevations of temperature are sufficient to produce an immense elastic force, and where the principal question arising is whether the effort of mechanical motion is to be most easily produced by an increase or diminution of heat by artificial means.’

Difficulties were suggested by Mr. Faraday as to the possibility of obtaining sufficient strength in the apparatus, but the small difference of temperature required to produce an elastic force of many atmospheres, he considered would render the risk of explosion small.

To construct the machinery whereby this new force could be practically applied as a substitute for steam, occupied the time of Sir Isambard Brunel and his son at intervals for several years; for although Mr. Brunel was satisfied at an early period of the enquiry that the liquefied gases could only be advantageously employed where the cost of motive force was secondary to economy of space and to the avoidance of the cumbrous apparatus required for the use of steam, still he was so impressed with the importance of the subject, if the difficulties he foresaw in its application could be overcome, that he continued his experiments for a long period with unflagging energy and perseverance.

The facts relating to the liquefaction of the gases, their elastic force when liquefied under different temperatures, the rapidity with which they could be alternately expanded and condensed, and the best mode of producing each gas, were determined by Mr. Faraday; and as Mr. Brunel was at that time attending the morning chemical lectures at the Royal Institution, he was in constant communication with him, and thoroughly conversant with his experiments.

After Mr. Brunel had made a few preliminary experiments, Sir Isambard determined to employ liquefied carbonic acid gas for the motive power of the proposed new engine, the facility and cheapness of its production, its great expansive force, and its neutral character distinguishing it from any other gas; but it was long before vessels were constructed, in which gas could be produced in sufficient quantity and purity to exert the force required to liquefy it in its own volume, for it was soon found to be impossible to obtain the required pressure with pumps.

Carbonate of ammonia and sulphuric acid were the elements used, and the generator was so arranged that it could be charged, emptied of atmospheric air, and the joints made perfect, before the commencement of the formation of the gas which was to be liquefied.

To the generator was attached a receiver, which could be surrounded with a freezing mixture, so that the temperature of the gas in the cylinder might be below that in the generator.

The gradual formation of the liquid, the development of its elastic force, and the regularity and rapidity with which it increased or diminished by each degree of heat or cold, were carefully watched through a glass gauge, and the receiver when filled with liquid could be disconnected from the generator.

The mechanical difficulties as they arose, one after the other, in the construction and arrangement of the various parts of the generator and receiver were at length overcome; and the receiver was not only filled with liquid gas, but found to be capable of retaining it, whether exerting an elastic force of 30 atmospheres at ordinary temperatures, or of 100 atmospheres when subjected to a slight degree of heat.

The receiver being satisfactorily completed, the next object of attention was the design and construction of a working cylinder capable of resisting at least 1,400 lbs. pressure on the square inch; a task which was one of great anxiety, as any weakness might have caused a serious accident.

It was only after the trial of every known method of making joints to resist high pressures had failed, that an arrangement was devised, requiring the most perfect workmanship, by which packing of any kind was dispensed with, and the cylinder fitted for use.

With the improved tools of the present day it is not easy to realise the difficulties, delays, and disappointments which forty-five years ago occurred from the failure, first of one part of a joint, and then of another; but the construction of vessels capable of producing and also of retaining the gas in its liquid state, with the means of alternately expanding and condensing it from thirty or forty to eighty or one hundred atmospheres, having been accomplished, the object of the expenditure of so much labour and inventive power appeared to be within reach.

The construction of the machinery to utilise the elastic force contained in the cylinder was now proceeded with. Day by day new difficulties arose, and each as it was successfully met seemed but to leave another of greater importance to be surmounted.

It is not necessary in this Note to describe the various arrangements which were devised for transferring the great elastic force in the cylinder of small diameter to a piston in another cylinder of much larger dimensions; it is sufficient to say, that after the devotion of much valuable time extending over several years, and a very large expenditure of money, and after carefully considering the cost of the liquid carbonic acid gas, the difficulty of preventing waste, and the necessarily very expensive character of the machinery, Mr. Brunel was satisfied ‘that no sufficient advantage in the sense of economy of fuel can be obtained by the application of liquefied carbonic acid gas as a motive power’; but so thoroughly did he exhaust the subject before he committed himself to this opinion, that no one has since renewed the enquiry or attempted to make a machine to be moved by the elastic force of liquefied gases, the construction of which, it was well known, had baffled the inventive genius of Sir Isambard Brunel and his son.

CHAPTER II.

THE CLIFTON SUSPENSION BRIDGE.

A.D. 1829—1853. ÆTATIS 24—48.

AFTER Mr. Brunel had recovered from his accident in the Thames Tunnel, he went for a trip to Plymouth, where he examined with great interest the Breakwater and other engineering works in the neighbourhood. He notes in his diary that he went to Saltash, and that he thought the river there ‘much too wide to be worth having a bridge.’ This remark was no doubt made in consequence of his father having some years before been consulted as to the construction of a suspension bridge at this place, which Mr. Brunel himself, eighteen years afterwards, selected for the crossing of the Tamar by the Cornwall Railway, and built there the largest and most remarkable of his bridges.

For the remainder of the year 1828, and during the greater part of 1829, Mr. Brunel kept himself fully employed in scientific researches, and in intercourse with Mr. Babbage, Mr. Faraday, and other friends; but he was without any regular occupation, until, in the autumn of 1829, he heard that designs were required for a suspension bridge over the Avon at Bristol, and he determined to compete.

This project originated in a bequest made in 1753, by Alderman William Vick, of the sum of 1,000l. to be placed in the hands of the Society of Merchant Venturers of Bristol, with directions that it should accumulate at compound interest until it reached 10,000l., when it was to be expended in the erection of a stone bridge over the river Avon, from Clifton Down to Leigh Down. Alderman Vick stated that he had heard and believed that the building of such a bridge was practicable, and might be completed for less than 10,000l.

The legacy was duly paid to the Society of Merchant Venturers, and invested by them. The interest accumulated; and in 1829, when the fund amounted to nearly 8,000l., a committee was appointed to consider in what way it would be possible to carry out Alderman Vick’s intentions.

An estimate for a stone bridge was procured, but as it gave the cost at 90,000l., it was evident that this scheme must be abandoned.

The committee then advertised for designs for a suspension bridge. Mr. Brunel, on hearing through a friend of the proposed competition, went to Bristol; and, after examining the locality, he selected four different points within the limits prescribed by the instructions of the committee, and made a separate design for each of them. His plans were sent in on the day appointed, Nov. 19, 1829, with a long statement, from which the following description of them is taken.

The first design was for a bridge of 760 feet span between the points of suspension, the length of the suspended floor being 720 feet. In order to obtain a height of 215 feet above high-water mark (which was the least that the levels allowed of), towers 70 feet high would have had to be built on the cliffs to carry the chains. The total length of chain, including the land-ties, was about 1,620 feet. Mr. Brunel did not approve of this design, as the situation was not favourable to architectural effect, a point to which the committee attached great importance; but he suggested it from its being somewhat more economical in construction than his other plans.

In another design, the situation being some way farther down the river than that of the design last mentioned, towers would also have been necessary. The distance between the points of suspension was 1,180 feet, with a suspended floor of over 900 feet. It is probable that Mr. Brunel only proposed this plan because the site came within the limits of deviation, as he does not say anything in favour of it in his report.

The two remaining plans are the most interesting of the series, as there can be no doubt that, if Mr. Brunel had had his own way, he would have adopted one of them for execution; and it appears from a little sketch on the top of one of his earliest letters from Bristol, that his first idea for the bridge was that which is carried out in these two designs. The site selected was one where the rocks rise perpendicularly for a considerable height above the proposed level of the bridge, and therefore piers and land-ties were dispensed with, the chains being hung directly from the rock. No masonry was required except for architectural effect.[25]

Plate I.
CLIFTON SUSPENSION BRIDGE.
Elevation of Drawing Nº 3 of Mr. Brunel’s Designs in the first competition. AD. 1829

Elevation of the Bridge according to the Design on which the works were commenced. AD. 1836.
[Larger view]
[Largest view]

The principal difference between these two designs is that in the second a short tunnel is avoided at one end. The style of architecture selected for the tunnel-front and the face of the rock, as shown on the drawings sent in to the committee, is Norman. There are also extant many beautiful sketches made by Mr. Brunel for different parts of the design.[26]

In determining upon the mode of construction, which was the same in the four designs, Mr. Brunel acted upon the principle which guided him in all his subsequent undertakings, which was, as he states in his report, ‘to make use of all that has been found good in similar works, and to avail himself of the experience gained in them, and to combine with all their advantages the precautions which time and experience had pointed out.’

He dismissed in a few words the plan of breaking the span into two or three lengths. This was in his opinion unnecessary, and he computed that the cost of a pier built up from the water’s edge to sufficient height above the bridge to carry the chains, would be at least 10,000l. For this reason he recommended the adoption of spans, the smallest of which far exceeded any up to that time constructed.

In designing the chains, he dispensed with the short connecting links, which had been previously adopted in suspension bridges, introducing instead the method now universally used, of connecting each set of links directly with the adjoining one by means of a pin passed through the holes of both. The number of joints and pins was thus reduced one half, and a considerable saving of expense, as well as diminution of weight, effected.

Another improvement, which diminished still further the weight of the chains, was making the links in lengths of 16 feet, or nearly double that of the longest links at the Menai bridge. The chief reason for this alteration was to ensure a near approximation to equality in the strains on the different links, should all the distances between the holes not be exactly equal. This improvement was afterwards carried still further in the Hungerford Suspension Bridge, the links of which were 24 feet long.[27]

Mr. Brunel also intended to introduce equalising beams in the supports of the floor, so that each chain should bear an equal share of the load. By this arrangement, there would have been comparatively few points of suspension, and ‘the view of the scenery would not be impeded from the observer being surrounded by a forest of suspension rods.’

The disturbance of the strains on the links arising from the greater expansion of the metal of the outer links by the direct heat of the sun, he proposed to obviate by sheet-iron plates placed on each side of the chains, but separated from them by a small interval, and thus screening them from the heat. He did not, however, use this protecting covering at the Hungerford bridge.

All the designs show a camber or rise in the centre of the platform of the bridge, to the extent of two or three feet; and the main chains are brought down almost to the level of the platform. To this last arrangement, as tending to prevent undulation, Mr. Brunel attached some importance; and he further intended to stiffen the bridge against the action of high winds by a system of transverse bracing, and by the addition of inverted chains, similar to those used with success by his father in the Bourbon bridges.[28]

Such, then, were the main features of the bold and carefully matured designs placed by Mr. Brunel before the committee. Out of twenty-two plans submitted, only those of Mr. Brunel and four other competitors were deemed worthy of consideration. He and his friends were naturally much gratified at this, and were full of hope for his ultimate victory. But now, when he seemed to have a fair chance of success in a contest which he justly deemed would have a most important bearing upon his future professional career, an obstacle presented itself, which for the time seemed almost insurmountable; for he met with an unexpected opponent in Mr. Telford, the foremost engineer of the day, and the designer of the famous suspension bridge over the Menai Straits.

The committee of the Society of Merchants had, not unnaturally, found themselves unable to decide upon the merits of designs for a suspension bridge, and had asked Mr. Telford to act as their adviser in the matter. Unfortunately for Mr. Brunel, Mr. Telford was of opinion that the maximum span admissible was that of the Menai bridge, i.e. under 600 feet, and that Mr. Brunel’s proposed bridge, though very pretty and ingenious, would most certainly tumble down in a high wind.

This decision was, of course, fatal to the success of any design which substituted one large span for two or more smaller ones, and dispensed with pillars. Mr. Brunel therefore obtained permission to withdraw his plans from the competition.

Mr. Telford then reported to the committee that none of the remaining designs were suitable for adoption without the introduction of such material alterations as would, in fact, constitute a new design. Whereupon the committee took the only course which, under the circumstances, was open to them, and requested Mr. Telford to prepare a design himself.

Mr. Brunel was not a little disappointed at the turn matters had taken; but, having, as he said,‘smoked away his anger,’ he took leave of his friends at Bristol, and went for a visit to some of the principal manufacturing towns in the north.

Meanwhile Mr. Telford prepared his design, and it was exhibited in Bristol in January 1830. It consisted of a suspension bridge of three spans (the centre span 360 feet, and the side ones 180 feet each), the chains being supported at the intermediate points by tall stone piers rising from the river’s banks at just sufficient distance apart to avoid interfering with the roadways on either side of the stream. The style of architecture was a florid Gothic; and, in order to display the peculiar features of that style, the faces of the piers were covered with elaborate panelling, and the chains ornamented with fret-work.

This design was received with a flourish of trumpets; numerous engravings were published, exhibiting the bridge from various points of view, and ‘thousands of copies were disposed of;’ but, after a time, it would appear that the captivating effect of the Gothic belfries wore off, and that the more the citizens of Bristol looked at Mr. Telford’s plan, the less they were satisfied with it; for, although it was deposited in the Private Bill Office, on application being made for an Act of Parliament, the trustees who were appointed under the Act determined to invite a second competition.

On this occasion, Mr. Telford appeared as a competitor and not as a referee, that office being filled by Mr. Davies Gilbert, sometime President of the Royal Society.

The site of the bridge was fixed, being that selected by Mr. Telford; but the trustees expressly left it to the judgment of the competitors to decide whether there should be intermediate piers or one unbroken span.

Of the thirteen designs sent in, five, including those submitted by Mr. Telford and Mr. Brunel, were reserved for further examination. On March 17, 1831, Mr. Davies Gilbert (who had been assisted by Mr. Seward) made his report. Mr. Telford’s design was put aside, ‘on account of the inadequacy of the funds requisite for meeting the cost of such high and massive towers as were essential to the plan which that distinguished individual had proposed.’

Mr. Brunel’s design was placed second.[29] Although Mr. Gilbert reported that it presented every desirable strength and security, he saw objections to many of the details, and therefore did not recommend it for adoption. However, on the following day, March 18, he stated to the trustees that he had seen Mr. Brunel, and that it gave him much pleasure to state that the explanations made by Mr. Brunel had materially altered his views as to the details of the plans, which he (Mr. Gilbert) was now satisfied were quite equal to those which he had placed first, and that, considering the superiority of Mr. Brunel’s design in the essential particular of strength, he should judge it preferable to any of the others.

Thereupon the trustees, ‘having considered Mr. Davies Gilbert’s report, and referred to all the plans, including Mr. Telford’s, unanimously gave the preference to Mr. Brunel’s,’ and appointed him their engineer.

Subscriptions came in but slowly, and it was not till 1836 that the works were commenced.

The first stone of the abutment on the Leigh woods or Somersetshire side of the river was laid on August 27 by the Marquis of Northampton, President of the British Association, which was then holding its meeting in Bristol.[30]

The span of the bridge is greater than that of Mr. Brunel’s design for the second competition, but much less than the spans of the earlier designs, to which he had given the preference.[31] On this point, as well as on the question of site, he had to conform to the wishes of the trustees.[32] The span approved of by them necessitated the building of a very large abutment on the Leigh woods side, the height of which, from the surface of the rock to the level of the roadway, is 110 feet. Above the roadway, the tower to carry the chains is built to a height of 86 feet. On the Clifton side, the base of the tower is formed by one of the boldest of the range of St. Vincent’s rocks, which here rise almost perpendicularly to a height of 230 feet above high water, and consequently a very small abutment was required. The tower on this side is 3 feet higher than that on the Leigh woods side, and the roadway has a general inclination of about 1 in 233. Mr. Brunel thought that if the roadway were level, it would have the appearance of falling towards Clifton, owing to the ground there being precipitous, while on the Leigh woods side it is sloping.

He intended, in the construction of the bridge, to have followed out the ideas embodied in his report of 1829, and would have preferred to have had only one chain on each side of the bridge, and that much stronger than was usually adopted; but, in deference to public opinion, he put two chains, though he doubted if they would expand equally. ‘A rigid platform would in some degree prevent the unequal distribution of load thus caused, but he endeavoured to lessen the effect of unequal expansion by arranging a stirrup at the top of each suspending rod, so as to hold equally at all times on both chains, and thus to cause each to sustain its proportion of the load.’

The road platform was to have had beneath it ‘a complete system of triangular bracing, which would render it very stiff.’

In order to lessen the action of wind on the bridge, he brought down the main chains in the centre nearly to the level of the platform, and intended to apply the system of brace chains at a small angle to check vibration. There were, moreover, to be two curved chains lying horizontally, and attached underneath the platform, so as to resist the lateral action of the wind.[33]

He here introduced movable saddles to carry the chains on the top of the towers, with rollers running on perfectly flat and horizontal roller beds.[34] By this arrangement no pressure except a vertical one could come on the towers.

He also devised means, by levers and hydraulic presses, for relieving the rollers and roller beds from pressure, in the event of their requiring renewal.

Mr. Brunel ultimately determined to adopt the Egyptian style of architecture. His brother-in-law, Mr. John Callcott Horsley, R.A., gives the following account of the proposed designs for the towers:—

‘His conception of the towers or gateways at either end of the bridge was peculiarly grand and effective, as may be seen from his sketches still existing. They were to be purely Egyptian; and, in his design, he had caught the true spirit of the great remains at Philæ and Thebes. He intended to case the towers with cast iron, and, as in perfect accordance with the Egyptian character of his design, to decorate them with a series of figure subjects, illustrating the whole work of constructing the bridge, with the manufacture of the materials—beginning with quarrying the iron ore, and making the iron, and ending with a design representing the last piece of construction necessary for the bridge itself. The subjects would have been arranged in tiers (divided by simple lines) from top to bottom of the towers, and in the exact proportion of those found upon Egyptian buildings. He made very clever sketches for some of these proposed figure subjects, just to show what he intended by them. I remember a group of men carrying one of the links of the chainwork, which was excellent in character. He proposed that I should design the figure subjects, and he asked me to go down with him to Merthyr Tydvil, and make sketches of the iron processes. We accomplished our journey, and all the requisite drawings for the intended designs were made.’

The works were commenced with the Leigh abutment, which was completed in 1840, great delay having been caused by the failure of the contractors. This misfortune led to a large excess of expenditure over the original estimates. In 1843 the whole of the funds raised (amounting to 45,000l.) were exhausted, and there still remained to be executed the ornamental additions to the piers (the cost of which was estimated at about 4,000l.), half of the iron work, the suspension of the chains and rods, the construction of the flooring, and the completion of the approaches, &c., the estimate for the execution of which was 30,000l.

Unfortunately, all efforts to raise further subscriptions were unsuccessful; and in July 1853, when the time limited for the completion of the bridge had expired, the works were closed in, and the undertaking abandoned.[35]

Several proposals for completing the bridge were made in Mr. Brunel’s lifetime, and he took every opportunity of furthering this object, which he had very much at heart. It was not, however, till about a year after his death that the superstructure of the bridge was actually commenced.

A company was formed in 1860 by some of the principal members of the Institution of Civil Engineers, ‘who had an interest in the work as completing a monument to their late friend Brunel, and at the same time removing a slur from the engineering talent of the country.’[36] Mr. John Hawkshaw, F.R.S., and Mr. W. H. Barlow, F.R.S., were appointed the engineers, and Mr. Brunel’s old friend Captain Christopher Claxton, R.N., the secretary. The works were carried on with vigour; and the bridge was opened with much ceremony on December 8, 1864.

The chains were brought from the Hungerford Suspension Bridge, then in process of demolition. A description of the Hungerford bridge will be found in the note to this chapter.[37]

Although the Clifton bridge was not completed by Mr. Brunel, his connection with it forms a very important passage in the history of his life. Doubtless, if he had never heard of the proposed competition in 1829, or if he had been one of the disappointed competitors, he would have found some other opportunity of making a name in his profession; but, as a matter of fact, the Clifton bridge competition did give him the opportunity he desired, and all his subsequent success was traced by him to this victory, which he fought hard for, and gained only by persevering struggles. He never forgot the debt he owed to Bristol, and to the friends who helped him there; and he would have greatly rejoiced to see the completion of his earliest and favourite work.

PLATE II

HUNGERFORD SUSPENSION BRIDGE
H. Adiard Sc.
[Larger view]
[Largest view]

NOTE (p. 58).

The Hungerford Suspension Bridge.

The suspension bridge which spanned the Thames at Charing Cross, on the site of the present railway bridge, was designed and constructed by Mr. Brunel between the years 1841 and 1845. It consisted of a centre span of 676 feet, and two side spans of 343 feet each. Being intended for foot passengers only, its width was 14 feet. The versed sine, or deflection of the middle of the catenary, was 50 feet. The two river piers, which still exist up to the level of the railway, and form piers of the present bridge, were of brickwork, with large footings at the bottom, so as to distribute the pressure over a considerable area. The whole structure was made hollow and as light as possible. From the level of the footway the piers were carried up as ornamental campanile towers, the weight of the chains being taken by four solid pillars of brickwork, 7 feet 3 inches square, forming the angles. Mr. Brunel introduced here many of the arrangements he had designed for the Clifton bridge. In order that the pressure from the chains might be always vertical on the piers, the saddles rested on rollers working in oil, on the level surface of a large cast-iron bed-plate. By this arrangement it was rendered possible for the chains of the land spans to leave the tower at a greater inclination than those of the middle span, so that the chains were made shorter, and as they were at a lower level where they met the abutment, there was less change in their direction at that point, and consequently less thrust on the brickwork. Freedom of horizontal motion was also secured, so that, in the case of unequal loading of the spans, the chains might accommodate themselves to the strains, and move horizontally until equilibrium was restored. At each of the land abutments the chains passed down over a fixed saddle, at an inclination, to anchorages placed at the bottom of the abutment. The brickwork under the fixed saddle was so disposed as to resist directly the thrust resulting from the change of direction between the main chains and the anchor chains. To resist any movement of the abutments, the piles on which they rested were driven obliquely, with their heads inclined from the river. These piles were very numerous, the abutments spreading out so as to cover a large area at the foundations. Nearly all the spaces between the longitudinal, cross, and outside walls were filled with concrete, in order that the abutments might be as massive as possible. The details of the brickwork in the piers and abutments showed Mr. Brunel’s skill in the economical employment of this material. The chains were constructed so that the sectional area was proportional to the strain; the total area at the centre was 296 square inches, while near the piers it was 312 square inches. There were four chains, two on each side of the bridge, placed one above the other, and consisting each alternately of ten and eleven links. The links were 24 feet long and 7 inches in depth, the thickness varying so as to give the requisite sectional area.

The relative diameter of pin, and proper form of the ends of the link, were subjects of much consideration, and many experiments were made in order to determine these points. The fact that two specimens of iron, apparently identical in every respect, sometimes exhibit considerable difference in their breaking weights, shows that an average of a great number of experiments is required in order to test satisfactorily any proposed refinements of construction. Mr. Brunel, however, convinced himself by experiment that he had practically arrived at such a form of link and diameter of pin that the chain would have no tendency to break at one point rather than another. The links were forged with shoulders near the eyes, in order that by means of clamps the pin could be taken out and the links disengaged, if necessary.

The efficient action of the rollers was demonstrated shortly after the completion of the bridge. On the occasion of the opening of the Corn Exchange by Prince Albert, one of the land spans was crowded with people, while the centre span was nearly empty. In consequence of this the land chains became depressed considerably below their normal position; and the saddles on the top of the tower nearest to the loaded span moved horizontally on the rollers to the extent of 3 inches; and, when the crowd had dispersed, they returned to their original position.

Many years after the completion of the bridge a proposal was made to widen it for carriage traffic; but this was not carried out, and eventually the superstructure was removed, to make way for the bridge of the Charing Cross Railway. As the Hungerford Suspension Bridge has ceased to exist, an engraving has been given of it (Plate II. p. 59), in order that some record of its appearance may remain.

CHAPTER III.

EARLY HISTORY OF THE GREAT WESTERN RAILWAY.

A.D. 1833—1835. ÆTATIS 27—30.

BEFORE entering upon the history of the Great Western and the other railways of which Mr. Brunel was the engineer, it may be useful to give a brief sketch of the development of the railway system, previous to the period when he first became engaged in works of this description.

The first railway in England designed for the conveyance of general merchandise and passengers, was the Stockton and Darlington. An Act of Parliament authorising the construction of this line was passed in 1821.

In 1823, a further Act was obtained, in which a clause was inserted, at the request of Mr. George Stephenson, then the engineer of the company, taking power to work the railway by locomotive engines, and to employ them for the haulage of passengers. This railway, which consisted of a single line with four sidings in the mile, was opened for traffic on September 27, 1825. Its success led at once to the promotion of similar works in other parts of the country.

Next in order must be noticed the celebrated railway between Liverpool and Manchester. A project for constructing a line of railway between these important towns was discussed as early as the year 1822; but a company for carrying it out was not formed till two years later. In 1825, the directors applied to Parliament for an Act; and after a long contest before a committee of the House of Commons, the preamble approving of the construction of the railway was carried by a majority of one. The Bill was, however, withdrawn, as the first two clauses empowering the company to make the line, and to acquire land for that purpose, were lost.[38] In the following year the Act was obtained, and the works were commenced under the direction of Mr. George Stephenson. The line was opened for traffic on September 15, 1830.

In 1824, Mr. George Stephenson wrote a report on a proposed line connecting Liverpool and Birmingham. Surveys were made, and plans deposited; but the Bill was thrown out on standing orders. A similar fate attended the introduction of a Bill in 1826. In 1830, a new line was surveyed by Mr. Joseph Locke and Mr. Rastrick, under the direction of Mr. George Stephenson. The Act was obtained in 1833, and the railway, which was called the Grand Junction, and is now a part of the London and North-Western system, was constructed by Mr. Locke.[39]

In 1830, surveys were commenced by Mr. Robert Stephenson for a line between London and Birmingham, and a Bill was introduced into Parliament in 1832. The Liverpool and Manchester Railway had now been opened for some time, and the promoters of the Birmingham line had the advantage of being able to give in evidence the results of the working of the earlier undertaking. Those results, it is said, were such as to startle most of those who heard them. It was shown that a speed had been attained double that of the fastest stage-coach, that the cost of travelling had been diminished by one half, and that out of 700,000 persons carried since the opening of the railway, only one had met with a fatal accident. The amount of travelling between Liverpool and Manchester had increased four-fold, and the value of the shares of the railway had risen one hundred per cent. Similar evidence was given as to the results of the working of the Stockton and Darlington Railway, and the promoters endeavoured to prove that advantages at least as great would arise from the construction of a railway between Birmingham and London. They were successful in the House of Commons; but, they failed to convince the Upper House that the benefits which such a railway would confer on the country traversed by it were sufficient to entitle its promoters to receive for it the sanction of the legislature. The Bill was again introduced in the following session (1833); and, strange to relate, it passed both Houses almost without opposition.[40]

Meanwhile, the principal merchants of Bristol, who had in 1825 made an attempt to get up a railway company, were urged forward, both by the inadequacy of their communications with the metropolis, and by the success of the Liverpool and Manchester Railway, to make another effort. In the autumn of 1832 a committee was formed of members of the corporation, and other public bodies of the city of Bristol, to carry out the project of a railway to London.

The first step taken by the committee was the appointment of an engineer to make the preliminary surveys, and to prepare an estimate of the cost of the undertaking.

Among the candidates for the post was Mr. Brunel. He was well known in Bristol as the engineer of the Clifton Suspension Bridge, and of the works for the improvement of the Floating Harbour. He had made many friends among the leading citizens, and they used their best exertions to procure his election; but there were several other candidates in the field who had great local interest, and the contest was a close one.

While the issue was yet undecided, an unexpected difficulty arose. Some members of the committee resolved to select their engineer by means of a competition among the candidates, as to which of them would provide the lowest estimate. Upon this being announced, Mr. Brunel declared that he must withdraw his name, as he could not consent to become a party to so objectionable a proceeding. ‘You are holding out,’ he wrote to the committee, ‘a premium to the man who will make you the most flattering promises. It is quite obvious that the man who has either least reputation at stake, or who has most to gain by temporary success, and least to lose by the consequences of disappointment, must be the winner in such a race.’ Happily, this plan was abandoned; Mr. Brunel obtained a majority of votes, and was appointed engineer on March 7, 1833.

He commenced the survey without delay; and in addition to his strictly professional duties, he assisted in forming a committee in London, and took a leading part in the consultations which were held upon various important matters connected with the general interests of the undertaking.

A hasty survey of the country between London and Bristol occupied him till the middle of June; and as soon as it was completed, and the course of the line settled on, preparations were made for placing the scheme before the public.

The first public meeting was held on July 30, 1833. Mr. Brunel thus refers to it in his diary:—‘Got through it very tolerably, which I consider great things. I hate public meetings: it is playing with a tiger, and all you can hope is, that you may not get scratched, or worse.’ The result, however, seems to have been successful, and in a month’s time a company was formally constituted, and the parliamentary survey commenced.

Mr. Brunel organised a staff of assistants, at that time rather a difficult task, and set them to work on various parts of the line. His own duty of superintendence severely taxed his great powers of work. He spent several weeks travelling from place to place by night, and riding about the country by day, directing his assistants, and endeavouring, very frequently without success, to conciliate the landowners on whose property he proposed to trespass.

His diary of this date shows that when he halted at an inn for the night, but little time was spent in rest, and that often he sat up writing letters and reports until it was almost time for his horse to come round to take him on the day’s work. ‘Between ourselves,’ he wrote to Mr. Hammond, his assistant, ‘it is harder work than I like. I am rarely much under twenty hours a day at it.’

A great portion of this labour was for the time thrown away, for as November 30 drew near, it became evident that subscriptions were not coming in to the extent which would enable the directors to lodge a Bill for the whole line in the session of 1834.

The directors therefore determined to apply to Parliament for powers to make a railway from London to Reading, and from Bath to Bristol, ‘as a means of facilitating the ultimate establishment of a railway between London and Bristol;’ postponing till a future session their application for an Act to enable them to complete the undertaking by making the line from Reading to Bath.

The Bill was introduced into the House of Commons, and on March 10, Lord Granville Somerset moved that it be read a second time. This motion was seconded by the Earl of Kerry, and supported by several influential members, amongst whom were Mr. Labouchere (the late Lord Taunton) and Mr. Daniel O’Connell.

The second reading was carried by a majority of ninety in a House of 274 members.

The Bill was then referred to a committee which met on April 16, Lord Granville Somerset being in the chair. Evidence was called to prove the advantages of the railway to the agricultural and trading community of the country through which it would pass, even if only the two proposed divisions of the line were constructed.

The traffic in merchandise between Bristol and London was at this time principally carried on by means of water carriage, consisting, first of the river Avon navigation from Bristol to Bath, next of the Kennet and Avon Canal from Bath to Reading, and lastly of the river Thames from Reading to London. The evidence went to show that the distance between London and Reading, which by railway would be thirty-six miles, amounted by the river to nearly eighty; that the delays and impediments arising from drought, flood, and frosts on the rivers, were such as sometimes to detain barges for several weeks; and that so great were the consequent uncertainties and inconveniences of this navigation, that goods which came as far as Reading by the canal, were frequently sent thence to London by road, although at a great increase of expense. Even under the most advantageous circumstances, goods could not be conveyed from Reading to London in less than three days, or in less than a day by the river Avon from Bath to Bristol. It was therefore contended, that to form a railway which should supersede, or at all events come in aid of, the worst portions of the navigation between London and Bristol, would be an important public benefit.[41] The various advantages of the measure were most fully discussed in an investigation which lasted during fifty-seven days. Against the Bill was arrayed every class of opponent that a private Bill could possibly encounter. Those interested in the canals, rivers, and stage-coaches, opposed it from the fear of competition; the inhabitants of Windsor opposed it, because the railway did not run so near to the town as they wished; the corporation of Maidenhead opposed it, because they thought that all the traffic which paid toll on their bridge over the Thames would be diverted to the railway; landowners and farmers near town opposed it, because they feared it would bring produce to London from a distance, as cheap as that supplied by themselves.

There was another very formidable class of opponents to the Bill, consisting of landed proprietors and owners of houses in the immediate neighbourhood of London.

Many engineers were called by these several opponents, to show that a more advantageous line of railway might have been selected; but, upon sifting the merits of the various new lines proposed, it became apparent that the one chosen by Mr. Brunel was the best. Indeed, although some trifling deviations of his line were suggested, the opposing engineers admitted that in all essential features the railway had been most skilfully laid out. It was generally agreed that the line through the valley of the Thames, and thence in a direction north of the Marlborough Downs, was the only proper course for a railway between Bristol and London, as the levels were much better, and communication could be made with much greater ease with the northern and South Wales districts, than if the route to the south of the Marlborough Downs had been selected.

The plans proposed for entering London raised great opposition. In this respect public feeling has greatly changed, for now no railway is thought complete which has not a terminus in the heart of London; and it is considered an advantage for houses to be within easy reach of a railway station; but in 1834 such a neighbour was looked upon with horror and dismay—a nuisance to be, if possible, absolutely prohibited.

When Mr. Brunel commenced the survey for the London terminus, he had some idea of bringing the railway in on the south side of the Thames; but this was abandoned, as it was found to involve very heavy works, and the line proposed in the first Bill was made to terminate on the north side of the river at Vauxhall Bridge. It was to have been carried on a viaduct 24 feet high, with a parapet 6 feet 6 inches high, to prevent the passengers looking into the windows of the neighbouring houses.

The owners of the land through which this part of the line would pass were influential members of the Upper House, and therefore the directors thought it useless to brave their opposition; accordingly, on the thirteenth day of the hearing, they abandoned the last two miles of the viaduct, and proposed to stop at the ‘Hoop and Toy,’ a public-house near the site of the South Kensington Station of the Metropolitan Railway.

But although the opposition of some of the landowners was conciliated by this concession, that portion of the line through Brompton which had not been abandoned was attacked with unabated energy. The residents in Brompton opposed the Bill from the apprehension that the railway would interfere with their quiet and seclusion; Brompton being at that time considered, at any rate by one of the counsel for the opposition, ‘the most famous of any place in the neighbourhood of London for the salubrity of its air, and calculated for retired residences.’ They could not, indeed, be blamed for indulging in these apprehensions, if they really believed in their counsel’s statement that ‘streams of fire would proceed from the locomotive engines.’

Others objected to the viaduct itself as being an undertaking of so colossal a nature as hardly to be practicable; and the supposed increase of traffic and consequent obstruction in Piccadilly and other leading thoroughfares brought down upon the promoters the opposition of the Commissioners of Metropolitan Roads.

All these objections were made the ground of much argument in committee, and doubtless had great influence over the minds of those who voted against the Bill.

The engineering evidence occupied, as might be expected, the greater part of the forty-two days during which witnesses were examined before the committee, and of these forty-two days no less than eleven were taken up by the cross-examination of Mr. Brunel. So protracted a cross-examination has probably never been heard in any court or committee-room. One of those present thus describes it:—

‘The committee-room was crowded with landowners and others interested in the success or defeat of the Bill, and eager to hear Brunel’s evidence. His knowledge of the country surveyed by him was marvellously great, and the explanations he gave of his plans, and the answers he returned to questions suggested by Dr. Lardner, showed a profound acquaintance with the principles of mechanics. He was rapid in thought, clear in his language, and never said too much, or lost his presence of mind. I do not remember ever having enjoyed so great an intellectual treat as that of listening to Brunel’s examination, and I was told at the time that George Stephenson and many others were much struck by the ability and knowledge shown by him.’

In his evidence, Mr. George Stephenson stated that he did not know any existing line so good as that proposed by Mr. Brunel. ‘I can imagine (he said) a better line, but I do not know of one so good.’[42]

At length, on the fifty-fourth day of the sittings of the committee, Mr. Harrison, K.C., rose to reply on behalf of the promoters, and on the conclusion of his address the Bill was passed.

In the House of Lords the second reading was moved by Lord Wharncliffe. It was opposed, and on a division being taken, the motion was lost by a majority of seventeen (30 content and 47 non-content). The Bill was therefore thrown out.

The directors, undaunted by their defeat, lost no time in making preparations for bringing a Bill before Parliament in the session of 1835, with such improvements as the experience of the past campaign suggested to them. Taking into consideration the various grounds on which opposition had been raised to the plans they had proposed for entering London through the Brompton district, they opened negotiations with the London and Birmingham Railway Company, and arrangements were concluded by which the traffic of the Great Western Railway was to be carried upon the London and Birmingham line for the first four miles out of London, the junction being made a little to the west of the Kensal Green Cemetery.

They had also during the autumn raised money enough to enable them to apply to Parliament for powers to construct the whole of the line from London to Bristol. They thus escaped all the sarcastic observations which had been made upon the scheme of 1834, of which it had been said, that it would be a head and a tail without a body, and neither ‘Great’ nor ‘Western,’ nor even a ‘railway’ at all, but ‘a gross deception, a trick, and a fraud upon the public, in name, in title, and in substance!’

On March 9, the earliest day allowed by the standing orders, the Bill was read a second time and committed. A division being taken on the motion for committal, there appeared in favour of the motion 160, and against it none but the tellers.

Shortly after its first meeting, the committee, of which Mr. Charles Russell, then member for Reading, was chairman, came to the resolution that, inasmuch as the evidence given in the previous year as to the public advantages of a Bristol railway had been referred to them by order of the House, they needed no further evidence on that subject. Counsel were therefore directed to confine their case as much as possible to the merits of the line proposed.

Evidence was called by the opponents chiefly with a view to show the advantages of a proposed line from Basing to Bath, and the inexpediency of granting an entirely new line of 115 miles in length to the Great Western Railway Company, which involved the construction of a ‘monstrous and extraordinary,’ ‘most dangerous and impracticable, tunnel’ at Box, and this, when 44 miles of railway in a western direction—viz. as far as Basingstoke, had already been sanctioned by the legislature in the Southampton Railway Act, passed in the previous session. The promoters of the Bill contended that the levels of the Basing and Bath line were not so good as those proposed for their own, and that the Great Western Railway would approach almost every town of importance situated on the proposed Basing and Bath line, by means of short branches; whilst at the same time it presented the great advantage of being capable of easy extension to Gloucester and Wales, and to Oxford, an object wholly unattainable by the other line. In reply to these assertions, the opponents maintained that although the levels of the Basing and Bath Railway presented greater inclinations than those of the Great Western, yet that they were so balanced as that the rises and falls compensated one for another, so as to render the line practically level. The enunciation of this theory called forth a remark by the chairman that according to this principle the Highlands of Scotland would be as good as any other place for the construction of a railway.

The preamble was voted proved, and the Bill passed the House of Commons without further opposition, and on May 27 was read a first time in the Lords. On June 10, the second reading was carried after a sharp debate, the numbers being 46 contents, and 34 non-contents.

Lord Wharncliffe was chairman of the committee.[43] The proceedings began by an opposition on the standing orders, which, after much skirmishing, were voted to have been complied with. The promoters, however, judged from the nature of the first day’s proceedings, that they had to expect a contest of no inconsiderable duration; and the result proved their anticipations to have been correct. For forty days the battle was fought with a degree of earnestness and vigour on both sides, almost unequalled in any similar proceedings.

The committee soon came to the same decision as the House of Commons, that, with regard to the advisability of a Bristol railway, they were satisfied, and needed no further evidence. The case became then one of mere comparison between the relative merits of the two lines proposed.

The case in support of the Bill occupied eighteen days, and was closed with a speech by the Hon. John Talbot.

Mr. Serjeant Merewether, whom the opponents had chosen as their leader in the House of Lords, was then heard on their behalf, and occupied no less than four days in the delivery of his speech, in which certainly no argument that ingenuity could devise was omitted to strengthen his case. There was hardly any conceivable injury which, according to the learned serjeant’s notions, the Great Western Railway would not inflict. It was said that the Thames would be choked up for want of traffic, the drainage of the country destroyed, and Windsor Castle left unsupplied with water. As for Eton College it would be absolutely and entirely ruined: London would pour forth the most abandoned of its inhabitants to come down by the railway and pollute the minds of the scholars, whilst the boys themselves would take advantage of the short interval of their play hours to run up to town, mix in all the dissipation of London life, and return before their absence could be discovered. Moreover, while the beauty of the country and the retirement of private dwellings would be destroyed, the interests of the public would be far more effectually served by the adoption of the Basing and Bath line, and a line from the London and Birmingham Railway to Gloucester. This was in fact the point at issue, and on this the result of the contest depended. The promoters of the Bill had called, in support of their line, in addition to Mr. Brunel, who being engineer to the company might be considered an interested witness, Mr. Locke, Mr. Palmer, Mr. Price, Mr. George Stephenson, and Mr. Vignoles. They expressed their unqualified approbation of the line chosen by Mr. Brunel, and of the estimates he had prepared.

The preamble was proved, and after an unsuccessful opposition the Bill was read a third time, on August 27. The Royal Assent was given on the last day of that month.[44]

During this contest Mr. Brunel made among his fellow-labourers many deep and lasting friendships. One of the most intimate of these friends, Mr. St. George Burke, Q.C., has, in compliance with a request made to him, furnished the following reminiscences of his intercourse with Mr. Brunel during the progress of the Bill through Parliament.

The following is an extract from Mr. Brunel’s diary, written at the end of the year 1835:—

CHAPTER IV.

RAILWAY WORKS.

A.D. 1835—1859. ÆTATIS 30—54.

IN the extract from Mr. Brunel’s diary given at the close of the last chapter he refers to the successful issue of the contest for the Great Western Railway Act as a very important event in his life.

As the result proved, he did not take too hopeful a view of his future prospects; for from that time to his death he was fully employed as the engineer of railways which, in number and importance, were not inferior to those of any of his contemporaries. Of the main lines he constructed, one extends uninterruptedly from London to the Land’s End, and another to the extremity of South Wales, at Milford Haven, 285 miles from Paddington.

It would be impossible to describe in detail all the engineering works which are to be found on Mr. Brunel’s railways, the aggregate length of which is upwards of 1,200 miles; but in this chapter it is proposed to give a brief sketch of the lines he constructed, omitting all that can be more properly inserted in the three chapters which follow, relating to the broad gauge, to the Atmospheric System, and to the bridges and viaducts.

The Great Western Railway was opened to Maidenhead, a distance of nearly twenty-three miles, in June 1838, and to Twyford, eight miles farther on, in July 1839. A description of the Wharncliffe Viaduct at Hanwell will be found at p. 172, and of the Maidenhead bridge at p. 173.

The line from Twyford to Reading was opened in March 1840, and from Reading to Chippenham by May 1841. Meanwhile the portion from Bristol to Bath had been opened in August 1840. The last division, namely, that from Chippenham to Bath, containing the Box Tunnel, was opened on June 30, 1841; and the railway was completed throughout its whole length.

A considerable part of the history of the Great Western Railway is connected with the adoption on it of the broad, or 7-foot gauge, and will be dealt with in the next chapter, in which is also given some account of the longitudinal system of permanent way.

The bridges are described in Chapter VII.; but some of the other works may be noticed here.

In laying out the line, Mr. Brunel endeavoured to make it as straight and as level as possible throughout, and to concentrate those changes of level, which could not be avoided, into short inclines, to be worked, if necessary, by auxiliary power.

Accordingly the line is thus divided:—

The steep inclines are two in number, of a gradient of 1 in 100, or about 53 feet in a mile, and descend towards the Bristol end of the line.

The Wootton Basset incline, 85½ miles from London, is 1 mile 550 yards long.

The second incline is at Box, 99 miles from London, and is 2 miles 660 yards in length. An assistant engine is still occasionally used to work heavy trains at this point.

On this incline the line passes through the Box Tunnel. This tunnel is the first out of London, and could only have been dispensed with by taking a circuitous route several miles longer than that adopted by Mr. Brunel.

The tunnel is 1⅞ mile in length, and is ventilated by six shafts. They are 30 feet in diameter, and from 70 to 300 feet deep.

The Box Tunnel had been the subject of much criticism before the works were commenced; and during its actual construction it did not escape the unfavourable notice of those who were ignorant of the difficulties which presented themselves, and the means which had been taken to overcome them. Indeed, for some time after the opening of the line, there were travellers who used to avoid the terrors of the tunnel by posting along the turnpike road in that part of their journey.

Mr. Brunel never troubled himself about the ordinary gossip which is always circulated concerning any remarkable work; but matters assumed a different aspect when, a year after the completion of the tunnel, doubts were expressed as to its safety by an eminent geologist, at a meeting of the Institution of Civil Engineers. Mr. Brunel, who was on terms of friendly intercourse with the speaker, addressed to him the following letter:—

Between Chippenham and Bristol the nature of the building stone enabled Mr. Brunel, at moderate cost, to make the bridges, tunnel fronts, and stations ornamental features in the picturesque scenery through which the railway passes.

He took great pleasure in finishing minutely the various designs, and making them correct in their proportions and details. One tunnel front, near Bristol, may be singled out for especial mention. During its construction a part of the ground behind slipped away, and it became unnecessary to complete the top of one of the side walls. It was therefore left unfinished, and was planted with ivy so as to present the appearance of a ruined gateway.

The roofs of the Bath and Bristol stations are of large span, and are handsome architectural structures. They are each in the form of a Tudor arch; the Bristol roof is 72 feet span, and the Bath roof 50 feet span. The framing is an example of a peculiar form of construction, somewhat analogous to that adopted in the large shipbuilding sheds in the dockyards. There are no cross tie-rods, but each principal of the roof is formed of two frameworks, like cranes, meeting in the middle of the roof; the weight being carried on columns near the edge of the platform, and the tail ends of the frames held down by the side walls. As the two frames do not press against each other at their meeting point at the ridge of the roof, there is no outward thrust. The side walls being on a viaduct could not without difficulty have been made to resist a horizontal thrust.

At the Bristol station Mr. Brunel introduced hydraulic machinery for working lifts. By these the waggons were lowered to and raised up from the goods shed, which was placed at the level of the ground, about 12 feet below the railway.

Although the works already described were completed in 1841, the permanent terminus at Paddington was not commenced till the year 1849. It was completed in 1854. Previously to that time a temporary station had been used, the booking offices being under the arches of the Bishop’s Road bridge.

As the level of the railway was lower than that of the surrounding land, no exterior architectural effect could be produced; but Mr. Brunel took this opportunity to carry out his views as to the proper structural use of metal in works of this description.

In the design of the ornamental details, he obtained the assistance of Mr. (now Sir Matthew) Digby Wyatt.

The interior of the principal part of the station is 700 feet long and 238 feet wide, divided in its width by two rows of columns into three spans of 68, 102, and 68 feet, and is crossed at two points by transepts 50 feet wide, which give space for large traversing frames. The roof is very light, consisting of wrought-iron arched ribs, covered partly with corrugated iron and partly with the Paxton glass roofing, which Mr. Brunel here adopted to a considerable extent. The columns which carry the roof are very strongly bolted down to large masses of concrete, to enable them to resist sideways pressure.

This station may be considered to hold its own in comparison with the gigantic structures which have since been built, as well as with older stations. The appearance of size it presents is due far more to the proportions of the design than to actual largeness of dimension. The spans of the roof give a very convenient subdivision for a large terminal station, dispensing with numerous supporting columns and at the same time avoiding heavy and expensive trusses. The graceful forms of the Paddington station, the absence of incongruous ornament and useless buildings, may be appealed to as a striking instance of Mr. Brunel’s taste in architecture and of his practice of combining beauty of design with economy of construction.

The goods station was erected at about the same time as the passenger station, and is remarkable for the completeness of its arrangements, and for the great use made of hydraulic machinery. This is also applied in the passenger station.[45]

In connection with the Paddington station mention may be made of the Great Western Hotel, which was built at the extremity of the land belonging to the railway company.

When, in 1854, no tenant could be found for it, a few of the shareholders of the Great Western Railway, being unwilling that the building should remain empty and be a loss to the proprietors, formed themselves into a company to lease and work the hotel. Mr. Brunel became a Director, and shortly afterwards (in December 1855) the chairman. He occupied this post till his death, by which time the hotel had become very prosperous. He found attendance at the meetings of the Directors and the supervision of the management of the hotel a very agreeable relaxation from the more important duties which took him to Paddington.

The branches and extensions of the Great Western Railway, as far as their history affected the general interests of the company, are referred to in the chapter on the broad gauge. Branches were opened to Oxford in 1844, to Windsor in 1849, to Wycombe in 1854, to Uxbridge in 1856, to Henley in 1857, and to Brentford in July 1859.

The Bristol and Exeter Railway is a continuation of the Great Western Railway, and was opened to Exeter in 1844. The two portions of it, from Bristol to Taunton, and from Taunton to Exeter, are in marked contrast to each other. The former part of the line is almost level, and has very easy curves. Between Taunton and Exeter it passes over the high ground on the borders of Devonshire, with the Whiteball Tunnel at the summit, ⅝ mile in length. On this part of the line there are long gradients of from 1 in 80 to 1 in 120. Mr. Brunel resigned the position of engineer in 1846, in consequence of differences having arisen between the Bristol and Exeter and the Great Western Companies, which, in Mr. Brunel’s opinion, made it impossible for him to continue engineer to both railways.

The South Devon Railway, and the adoption on it of the Atmospheric System, are described in Chapter VI. In connection with this line is the important Torquay branch, and the railway in continuation of it to Dartmouth. This was completed as far as Paignton during Mr. Brunel’s lifetime.

The South Devon and Tavistock Railway branches off from the South Devon Railway near Plymouth, and has several large viaducts.

On the Cornwall Railway from Plymouth to Truro, and the West Cornwall Railway from Truro to Penzance, the most remarkable works are the viaducts, and the Royal Albert Bridge.

In the case of the Cornwall Railway, it became necessary to reduce the capital expenditure, even at the cost of increasing the charges for maintenance. With this object the line was re-examined and modifications introduced, principally by an increase in the extent of viaduct. These lines pass through a very difficult country; involving the adoption of steep gradients and sharp curves. Mr. Brunel, in a memorandum written in 1845, after having explained his reasons for considering that the prejudicial effects of gradients and curves were commonly overrated, gives the following opinion in reference to the proposed Cornwall Railway:—

The principal lines branching off from the Great Western, and since incorporated with it, are, on the south, the Berks and Hants, from Reading to Basingstoke and Hungerford; and the Wilts and Somerset, to Weymouth and Salisbury. On the north-west is the Cheltenham and Great Western Union Railway, from Swindon to Cheltenham and Gloucester. This line passes through the Cotswold Hills at Sapperton by a tunnel 1⅜ mile in length. The Gloucester and Dean Forest Railway runs from Gloucester to Grange Court, and thence to Ross and Hereford.

The South Wales Railway, which extends from Grange Court to Milford Haven, contains a tunnel at Swansea ⅓ mile long, and some of Mr. Brunel’s most important works, including the Chepstow bridge and several other bridges of considerable size, and the viaducts at Landore and Newport. There are also on this line four opening bridges across navigable channels. The works at the termination of the line at Neyland, in Milford Haven, are described in Chapter XIV. Mr. Brunel considered that Milford Haven, with its excellent harbour, which can be entered at all times of tide by the largest vessels, would probably become a great port for ocean steamers, and especially for the ‘Great Eastern’ and ships of her class.

There are also in South Wales the following railways: the Taff Vale, the Vale of Neath, the Llynvi Valley, and the South Wales Mineral. The Taff Vale, a line from Cardiff to Merthyr, was opened on the narrow gauge in 1841.[46] On this railway is the lofty masonry viaduct at Quaker’s Yard.

On the Vale of Neath Railway, from Neath to Aberdare and Merthyr, there is a tunnel, near Merthyr, 1¼ mile long, and 650 feet below the summit of the hill.

Full advantage is taken on this railway of the facilities which the broad gauge offers for heavy traffic. The line has long steep gradients, and the locomotives used on it, of the class known as tank engines, are of great power. One of these gradients is 4½ miles long, with an inclination of 1 in 50. Large quantities of coal are brought down by this railway to the Swansea and Briton Ferry Docks. The coal of South Wales is of a friable nature, and, in order to avoid the breakage consequent on the ordinary mode of shipping coal, by tipping it down a shoot, Mr. Brunel introduced on a large scale the use of trucks carrying four iron boxes, each box about 4 feet 8 inches cube, and containing two and a half tons of coal. At the docks machinery is provided by which each box is lowered down into the hold of the ship, and the under side being allowed to open, the coal is deposited at once on the bottom of the vessel.

The Llynvi Valley Railway is a short line, leading from the South Wales Railway at Bridgend into the coal and iron districts.

The South Wales Mineral Railway is another line of the same class. It passes through a very heavy country, and has on it a self-acting incline of 1 in 9, ¾ mile long, worked by a rope, and a tunnel ⅝ mile long, and 470 feet below the surface.

In connection with the South Wales district is the Bristol and South Wales Union Railway, a line running from Bristol to the banks of the Severn, across which the traffic is carried by a steamer to a short branch from the South Wales Railway on the other side. This railway had been for a long time contemplated, and Mr. Brunel devoted much time to a careful investigation of the Severn in order to determine the most suitable point for the crossing. He decided that the best place would be at what is known as the New Passage. The arrangements had to be made in accordance with the requirements of the Admiralty. Trains run to the end of timber piers extending into deep water, and there are staircases and lifts leading to pontoons, alongside which a steamer can come at all times of tide. The tide at this part of the Severn rises 46 feet.

The three railways last mentioned were not completed during Mr. Brunel’s lifetime.

The Bristol and Gloucester Railway, on which is the tunnel at Wickwar, ¾ mile long, was opened in 1844, and passed into the hands of the Midland Company in 1846.

The northern extensions of the Great Western Railway are the Oxford and Rugby, constructed as far as Fenny Compton; the Birmingham and Oxford Junction; and the Oxford, Worcester, and Wolverhampton Railways.

Mr. Brunel ceased to be engineer of the last-mentioned company in 1851, and the works were completed by Mr. Fowler. The Oxford, Worcester, and Wolverhampton line has since, under the title of the West Midland, become a part of the Great Western Railway.

In Ireland Mr. Brunel was engineer of the line from Dublin to Wicklow, round Bray Head, and of a line from Cork to Youghal.

He laid out two railways in Italy, the line from Florence to Pistoja, and that across the Apennines from Genoa to Novi and Alessandria, in the direction of Turin and Milan. He acted as engineer during the construction of the former line; but the works of the latter were carried out by the Sardinian Government.

One of the last of Mr. Brunel’s important railways was the Eastern Bengal Railway, a line of about 100 miles in length, in a north-easterly direction from Calcutta. He took a great interest in the work and devoted much time to the special arrangements and designs, and to the best way of crossing the Ganges and its branches in the future extension of the railway; but no part of it was opened during his lifetime.

It was impossible for Mr. Brunel to look after all his works to the same extent as he had done in the case of the Great Western Railway; and he was compelled to spend a very considerable amount of time in attendance on Committees of the Houses of Parliament on behalf of the railways to which he was engineer. Mr. Brunel frequently regretted this, and considered it a great evil that engineers were prevented by their duties during the session from attending properly to the construction of their works. He endeavoured as far as possible to superintend the execution of his different undertakings. He availed himself of every opportunity of examining them, and was acquainted throughout with all the designs which were prepared. He would take advantage of two or three free days to go down to the distant works in South Wales or in Cornwall, looking after details, such as the pickling tanks for timber, and the masonry of the viaducts.

He was fortunate in the selection of the members of his staff, and in his organisation of it. He had a rare power of utilising the capabilities of his different assistants; and although he had to deal with a great variety of men, he managed that they should work in harmony with him. From the complete personal supervision Mr. Brunel sought to maintain over all his works, his assistants had not perhaps so many opportunities of independent action as they might otherwise have obtained, but they had, on the other hand, the advantage of constant personal communication with their chief.

After the time when Mr. Brunel’s works became so numerous, and his time so much occupied, that he could not exercise in person that general supervision which he conceived to be necessary, he was ably assisted by Mr. Robert Pearson Brereton, who, on the death of Mr. Hammond in 1847, became the chief of his engineering staff.

Mr. Brunel rarely made any changes in the personnel of his office. Mr. Brereton had become one of his assistants in 1836; and his secretary, the late Mr. Joseph Bennett, came to him in the same year.

The Great Western Railway retained its early place in his affections, and among his most valued friends were members of the Board of Directors, Mr. Saunders the Secretary, and other officers of the company. When in the last year of his life he was obliged to go to Egypt for his health, it was a matter of deep anxiety to him lest his absence from England should cause any alteration in his relations with the Company, and it was a source of great pleasure to him that no such consequences followed.

Mr. Brunel’s position as confidential adviser of so large a number of railway companies gave him frequent opportunities of acting as mediator between contending parties; and his decisions were always received with respect, for he was known to be scrupulously just.

Besides the more friendly task of reconciling opponents he had a large practice as a referee under Acts of Parliament and orders of the superior courts; and displayed in these matters great judicial abilities.

In all the causes and parliamentary contests affecting the various companies of which he was engineer, Mr. Brunel was a very important member of the preliminary consultations, and during the proceedings counsel relied with confidence on his suggestions.

One of the most arduous parts of his duty, as engineer of the Great Western Railway Company, was connected with the conduct of the great cases of Ranger and MacIntosh. To the former of these reference is made in the letter printed below, at p. 478. The MacIntosh case, which was commenced shortly after the opening of the line, was not concluded before Mr. Brunel’s death. He was compelled to devote a considerable portion of his time to it, even after his return home in the evening, during the launch of the ‘Great Eastern.’

Mr. Brunel had a very high reputation as a witness. Mr. St. George Burke, Q.C., has communicated a memorandum on this subject.

The following memorandum from Mr. George T. Clark, of Dowlais, formerly one of Mr. Brunel’s assistants, contains his recollections of Mr. Brunel during the construction of the Great Western Railway:—

In the press of work and the altered circumstances under which he superintended the construction of his later railways, many changes inevitably followed. The open britzska gave place to a close travelling carriage, which in its turn became useless; and no time was left for fun or practical jokes; but the same energy of mind and the same kindliness of heart remained uninfluenced by increasing occupations or advancing years.

CHAPTER V.

THE BROAD GAUGE.

THE railways designed by Mr. Brunel were, with a few exceptions, distinguished from those in all other parts of England by a peculiarity in the width between the two rails forming each line of way, or in what is called the gauge. In most railways, the distance between the internal edges of the rails is 4 feet 8½ inches, being what is termed the narrow gauge; on Mr. Brunel’s railways, it was seven feet, or what is termed the broad gauge.

The gauge of the earlier railways, which were but a modification of the old wooden tramway, was made that of the tram plates which they superseded; and this had been originally fixed to suit the distance between the wheels of the country carts in the north of England.

When Mr. George Stephenson introduced the locomotive engine, the gauge of the lines in the Northumberland district had been already fixed. In laying out the Stockton and Darlington line (1821-1825) he saw no reason to depart from the gauge he had previously adopted; and, indeed, some of the waggons to be used on this line were brought from the Northumberland collieries. In this way the first important railway in England was made with the gauge of 4 feet 8½ inches; not from a deliberate choice of this width on the ground of any peculiar advantages, but from the mere fact of its already being established elsewhere.

In the construction of the Manchester and Liverpool Railway, in 1826, the same gauge was adopted as on the Stockton and Darlington; this course was also followed by the Grand Junction and the London and Birmingham Railways, and thus the 4 feet 8½ inches gauge became established in that part of the country.

Long experience appears to have determined the general type of wheeled vehicles: the wheels being of somewhat large size, and the body placed between them, so as to come down close upon the axle-tree.

This type, which gives obvious advantages in a mechanical point of view, appears to have been adhered to in all railway vehicles used before the opening of the Liverpool and Manchester Railway; these, however, were chiefly coal-waggons. But on the Liverpool and Manchester Railway it was soon perceived that the great increase of carrying power which the railway afforded must be met by a corresponding increase of space in the rolling stock, as it was necessary to accommodate light bulky goods and passenger traffic. The available width between the wheels was limited to about 4 feet 6 inches, and to carry in this width any large amount of cotton goods, or of passengers, would have required a train of an inordinate length. To meet this difficulty a new form of vehicle was designed; the wheels were made small, and the body was raised and widened out, projecting on either side over the tops of the wheels.

The earliest description of this form of waggon is contained in the second edition of Wood’s ‘Practical Treatise on Railroads,’ published in 1832, about two years after the opening of the Liverpool and Manchester Railway. In Plate III., Mr. Wood shows a truck with a raised platform overhanging the wheels, and adapted for carrying loose boxes of coals; adding, in the description:

Such was the state of matters when, in the year 1833, Mr. Brunel was appointed Engineer of the Great Western Railway. With the view of leaving the question of gauge open for future consideration, he procured the omission in the Great Western Act of a clause defining it. He came to the conclusion that it would be desirable to adopt a wider gauge, and he recommended this measure to the Directors in a report dated October 1835.[47]

In October 1836 a Royal Commission, consisting of Mr. Drummond, Under-Secretary for Ireland, Mr. R. Griffith, Colonel (now Field-Marshal) Sir John Burgoyne, R.E., and Professor Barlow, of Woolwich, was appointed to report on the establishment of railways in Ireland. They considered carefully the question of gauge, and their arguments in favour of an increase in the gauge were afterwards stated by Mr. Brunel to be identical with his own.

They drew attention to the advantage of large wheels, the use of which would be facilitated by a wider gauge; and they thought it a matter of importance to be able to place the bodies of the carriages between the wheels, instead of over them.

It was the width of the carriages, and not the distance between the rails, that determined the general dimensions, and therefore the cost, of the works of a railway. Mr. Brunel saw many advantages to be gained by an increase in the gauge, even while retaining the existing dimensions of carriages; and he thought it unwise at the commencement of a work of such magnitude as the Great Western Railway to retain a limit the inconvenience of which had already become apparent.

He says, in his evidence before the Gauge Commission:

The width between the rails being the fundamental dimension of ‘the whole machine,’ on which its entire development must depend, Mr. Brunel proposed to begin by the enlargement of this dimension, and recommended that on the Great Western Railway the gauge should be seven feet. He considered that the whole of the parts of the railway and of its rolling stock would be susceptible of continual, though gradual improvement, and that it was highly advisable to remove, in the outset, a great obstacle in the way of this progress.

He did not in the first instance propose any important change in the details as consequent on the wider gauge; and in regard to one of the principal points, the diameter of the wheels, he said:—

Mr. Brunel also looked forward to the advantages which a wider gauge would give for the construction of the locomotive engines. Difficulties had been already experienced from the limited width between the wheels, which cramped the machinery, rendering it difficult of access for repairs; it also limited the size of the boiler and fire-box, on which the power depended. For this reason Mr. Brunel considered that a wider gauge would present great advantages, as it would allow the locomotives to be constructed of greater power, and with their machinery arranged in a more advantageous manner. He also thought that the greater width of base for the carriages would give increased steadiness and smoothness of motion, with greater safety, particularly at high speeds, and that there would be the advantage of being able to use larger wheels for the carriages. Moreover, he had in view the possibility which the broad gauge would give of adopting wheels of a still larger diameter without raising the centre of gravity, the body of the carriage being placed between them, as in the original type of common road vehicles.

The broad gauge was also considered by Mr. Brunel in prominent connection with the peculiarly favourable circumstances of the Great Western line, in regard to its gradients and curves. He thought that ‘it would not have been embracing all the benefits derivable from the gradients of the Great Western Railway, unless a more extended gauge was adopted.’ In the first place, it was evident that a diminution of the frictional resistance would present the greatest advantage where the gradients were flat. In regard to curves, the wider gauge was at that time considered by him to be more advantageously applied where the curves were of large radius than where they were sharp.[48] On the Great Western Railway both gradients and curves were remarkably good; with the exception of two inclines of 1 in 100, on which auxiliary power was proposed to be used, there was no gradient between London and Bristol steeper than 1 in 660, the greater part of the line being nearly level, and except between Bath and Bristol there was no curve sharper than about one mile radius.

For these reasons Mr. Brunel thought that unusually high speed might easily be attained for passengers, and great tractive power for goods. He said:—

In deciding that the distance between the rails should be seven feet, Mr. Brunel seems to have been guided by the principle that the wheels should be put sufficiently far apart to admit of an ordinary carriage body being placed between them.[49]

Mr. Brunel did not anticipate that the difference between the gauge he proposed and that of other railways would lead to any important inconvenience. The views he held on this subject were expressed fully by him in a report of December 13, 1838. He says, speaking of the difficulty of communication between the Great Western and other railways:—

Mr. Brunel was not singular in holding the opinion that it would be desirable to allot a given district to one railway, which might conveniently serve it by means of a trunk line and branches of a special gauge. In the Eastern Counties line, designed in 1836, by Mr. Braithwaite, and opened in 1839, a gauge of 5 feet was adopted; and Mr. Robert Stephenson, as engineer of another line, the Northern and Eastern Railway, branching out from the Eastern Counties to the northward, adopted the same gauge. It was not till the Northern and Eastern line was extended, some years afterwards, that the rails of the whole system were altered to the narrow gauge.

Mr. Brunel’s recommendation was adopted by the Directors of the Great Western Railway; and, in their report of August 25, 1836, after observing that the generally level character of the line would greatly facilitate the attainment of a higher speed of travelling, they pointed out the advantages of the broad gauge, and stated that engines had been ordered specially adapted to the nature of the line, which would be capable of attaining with facility a rate of from thirty-five to forty miles per hour.

The line was opened between Paddington and Maidenhead on June 4, 1838, and the performance of the engines was considered satisfactory, trains of eighty tons and upwards being drawn at speeds of from thirty-eight to forty miles per hour.

Notwithstanding these favourable results, the change in regard to the gauge did not pass unquestioned. Attacks were made on it in various quarters, and considerable excitement was caused among the shareholders and the public.

It was asserted that the width of 4 feet 8½ inches was exactly the proper width for all railways, and that a deviation from it was tantamount to the abandonment of an established principle which experience had proved to be correct. It was further alleged that the cost of all the works connected with the formation of the line would be greatly increased; that the carriages must be stronger and heavier, that they would not run round the curves, and would be liable to run off the rails, and particularly that the increased length of the axles would render them liable to be broken. These were not advanced as difficulties which, existing in all railways, might be somewhat increased by the increase of gauge, but they were assumed to be peculiar to the broad gauge, and fatal to it. Some urgent representations appear to have been made to the Directors; for in their report of August 15, 1838, they state, that as the gauge and the permanent way, which had also been the subject of adverse criticism, had been sources of some anxiety to them, they had applied to three of the most eminent authorities on the construction and working of railways—Mr. James Walker, President of the Institution of Civil Engineers, Mr. Robert Stephenson, and Mr. Nicholas Wood, of Newcastle-on-Tyne—to undertake a thorough inspection of the line, to investigate the working of it, and to give their opinion on the plan adopted.

Mr. Walker and Mr. Stephenson declined the task, on the ground that they did not wish to become embroiled in professional controversy, but Mr. Wood undertook it; and a similar commission was afterwards given to Mr. Hawkshaw.

In order to put the shareholders fully in possession of all the information in their power, the Directors published a very complete statement by Mr. Brunel on the arrangements adopted by him. It will be seen that in this report, which is given in Appendix I. p. 525, he states his original arguments, and answers the objections brought against his plans; and he contends that the result of experience establishes their success. In regard to the gauge, he says:—

But the two engineers, to whom the consideration of this matter had been referred, differed materially in opinion from Mr. Brunel. The nature of their investigations and reports, and of Mr. Brunel’s replies, is stated in the extracts given below from the report of the Directors in January 1839.

In addition to the question of gauge, another important matter referred to the consideration of Mr. Wood and Mr. Hawkshaw was the construction of the permanent way.[50] On the Great Western a construction had been introduced by Mr. Brunel differing materially from that ordinarily used; and as defects had shown themselves after the opening of the railway, some anxiety was felt in reference to it by many of the shareholders.

The subject of the permanent way adopted on the Great Western Railway does not necessarily belong to the gauge question, and would, perhaps, have been more properly considered in the chapter on Mr. Brunel’s railway works; but, as a matter of fact, the controversy concerning it became so interwoven with that of the broad gauge, that in a historical account it would be difficult to separate them.

It appeared to Mr. Brunel that, with a view of applying the engine power to the greatest advantage, particularly in attaining high speed, more attention ought to be paid to the construction of the permanent way. He says, in a report dated February 1837:—

With a view to improvement on this point, Mr. Brunel considered it would be advantageous if two important changes were made. He proposed, in the first place, to abolish the use of stone blocks for the rails to rest on, and to substitute timber; and, secondly, to apply the support uniformly and continuously along the whole length of the rails, instead of only at intervals.

The first of these changes, namely, the substitution of timber for stone, was not wholly new, for transverse wood sleepers were often used in exceptional situations; but it was the general opinion that stone, where it could be applied, formed the best support for the rails,[51] and the exclusive employment of timber was considered a great innovation.

The other principle, that of ‘continuous bearing,’ was similar to that of the old wooden and stone tramways; and, even as applied to iron rails it had been extensively used before, as Mr. Brunel mentions in his report of August 1838 (see Appendix I. p. 535.)

Mr. Brunel designed for this continuous bearing a peculiar shape of rail, which, from the form of its section, acquired the name of the ‘bridge rail.’ The rail was bolted down to the longitudinal timbers, and the timbers of the two rails were connected together at intervals by cross-pieces, called transoms, bolted to them; these served to keep the two rails at a proper distance apart. The longitudinal timbers lay on gravel or other ‘ballast,’ which had been found to form the best foundation, as being firm and solid, easy of adjustment, and allowing free drainage.[52]

Mr. Brunel, however, thought there would be difficulty in giving the longitudinal baulks a sufficiently solid bearing on the gravel below them.

A similar difficulty had already been experienced with the heavy stone blocks used on other railways. As a remedy for this, Mr. Stephenson caused each block to be lifted and dropped several times on its place, so as to consolidate the ballast below.

The same thing could not be done with a long wooden baulk, and Mr. Brunel therefore contrived another mode of overcoming the difficulty. Piles were driven into the ground between the rails, and their heads bolted to the cross-transoms, the object being to hold the timber framework firmly down. The gravel was then rammed hard under the longitudinal baulks, to give the consolidation desired. The result, however, of this mode of construction was far from successful, and the state of the road, when run over by the trains, was in many places very defective.[53]

In the course of his enquiry Mr. Wood tried a large number of experiments on the Great Western and other lines. He was of opinion that stone blocks afforded a permanently firmer base, and so caused less resistance to the train, but that there was less noise with continuous timber bearings, and that they gave a smoother and a more perfect road for high rates of speed. He thought, however, that the piles were objectionable, and that the weight of the trains would in the course of time sufficiently consolidate the foundation. Mr. Brunel accepted Mr. Wood’s conclusions and abandoned the piling, adopting at the same time larger timbers and heavier rails.

The experience of the permanent way, as thus altered, fully justified the favourable anticipations Mr. Brunel had formed of the continuous timber bearing.[54]

After the reports of Mr. Wood and Mr. Hawkshaw, with Mr. Brunel’s replies to them, had been circulated among the shareholders, a special general meeting was called in London, to receive and consider these documents. It was convened for December 20, 1838, but was adjourned till January 9, 1839. This meeting was of great importance, not only to the Company, but to Mr. Brunel personally, as on the resolutions to be passed depended whether or not his plans should be proceeded with.

He had, however, the warm support of the Directors, as will appear from the following extracts from their report.

The views of the Directors were approved of by the majority of the shareholders (the numbers being 7,792 for, and 6,145 against); and the construction of the line was proceeded with according to Mr. Brunel’s plans.

By June 30, 1841, the whole length of the Great Western Railway was opened from London to Bristol. Some of the Directors’ reports mention the fact that the speed uniformly maintained by the engines much exceeded the ordinary rate of railway travelling, and allude to the ‘general testimony borne to the smoothness and comfort of the line and carriages.’

As has been before mentioned, extensions and branches on the same gauge, to all of which Mr. Brunel was engineer, were projected and ultimately carried out, in accordance with the original scheme of the undertaking, to Exeter, Plymouth, and Cornwall, and to Gloucester, Hereford, and South Wales, as well as to Oxford, Windsor, and other towns in the immediate neighbourhood of the line.

About 1844, the attention of the Company began to be directed to projects involving extensions of a much more serious character, and which were destined to have a powerful influence on the position of the gauge question. During the railway mania, the Great Western Company found it impossible to stand aloof from the contests which were going on around them, and thought it necessary, in order to protect their own interests, to extend their lines beyond the district to which they had originally intended to confine themselves.

At the general meeting in August, an extension from Oxford to Rugby was determined on, as ‘of the greatest importance to the Great Western line.’ About the same time a broad-gauge line was promoted from Oxford to Worcester, and thence by Kidderminster and Dudley to Wolverhampton, in order to open an immediate communication with the Staffordshire and Worcestershire districts. There were also rival projects on the narrow gauge, promoted by the London and Birmingham Company; and the competing plans were referred, as was the custom at that time, for the examination of the Railway Department of the Board of Trade.

In regard to the communication from north to south, through Oxford, the question was, where the break of gauge should be.[56] The Board of Trade saw nothing in the relative merits of the gauges to determine this question, and from commercial considerations, they recommended that the change of gauge should be made at Oxford. On this and other grounds they considered that the narrow gauge schemes to the north of Oxford were preferable to those of the Great Western Railway.

The rival schemes then went before Parliament, and after a protracted enquiry, obstinately fought between the parties, the decision was given in favour of the Great Western lines, contrary to the recommendation of the Board of Trade. It was, however, stated by the chairman of the Commons Committee that the decision had been founded on the local and general merits of the respective lines, without any reference to the comparative merits of the two gauges. On this account some peculiar provisions were made in the Acts; for though the lines were sanctioned on the broad gauge, the proprietors were bound also to lay down narrow gauge rails upon them, if required to do so by the Board of Trade. At the same time the House of Commons, on the motion of Mr. Cobden, passed a Resolution praying her Majesty to refer the gauge question to a Royal Commission.

A Commission was issued in July; the Commissioners being three in number—Sir J. M. Frederic Smith, R.E.; Mr. G. B. Airy, Astronomer Royal; and Professor Barlow, of the Royal Military Academy, Woolwich. They took a large amount of evidence, both oral and documentary, and made some examinations of the working of the two gauges. Their report was presented to Parliament early in the session of 1846.

Of forty-eight witnesses, thirty-five were advocates of the narrow gauge; and against these were arrayed but four champions of the broad gauge, all officers of the Great Western Railway:—Mr. Charles Alexander Saunders, the secretary; Mr. Seymour Clarke, the traffic superintendent; Mr. (now Sir Daniel) Gooch, the locomotive superintendent; and Mr. Brunel.

The report was of considerable length, and in it the Commissioners addressed themselves to three heads of enquiry, viz.:—

1. Whether the break of gauge was an inconvenience of so much importance as to demand the interference of the legislature.

2. What means could be adopted for obviating or mitigating such inconvenience.

3. Considerations on the general policy of establishing a uniformity of gauge throughout the country.

The general conclusions arrived at on these points were thus summed up by the Commissioners:—

Guided by the foregoing considerations, the Commissioners recommended that 4 feet 8½ inches should be fixed by law as the standard gauge of the country; and that as to the existing broad gauge lines, either they should be altered to the narrow gauge, or some course adopted which would admit of narrow gauge carriages passing along them.[57]

This adverse report was a great surprise to the supporters of the broad gauge system, as rumours had led them to hope for a different result. Immediately after its appearance, several documents were published, containing powerful and severe strictures on the proceedings and opinions of the Commissioners. The most important of these was written by Mr. Saunders, Mr. Daniel Gooch, and Mr. Brunel. It occupied fifty closely printed folio pages, and was entitled, ‘Observations on the Report of the Gauge Commissioners, presented to Parliament.’ To this, ‘Supplemental Observations’ were added, after the publication of the Evidence and the Appendix to the Report.

In the conclusion of the ‘Observations’ the writers gave a summary of the points they considered to have been proved in the controversy, namely—

That the question of ‘break of gauge’ originated as a cloak to a monopoly.

That even if the gauge were uniform, through trains would be impracticable.

That the transfer would be of little inconvenience.

That any advantage of small waggons was applicable to the broad gauge, but that the advantage of large waggons was not applicable to the narrow.

That the competition between the two systems was advantageous.

That the final recommendations of the Commissioners were at variance with their separate conclusions.

That it would be unjust to refuse to allow the broad gauge to be laid down on lines for which it was already sanctioned by Parliament.

That the enquiry before the Commissioners was not properly conducted, and that consequently no legislation ought to be founded on it.

That the data published by the Commissioners were often wrong, and in some cases led to the reverse of their conclusions.

That greater economy was proved on the broad gauge.

That the broad gauge was superior in the points of safety, speed, and conveyance of troops.

That the experiments made in the presence of the Commissioners had demonstrated beyond all controversy the complete success of the broad-gauge system.

For these and other reasons, a strong protest was made against any legislative interference with the broad-gauge system.

A reply was published to these arguments; and during the controversy a large number of pamphlets, articles, and other publications appeared on both sides.

Mr. Brunel’s views on the whole question, about this time, are concisely expressed in the following letter, written to a friend in France, who asked for information on the subject of the broad gauge:—

The report of the Gauge Commission, on being presented to Parliament, was referred by the House of Commons to the Board of Trade, who reported on it in June 1846. They did not, however, concur with the Commissioners to the full extent of their recommendations; for, while admitting the break of gauge to be an evil, they could not, having regard to the circumstances under which the broad gauge companies had been established, and the interest they had acquired, recommend either that the broad gauge should be reduced to narrow, or that rails should be laid down for narrow gauge traffic over all their lines. Such measures would involve great expense, and they were unable to suggest any equitable mode of meeting it.

This conclusion necessarily affected the opinion of the Board of Trade in regard to the several lines under construction connected with the Great Western Railway, which the Board recommended should be all made on the broad gauge.

In regard to the broad-gauge lines sanctioned by Parliament from Oxford to Rugby, and from Oxford to Worcester and Wolverhampton, the Board determined to exercise their powers in requiring the narrow gauge to be laid down, in addition to the broad.

The House of Commons adopted the recommendations of the Board of Trade, and passed a series of resolutions in conformity thereto, and ‘An Act for regulating the Gauge of Railways’ received the Royal Assent on August 18, 1846.

It was enacted that it should not be lawful to construct any new passenger railway on any other gauge than 4 feet 8½ inches in England, and 5 feet 3 inches in Ireland.

Exceptions, however, were made in favour of certain lines in the west of England and South Wales.

The provisions relating to the gauge in the Acts for the Oxford and Rugby, and the Oxford, Worcester, and Wolverhampton Railways, were left in force.

The Act also generally excepted ‘any railway constructed or to be constructed under the provisions of any present or future Act containing any special enactment defining the gauge or gauges of such railway or any part thereof.’

This Act, while it professed to establish the narrow gauge as the standard throughout the kingdom, did so only nominally; in reality, by the words ‘present or future,’ in the passage above quoted, it left the question of the gauge of any new railway open for the consideration of the committee on the particular bill; and it only obliged the promoters of the undertaking to adopt the narrow gauge when no case could be proved by them for the adoption of some other. This was equivalent to the former state of things, so that all the agitation of the question had ended in a mere expression of opinion, and the broad-gauge party were not only left with all their former liberty, but were encouraged, and almost compelled, to push their system still farther wherever they could.

About the time of the passing of the Gauge Act, a Board of Commissioners of Railways was established, to whom the powers formerly possessed by the Board of Trade were transferred.

One of the first duties of the Commissioners was to provide for the due compliance with the order of the Board of Trade respecting the introduction of the narrow gauge, in conjunction with the broad, on the Oxford and Rugby Railway.

It was proposed to effect this either by laying a narrow gauge line concentrically between the two rails of the broad gauge, or by laying down only one additional rail between the two broad-gauge rails, making one of the latter serve for both broad and narrow gauges. Mr. Brunel recommended the second of these plans to be adopted on the Oxford and Rugby line.

After a careful consideration of the question, the Commissioners sanctioned the mixed gauge formed by the introduction of a third rail; this was accordingly laid down, and none of the dangers which were at the time prognosticated in reference to it were found to exist. It has been the plan almost exclusively used in the many cases where the combination of the two gauges has been required.

In 1846 the Great Western Railway Company had promoted a bill for a branch to Birmingham from the Oxford and Rugby line at Fenny Compton. The Act was obtained, but they were defeated on the question of the gauge. However, after the passing of the Gauge Act, the Company again attempted to carry the broad gauge to Birmingham. Their application was backed by a strong memorial from the districts interested, and in June 1847 an order was passed by the House of Lords directing the Board of Commissioners of Railways—

This, of course, opened up again the whole question of the comparative merits of the two gauges.

The Railway Commissioners issued a series of queries addressed to the officials of the Great Western and the London and North Western Railway Companies, and others. On the part of the Great Western, answers were given by Mr. Brunel and Mr. Daniel Gooch. Mr. Gooch also furnished the results, with tables and diagrams, of a very comprehensive series of dynamometrical experiments, made by him on a mile of straight and level line on the Bristol and Exeter Railway. These experiments fully demonstrated the advantages of the broad gauge, and are still the chief authority on train resistances.[58]

In their report the Commissioners adopted the opinion of the Gauge Commissioners ‘that a break of gauge was a most serious impediment in the transport of merchandise, and that the broad gauge did not offer any compensating advantage so far as that description of traffic was concerned.’ In regard, however, to passenger traffic, they found a case for further enquiry. They said—

They assumed that the greater speed was due to greater engine power, and they admitted that the increase of gauge allowed of an increase in the size and power of the locomotive. They arrived at the result that the broad-gauge engine ‘can draw on a level an ordinary ‘passenger train of 60 tons with as much facility at ‘sixty miles an hour as the narrow-gauge engines can at ‘fifty,’ the advantage, however, diminishing with steep gradients. In their report the following passages are to be found:—

The report of the Railway Commissioners was presented in May 1848. Their decision was ratified by the passing of an Act in the same session for extending the broad gauge from Oxford to Birmingham; and the line was opened in October 1852.

Beyond Birmingham the Great Western Company purchased existing railways leading through Wolverhampton and Shrewsbury to Chester, and obtained access to Birkenhead and Manchester. It thus secured a communication with the great Lancashire towns and the manufacturing districts.

But all the lines north of Wolverhampton had been constructed on the narrow gauge, and therefore, unless the broad gauge had been laid down on these lines, there was a break of gauge between the northern districts and London.

The break of gauge was found to be a much more serious evil than had been anticipated by the Great Western Company when they were fighting their great battle in 1845. For passengers the inconvenience was unimportant; but for the goods traffic between the manufacturing towns and London it was serious, partly on account of the expense, but more especially in consequence of the loss of time. The delay of some hours by change of waggons, where great competition existed, was fatal.

For these reasons the abolition of the break of gauge became desirable. The number of narrow-gauge lines had by the year 1861 been so increased that there was no longer any hope of advantageously extending the broad gauge in the north. Therefore the mixed gauge was completed to London.

After the establishment of the narrow-gauge communication on the northern lines of the Great Western, and its prolongation to London, there was but little inducement to use the broad gauge north of Didcot.

So far as it extended, the broad gauge had exhibited in a marked degree the advantages Mr. Brunel claimed for it, and which were neither few nor unimportant.

It may be desirable before concluding this chapter to sum up those advantages:—

1. It gave the power of constructing more powerful engines, by which greater speed for passenger trains and greater tractive power for heavy goods trains were obtained.[60]

2. It gave more space for the convenient arrangement and beneficial proportions of the machinery, as well as for convenient access to it. In all these points difficulties had been found on the narrow gauge; and the compulsory restriction of so important a dimension as the width between the rails has been a bar to any improvements of great magnitude or comprehensive nature.

3. It gave, even with the overhanging carriage, the facility for obtaining large wheels, and consequently diminishing the axle friction without sacrifice of stability.

4. The greater width of base for the carriages to rest on gave increased steadiness and smoothness of motion, particularly at high speeds. It was the impulse given by the increase of speed and comfort obtained without difficulty on the broad gauge, which had led to the chief improvements introduced in railway travelling.

5. Greater safety was secured, particularly at high speed, from the greater stability of position due to the wider base, producing increased steadiness and diminishing the chance under exceptional circumstances of the derangement of any part of the train.

6. While the broad gauge was but little more costly than the narrow, the width of the works being determined not by the width of the rails, but by the width of the carriages, and the extra cost of rolling stock being very small,[61] the broad gauge could be worked more economically under parallel circumstances than the narrow.

7. It gave the facility of using broader vehicles with equal steadiness, in cases where the extra breadth would be useful, though the extra breadth was by no means an essential part of the scheme.

The truth of these assertions, as establishing the superiority of the broad gauge, was of course vehemently denied by the advocates of the narrow gauge.

One objection urged by them, the inconveniences of the break of gauge, has undoubtedly been proved by experience to be a very powerful one, so powerful indeed as to compel the abandonment of the broad gauge on the lines where any considerable quantity of goods traffic has to be carried in competition with other companies.

Had Mr. Brunel’s original plan been carried out, and had the broad-gauge companies taken possession of all the western portions of England, and avoided extensions into the north, the points of contact would no doubt have been so unimportant that no great inconvenience would have arisen, or a few miles of double gauge would have removed any difficulty; but, under the actual circumstances of the case, the Great Western Company were forced to yield.

The advantages of the broad gauge were so much appreciated by the districts it served, that its abandonment was viewed with considerable displeasure, particularly in the neighbourhood of Birmingham; but the inconvenience of double traffic arrangements far outweighed the advantages derivable from the use of the broad gauge, to the limited extent it could be applied on those outlying portions of the Great Western system. For these reasons the Company came to the determination to work their northern lines on the narrow gauge only.

The broad gauge is therefore now confined to the district for which it was originally intended. Even in this district there are many points of contact with the narrow gauge; but the inconveniences of break of gauge are by no means so important as they were in the north, and do not, at present at least, menace the continued existence of Mr. Brunel’s design.

CHAPTER VI.

THE ATMOSPHERIC SYSTEM.

A.D. 1840—1848. ÆTATIS 35—43.

IN the year 1844 Mr. Brunel recommended the adoption of the Atmospheric System of propulsion on the South Devon Railway, a line of 52 miles in length, which he was then constructing between Exeter and Plymouth. This system had, under the management of Messrs. Clegg and Samuda, been in operation with success on the Dalkey line for some time before Mr. Brunel adopted their apparatus on the South Devon Railway. After it had been in use on the South Devon for about twelve months, it was abandoned, and the railway worked throughout by locomotives.

It is therefore as important as it is interesting to examine the causes of the failure of the Atmospheric System, and to consider the reasons which induced Mr. Brunel in the first instance to adopt it, and afterwards to recommend its abandonment.

Up to about the year 1843, the cost of railways, which was in a great measure due to the conditions imposed by the limited capabilities of the locomotive, had prevented their construction, except in cases where they would secure a large traffic, and at the same time traverse what was then considered a practicable country.

A curvature of one mile radius was regarded as the maximum generally admissible on a line where high speeds were aimed at, and auxiliary locomotives were required to work heavy gradients.

Nevertheless, by the growing wants of the public and the growing boldness of engineers, the railway system was gradually being forced into districts hitherto regarded as unsuitable for it; and no country was held to be impracticable where the gradients could be surmounted by the inconvenient and costly expedient of auxiliary power.

The south of Devon had for several years demanded railway accommodation, and at the period now under review, Mr. Brunel projected what was called the coast line. This line, while it best accommodated the population of the district, passed through a very difficult country. If it was to be constructed at a moderate cost, curves of a quarter of a mile radius had to be admitted; and above 30 miles of its entire length traversed a district involving the adoption of gradients steeper than had been elsewhere used for such considerable distances. The Act for this railway was obtained in the Session of 1844.

The South Devon Railway, on leaving Exeter, crosses the flat country on the right bank of the river Exe, as far as Starcross, a village nearly opposite to Exmouth. From this point it runs down to the coast and along the sea-shore, by Dawlish, to Teignmouth; being protected by a sea-wall for the greater part of the distance, and passing through several headlands by short tunnels. Beyond Teignmouth it follows the left bank of the river Teign, which it crosses a short distance before reaching the station at Newton Abbott. The portion of the line from Exeter to Newton—21½ miles in length—is very nearly level, the steep inclines for which the railway is noted being west of Newton. Between Newton and Totness, for the first mile and a half the line is almost level, and in the next two miles it rises 200 feet, with gradients of 1 in 100, 1 in 60, and nearly a mile of 1 in 43. At the summit is a short tunnel; and thence the line descends 170 feet in a mile and three-quarters, with gradients of 1 in 40 and 1 in 43 for about three-quarters of a mile, and gradients of 1 in 57 and 1 in 88 for the rest of the incline. It then runs with more moderate gradients and about a mile and a half of level line to Totness.

From the valley of the Dart at Totness the line rises at once by a rapid ascent of 350 feet in four miles and a half, with gradients varying from 1 in 48 to 1 in 90, more than a mile and a half averaging 1 in 50. Thence it runs, with easy up and down gradients, for a distance of 12 miles along the skirts of Dartmoor, crossing by lofty viaducts the deep valleys which penetrate the moor. It then descends to Plympton, in the valley of the Plym, falling 273 feet in a little more than two miles, with a gradient of 1 in 42½. From Plympton the line for two miles is level, and then rises on an incline of 1 in 80 for a mile and a half, and descends by a similar gradient into the Plymouth station.

The main characteristics of the railway are that, while it traverses a very heavy country, its principal changes of level are concentrated into four long and steep inclines. These four inclines were intended to be worked by auxiliary power.

Hitherto on gradients of unusual steepness a stationary engine with rope traction had been generally regarded as the only available expedient; but the special difficulties by which this system was encumbered rendered it unsuitable for high-speed passenger traffic, and practically inapplicable to an extended line. It had, however, been very successfully employed by Mr. Robert Stephenson on the Blackwall Railway, a line of about 3¾ miles in length.

Messrs. Clegg and Samuda, the projectors of the Atmospheric System, which was another mode of using stationary power, had, previously to this period, laboured to attract the attention and win the favourable opinion of engineers and the general public.

It is desirable, before proceeding further, to give a brief description of this system of traction, upon the merits of which distinguished engineers entertained widely different opinions.

Between the two rails of the line of way was laid a cast-iron tube, which on the Croydon and Dalkey railways and the completed or level portion of the South Devon Railway was fifteen inches in diameter. On the inclines it was proposed to use a twenty-two inch tube.

At intervals of about three miles along the line were erected stationary engines, working large air-pumps, by means of which air could be exhausted from the tube, and a partial vacuum created within it. A close-fitting piston was placed in one end of the tube, and the air being exhausted from it, the pressure of the external air on the surface of the piston which was towards the open end of the tube forced the piston through the tube towards the end where the air-pumps were working; so that if the piston were connected with a carriage running on the rails, it would draw the carriage with it. The connection between the piston and the carriage was arranged by Messrs. Clegg and Samuda in the following way:[62] Along the top of the tube was a slit about 2½ inches wide; this slit was closed by a long flap of leather, which was strengthened with iron plates, and secured to the tube at one side of the slit. One edge of the leather thus formed a continuous hinge; the other edge, where it closed on the tube, was sealed with a composition of grease, to render it air-tight. This flap was known by the name of the longitudinal valve.

When the valve was closed, the air could be exhausted from the tube in front of the piston, and a partial vacuum formed. Behind the piston, the air being at atmospheric pressure both within and without the tube, there was no objection to opening the longitudinal valve; and a bar, extending downwards from the under side of the carriage, entered the slit obliquely under the opened valve, and was connected to the rear end of a frame about ten feet long, the front end of which carried the piston. To allow the bar to pass along the slit, the valve was opened on its hinge, being pressed upwards by a series of wheels carried by the moving piston-frame inside the tube. The valve closed again after the passage of the train; and the tube was ready to be exhausted in preparation for the passage of the next train.[63]

The Atmospheric System was first tried in 1840. An experimental tube was laid down at Wormwood Scrubs on part of the short line now incorporated into the West London Railway, and then known by the title of the Bristol, Birmingham, and Thames Junction Railway. Its working was the subject of eager discussion among engineers.

In 1842 Sir Frederic Smith, R.E., and Professor Barlow, under an order from the Board of Trade, reported so favourably on the system with reference to the proposal for its application on the Dalkey branch of the Dublin and Kingstown Railway, that it was adopted there. In 1843 Mr. (afterwards Sir William) Cubitt determined to employ it on the Croydon Railway; and about the same time Mr. Robert Stephenson was desired by the Directors of the Chester and Holyhead Railway to report on the propriety of introducing it on that line.

Mr. Stephenson’s report was based on a series of experiments on the working of the system at Dalkey. The view he took was adverse to its adoption, not only on the Chester and Holyhead, but on almost every railway whatsoever; and this on the ground that, though it was quite capable of being developed into a practical working system, yet on lines with ordinary gradients the atmospheric traction must be considerably more costly than locomotive traction, and on steep gradients than rope traction; in other words, that, as a mechanical appliance it was, though practicable, not economical.

Mr. Stephenson’s report had no sooner appeared than the correctness of his conclusions was disputed on his giving evidence before a Committee of the House of Commons, in the spring of 1844, on the Croydon and Epsom Railway Bill.

Mr. Brunel also was summoned as a witness. Previously to this time he had taken a great interest in the various attempts which had been made to introduce the Atmospheric System, and he had himself conducted experiments at Wormwood Scrubs and at Dalkey. As early as July 1840 he had considered its applicability to the Box Tunnel incline on the Great Western Railway. He had also considered it in reference to various projected lines; and in 1843 he recommended it for adoption in a long tunnel on one of the steep inclines of the Genoa and Turin Railway, the success of the system being then (he wrote) sufficient to justify its use on a part of the line protected from weather. It was not, however, applied on this railway.[64]

Mr. Brunel’s views at this time are indicated in the following letter:—

Although unwilling to express general opinions, Mr. Brunel spoke strongly before the Croydon and Epsom Railway Committee in favour of the advantages of the Atmospheric System under certain circumstances, and approved of its use on that line.

A few months later Mr. Brunel recommended the Directors of the South Devon Railway Company to adopt the Atmospheric System, and they resolved to act on his advice.

His report was as follows:—

In this report Mr. Brunel rested his recommendation principally on two assumptions, which he held to be indisputable—(1) That stationary power, if freed from incumbrances such as the friction and dead weight of a rope, was superior to locomotive power; and (2) That the Atmospheric System of traction was theoretically a good and economical method of applying stationary power, and that it was also a practical and working system, as had been shown in its first and somewhat crude application at Dalkey.

The superiority of stationary as compared with locomotive power depends on two principles—(a) That a given amount of power may be supplied by a stationary engine at a less cost than if supplied by a locomotive. (b) That the dead weight of a locomotive forms a large proportion of the whole travelling load, and thus inherently involves a proportionate waste of power—a waste which is enhanced by the steepness of the gradients and the speed of the trains.

A detailed examination of these principles is given in the note to this chapter.

It is there shown that at the time referred to stationary power could be obtained for one farthing per horse-power per hour, while locomotive power cost more than one penny per indicated horse-power per hour, the cost of the locomotive power being more than four times that of the stationary power. On a level line at a speed of 60 miles per hour, for each horse-power usefully employed, a locomotive, in consequence of its own dead weight and the friction of its machinery, is obliged to expend more than one and a half horse-power; in this case, therefore, the useful work done costs nearly seven times as much as if it had been performed by a stationary engine. Again, on so moderate an ascent as one in 75, for each horse-power usefully employed, the locomotive has to expend at 40 miles per hour more than two horse-power, and at 60 miles per hour three horse-power; so that the useful work done costs in the one case nearly ten times, in the other thirteen times, as much as if it had been performed by a stationary engine.

This great advantage of stationary over locomotive power was a sufficient justification for introducing a system which promised to realise it to any considerable extent; although many difficulties might have to be encountered.

As has been already stated, Mr. Brunel had satisfied himself that the Atmospheric System was theoretically economical, and that its trial at Dalkey had shown that it was practically free from mechanical objections. Mr. Stephenson, indeed, had admitted that the mechanical details had been brought to a remarkable degree of perfection; but this admission was not any qualification of the radical difference of opinion which existed between him and Mr. Brunel, to which Mr. Brunel drew attention in his report of August 1844.

The subsequent abandonment of the Atmospheric System led many to believe that Mr. Brunel had been rash in rejecting the detailed investigations and conclusions of Mr. Stephenson, and that the adverse conclusions which Mr. Brunel had refused to entertain were subsequently established.

But, in fact, the failure of the Atmospheric System was due to failure in some of its mechanical details, and was not due to those inherent defects in its principle which Mr. Stephenson in his report considered that his experimental data had established.

Mr. Brunel’s opinions were again brought prominently into notice in the evidence given by him before a Select Committee of the House of Commons, which was appointed in the Session of 1845, in consequence of the number of projected lines which it was proposed to work by the Atmospheric System.

The following letter, written by Mr. Brunel to one of the members of the Committee, explains what he considered to be his position at this time:—

(Enclosure.)

It is unnecessary to give any extracts from Mr. Brunel’s evidence,[68] as it only repeats the opinions and calculations embodied in his report of August 1844.

The Committee, while they allowed that experience could alone determine under what circumstances of traffic or of country the preference to the Atmospheric or the Locomotive System should be given, reported very strongly in favour of the general merits of the Atmospheric System.

As soon as it had been decided that the South Devon was to be constructed as an Atmospheric line, the dimensions of the cuttings, embankments, and tunnels were arranged for a single line, except on the long incline west of Totness, and on that east of Plympton. In the approaches to the principal summits the gradients were made somewhat steeper, so as to reduce the excavations.

In December 1844, Mr. Brunel prepared a specification and drawing of a steam-engine and vacuum pump, and a copy was sent to the most eminent engine-builders, together with a letter inviting tenders for six pairs of engines. The letter concluded as follows:—

The economical character of the engines which Mr. Brunel desired to obtain is sufficiently indicated by the requirement that they were to be high-pressure condensing engines, fitted with double-seated expansion valves, and having boilers proved to 100 lbs. per square inch, and guaranteed to work with safety valves loaded to 40 lbs. per square inch.

The tenders accepted were those of Messrs. Boulton and Watt, Messrs. Rennie, and Messrs. Maudslay and Field.

Mr. Brunel left it to the contractors to prepare their designs without any interference on his part, deeming it best to rely on their unfettered judgment.

The task of manufacturing and fitting the cast-iron tube was one of some difficulty, the longitudinal slit allowing of considerable distortion in the casting. This work was undertaken by Mr. George Hennett, by the aid of a set of very effective tools devised by Mr. T. R. Guppy.

The tubes were supplied at the rate of one mile per week, and by the middle of 1846 nearly the whole line was laid to Newton, and the valve was ready to be fixed.

In the autumn of 1846, Mr. Joseph Samuda went to Dawlish, taking with him a staff of assistants trained in the working of the system at Croydon; and every effort was made to advance the completion of the engines and the other parts of the apparatus.

Owing, however, to vexatious delays in the erection of the engine-houses and engines, it was not until the commencement of 1847 that a piston-carriage was able to traverse the first six miles out of Exeter. And, though repeated experimental trains continued to be run, no passengers had been conveyed by Atmospheric trains prior to the general meeting of the shareholders, at the end of August. Mr. Brunel’s report on this occasion was as follows:—

The stress of personal anxiety and personal fatigue, experienced by Mr. Brunel and by all who were engaged in the work, was very severe, and continued so to the end. Not only was the progress in the completion of the work slow, but in spite of every exertion the results were incessantly marred by unfortunate contingencies which involved further delay, discouragement, and expenditure. Moreover, the reaction which followed the railway mania had set in; calls were ill responded to, and great difficulty was experienced in raising the money requisite for the completion of the line.

Under these circumstances it was resolved, on September 1, not to incur any new expenses in relation to the Atmospheric System beyond Totness, and to limit any expenditure already contracted for, until its working between Exeter and Totness had been fairly tried, except to provide assistant power up the two inclines.

On September 8 the Atmospheric trains began to take their share in the passenger duty of the line, four trains running each way daily; and, except when occasional mishaps caused delay, the new mode of traction was almost universally approved of. The motion of the train, relieved of the impulsive action of the locomotive, was singularly smooth and agreeable; and the passengers were freed from the annoyance of coke dust and the sulphureous smell from the engine chimney.

In other respects the record of progress is but a chequered one, and exhibits, in spite of great and able efforts and brightening intervals of occasional improvement, indications of growing difficulties deepening into ultimate defeat.

In examining the chronicle of events which correspondence and memoranda supply, it is inevitable that references to failure and disaster should be found relatively in far greater abundance than records of success; and this for the simple reason that there was at that time great use in taking note of the unfavourable incidents that occurred, almost none in mentioning successful work.

There is therefore some danger of falling into a mood of unjust depreciation, such as Mr. Brunel had in energetic terms urged the Directors to guard themselves against. He protested against their requiring (as they once intended to do)—

The Atmospheric System was vaguely credited with every delay which a train had experienced in any part of its journey; though, in point of fact, a large proportion of these delays was really chargeable to that part of the journey which was performed with locomotives. It often happened that time thus lost was made up on the Atmospheric part of the line, as is shown by a record of the working, which is still extant. In the week, September 20-25, 1847, it appears that the Atmospheric trains are chargeable with a delay of 28 minutes in all; while delays due to the late arrival of the locomotive trains, amounting in all to 62 minutes, were made up by the extra speed attainable on the Atmospheric part of the line.

Not unfrequently, however, casualties occurred; due indeed to remediable causes, but yet of discouraging aspect in themselves, and deriving additional weight from the manner in which they reacted on the cost of working. Such, for instance, were the frequent and occasionally very serious breakages in essential parts of the pumping-engines. Again, the cupped leathers of the travelling-piston, which made it air-tight, were often destroyed while it was passing the various inlet and outlet valves. Improvements in the valves were introduced to meet this difficulty; but the remedy could not be applied at once throughout the line, and much inconvenience was thus experienced, and a considerable expense incurred. Another source of inconvenience was the water which at times accumulated within the tube.

In many respects the results which had been calculated on were realised, and the new arrangements necessary to the working of the system were successfully brought into operation.

The speed of the trains corresponded fully with the degree of vacuum obtained; that is to say, the train resistances proved to be what had been anticipated.[69]

After the trial of a great variety of air-pump valves, a form was adopted which was found to answer exceedingly well.[70]

In the Atmospheric tube, the system of self-acting inlet and outlet valves, by which the piston was enabled to leave the tube on approaching a station and enter it again on recommencing its journey, were, on the whole, successfully adapted to their duty.

Again, an arrangement for starting the train rapidly from the station, without the help of horses or of locomotives, had been brought practically into operation. This arrangement consisted of a short auxiliary vacuum tube containing a piston which could be connected with the train by means of a tow-rope, and thus draw it along till the piston of the piston carriage entered the main Atmospheric tube. Some accidents at first occurred in using this apparatus, but its defects were after a time removed; and it is hardly to be doubted that the various minor difficulties of the Atmospheric System could soon have been effectually mastered.

It now remains to show how it was that, in spite of much that was hopeful, a vigorously sustained contest ended in defeat, instead of being prolonged into victory.

In working the Atmospheric System on the South Devon Railway grave difficulties were throughout encountered, for which to the last only imperfect remedies could be found.

As regards the power consumed, the engines of each pumping station worked up to about 236 indicated horse-power, and their regulated duty for each train, including the anticipatory pumping, was equivalent to 5·5 minutes of work for every mile of the length of tube they had to exhaust. As the running speed averaged 40 miles per hour, or a mile in 1·5 minutes, the 236 horse-power during the 5·5 minutes of pumping must be regarded as equivalent to 865 horse-power during the actual passage of the train. Now, making full allowance for piston friction and extra friction on curves, for the power expended in getting up speed, for the excess of air-pump resistance due to the changes of temperature experienced by the air under exhaustion, and even for the very large actual amount of friction in the engines employed, the work done should have been represented by an expenditure of 240 horse-power during the passage of the train. If to this is added an allowance for leakage, such as the experiments at Dalkey indicated would be amply sufficient with the longitudinal valve in good condition, it may be said that Mr. Brunel had a right to expect that the duty would be performed with an expenditure of 300 horse-power; whereas it actually required 865 horse-power, or nearly three times the amount.

The explanation of this waste is simple.

Serious and unexpected causes of failure developed themselves in the longitudinal valve, and led to an excessive amount of leakage. A great part of the normal duty of the engines was, as has been stated, to exhaust the tube previous to the entry of the train; and when, owing to leakage, the amount of air to be so pumped out was greatly increased, it became necessary that the operation should be commenced much earlier. There was thus a longer time during which the leakage could take place, and a still greater amount of air to be pumped out. It therefore followed that a large increase of leakage involved waste of power in an enormously increased proportion.

The length of time occupied by the anticipatory pumping was often increased by the difficulty of arranging proper telegraphic communication on the South Devon Railway, and by the absence of it on the Bristol and Exeter Railway. The Electric Telegraph was in its infancy, and though Mr. Brunel had been the first to apply it in connection with railways, namely, between London and Slough on the Great Western Railway in the year 1839, it was not brought into perfect working order on the South Devon Railway till the Atmospheric System was on the point of being abandoned. The result of the defects in the telegraph was that, when a train was late, warning was not received at the several engine-houses;[71] and thus, when this was the case, the pumping-engines which had been started at the right interval of time before the train was due, had to be kept at work for a needlessly long period pumping out the air, which was all the while leaking in through the deteriorated valve. This inefficiency of the telegraphic apparatus would have been of trifling importance but for the defects of the valve. Had the valve been as perfect as it was expected to be, the vacuum, after it had been formed, could have been maintained by an expenditure of power very moderate in comparison with that which was actually required.

As regards the relative cost of the power consumed, it appears that, owing to imperfections in the engines, their expenditure of fuel per indicated horse-power was more than double that of the best of the Cornish pumping-engines, to which they were analogous; while the cost of working was more than three times as great.

The defects in the engines were for the most part such as might have been remedied; and this would have been done, had not the excessive duty imposed on them by the leakage of the longitudinal valve prevented their being stopped for repairs and alterations. In this way the defects of the different parts of the apparatus mutually aggravated each other.

It appears then that, chiefly owing to the defective longitudinal valve, the engines were expending nearly three times the power which they should have done for a given tractive duty, according to previous experience, and the results obtained on the Dalkey line, and that they cost per horse-power at least three times as much as was expected.

The cost of traction, nearly nine times as much as had been calculated on, was between two and a half and three times what it would have been with locomotive power; and this was on a level part of the line, where the comparative advantages of the Atmospheric System were not exhibited as they would have been in the part which had steep gradients.

The imperfections of the longitudinal valve have now to be described. By its condition the Atmospheric System had to stand or fall. With an efficient valve, the defects of the other parts of the apparatus would have been of minor importance, and time would have been given for remedying them. When the leakage became considerable, the defects of the telegraph and the defects of the engines alike assumed a formidable aspect.

The failure of the valve was due, partly to the composition which was used to seal the joint where it opened, and partly to the material of which the valve consisted. The difficulty of obtaining a suitable composition was the first which had to be encountered. On the South Devon a lime soap was eventually found to answer the purpose well. Its surface, however, from exposure to light and air, formed into a hard skin; and to remedy this a thinner and more fluid material, a compound of cod-oil and soap, was laid on to keep it soft. This answered satisfactorily, but it required frequent renewal, as it was apt to be drawn into the tube by the rush of air when the valve was opened. The renewal of the various compositions, and the careful examination and repair which the valve constantly required, was a cause of great anxiety and expense.

But in the materials of the valve lay the source of the more serious difficulty.

The ready affinity of leather for oil and grease, and its suppleness and closeness of grain when saturated with substances of that nature, had long been known and utilised. It had not been anticipated how readily, with air-pressure on one side and a partial vacuum on the other, the oily matters with which the leather was charged would escape from it, especially in the presence of water. Although, while the leather was saturated with water, the valve was remarkably air-tight; when frost supervened the water became frozen, and gave a fatal stubbornness of texture, which rendered the valve incapable of closing properly. Again, in long-continued drought the leather became intractable from its dryness; and the stiffening, whether from frost or drought, rendered it liable to be torn. An immediate application of seal-oil penetrated the leather, and relaxed its stiffness; but the remedy often could not be applied in time, and, moreover, was expensive.

A still more grave defect was all the while becoming matured, and was undermining every hope that a suitable dressing could be discovered, and that the longitudinal valve might be made perfect.

Under the joint action of water in the leather, and of the affinity of iron for tannin—and on the enduring presence of tannin within its texture the consistency of leather depends—a destructive decomposition had long been at work; the oxide, established in the iron plates of the valve by continued contact with damp leather, had been steadily abstracting the tannin; thus the leather had become converted into an ink-stained and comparatively decomposed tissue. Large portions of it became torn, and incurably pervious to air.

It was not until early in June 1848 that Mr. Brunel discovered the condition which the valve had assumed. He then instituted a careful examination throughout the line, and the extent of the disorder was realised.

The state of things which existed when this discovery was made in effect involved the renewal of the valve the whole distance from Exeter to Newton; so that, as the cost of the valve was 1,160l. per mile, an immediate outlay of some 25,000l. became essential to the maintenance of the system, and this at the time when the real difficulties of the valve question had become most apparent. By galvanising the iron plates of the valve the mutually destructive action of the iron and the leather might have been prevented; but a remedy was also required for the other serious defect which leather, as the material of the valve, was found to exhibit, namely, its tendency to become permeable to air after long-continued use under air-pressure, owing to the inward escape of the material with which it had been dressed.

These difficulties were not only such as had not been anticipated, but such as no one was justified in anticipating.

It now became necessary for Mr. Brunel to consider what course, under the circumstances, it was most advisable for the Company to adopt.

A Committee of the Board was appointed to examine the whole question; and, at their desire, Mr. Brunel made a report upon it, which was as follows:—

The Committee to whom this report was made, and who had been also in constant communication with Mr. Brunel, placed the result of their investigation before the Board. The Directors, after carefully considering the information given them, reported as follows:—

At the meeting in August, the proprietors adopted the Directors’ report, and the line was worked throughout by locomotives on and after September 9.

In the following November Mr. Thomas Gill, the chairman of the Board of Directors, published an ‘Address to the Proprietors,’ in which he strongly deprecated the abandonment of the Atmospheric System, and proposed that the Company should embark on a further experiment. Mr. Gill’s pamphlet was referred to three of the Directors, Mr. Thomas Woollcombe, Mr. Charles Russell, and Mr. James Wentworth Buller. With Mr. Brunel’s assistance, and to a great extent from memoranda written by him, they prepared a statement which went very fully into all the points raised by Mr. Gill.

After combating Mr. Gill’s propositions, they observe:—

In conclusion they express an opinion that the suspension of the Atmospheric System in the previous September was a prudent and necessary step, and that nothing had since occurred to justify its resumption.

The proprietors adopted the view taken by the Committee, and no further attempt was made to work the railway on the Atmospheric System.

Under these circumstances, it cannot be a matter of surprise that Mr. Brunel was much censured for having advised the South Devon Railway Company to work their line on the Atmospheric System.

The reasons which led him to recommend the use of the Atmospheric System on the South Devon, and the causes of its failure, have been very fully described, and it has been also shown that the most important of these were the defects of the pumping-engines, and the deterioration of the longitudinal valve.

When the formidable character of these difficulties had fully declared itself, the South Devon Railway Company were not in a position to spend any more money upon a system which, as the event had proved, was, in one of its most important details, still in the experimental stage.

There can be no doubt that the abandonment of the Atmospheric System was the wisest step which, under the circumstances, could be adopted; and it was recommended to the Directors by Mr. Brunel with a simple and self-sacrificing disregard of every consideration except that which was always paramount with him, the interests of those by whom he was employed.[72]

NOTE (p. 143).

Comparison of Stationary and Locomotive Power.

In order clearly to set forth the reasons which justify the statement made by Mr. Brunel,[73] that stationary power if freed from the weight and friction of any medium of communication, such as a rope, must be cheaper than locomotive power, it is desirable to consider, (1) the waste of power which arises from the locomotive having to move itself as well as the train; and (2) the excess of cost at which a given power was supplied by a locomotive, as compared with that at which it could have been supplied by a stationary engine.

On the first point, the best information can be obtained from experiments made by Mr. Daniel Gooch during the gauge controversy. The results are very suitable for use in the present investigation, as the South Devon was to be a broad-gauge railway. Moreover, as the broad-gauge engine with which these experiments were tried was one of a class more powerful for their weight not only than the contemporary narrow-gauge engine, but also than the engines Mr. Brunel had experience of when he wrote his report three years previously, the results may be considered to represent very favourably the then existing case for the locomotives.

The engine employed in the experiments weighed, with its tender, about fifty tons. The maximum power it was capable of delivering by the pressure of steam in its cylinders was represented as a tractive force of 4,900 lbs. at a speed of 60 miles an hour, equivalent to 784 indicated horse-power; and at 40 miles an hour 5,200 lbs., equivalent to 555 indicated horse-power.

It is next to be considered how this power would, when running at the speeds mentioned, be employed in overcoming the elements of resistance. These are:—

(1) The working friction of the machinery.
(2) The rolling resistance of the engine and tender.
(3) The air resistance due to the engine frontage.

(4) The rolling resistance of the train.
(5) The air resistance on the portion of the train unprotected by the tender.
(6) The resistance due to gradient.

The following symbols and quantities may be conveniently made
use of to denote the various terms of the equation between force
and resistance.

For a locomotive train therefore

For a system that dispenses with the locomotive

Therefore

Therefore
  F={R + 112000 G-·0975 V²} + {W (K + 2240 G) +·1575 V²}

and the useful load

The values which Mr. Gooch’s experiments give for the two selected speeds are as follows[74]:—

Using these values, the results in the following table are obtained, being the conditions appropriate to the two speeds at successive ascending gradients:—

Thus, on a level line, the engine, working up to 555 horse-power, could just draw 288 tons of train at the rate of 40 miles per hour, wasting on its own resistance only one-third of the power usefully employed on the train; but when the speed was increased to 60 miles per hour, it could not, though working up to 784 horse-power, draw more than 139 tons of train, wasting on its own resistance more than half the power usefully employed on the train. And again, at 40 miles per hour, though, as just stated, it could draw on the level 288 tons, it could only draw 24 tons of useful load at that speed up 1 in 50; while at 60 miles per hour, though it could draw, as stated, 139 tons of train on the level, it could only draw 23 tons of useful load up 1 in 75; and at the respective speeds of 40 and 60 miles per hour, it could only take one carriage (7 tons) up the respective gradients of 1 in 36, and 1 in 52.

Hence to maintain a minimum speed of 40 miles per hour with locomotive power on a line with long gradients of 1 in 40 involved on those parts of the line a wasted power of nearly 4 times that usefully employed; and if a minimum limit of 60 miles per hour were contemplated, a locomotive of the most powerful class in existence three years subsequent to Mr. Brunel’s report advising the adoption of the Atmospheric System would only have been able to take a single carriage up an incline of 1 in 52. So heavily at high speeds on steep gradients is the performance of a locomotive taxed by the resistance due to its own dead weight.[75]

A comparison has now to be made between the cost of power as developed by a locomotive and as developed by a stationary engine.

From the well-known experiments made for the information of the Gauge Commissioners in December 1845, taking the high speed trials as the basis of calculation, it appears that 4·5 lbs. of coke per horse-power per hour may be taken as the average consumption of the engine.[76]

It will be well, however, to allow for the improvement which was at the time anticipated in locomotive working, and to assume an expenditure of 4 lbs. of coke per indicated horse-power per hour, as representing the case then for the locomotive engine.

Coke may be taken to have at that time cost 21s. a ton, or ·0094s. per lb. Moreover, a careful analysis of the Great Western Railway half-yearly reports, for 1844 and 1845, shows that for every shilling expended in coke, 1·44 shillings were expended on the average in wages, oil and waste, repairs, etc.

Putting the results together, it appears that for each single indicated horse-power delivered by a high-speed locomotive, the cost per hour was 0·0915s. or 1·098d.; that is to say, about 1¹/₁₀ d. per hour.

Let this now be compared with the cost per horse-power per hour at which the best Cornish pumping engines had long been known to perform the work. This comparison is manifestly a rational one—with reference to the kindred employment of engine power in atmospheric pumping-engines.

The performances of nearly all the pumping-engines in Cornwall were for many years so systematically and exactly reported, and the reports of each were so critically scrutinised by the rival makers, that the data they supply may be relied on without hesitation. It was well known that the best of the engines continuously performed useful work with a consumption of coal at the rate of 2·33 lbs. per delivered horse-power per hour, or, counting coal at 16s. per ton (a fair price on the South Devon), at the cost of ·2d., or one-fifth of a penny per horse-power per hour.

But it was not in its consumption of fuel alone that stationary power was the more economical; the expenditure in wages, oil, and tallow on one of the pumping-engines above referred to, when doing 200 horse-power of useful work, did not exceed 20s. for the twenty-four hours, or one-twentieth of a penny per horse-power per hour, while the cost of repairs was merely nominal.

Thus if fuel, wages, oil, and tallow be brought into one item, it is seen that the cost of one horse-power in stationary engines such as the then existing Cornish engines was only ·25d. per hour, or less than one-fourth of its cost when developed by a locomotive, which has been shown to have been 1·098d. per hour.

PLATE III

THE ROYAL ALBERT BRIDGE.
H. Adlard. Sc.

CHAPTER VII.

RAILWAY BRIDGES AND VIADUCTS.

IN Chapter IV. a general history has been given of the railways of which Mr. Brunel was the engineer; but the bridges and viaducts designed by him are so numerous and important that it has been thought advisable to devote a separate chapter to their consideration.

The bridges selected for mention have been grouped according to the nature of the material used in their superstructure. This arrangement is the most convenient one for giving a concise description of the most remarkable of Mr. Brunel’s bridges, and for stating the circumstances which guided him in the determination of the particular form of construction used in each case.

The works are therefore divided into four groups, namely, brickwork and masonry, timber, cast iron, and wrought iron.[77]

Brickwork and Masonry Bridges.[78]

The viaduct which carries the Great Western Railway over the valley of the river Brent near Hanwell is the first of Mr. Brunel’s important railway works.[79] It is a handsome brickwork structure, 65 feet high, with eight semi-elliptical arches, each 70 feet span and 17 feet 6 inches rise. The spandrils of the arches are lightened by longitudinal spandril-walls; the piers are also hollow, and the structure is throughout made as light as possible. It is on this account interesting, as showing the care taken by Mr. Brunel from the commencement of his practice to distribute the material in the simplest and most effective manner.[80]

The great bridge over the Thames at Maidenhead contains two of the flattest, and probably the largest arches that have yet been constructed in brickwork. The river, which is about 290 feet wide, flows between low banks; in the middle of the stream there is a small shoal, of which Mr. Brunel took advantage in building the centre pier.

It was originally intended that the foundation of the bridge should be on the chalk, which was at a short distance below the surface; but it was found to be very soft, and Mr. Brunel therefore decided to place the foundations of the bridge on a hard gravel conglomerate overlying the chalk. The main arches are semi-elliptical, each of 128 feet span and 24 feet 3 inches rise. They are flanked at each end by four semicircular arches, one of 21 feet span, and three of 28 feet span, intended to give additional water-way during floods. The radius of curvature at the crown of the large arches is 165 feet, and the horizontal thrust on the brickwork at that point is about 10 tons per square foot.

In the interior of the structure immediately landward of the large arches, Mr. Brunel constructed flat arches loaded with concrete. The centerings of these were struck, and an active thrust opposed to the main arches before their centerings were eased.[81] The line of pressure of each main arch was diverted downwards by the thrust of the flat arch adjoining it without the necessity of employing a great mass of brickwork in the abutment.

The woodcut (fig. 1) shows the form of the main arches and the flat arch referred to.[82]

The Maidenhead bridge is remarkable not only for the boldness and ingenuity of its design, but also for the gracefulness of its appearance. If Mr. Brunel had erected this bridge at a later period, he would probably have employed timber or iron; but it cannot be a matter of regret that this part of the Thames, although subjected to the dreaded invasion of a railway, has been crossed by a structure which enhances the beauty of the scenery.

There are two other large brick bridges over the Thames, one at Gathampton and another at Moulsford, that at Moulsford crossing the river obliquely at an angle of 45°. In each of these bridges there are four arches, of 62 feet span on the square.

Other good examples of brick bridges are the turnpike road bridge, 60 feet high, with three arches, across the deep cutting at Sonning Hill, and the bridge, with one opening of 60 feet and four side arches of 18 feet span, over the river Kennet at Reading.

The bridge over the Avon at Bathford, of 87 feet span, and the bridge crossing the same river at Bath, with an arch of 88 feet span, are handsome Bath-stone structures with semi-elliptical arches. Near Bristol there is an ornamental bridge of masonry with three Gothic arches, the centre arch having a span of 100 feet.[83] Another bridge of Gothic design, with two arches of 56 feet span, carries the railway over the Floating Harbour.[84]

The bridges which have hitherto been noticed are all on the Great Western Railway. On the Bristol and Exeter Railway there is a large stone bridge over the New Cut at Bristol, built in 1840, which has a single segmental arch of 120 feet span, and 20 feet rise. Owing to some imperfect workmanship in the interior masonry of the arch, and possibly to some unequal yielding of the abutments, the crown sunk much more than had been expected.

On his later railways Mr. Brunel did not build large arches of brickwork or masonry, though he constructed several lofty and extensive viaducts of these materials with spans varying from 40 to 60 feet.

Mr. Brunel seldom employed artificially piled foundations to support masonry. When the ground was soft, he preferred to rely on a large extent of bearing surface, and ensured uniformity of settlement by an accurate distribution of the load. Several of his large viaducts and bridges, standing on ground of a soft and spongy nature, were constructed on this principle.

A class of bridge of striking outline was used in the cuttings on the Bristol and Exeter Railway, and on the other railways subsequently made. Bridges of this class were called flying bridges. Instead of arches resting on piers and abutments, the bridge has a single arch, reaching from one side of the cutting to the other, and springing from the slopes, which it helps in some measure to support. A flying bridge of large dimensions near Weston-super-Mare carries a road across the cutting at a height of 60 feet above the line of rails, with a clear span of 110 feet.

The quantity of masonry in these bridges is much less than in those of the ordinary construction; and lofty and expensive centering is not required, as the bridge can be built before the cutting is excavated to its full dimensions.

This class of bridge, by the avoidance of abutments and counterforts, simplifies the construction of skew arches, while on sharp curves it presents but little obstruction to the view along the line.

A curious use of arches of this construction, as applied by Mr. Brunel, may be seen on the South Wales Railway near Llansamlet, between Neath and Swansea. A deep cutting through the coal measures showed a tendency to slip, and a large amount of excavation would have been required to flatten the slope, as a hill rose immediately above the side of the cutting. Four of these flying arches were thrown across the cutting at short intervals, and weighted with heavy copper slag, so that the sides of the cutting are kept apart by the thrust of the loaded arches.

Among the skew bridges on Mr. Brunel’s railways, there are a few of extreme obliquity. Of these may be mentioned two large road bridges near Berkeley, over the Bristol and Gloucester Railway, one being 48° and the other 53° off the square. Both the bridges are of brickwork, and in the arch of the first one, which was set in Roman cement, hoop iron was introduced in the manner successfully employed by Sir Isambard Brunel. On the South Devon Railway, near Plympton, there is a skew bridge 63° off the square.

On the Great Western Railway, in the neighbourhood of Bath and Bristol, there are skew bridges of ashlar masonry built on the mechanically correct principle of spiral tapering courses, the bed-joints in every part of the arch being made at right angles to the lines of pressure. By this method the arch does not depend for its stability on the friction and cohesion of the materials, as it does to a great extent in very skew bridges, built in the usual way with spiral parallel courses, especially when the arches are semi-circular or semi-elliptical.

Mr. Brunel’s bridges of masonry and brickwork were well known for the comparatively small quantity of material used in them; and, though it was requisite that the materials and workmanship should be of superior quality, their cost was comparatively small.

The specifications he prepared for all his works, and on which the contracts were based, were noted for the completeness with which they were drawn up, and for their not requiring a standard of perfection higher than that which was actually to be carried out. The confidence with which Mr. Brunel was regarded enabled him to insist with effect on the work being executed according to his interpretation of the contract.

In connection with the design of engineering works, and especially of brickwork and masonry bridges, the following letter from Mr. Brunel to one of his assistants, who was abroad, will be found interesting:—

Timber Bridges and Viaducts.

Mr. Brunel’s timber bridges and viaducts are remarkable on account of the extensive scale on which he employed that material, and the simple and efficient type of construction which he adopted in the largest structure as well as in the smallest.

In 1841 Mr. Brunel constructed a timber bridge of five spans to carry a public road over the Sonning cutting of the Great Western Railway, a short distance east of Reading. The total width of the space across which the road had to be carried was 240 feet. The superstructure rests on four tall frameworks or trestles of timber forming the piers. Two of these piers are on either side of the railway, and the others are about halfway up each slope.

The road rests on a platform of timber planking, carried on three longitudinal beams, which are supported at nearly equal distances by timber struts radiating from points on the piers about 12 feet below the level of the carriage road. The system of arrangement of these struts will be best understood by a reference to the woodcut given below (fig. 5, p. 187) of one of the Cornwall viaducts, of which the Sonning bridge may be regarded as in some measure the prototype.[85]

The skew timber bridge on the Great Western Railway near the Bath Station, carrying the line over the river Avon, was constructed about the same time as the Sonning bridge. It has two spans of 36 feet each on the square, but the obliquity is so great that the span on the skew is 89 feet. Each opening has six laminated arched ribs parallel to the line of the railway. These support the platform of the bridge, and are built up in five layers of curved Memel timber, six inches thick, bolted together. The thrust is counteracted by iron ties connecting the ends of the ribs. The inner spandrils are filled in by cross-ties and braces, and those of the outer ribs by ornamental cast ironwork.

The two bridges already described are almost the only timber bridges of importance on the main line of the Great Western Railway from London to Bristol. Shortly after the completion of this railway Mr. Brunel began to make an extensive use of timber in his designs, and in so doing took full advantage of the largeness of the material, in order to avoid intricacy of construction.

A well-known arrangement for forming beams of greater strength than could be obtained by single pieces of timber was adopted by Mr. Brunel after a careful investigation of its merits. This arrangement consists in joining together two beams of timber placed one above the other, by means of bolts and joggles, so as to form a beam nearly equivalent in strength to a single piece of timber of the same depth as the two pieces united.[86] By this plan, the length which could be spanned by simple beams, without the introduction of trussed framework, was nearly doubled.

The distance between the piers of railway bridges is generally too great to allow of the superstructure being constructed of simple beams, and in such cases Mr. Brunel adopted forms of framing similar in the arrangement of their parts to the common designs of king and queen trusses employed in roofs.

One of Mr. Brunel’s early timber viaducts was that erected in 1842 at Stonehouse, on the Bristol and Gloucester Railway. It consisted of a series of five openings of queen trusses 50 feet span, resting on piers formed of timber trestles.

In the Bourne viaduct, across the Stroudwater Canal, on the Cheltenham and Great Western Union Railway, there was a span of 66 feet, with three timber trusses, for the two lines of way. Each of these trusses may be described as a king truss with an internal queen truss. The inclined timbers or principals rested in iron shoes upon the piers, and were connected together by bolts and joggles.

The upper horizontal or collar beam of the queen truss carried the roadway planking, which was continued upon beams supported by the principals. The timbers carrying the roadway received support from struts radiating from the feet of the queen posts, which were connected with the apex of the king truss by iron ties. The horizontal tie bars were of wrought iron. The arrangement of the truss is shown in the woodcut (fig. 2).

The side openings consisted of four spans of 30 feet, with trusses of the Stonehouse viaduct type, of one span of 25 feet and ten spans of 20 feet, with double beams.

The St. Mary’s viaduct, across the canal in the Stroud Valley, was constructed with one span of 74 feet, with trusses similar to those at the Bourne viaduct.[87]

In the year 1846 Mr. Brunel made an elaborate series of experiments on the strength of large timber. Some account of these is given in the note to this chapter.

Fortified by the information thus obtained, he was able to proceed with confidence to an extensive use of timber in the viaducts of the South Devon, the Cornwall, and other railways.

Between Totness and Plympton, the South Devon Railway, running along the skirts of Dartmoor, crosses four deep valleys, by lofty viaducts, all of the same design.

Three of them can be seen at one time, and they form striking and elegant features in the landscape.

The viaduct at Ivybridge is the highest of these. It is on a curve, and has eleven openings of 61 feet each; the extreme height is 104 feet.

The piers are of masonry, each consisting of two slender and slightly tapered shafts about 7 feet square, rising to the level of the rails. The superstructure was originally designed for a railway on the Atmospheric System, and was therefore only intended to bear the load of a train of carriages. The framework was placed below the level of the rails, and, as will be seen in the woodcut (fig. 3), it consists of a polygonal frame, with a few subsidiary struts, the feet of the main timbers being tied together by wrought-iron rods. There are two of these frames, one at each side of the bridge, to support the planking of the roadway. Before the construction of the viaducts was proceeded with, a complete span of the superstructure, consisting of a pair of the frames with the planking, was erected at Bristol, and tested to ascertain the efficiency of every part.

When it became necessary to strengthen the superstructure to enable it to carry the weight of locomotives, a strongly trussed parapet was added above the trusses, as shown in the woodcut. After the lapse of twenty years, the timber having begun to decay, wrought-iron girders have been inserted, which rest on the stone piers; the framing, however, has not been removed.

Shortly after the completion of the viaducts on the South Devon Railway, those on the South Wales Railway were constructed. The most important on this line are those at Landore and Newport.

The viaduct at Landore, near Swansea, is 1,760 feet long, as the railway here crosses a wide valley. It has 37 openings, and there are a variety of spans, one of 100 feet, two of 73 feet, two of 64 feet, two of 50 feet, and the rest of about 40 feet each. Most of these consist of a superstructure of queen trusses. The piers are of different materials, some being almost entirely of masonry, some partly of masonry and partly of timber, and others entirely of timber, according to the nature of the foundation.[88] The chief feature is the centre span, with an opening of 100 feet, the superstructure of which is a very fine piece of timber-work.[89] It has four trusses, one on either side of the two lines of rails, of the form shown in the woodcut (fig. 4). The truss consists of a four-sided frame placed within a five-sided frame, the angles of each polygon being connected by bolts and struts with the middle of the sides of the other polygon.

The planking of the roadway rests on double beams, supported at several points in the manner shown in the woodcut, each point having suspension-rods to connect it with the nearest angles of the frames. The arrangement of the double polygonal frame and of the tie-rods enables the transverse strength of the timbers to exercise considerable resistance to any distortion of the shape of the truss by a rolling load. To prevent any tendency of the top of the frame to yield sideways under the compressive strain, the tops of the trusses are connected by transverse struts or braces, the two outside trusses being steadied by raking ties attached to outriggers projecting from below the flooring of the bridge. The thrust of the polygonal frames is resisted by wrought-iron tie-bars at the level of the roadway beams. All the tie-rods in this bridge are double, with one bar on each side of the timbers, to avoid the necessity of making large bolt-holes.[90]

The viaduct at Newport consists of eleven spans with queen trusses, resting on piles. The main span, over the river Usk, is 100 feet, and was constructed with timber trusses very similar to those at Landore. Shortly before it was finished, the viaduct was burnt down. In rebuilding it, wrought-iron trusses were employed for the main span.

The works of the Cornwall Railway were commenced in the year 1852. The district through which the line passes is very deficient in the materials requisite for the construction of a railway. The granite of the country is for the most part only applicable for ashlar; and the slate, which is flat-bedded and so far fit for rubble masonry, is frequently inferior in quality.

In consequence of the number of valleys that the railway had to cross, the aggregate length of the viaducts, thirty-four in number, exclusive of the Saltash bridge, is upwards of four miles on a line of sixty miles. By the use of timber, a great saving was effected in the first cost of the works; and though it is a material which in time requires renewal, its use on the Cornwall Railway enabled the line to be made with the capital at the command of the Company; while, allowing for the cost of subsequent repairs, the total expenditure did not differ much from what it would have been had the superstructure of the viaducts been of more durable materials. The comparatively small cost of these structures enables them to be, in certain places, economically substituted for embankments, as was done on the Cornwall Railway.

The viaducts are to be found over the whole length of the line, but they are most frequent between the Liskeard and Bodmin Road stations, where the railway crosses numerous branches of the Glynn valley.

Most of these viaducts are of one type of construction.

The piers are formed of plain walls, built up to thirty-five feet below the level of the rails, those of the more lofty viaducts being strengthened by buttresses. In the woodcut (fig. 5) is shown a portion of the St. Pinnock viaduct, from which the form of these piers will be understood.

This viaduct is the loftiest on the Cornwall Railway, the rails being at a height of 153 feet above the ground. A description of the superstructure will serve to explain the design of the principal viaducts on the line.

The roadway planking rests on three beams, which run longitudinally throughout the whole length of the viaduct. Each of these beams consists of two pieces of timber, one above the other, fastened together by bolts and joggles. The piers are 66 feet apart, centre to centre, and the longitudinal beams are supported, at four nearly equidistant points in this space, by straight single timbers radiating from the tops of the piers. The feet of the timbers, which rest on the masonry in cast-iron shoes, are connected together by wrought-iron tie-bars; and the framework is made rigid by iron diagonals.

It will be observed in the transverse section (fig. 5) that the whole weight of the superstructure is concentrated immediately over those points in the piers where the three buttresses meet. The diagonal braces which are attached to each set of the main timbers give transverse stability to the superstructure.[91]

It was desirable, both in first construction and in subsequent repairs, to have a uniform dimension for the spans, and the subdivision of 66 feet was determined on as being suitable for the economic construction of the greater part of the work. The subdivision of this length was such as to allow of single whole timbers being sufficient for the direct supports of the longitudinal beams; and as these beams were supported at intervals of 15 to 20 feet, no intermediate trussing was required. As the inclined timbers met the tops of the piers at a moderate inclination, the outward thrust caused by unequal loading of the spans of the viaduct was inconsiderable, and was easily counteracted by light iron ties.

The stone for the piers was for the most part procured in the neighbourhood, the design of the masonry being such as to enable stone of the country to be used; and, as the timber superstructure was built in pieces of moderate size,[92] and easily obtained, the expenditure was probably not far from the minimum under the existing conditions.[93]

On the South Devon and Tavistock Railway, the viaducts are six in number, and from 62 to 132 feet in height. In these the piers were made of a somewhat simpler form than those just described. At the lofty viaducts, the buttresses were made with a uniform batter throughout their height. The Walkham viaduct, near Tavistock, 132 feet high, with fifteen openings of 66 feet span each, may be considered to exhibit the most matured design of Mr. Brunel’s timber viaducts.

On the West Cornwall Railway a type of viaduct similar to that described above was adopted; but as the general height was not so great, the spans were 50 feet each, and the longitudinal beams were supported at three points in each span, instead of at four as on the Cornwall Railway. In consequence of the nature of the foundations, the piers of the nine viaducts on this line were for the most part formed of upright timbers well braced together, standing upon masonry footings. The viaduct at Angarrack, 98 feet high, with 16 spans, which was constructed in 1851, was remarkable for its light appearance, owing to the small number of timbers in the superstructure and piers.

Mr. Brunel paid great attention to the preservation of the material of the timber bridges and viaducts. As early as 1835 he had been in communication with Mr. Faraday as to the best method of testing the extent to which the Kyanising solution penetrated into wood. Mr. Brunel made a careful trial of all the different methods of preserving timber, and employed the more successful of them on a very considerable scale. He was so impressed with the importance of the preserving processes being properly applied, that he on several occasions preferred to keep the operation of preserving the timber in the hands of the Company, in order that it might be done thoroughly, and under his own supervision. He also minutely attended to the details by which timber structures may be protected from decaying influences.

Cast-Iron Bridges.

Mr. Brunel did not make an extensive use of cast iron for the superstructure of bridges. His views as to the employment of this material in girders are clearly expressed in the following extract from a letter to one of the Directors of the Great Western Railway:—

The bridge at Hanwell referred to in this letter was one on the main line of the Great Western Railway, over the Uxbridge road. In 1847 the planking caught fire, and the cast-iron girders were destroyed by the heat.

The researches of Mr. Eaton Hodgkinson had drawn attention to the importance of a proper proportionment of the top and bottom flanges of cast-iron girders, and Mr. Brunel now made some experiments on this point. As part of this investigation, eight girders, 30 feet long and 16 inches deep, were tested by weights until they gave way. The comparative areas of the top and bottom flanges were varied until a correct proportion between the two was arrived at. The general result of these large-scale experiments showed a lower breaking-weight than that deduced from Mr. Hodgkinson’s formula.

When Mr. Brunel afterwards had occasion to use cast-iron girders, which was chiefly for road bridges over railways, they were made of the form which his experiments had shown to be the best;[94] but he repaired the Hanwell Bridge with wrought iron.

At about the same time the necessity for spanning wide openings had led to larger girders being required than could be manufactured in single castings, and Mr. Brunel had a large cast-iron girder made, 46 feet long and 4 feet deep, of five pieces bolted and keyed together. It was tested until it gave way with a load of 92 tons on the middle. The result showed that the several parts had been well connected, and that the strength of the beam was not much less than the calculated strength of a beam of the same size in a single piece. Mr. Brunel did not, however, use girders of this construction, as the rapid introduction of wrought iron rendered it unnecessary.

Cast iron was introduced, though not for girders, in many of the brick and stone bridges on the Great Western Railway. It was used in the form of troughs sunk into the crown of the arch in bridges where the headway was very limited. The rails were laid along the bottom of the trough within a few inches of the soffit or underside of the arch.

Although, after the careful experiments and investigations he had made, and the experience he had obtained, Mr. Brunel did not make use of cast iron for large girders, he looked forward to the possibility of such improvements being introduced into the manufacture as would enable sound castings of considerable size to be made of homogeneous material.

He expressed this opinion in a letter to the Secretary of the Commission on the Application of Iron to Railway Structures. This Commission (which Mr. Brunel called ‘The Commission for stopping further improvements in bridge building’) was appointed ‘for the purpose of inquiring into the conditions to be observed by engineers in the application of iron in structures exposed to violent concussions and vibration.’ Mr. Brunel, in common with most engineers, thought it would be very inexpedient that any règles de l’art should be laid down, and took up the cudgels boldly on behalf of the liberty of the profession:—

Wrought-Iron Bridges.

Notwithstanding the cost of wrought iron, but a short time elapsed between its introduction into bridge building and its use in structures of great magnitude. Mr. Brunel had been long familiar with the application of riveted wrought-iron work, and he was the first to encourage its use on a large scale in shipbuilding by recommending its adoption in the ‘Great Britain’ steam-ship in 1838.

Girder Bridges.

The strains on girders made of homogeneous material have been carefully and ably calculated by mathematicians; and the investigations thus made have directed inquiry into the right channels for determining the nature of the stresses on the several parts of the built-up structures now so much in use. Principles have by degrees been laid down, and lines of thought have been suggested and followed out which were unknown at the time when wrought-iron girders were first introduced in the construction of railway bridges.[96]

Shortly after Mr. Brunel began to use wrought iron for bridge girders, he made an experiment in order to determine the weak points of a large wrought-iron plate-girder. Mr. Edwin Clark, in his work on the ‘Britannia and Conway Tubular Bridges,’ vol. i. p. 437, gives a description of what he justly terms ‘this magnificent experiment.’ The girder was of the section shown in the woodcut (fig. 6), 70 feet in length, and of ¼-inch plate throughout. It was weighted gradually, and gave way with a load of 165 tons on the centre, by the tearing apart of the vertical web plate near the ends of the girder. When this portion had been strengthened, and the girder again loaded, it gave way with a load of 188 tons by the simultaneous failure of the top and bottom flanges, that is to say, of the plates forming the triangles shown in the woodcut.[97]

The superior tensile strength of wrought iron to that of cast iron, and the facility with which pieces could be joined together by riveting, enabled girders of great size to be made. The thin wrought-iron plates were arranged so as to form the top and bottom flanges of the girders as well as the upright web connecting them. The metal in the top of a girder being in compression, it was important so to dispose it that it should resist the tendency to yield sideways under the strain. This requirement was met in the experimental girder by the triangular section of the top flange; and the convenience of this form for joining together a number of plates, without difficulty or the use of long rivets, led Mr. Brunel to use the triangular section also for the bottom flange.

Subsequent improvements in the facilities for bending wrought-iron plates enabled him to use a form of cross section of wrought-iron girder, the top flange of which was a nearly circular tube, the best shape of strut to resist longitudinal compression. It is shown in the woodcut (fig. 7), and was used in many of his bridges.

This form was afterwards modified to that shown in fig. 8. The semicircular top plate is stiffened by occasional cross diaphragms, and while it was a good form to resist compression, it was more easily painted than the closed-in top flanges shown in figs. 6 and 7.

The forms of wrought-iron girder already referred to are those known as plate girders, with continuous webs made of plates riveted together, and therefore analogous to the beams of cast iron which they almost entirely superseded. On Mr. Brunel’s railways there are a great number of bridges of these forms of girder, where the spans do not exceed 100 feet. For larger spans he used wrought iron, in large and deep trussed frames, by which means a great degree of economy was attained in the employment of the material.

The care which he had taken to satisfy himself of the action of the strains in plate girders was of service in all the greater structures he designed, as in all of them he employed wrought-iron girders to carry the roadway, of a type somewhat similar to those already described, the girders being supported at frequent intervals by the main framework or truss.

Opening Bridges.

The first large opening bridge which Mr. Brunel constructed was a roadway swing bridge, 12 feet wide, across the new lock at the Bristol Docks. The length of the overhanging end is 88 feet, and the other, or tail end, which is 34 feet long, rests upon two wheels, which travel on a circular rail. The weight of the overhanging end is rather more than counterbalanced by large blocks of cast iron, forming part of the pavement of the tail end. Almost the whole weight is borne on a centre pivot, assisted by four wheels in fixed bearings, upon which runs an inverted circular rail attached to the underside of the bridge. On the pivot, which rests on a large cast-iron bed-plate, are two discs, one of steel and the other of brass, which can readily be lubricated, or taken out and renewed.

On the sides of the bridge are longitudinal wrought-iron plate-girders. The top flange is pear-shaped, and the bottom flange triangular, having three curved plates. The flanges are connected together by a vertical plate web of wrought iron. The section is shown on the woodcut (fig. 9). It admits of very simple riveting, without the use of angle irons. The form of the bottom flange is suited to the compressive strain it has to bear when the bridge is being moved. The top flange has also wrought-iron tie-bars within the tube. When the bridge is across the lock and open for traffic, the overhanging end rests on cams, which are tightened up so as to lift and support the ends of the girders. As the bridge rests almost entirely on a pivot of small diameter, it turns with great ease.

Near Gloucester there are two skew swing bridges somewhat similar to each other in arrangement. Almost all the weight while turning is supported on the piston of a hydraulic press, and the bridge therefore turns round on the water in the cylinder. The first bridge is on the main line of railway leading to South Wales, across a branch of the River Severn, and is for two lines of way. It has three girders, 125 feet long, of the form shown in fig. 7 (p. 194). The water pivot is in the middle of the length of the bridge, which spans two openings of 50 feet on the square. Before being turned the bridge was intended to be lifted slightly off its bearings by the hydraulic press, and steadied by four wheels, on which a portion of the weight was to be made to rest by long springs within the girders, the range of which was to be limited in one direction by a fixed stop. The central pier consists of five cylinders of cast iron, each 6 feet in diameter, filled with concrete, surmounted by a cast-iron ring or roller path. The railway company was obliged to make this an opening bridge in order to provide for the free navigation of the river should the old stone bridge lower down be altered. This has not been done, and the railway swing bridge, constructed in 1851, has not yet been opened.

The other swing bridge at Gloucester is on the Dock branch, for one line of way, with an opening of 50 feet on the square, the overhanging length of the girders being 70 feet. While raised from its bearing and turning on its water pivot it is steadied by two tail wheels, like the bridge at the Bristol Docks.

On the Bullo Pill branch of the South Wales Railway there is a small wrought-iron drawbridge, for one line of way, of 30 feet span. It is a lifting bridge on the bascule principle, like many bridges over canals in this country and in Holland. The opening part turns on a horizontal axle, and is lifted by rods attached to the ends of two large beams or levers, turning vertically, which are supported above the railway on a timber framework. At the other ends of these beams is a counterbalance weight. The bridge is opened or shut by pulling down either end of the beams with a small chain.

The other bridges are on the main line of the South Wales Railway, and are four in number, each for two lines of way.

One at Loughor is a wrought-iron swing bridge, of 30 feet opening, of the ordinary construction, with girders 90 feet in length, resting upon 36 rollers, which are secured in a ring concentric with the pivot. The opening and closing is effected by means of a crab, fixed clear of the bridge, near the centre. A chain passes from the overhanging end of the bridge to this crab, and taking one or two turns round the barrel, to ensure a sufficient amount of friction, is led to the tail end. The bridge can thus be opened or shut by turning the crab handle in opposite directions. The overhanging end, when across the river, is raised upwards to a small extent by weighted levers, and wedges are then drawn in under it to give it a solid bearing.

At Kidwelly and at Haverfordwest there are wrought-iron lifting bridges, the former of 20 feet, and the latter of 30 feet span. Each of these turns on a horizontal axle like the Bullo Pill bridge; but, instead of being lifted by levers overhead, it has a narrow, heavily-weighted tail end, beneath the planking of the viaduct, which is pulled down with a chain worked by a crab. The portion which carries each line of way is made to open independently. In this form of bridge no wedges or adjusting arrangements are required for the bearings of the overhanging end.

Over the river at Caermarthen is a skew bridge of three girders, each 116 feet long, for a double line of way. It occupies two spans and rolls back, so as to leave a 50-feet opening for the navigation. The swing bridge at Bristol, already described, was at first intended to be a rolling bridge, and to be furnished with wheels to run back on fixed rails, but the difficulty of forming a good foundation for the wheel path led to the design being altered. At Caermarthen the same difficulty was overcome by putting wheels turning in fixed bearings on the pier and abutment of the bridge. The undersides of the girders carry inverted rails, and run back on the wheels. The bridge, when shut, is on an incline of 1 in 50. When about to be opened it is made to assume a horizontal position by turning a supporting cam to lower the overhanging end, and the tail end then rises sufficiently to pass clear above the part of the railway over which it runs back.

By this arrangement the bridge, while in motion, moves along a level path. It is opened and closed by hydraulic machinery.

All these opening bridges have worked satisfactorily since they were constructed.

Trussed Bridges.

When the timber viaduct over the river Usk, at Newport, was burnt down,[98] Mr. Brunel decided to form the new superstructure of the centre opening with three iron trusses, for the two lines of way.

These are bow and string girders, of 100 feet span, and were made of considerable height, not only to reduce the strain on each of the members of the framework, but also in order that the rib or upper portion of each truss might be braced diagonally to the corresponding portion of the other trusses, and headway left for the locomotive chimneys to pass underneath. This bracing counteracts any tendency of the ribs to bend sideways under the compressive strain. The form of the trusses is shown in fig. 1, Pl. IV. (p. 206). Each truss is a wrought-iron polygonal arch of triangular section, from which is suspended a horizontal girder supporting the roadway. This girder also forms the tie which connects the feet of the arch and counteracts its thrust. The diagonal braces shown on the elevation of the bridge prevent the arch from being distorted by the unequal loading caused by a passing train. The middle truss is twice the strength of each of those at the outside, being made so by increasing the thickness of the plates. One of the outside trusses was tested with a distributed load of 1½ tons per foot-run of its length.

At about the same time that the Newport viaduct was reconstructed, Mr. Brunel designed the bridge over the Thames on the Windsor branch of the Great Western Railway. This is a very large example of the bow and string girder, the span being 202 feet, and the height of the truss 23 feet. The trusses are three in number, for two lines of way, the middle one being twice the strength of the outside trusses. The elevation of the Windsor bridge is shown in fig. 2, Pl. IV. (p. 206). The bridge is oblique to the river, being 20° off the square. To steady the arched ribs sideways a system of diagonal bracing extends over the whole of the top of the trusses, except at the ends, where headway has to be left for the trains.

A section of the arched ribs and of the roadway girders in the centre of one of the trusses is given in the woodcut (fig. 10). The arched rib, to resist compression, is of triangular section.[99]

The borings to ascertain the nature of the ground at the foundations of the piers were made in 1846, but it was not until 1848 that the works were commenced. Each abutment consists of six cast-iron cylinders, 6 feet diameter, which were sunk by excavating the gravel from their interior by hand dredging and by placing weights on the top so as to force them down.

When each cylinder had been by this means sunk low enough to ensure a good foundation, it was filled with concrete in the following manner. A mixture formed of Thames ballast and Portland cement, in the proportions of 8 to 1, was put into a canvas bag; this was lowered inside the cylinder to the bottom, and, by pulling a rope, the mouth of the bag was opened, and the concrete deposited under water in the bottom of the cylinder. Whenever the work was interrupted, great care was taken before recommencing it to clean off any deposit, in order that the new concrete might adhere well to the old. When the cylinder had been filled to such a height that there was no danger of its floating up when emptied, the water was pumped out. The inside was then filled with concrete in the ordinary manner. On the top were placed oak platforms, which support the trusses of the bridge.

One of the outside trusses was tested at Bristol in July 1849, by loading it gradually with iron rails, beginning from one end, until the whole truss was uniformly weighted with 270 tons, or 1½ tons per foot-run, observations on the deflection of different points of the bottom girder being made both during the loading and unloading. The results of this test were perfectly satisfactory.

The superstructure of the bridge was erected on scaffolding, and the line was opened on October 8, 1849.

It will be desirable here to notice one or two important features in this as in almost all Mr. Brunel’s bridges.

The ordinary permanent way was laid over the bridges with ballast of sufficient thickness to enable the road to be kept in repair in the same manner as the other parts of the line. As there was no change in the nature of the support given to the rails, no concussion was caused on a train entering or leaving a bridge. The ballast took off from the structure the vibration of the train; and, in the event of carriages or even engines getting off the line, it helped in a great measure to prevent their ploughing through the flooring. Where the flooring was of timber the ballast protected it from fire. Also in long bridges there was no necessity for any contrivance of sliding rails to allow for the effects on the structure of changes of temperature. On the other hand, the ballast added to the weight on the bridge. With the timber viaducts this was an advantage, since it kept the various parts of the framework in close contact, and prevented sudden jars being brought on them by the rapidly applied load of a passing train. Even on the large bridges the cost of the extra material requisite to support the weight of the ballast was more than compensated for by the advantages above referred to.

Mr. Brunel employed timber flooring, as being the safest in the case of carriages getting off the line, and also as being the cheapest. This flooring in the iron bridges was generally laid diagonally on wrought-iron cross girders, which were placed not at right angles to the line, but obliquely, in order that the two wheels of the same axle of an engine or heavy waggon might be on different cross girders at the same time. By this arrangement the cross girders could be made of less strength, and a saving effected in their cost and weight.

The bridge over the Wye at Chepstow, and the Royal Albert Bridge over the Tamar at Saltash, are the largest and most important of Mr. Brunel’s bridges.

They are remarkable not only for their dimensions, but also for the economical character of the designs, the form of their superstructures, and the methods by which the foundations of the piers were made.

At the part of the river Wye where it is crossed by the Chepstow Bridge, a cliff of limestone rock rises on the left bank to a height of 120 feet above the bed of the river, forming the precipitous edge of a broad table-land; while on the right bank the ground slopes gently for a considerable distance, rising only a little above high water, and is composed partly of clay and partly of loose shingle interspersed with large boulder stones. As it was necessary to leave a clear headway of 50 feet above high water for the navigation, the line on one side of the river is on an embankment of great height, and on the other side it penetrates the cliff about 20 feet below the top. The whole space to be bridged over, 600 feet wide, was divided into a river span of 300 feet, and three land spans of 100 feet each (see fig. 3, Pl. V. p. 206.) At one end of the great span a secure abutment was offered by the cliff of limestone rock; but at the other end, and under the piers of the smaller spans, the ground throughout was soft, and full of water. There was, however, rock at a depth of 30 feet below the bed of the river.

To reach this foundation with masonry, by means of a coffer dam, was almost impracticable, as it was 84 feet below high water.

The plan of building a stone pier on a foundation of piles was considered, and abandoned on account of the expense.

The method of sinking the cast-iron cylinders of the Windsor bridge has been already described. The pneumatic process of sinking cylinders had been introduced with great success at the Rochester bridge.

In this process the cylinder is closed at the top and air forced in by pumps until the water is expelled at the bottom. Workmen in the interior excavate the ground and remove any obstacles which prevent the cylinder from sinking, weights being added to force it down. As the air within is at high pressure, the workmen enter, and the materials are passed in and out, through an intermediate chamber, called an ‘air lock,’ fitted with air-tight doors. The pneumatic method was ultimately employed at Chepstow, to assist in sinking the cylinders.

Before he decided on the plan for the foundations, Mr. Brunel had an experimental cylinder made of cast iron, 3 feet in diameter, at the bottom of which was an exterior screw flange 12 inches broad, and 7 inches pitch, making one complete turn. This screw cylinder penetrated the ground like an ordinary screw pile. In one instance it was rapidly sunk to a depth of 58 feet, through stiff clay and sand, in 142 revolutions;[100] yet, on another trial, when boulders were encountered, there did not appear to be sufficient penetrating power. In one of these trials, the screw, having got into a bed of running sand, had no hold, and failed to descend. Mr. Brunel then had the cylinder partly raised, and another screw added at some distance above the lower one. It was then successfully screwed down.

Mr. Brunel, however, ultimately decided on forming the piers of cast-iron cylinders forced down by loading and afterwards filled with concrete, and the work was commenced in the spring of 1849.

With this form of construction all uncertainty of obtaining a secure foundation was removed, as the pneumatic method was in reserve, in case of excessive influx of water, to sink the cylinders to the rock, if it could not be reached by simpler means; and additional cylinders could be added, so as to obtain any amount of area of base that might be thought necessary.

The land piers for the 100 feet spans consist each of three cylinders, which are 6 feet in diameter, joined together in lengths of 7 feet. The main pier, which supports one end of the great truss, consists of a double row of cylinders, six in all, the lower parts of which are 8 feet in diameter, joined together in lengths of 6 feet. The bottom of each cylinder was made with a cutting edge, so as to penetrate the ground easily.

Most of the cylinders were sunk by the process of excavating the ground within them and weighting the top, the water being kept down by pumping. As the ground consisted chiefly of wet sand and shingle, danger was apprehended from its tendency to run in from the outside, while the excavation was in progress. This would have diminished the lateral stability of the cylinders; and great care was taken not to excavate too near the bottom, but merely to loosen the ground round the cutting edge and to force the cylinder down by weights. Stiff clay was sometimes used to prevent the wet sand and gravel from being squeezed in from the outside. When the cylinders had been sunk to the rock, and it had been dressed off to form a level foundation, they were filled with concrete in the same manner as at the Windsor bridge.

In sinking the cylinders of the main pier, much greater difficulties were encountered than with those of the land piers, owing to large boulders and pieces of timber being met with near the bottom. When still at some distance from the rock, a length of one of these large cylinders cracked, from its having met with an obstruction. Timber struts were then fixed within it, until the obstacle was passed, when it was strengthened by a strong wrought-iron hoop, and forced down to the rock.

In April 1851, when the greater number of the cylinders had been sunk, it was apparent that, from delays due to the influx of water and other causes, some of them could not be completed by the time that the superstructure would be ready. Mr. Brunel then decided to employ the pneumatic method, and by means of this apparatus some of the remaining cylinders were sunk. In the main pier four auxiliary columns, formed of 7-feet cylinders, were placed close to the others. They were connected to the 8-feet cylinders by strong brackets, and supplied a great additional bearing surface. Any slight inaccuracy of position in the cylinders was corrected by adjusting cones at the level of the ground; on these cones 6-feet cylinders were built up to the level of the railway.

The depth to which the cylinders were sunk and their position are shown in fig. 3, Pl. IV. From this drawing also the general form of the superstructure will be understood.

The bridge is for two lines of way; each line is carried between two longitudinal girders 7½ feet deep, of the section given in the woodcut, fig. 11 (p. 208). Each girder has a triangular top flange with a plate iron vertical web, and a slightly curved plate for the bottom flange. The roadway girders over the three land spans of 100 feet are in one piece, and are therefore continuous girders, 300 feet long, supported at two intermediate points. Those across the main span are also 300 feet long, and are supported by the main truss.

PLATE IV
IRON BRIDGES

[Larger view]
[Largest view]

The truss for each line of way consists of two suspension chains, one on each side of the roadway, hung from either side of the ends of a horizontal circular tube, arched slightly for the sake of appearance, which rests on piers rising about 50 feet above the level of the rails. The pier at the land end is of masonry, and the upper part of the middle pier is of cast iron, resting on the cylinders already mentioned. Each pier has two archways for the trains to pass through. The chains carry the roadway girders at four points, and the tube is supported at two intermediate points in its length by upright standards resting on the chains. Thus, while the weight of the structure is supported somewhat in the same manner as in a suspension bridge, the inward drag of the chains is resisted by the tube. To prevent the framework from being distorted by unequal loading, it is made rigid by diagonal chains connecting the upper and lower ends of the two upright standards.

The main truss may be described as an inverted queen truss. The tube which has to resist the compressive strain due to the inward pull of the chains is 9 feet in diameter, and is made of boiler plate ¾ and ⅝ of an inch thick, stiffened at intervals by diaphragms. The chains are like those of suspension bridges, each formed of 12 and 14 links alternately, these being 10 inches deep, and varying from ¾ to ¹¹/₁₆ of an inch thick.[101]

At the ends of the tube, where the chains are connected to it, there are several thicknesses of plate, between which the links of the chains are introduced, and a round pin, 7 inches in diameter, passes through both plates and links. The strain is thus conveyed from the chains to the ends of the tube.

Though the trusses for the two lines of way are completely distinct, the tubes are braced together horizontally, to increase their stiffness sideways.

The woodcut (fig. 11) represents a transverse section of the truss for one line of way, and shows the circular tube with the internal diaphragms, the upright standards which support it, the roadway girders, and the chains.

In consequence of the great depth of the truss, which is about 50 feet, or one-sixth of the length, the strains on the several parts are comparatively small for such a large span.

The weight of wrought-iron work in each of the trusses of the main opening is 460 tons, inclusive of the longitudinal and cross girders, which weigh 130 tons.

At the points where the roadway girders are intersected by the inclined chains, they are not fixed to the chains, but rest upon them, rollers and saddles being placed between; and at the ends of the short horizontal links, in the middle of the span, there are screws for adjusting the level of the girders.

These arrangements were made in order that the roadway girders might not be strained by the slight alteration in the form of the truss which takes place when a load comes on the bridge.

The continuous roadway girders were, in the case of the large span, supported at six points, and in those over the three land spans at four points. As the strains on continuous beams, supported at so many points, had not at that time been fully investigated, Mr. Brunel had the subject carefully enquired into both by calculation and experiment, and was thus enabled to proportion the section of the girders to the strains at each point in their length. Some account of this investigation is given in the note at the end of this chapter.

As soon as the ironwork for the first truss was completed, it was put together parallel to the river bank close to the site of the bridge. The ends were supported on temporary piers, and the structure was uniformly weighted with a load of 770 tons, or 2¾ tons per foot run. In unloading it, the weight was taken off from one end of the truss, so as to test its strength when unequally loaded. The testing having been satisfactorily completed, the truss was taken to pieces, and preparations were made for erecting it.

It was necessary that the river traffic should not be interrupted for any long period; this circumstance materially influenced the nature of the design of the superstructure, which was such that no scaffolding was required in its erection, nor was there any interference with the navigation for more than a single tide. The truss was made so that it could be divided into parts, each of which could be lifted separately and quickly. For the operation of lifting Mr. Brunel determined to use chain purchases worked by crabs.[102] The tube was temporarily stiffened by portions of the main chains, arranged so as to form a truss. With this assistance it was able to carry its own weight when suspended by the two ends.

The preliminary operation of slewing the tube to its position on a platform at right angles to the river, was a work requiring a good deal of careful contrivance. When this had been accomplished, a pontoon, consisting of six wrought-iron barges, was placed opposite the end of the tube, and all was ready for floating it across the river.

The floating took place on Thursday morning, April 8, 1852. The tube had been rolled forward on two trucks till its end overhung the pontoon; and, as the tide rose, the pontoon floated with the end of the tube resting on it. In order to guide it in a straight line across the river, hawsers were attached to points on the bank up and down the stream, and were led to crabs on the pontoon, so that by hauling on either hawser the tube was kept in its right course. As spring tides at Chepstow rise 40 feet, there is a rapid current except for a very short time.

The operation of drawing the tube across was commenced at a little after nine o’clock, and by a quarter to ten the pontoon had reached the other side safely, and the tube spanned the river. All proceeded with perfect quiet and regularity under the management of Mr. Brunel, who was assisted by Mr. Brereton and Captain Claxton. As soon as the pontoon reached the further shore, the chains of the lifting tackles were attached to the tube. The tube was lifted in the course of the day to the level of the railway, and afterwards to its place on the top of the piers, when the suspension chains and the rest of the truss were attached to it. The bridge was opened for a single line of way on July 14, 1852. The second tube was floated in a similar manner to the first, and the bridge was completed shortly afterwards.

The total cost of the Chepstow bridge was 77,000l.[103]

The Royal Albert Bridge, which carries the Cornwall Railway across the River Tamar at Saltash, is the last and greatest of Mr. Brunel’s railway works.

A railway into Cornwall, crossing the river Tamar, was proposed as early as 1844. Mr. Brunel at one time thought of carrying the trains across on a steam ferry similar to those which had been successfully introduced by Mr. Rendel.

In 1845 a company was formed and an application made for an Act to construct the railway either with a steam ferry at Torpoint or by a bridge at Saltash. The latter plan was sanctioned by Parliament.

The height of the line shown on the section at the crossing of the Tamar was 80 feet above high water. The Admiralty, however, required that this height should be increased. No further steps were taken till the beginning of 1847, when some preliminary borings and sections were made, in order to prepare definite plans for the bridge. The facts then ascertained were so encouraging as to strengthen Mr. Brunel in his opinion that the difficulties to be encountered would not be found greater than had been anticipated.

The river at Saltash is 1,100 feet wide, with a depth in the middle of about 70 feet at high water. It had at first been intended to construct the bridge with one span of 255 feet, and six of 105 feet, with superstructures of timber-trussed arches.[104] In compliance with the requirements of the Admiralty, the design was altered to two spans of 300 feet, and two of 200 feet, with a clear headway of 100 feet. This arrangement would have required three piers in deep water. Mr. Brunel subsequently decided to have only one pier in deep water, and to have two spans of 465 feet each. It was afterwards found that these could be reduced to 455 feet.[105]

Twenty years before, while engaged with his father on the Thames Tunnel, he had conceived the idea of working under a diving-bell of great dimensions. Sir Isambard approved of the suggestion, and thought of applying it in sinking the shafts of the Tunnel. Drawings were prepared, but the circumstance of a patent for a similar idea having been taken out by Lord Cochrane partly deterred him from carrying out the project, though some sketches were afterwards made for constructing a lighthouse by means of this arrangement. When the construction of the Cornwall Railway had to be considered, Mr. Brunel thought that his old idea would be applicable to the difficulties to be encountered at Saltash.

Although the plan of using a large diving-bell was one which was nearly certain to be successful, Mr. Brunel thought it probable that a large cylinder of wrought iron could be constructed to serve as a coffer-dam, and that after sinking it through the mud, the bottom edge might be sufficiently water-tight to admit of the water being pumped out, and the masonry of the pier built in the ordinary manner.

A trial cylinder, 6 feet diameter and 85 feet long, was made, partly to ascertain whether or not this plan was practicable, but mainly for the purpose of thoroughly examining the site of the centre pier, where the surface of the rock was 80 feet below high water.

A strong framework was fitted on two gun-brig hulks, with powerful tackle for lowering and raising the cylinder. After it had been lowered to the bottom, five borings were taken within it, reaching through the mud to the rock. The cylinder was then shifted and similar borings made.

The positions of the borings, one hundred and seventy five in all, were carefully recorded; and thus a minute and accurate survey was obtained of the surface of the rock. The site of the pier was afterwards determined by means of a model constructed from these observations. In January 1849, when sufficient information had been obtained, the water was pumped out of the trial cylinder, and the mud excavated down to the rock. A short piece of masonry was then built, to demonstrate the practicability of building a pier in such a situation.

The expenditure of the Company for works of all kinds was shortly afterwards curtailed as much as possible, and no further progress was made for upwards of three years. However, information had been gained which proved that a masonry pier could be built in the middle of the river, on a good rock foundation which was there covered by a thickness of about 16 feet of mud.

During the suspension of the works, all the plans were revised, with the view of reducing the first cost wherever practicable; and Mr. Brunel decided not to make the bridge for a double line, even if there were money forthcoming to do so. His reason for this is given in the following report to the Board of Trade, made in 1852:—

In the summer of 1852 the designs of the bridge were matured, and by the beginning of 1853 the Admiralty had approved of them; the work of constructing the great cylinder for the centre pier was then commenced.

It was determined to provide for the possibility of having to employ the pneumatic process. The cylinder had a diameter of 35 feet at the bottom, and about 20 feet above the lower end of it a dome was made to form the roof of the diving-bell; from the centre of the dome rose a tube 10 feet in diameter to the level of the top of the great cylinder. As a diving-bell of this size, under 80 feet of water, might have proved unmanageable, an annular space, forming a gallery or jacket of 4 feet in width and 20 feet high, was formed round the inner circumference of the bottom of the cylinder below the dome. This annular space was divided by radial vertical partitions into eleven compartments, and was connected at the top by an air-passage with a 6-foot cylinder, which was placed eccentrically inside the 10-foot cylinder already mentioned, and served as a communication between the outside and the annulus. On the top of the 6-foot cylinder were placed the air-locks of the pneumatic apparatus which had been used at Chepstow. Thus air might be pumped into the annular space, the water expelled, and the work carried on without having to use air pressure under the whole of the dome. In that part of the 10-foot cylinder which was not occupied by the 6-foot cylinder a powerful set of pumps were fixed to keep down the water in the central space, and diminish the pressure under which the men worked, thus utilising whatever advantage could be gained from the great cylinder acting as a coffer-dam. As it had been ascertained that the surface of the rock dipped to the south-west to the extent of about 6 feet in the width of the pier, the bottom of the cylinder was made oblique, so as to fit the surface of the rock. These arrangements are represented in the transverse section of the great cylinder (Pl. V. p. 218).[106]

The great cylinder, having been constructed on the river-bank, was moved down to low water on launching-ways, and floated off by the rising tide. Guided between four pontoons, it was finally sunk in correct position in June 1854.

Some delay in penetrating the mud was caused by a bed of oyster shells, which had to be cut through by one edge of the cylinder. In consequence of some irregularities of the surface of the rock, the cylinder at first deviated considerably from an upright position; and it was necessary to use the pneumatic apparatus to gain access to the rock, and excavate it. The height of the annulus below the dome was such that it was not quite filled by the mud when the cylinder rested on the bottom. The work of getting the mud out of the annular space was much facilitated by the division of it into compartments.

By February 1855, the cylinder had been sunk to its full depth in an upright position, and it then rested everywhere on the rock, its lowest point being 87 feet 6 inches below high water.

Much trouble was given by a spring of water issuing out of a fissure in the rock, in one of the compartments, but the flow was stopped by driving close sheet piles into the fissure. The rock in the annulus was dressed, and the space filled by a ring of granite ashlar masonry which was built to a height of about 7 feet all round. The state of the work at this time is that represented in the section of the cylinder, (Pl. V. p. 218).

The rock consisted of greenstone trap, so hard that tools could with difficulty be got to work it. When the ring of masonry was completed, it was expected that the bottom might be sufficiently water-tight to act as a coffer-dam, and allow of the mud being taken out from the central part of the cylinder, below the dome. But the pumping power was not at first sufficient for this purpose, and it was thought that it would be necessary to employ the pneumatic process in this space also.

However, by rapid and incessant pumping the water was lowered so as to allow of the mud and rock being excavated, and the masonry in the central space built without having again recourse to the use of air pressure. The leakage water was conveyed to two wells, formed of cast-iron pipes built into the masonry, from which the water was pumped. The inner plates of the annulus were cut out, and the work in the centre which consisted of granite ashlar set in cement was thoroughly bonded into the ring of masonry already built. When the work was carried up to the level of the dome, both the dome and the internal 10-foot cylinder were cut out and removed. When the building had been carried up some height, the pump wells were filled with cement concrete, and the influx of water stopped. Finally, about the end of 1856, when the masonry was completed to the cap of the pier, the upper part of the great cylinder was unbolted and taken ashore, it having been made in two halves with that object. Thus the most difficult part of the undertaking was successfully completed.[107]

The centre pier of the Saltash bridge is, like many great engineering works, out of sight, and little regarded by any but professional men. The rest of the bridge forms a striking feature in a beautiful landscape, and its appearance is well known.

The whole length of the bridge is about 2,200 feet, and is divided into two great spans over the river of 455 feet each and seventeen side spans, varying from 70 to 90 feet, which are on sharp curves. The piers of the side spans, as well as the two large piers carrying the land ends of the main trusses, are of masonry. The masonry of the centre pier is 35 feet in diameter, and is carried up about 12 feet above high water level. On it stand four cast-iron octagonal columns, rising up to the level of the railway. The piers which support the ends of the great trusses are constructed with arched openings, through which the trains pass.

The transverse elevation of the centre pier (Pl. V.) shows the octagonal columns connected by cast-iron open-work, and the arched opening. The upper part of the centre pier is a cast-iron standard, and that of the land piers is of masonry cased with cast iron.[108]

The elevation shows the great height of the structure, the rails being 190 feet and the highest part of the truss 260 feet above the lowest point of the foundations.

The railway is carried over each of the smaller openings between two longitudinal girders, and over the main spans it is carried between similar longitudinal girders, which are suspended at intervals from the main truss.

PLATE V
THE ROYAL ALBERT BRIDGE

[Larger view]
[Largest view]

Each truss consists of a wrought-iron oval tube, which forms an arch, and of two suspension chains,[109] one on either side of the tube, connecting its two ends. The rise of the arched tube above its abutments on the top of the piers is the same as the fall of the suspension chains below the same level. At eleven points in the length of the truss the chains are connected to the tube by upright standards, which are braced together by diagonal bars, in order to resist the strains due to unequal loading. The roadway girders are suspended from the truss at the upright standards already mentioned, and at an intermediate point between each of them.

The truss has the great depth of 56 feet in the centre; this conduces materially to the economy of the construction, as it diminishes the strain upon the principal parts, the tube and the chains, and so enables them to be made of smaller dimensions.

The woodcut (fig. 12) is a transverse section in the centre of the truss, showing the oval tube, the chains, the upright and standards, the roadway girders.

The tube is made oval in section with the greater diameter horizontal, in order that it may have stiffness sideways under the compressive strain, and that the main chains may hang vertically at such a distance as to leave room for the roadway between them. The tube is 16 feet 9 inches broad and 12 feet 3 inches in height. Each chain consists of two tiers of links, each tier formed of 14 and 15 links alternately. These are 7 inches deep and about 1 inch thick. The arrangements of the ironwork of the tube and its connections with the main chains are generally similar to those at Chepstow.

The truss may be described as a combination of an arch and a suspension bridge, half the weight being placed on the one and half on the other, the outward thrust of the arch on the abutments being counterbalanced by the inward drag of the chains.

The mechanical arrangement of the Saltash truss is similar to that of the one at Chepstow.[110] The tube, resting on standards, the railway passing beneath, the suspension chains hung from either side of the tube, the upright standards, and the diagonal bracing are common to the two structures.

The difference in the form of the two trusses is principally the result of the difference in the circumstances attending the construction of the bridges at Chepstow and Saltash. The design of the Chepstow truss was chiefly determined by the necessity of lifting up the separate parts of it under conditions of peculiar difficulty; while at Saltash the mode of floating and lifting the superstructure had great influence in the preparation of the design.

On Plate V. (p. 218) is given an elevation of one span of the Saltash bridge, and a general elevation on a smaller scale of the whole bridge.

The total weight of wrought ironwork in the superstructure of each span is 1,060 tons.[111]

The trusses at Saltash were not lifted in parts, as at Chepstow; for, as the river was divided by the centre pier into two openings, one of them could be left clear for the navigation, and each truss, with its roadway girders attached, could be raised to its position slowly and in one piece. The trusses were constructed parallel to the river on the Devonshire side, close to the site of the bridge. When the truss for the Cornwall or western span was completed, temporary piers were erected to support the ends, and the scaffolding having been removed, the roadway was loaded with 1,190 tons, uniformly distributed.[112]

This test having proved satisfactory, preparations were made for floating the truss. Docks were made underneath it near the two ends, and in each of these docks two iron pontoons were placed. Valves were then opened to admit water, and the pontoons were allowed to sink on timbers prepared to receive them.

Upon each pair of pontoons was erected an elaborate framework of timber to carry the weight of half the truss, or between 500 and 600 tons. The framework consisted of stout timber props, some of them 40 feet long, extending from the pontoon to the arched tube, and was attached to the tube by iron suspension rods, so that when the operation of floating was completed, the pontoons would be free to pass from underneath the truss.

Mr. Brunel had previously taken part in operations of this nature. When Mr. Robert Stephenson was about to undertake the floating of the tubes of the Conway and Britannia bridges, he asked his friends Mr. Brunel and Mr. Locke to give him their assistance. They were present at all, or nearly all, these difficult operations, and Mr. Brunel had an active share in the work, especially in the floating of the first Conway tube. By Mr. Brunel’s advice Mr. Stephenson had obtained the services of Captain Claxton to superintend the nautical part of the work; and Captain Claxton was, as a matter of course, with Mr. Brunel in a similar capacity at Chepstow and Saltash.

At Saltash fortunately there was not so swift a tide as there had been at the Britannia and Conway floatings.

In order to haul the truss out, warps were laid from the pontoons to a gun-brig hulk near the centre pier, and to a barge higher up the river. On this barge were also placed ready for use the ends of four warps, leading to capstans and crabs on board vessels moored at various points. To keep the truss from being drifted up or down the river while being moved out, radius lines were laid from the pontoons to moorings, with arrangements for hauling in on them if required.

In order to ensure his directions being clearly understood and promptly attended to, Mr. Brunel assembled a number of his assistants, one of whom was placed as ‘Captain’ in each of the vessels containing the hauling capstans, to superintend the men, and to execute orders. These orders were given by signals.

It was most important that the attention of the captain should not be diverted by looking out for the signals, and that there should be no chance of a signal not being seen by him because he was attending to some other of his duties. There was, therefore, in each vessel an assistant whose sole duty it was to watch for the signals, to give the appropriate interpretation to the captain, and to acknowledge the signal by a flag corresponding to that by which it was given.

Mr. Brunel directed the operations from a platform in the centre of the truss. The signals were given from a smaller platform immediately above, and were made by red and white flags, held in front of black boards, which were turned towards the vessel signalled to. Printed papers containing instructions were distributed to all engaged; the signalling was carefully rehearsed, as also was every other part of the operations which could be tried beforehand.

September 1, 1857, was the day fixed for the floating. During the morning, the men, about 500 in number, assembled at their stations on the vessels and pontoons. Captain Claxton had command of the arrangements afloat, and as a reserve force to act in any emergency several boats were lent from H.M.S. ‘Ajax’ and the Dockyard. With Mr. Brunel were Mr. Brereton and Captain Harrison, the commander of the ‘Great Eastern.’ Mr. Robert Stephenson was expected, but a serious attack of illness prevented him from being present.

At about one o’clock in the afternoon signals from the tops of the temporary piers on which the truss rested, showed that the ends had been lifted three inches clear. Mr. Brunel then gave the signal for the men in the pontoons to haul on the warps, and the great structure glided slowly out to the centre of the river. A pause was then made, while the warps which were to swing the truss round into its place were being attached to the pontoon which was farthest from the centre pier. When this was done, the different ropes were hauled upon in obedience to signals, so as to keep the other pontoon close to the centre pier, upon which, as a pivot, the truss swung round in a quarter circle till it occupied the whole of the western half of the river, and was brought close to its appointed resting-place. It was finally adjusted to its exact position by strong tackles attached to the piers. Water was then admitted into the pontoons; and, as the tide fell, they were allowed to drift away, leaving the truss resting on the piers, the roadway girders being but a few feet above the water.

The whole operation was conducted with the most perfect order and regularity. The beauty of the scenery and the changing effect produced by the truss in the various positions it assumed as it was being moved forward and swung round into its place, rendered the operation as interesting to the spectators as its results were satisfactory to Mr. Brunel and to those who assisted him.[113]

In the task of lifting the truss, as well as in that of floating it, Mr. Brunel had the great advantage of the experience gained at the Britannia Bridge. There the piers were built first, and the tubes hauled up with link chains by hydraulic presses placed on the tops of the towers. The design of the piers at Saltash did not allow of this plan being adopted, and they were built up under the truss as it was lifted. Under each end of the truss were three hydraulic presses; the two outside presses combined, or the middle one by itself, were sufficient to lift the weight. Mr. Brunel had also at first intended to have strong screw-jacks, which were to be kept screwed up underneath the truss, and so to support the weight, if by any accident the presses failed. A modification of this plan was adopted; the rams of the presses had a screw thread cut on them, and a large nut on each was kept screwed up hard against the top of the press as the ram emerged from it. As an additional precaution, timber packing, in thin layers, was placed in the space between the completed portion of the pier and the end of the truss as it was lifted. Great care was thus taken to guard against any mishap.

The tube was lifted 3 feet at a time at each end. The operation went on slowly, in order to allow the masonry of the land pier to set after it had been built up underneath the truss. The work was carried on with great system and care under the immediate superintendence of Mr. Brereton. Mr. Brunel was only able to be present during one of the lifting operations, as he was then engaged in the launch of the ‘Great Eastern.’

By July 1858, the first truss had been lifted to its full height, and the second truss was ready for floating. The arrangements were generally similar to those on the previous occasion; the course, however, to be traversed by the pontoons was more intricate than on the previous occasion, as the land pier on the Devonshire side of the river, over which the first truss had passed, had been built up to receive the end of the second.

This truss had, therefore, to be moved first outwards till the pontoons were clear of the docks, then it had to move endways up the river, and to swing round into position. Mr. Brunel was obliged to remain abroad from ill-health, and Mr. Brereton conducted the operations. Although the weather was not favourable, and the wind high, the truss was safely landed on the piers; and was afterwards raised in the same manner as the first one.[114]

The general elevation, Plate V., shows the proportions of the bridge. On the Devonshire side, the side spans pass over fields, and on the Cornwall side over the town of Saltash.

The general effect of the bridge is in no way heightened by an expenditure of money on architectural ornament; for, with the exception of a few unimportant mouldings, the bridge is absolutely unadorned. The total cost was 225,000l.—a very moderate expenditure, especially when the difficult work at the centre pier is taken into account. This result is due not only to the careful manner in which all the details of the design were prepared, but also to the great attention given throughout to the construction.

His Royal Highness the Prince Consort, as Lord Warden of the Stannaries, permitted the bridge to be called the Royal Albert Bridge, and consented to open it in person. The ceremony was performed on May 3, 1859. Mr. Brunel was compelled to be absent on the Continent, for the sake of his health, and was represented on the occasion by Mr. Brereton.

After Mr. Brunel’s return to England, he paid a hurried visit to the Cornwall Railway, and, for the first and last time, saw in its completed state the great work on which he had expended so much thought and care.

NOTE, (pp. 182, 194, 209).

Experiments on Matters connected with Bridge Construction.

No account of the structures designed by Mr. Brunel would be complete without a reference to the elaborate care he always took, wherever it was practicable, to satisfy himself by experiment of the qualities of the materials employed, and of the correctness of the principles followed. It would not here be possible to give a detailed record of all his experiments, but an account of some of the methods employed by him will be interesting.

Some of the larger of Mr. Brunel’s experiments on cast and wrought-iron girders have already been mentioned.[115] He scarcely ever made any large girder or framework without having it fully tested, and he made extensive and elaborate experiments, most of them on a very large scale, on the strength of some of the materials and component parts of his different structures.

Among the large scale experiments tried by Mr. Brunel, were those on the compressive strength of yellow pine-timber, which were made at Bristol in 1846, and were on specimens from 10 to 40 feet in length, and from 6 to 15 inches square. A framework of four upright pieces of whole timber, nearly 50 feet high, contained four strong bars of wrought iron, placed vertically, and attached at their lower ends to the cylinder of a hydraulic press. Along these bars, a casting could be moved, and fastened at different heights by keys, in such a manner as to have its under-surface, which was planed, perfectly horizontal. The ends of a specimen having been made exactly square to its length, it was put in this apparatus, with the upper end bearing against the lower surface of the movable casting, and the lower end resting on the top-surface of the ram of the hydraulic press, which was also planed and adjusted so as to be horizontal. The keys, which attached the movable casting to the bars, were now driven tight, and the pump of the press worked, weights being placed on the end of the lever, to correspond with increments of pressure on the ram. These weights were added gradually, until the specimen gave way. The accuracy of this mode of measuring the pressure was tested by direct loading of the ram with rails, which was repeated several times during the course of the experiments, so as to guard against any change in the amount of friction of the press. For each increment of weight, the compression of the specimen was measured on its four faces, and its deflection, or amount of bending, on two adjacent faces. The transverse stiffness of long specimens was also tried, by supporting them at each end, and loading them in the middle. The deflection in the middle thus observed corresponded very closely with what might have been expected from the observations on the direct compression; and from the constants so obtained, the strength of those specimens, whose length was very great as compared with their transverse dimensions, could be obtained by Euler’s theory, but for the stouter specimens the strength per square inch was found to be nearly constant. From these experiments, a complete practical knowledge of the properties of yellow pine timber, when subjected to end pressures, was obtained, knowledge new at the time, and almost essential to Mr. Brunel in designing the many viaducts which he afterwards constructed.

Mr. Brunel also made experiments on the strength of pine timber when exposed to pressure on the side or at right angles to the fibre. By this means he determined the area which it was desirable to provide for the washers of bolts, and the weight which might safely be placed on transverse timbers or sills of viaducts.

Mr. Brunel’s experiments on riveting were also important. Most of these were made with specimens 20 inches wide, and half an inch thick. They were compared with specimens of solid iron, of the same quality and thickness as the riveted specimens, and also the same width minus the rivet holes, so as to have equal efficient sectional areas. Double covering plates and double riveting were used in all cases, the variation being in the widths of the covering plates, and the number and arrangement of the rivets. The experiments were continued until thirty in all had been made, and the strongest form of joint was considered to have been arrived at.

In connection with the lifting of the parts of the Chepstow Bridge, an elaborate series of experiments was made on ropes, chains, and wire-rope, so as to ascertain which of these it was desirable to employ, as possessing the greatest advantages. The experiments made were of two kinds, one to determine the absolute strength of the specimen when subjected to a straight pull, and the other to observe what took place when it was worked over a sheave. In the first set the specimen was held at each end in the jaws of a pair of wrought-iron clamps, which were tightened up by means of screws. One of the clamps was attached to a fixed beam, and from the other was suspended a large cylindrical tank, which was gradually filled with water until the specimen gave way, the breaking strain being the weight of the tank and water. This weight was ascertained by actual weighing with a steelyard when the water in the tank was at different heights. Observations on the extension, shrinkage of the circumference, and change in the pitch of the spiral of the rope were made with different loads, and the strength of a sufficient number of the yarns of which the rope was composed was tried to ascertain the loss of strength by combining the yarns into a rope. In the second set the specimen, clamped as before, was passed over a sheave, the axle of which rolled horizontally on planed cast-iron plates, in order to diminish friction. To each clamp was attached a cylindrical iron tank. Water being admitted to the highest tank until downward motion commenced, its influx was stopped, and the tank descended, the other one rising. Water was then admitted to the now highest tank until motion again commenced, and this process was repeated until the specimen gave way, the tanks getting fuller of water at each movement, at which times the difference of weight of the two tanks was observed. This, minus the slight friction of the apparatus, represented the rigidity of the rope. The extensions were observed as in the first set of experiments.

The specimens consisted of hemp, manilla, shroud laid and hawser laid ropes, from 8 to 10 inches in circumference, round and flat wire ropes, and chains of different sizes of about the same strength as the ropes. The sheaves also were of different diameters. These experiments resulted in Mr. Brunel deciding to use chains for lifting the bridge, and this mainly from the circumstance that chains work more satisfactorily over a sheave than either hemp or wire ropes.

Some small scale experiments made by Mr. Brunel are deserving of notice. These were made to verify calculations on the longitudinal girders of the Chepstow truss, which are virtually continuous beams of five unequal spans. It was desirable to test the results of analysis by experiment, in order to be assured that no errors had been committed in its application. Mr. Brunel accordingly devised the following simple form of experiment for this purpose. A deal rod, exactly half an inch square and 38 feet long, quite free from knots, was supported on props of equal height, above the perfectly horizontal and planed surface of a large beam of timber. The props were placed so as to correspond relatively to the actual spans, and the rod was loaded uniformly by means of a chain. It was thus bent into an elastic curve, the ordinates of which were very carefully measured, at every foot along the length, by a finely divided scale and magnifier. The pressure on each prop was also determined, by removing any particular one, and suspending the point of the rod immediately over it to a steel-yard, the weight being observed when the point of the rod was exactly at the same level as before the prop was removed. The obvious condition, that the sum of the pressures on the props should be equal to the weight of the rod and its load, furnished a satisfactory means of testing the results of these weighings. The rod being turned over on each of its four sides, the experiments were repeated, and the average taken, in order to eliminate the effects of initial curvature, or of unequal elasticity. Diagrams of the elastic curves were then made, showing the correspondence of theory with experiment, and this was so close as to leave no doubt that a true knowledge of the nature of the strains had been arrived at. One of these diagrams is given by Mr. Edwin Clark in his work on the ‘Britannia and Conway Tubular Bridges,’ vol. i. p. 462.

By modifications of the plan Mr. Brunel adopted in this experiment, the strains on continuous beams of varying section may be ascertained with considerable accuracy.

CHAPTER VIII.

STEAM NAVIGATION. THE ‘GREAT WESTERN’ STEAM-SHIP.

A.D. 1835—1847. ÆTATIS 30—42.

IT will readily be conceded that Mr. Brunel’s railway works, which have formed the subject of the five preceding chapters, would have given him ample employment for the thirty years of his professional life.

Nevertheless, during almost the whole of that period—namely, from 1835, the year of the passing of the Great Western Railway Bill, to his death in 1859—he was also engaged in the accomplishment of undertakings which had for their object the systematic development of Ocean Steam Navigation.[116]

The ‘Great Western,’ the first steam-ship which made regular voyages across the Atlantic, the ‘Great Britain,’ the first large iron steam-ship, and the first large ship in which the screw propeller was used, and, lastly, the ‘Great Eastern,’ were Mr. Brunel’s works, built under his direction, in the midst of his other engrossing occupations, and at the sacrifice of his health and life.

The history of these projects will contain records of many disappointments as well as of success; for no great and novel undertaking can be perfected at once and without changes of plan and arrangement. As engineer to the Companies which built these steam-ships, Mr. Brunel advised the adoption of measures strongly in opposition to current popular opinion, and far bolder and more daring than even his recommendation of the broad gauge and the atmospheric system. The results obtained have verified his calculations, and the conclusions he sought to establish are now so generally accepted that it is difficult to believe that they were ever questioned. No one now has any doubt that large vessels can with safety be built of iron, or that the screw propeller can be advantageously employed in ships of war and the mercantile navy; no one can now deny that it is practicable for steam-ships to make long voyages across the ocean with regularity and speed.

A detailed account will now be given of the ships whose performances first demonstrated the truth of these propositions.

Although the ‘Great Western’ was the first steamer which was built for regular voyages between Europe and America, the first attempt to use steam in the direct voyage across the Atlantic was made by an American ship of 300 tons burden, called the ‘Savannah,’ and built at New York. Her engines were of small power, with paddles made to ship and unship. She made only two voyages to and from Europe: in the first of these she left the port of Savannah on May 25, and anchored at Liverpool on June 20, 1819.

No further advance in Ocean Steam Navigation seems to have been attempted until 1835. In the October of that year, at a meeting of the Directors of the Great Western Railway Company, at Radley’s Hotel, in Bridge Street, Blackfriars, one of the party spoke of the enormous length, as it then appeared, of the proposed railway from London to Bristol. Mr. Brunel exclaimed, ‘Why not make it longer, and have a steamboat to go from Bristol to New York, and call it the “Great Western?”’ This suggestion was treated as a joke by most of those who heard it; but at night Mr. Brunel and Mr. T. R. Guppy, one of the Directors, talked it over, and afterwards consulted three of the leading members of the Board—Mr. Scott, Mr. Pycroft, and Mr. Robert Bright. They took up the idea warmly, and a committee was formed to carry out the project.

As a preliminary measure, Mr. Guppy and Captain Christopher Claxton, R.N., made a tour of the great ship-building ports of the kingdom, in order to collect information. The results of their inquiries were embodied in a report, dated January 1, 1836, which describes at great length the advantages to be gained in large vessels. The manuscript was submitted to Mr. Brunel previously to its publication, and he inserted the following passage:—

This was an important addition to the report, for it enunciates the principle which governed Mr. Brunel in determining the dimensions and power, not only of the ‘Great Western,’ but also of the ‘Great Britain’ and ‘Great Eastern’ steam-ships.

Immediately after the publication of this report a Company was formed in Bristol called ‘The Great Western Steam-Ship Company,’ Mr. Peter Maze being the Chairman, and Captain Claxton the Managing Director. Captain Claxton’s exertions in the service of the Company from its formation to its dissolution were unremitting and invaluable. He was also, from the date of Mr. Brunel’s first connection with Bristol, one of his most intimate friends, and his confidential adviser on all points on which nautical experience was of value.[117]

Mr. Patterson (an eminent ship-builder of Bristol) was selected to superintend the building of the first ship, under the direction of a ‘Building Committee’ consisting of Captain Claxton, Mr. Guppy, and Mr. Brunel. Whenever railway business called Mr. Brunel to Bristol, which at this time was at least once in every week, the Committee and Mr. Patterson used to meet at the office, or at Captain Claxton’s or Mr. Guppy’s house, and often sat far into the night discussing the details of the design of the ship.[118]

One of the most important questions which occupied Mr. Brunel’s attention was the selection of the builders of the engines. Tenders were invited; and on receiving them, he addressed the following report to Captain Claxton, the Managing Director:—

This report was read by Mr. Brunel at a meeting of the Board, summoned at his request; the Directors adopted his advice, and accepted the offer of Messrs. Maudslay & Field, of Lambeth.[119]

The ‘Great Western,’ for so the ship was called, had not been long commenced when a somewhat celebrated controversy arose, in which the correctness of Mr. Brunel’s views was questioned by the late Dr. Dionysius Lardner.

The circumstances which led to this discussion were as follows:—

The British Association for the Advancement of Science held its sixth meeting at Bristol in August 1836; and, as Dr. Lardner was announced to lecture on Transatlantic Steam Navigation, great interest was felt in Bristol on the occasion.

After some postponement, he delivered his lecture on August 25, to a crowded meeting of the Mechanical Section. The proceedings of the Association unfortunately do not give any report of Dr. Lardner’s observations; but, as in his latest work on the subject[120] he speaks in commendatory terms of the report given in the ‘Times’ newspaper, that account may be relied on as correct.

In the ‘Times’ of August 27, 1836, it is stated that in the course of his lecture Dr. Lardner said,—

There is no detailed report remaining of the animated discussion which followed the lecture, and in which Mr. Brunel took part. He exposed several errors in Dr. Lardner’s calculations, but failed to produce any effect upon the majority of those present, who were powerfully impressed by the lecturer’s dogmatic assertions.

Those assertions seem to have had a wide circulation beyond the walls of the lecture-room; and if Dr. Lardner’s arguments were sound, and if transatlantic steamers ought to have taken their departure from ‘the most western shore of the British Isles,’ the enthusiastic advocate of a railway scheme in Ireland might well exclaim,—

Dr. Lardner’s views are repeated in an article in the ‘Edinburgh Review’ for April 1837 (vol. lxv.); and in the report of the proceedings of the British Association for 1836 (p. 130 of the proceedings of the sections), the reader is referred to this article, apparently as a substitute for an abstract of the lecture.

The following résumé is there given of the lecture:—

Among other objections to long voyages the reviewer enumerates the incrustation of boilers, and the choking of smoke flues; and then, with reference to the quantity of fuel required, he proceeds:—

To sum up Dr. Lardner’s views in his own words written at about this time,[122] ‘We have as an extreme limit of a steamer’s practicable voyage, without receiving a relay of coals, a run of about 2,000 miles.’[123]

It will be seen from these extracts that the proposition Dr. Lardner laid down as the basis of his ‘demonstration’ was, that the power of the engines must be increased as the size of the vessel. Were this true his conclusion would also be true—namely, that the capacity of a given vessel regularly to accomplish a given voyage does not increase with the increase of size, since the consumption of fuel is augmented in about the same ratio.

This assumption is directly opposed to the opinion held by Mr. Brunel, and acted on by him in his recommendations to the Steam-Ship Company—namely, that while the tonnage of a ship is increased as the cube of her dimensions, the resistance is increased only about as the square.

This question was the main point at issue between Dr. Lardner and Mr. Brunel; and the proposition which Mr. Brunel then asserted is at the present time the basis of the calculations which determine the proportion between the tonnage of a steam-ship and the length of voyage she has to perform without a relay of fuel.

The history of the ‘Great Western’ steam-ship has been interrupted by this examination of Dr. Lardner’s propositions. The weight at one time attached to his opinions, the sinister influence they exercised over the early efforts of those who differed from him, and the great and enduring importance of the points at issue, have made it necessary to refer to them at length.

The ship had been steadily proceeded with, notwithstanding the adverse criticism of philosophers, and she was launched on July 19, 1837. On August 18 she left with a tug-boat for London to take her engines on board, and arrived in the Thames after a passage of four days, four-fifths of the way under sail.

When anchored in the river she was crowded with visitors, who, according to the newspapers of the day, were astonished at ‘her magnificent proportions and stupendous machinery.’

The engines were at length completed, and received in every detail Mr. Brunel’s constant supervision.

Extraordinary efforts were made to get the ship back to Bristol and to start her on her voyage across the Atlantic before the departure of the ‘Sirius’—a vessel of about 700 tons and 320 horse-power, bought by the St. George’s Steam Packet Company in order to anticipate the ‘Great Western.’

At length the ‘Great Western’ left Blackwall for Bristol, at 6.10 A.M. on Saturday, March 31, 1838, having on board Captain Claxton, Mr. Guppy, Mr. Brunel, and many other persons interested in her success. All went well at first, but at about half-past eight o’clock a very alarming fire broke out. The felt which covered the boilers had been carried up too high, and the red lead which fastened it became hot; oil gas was generated, and it burst into a fearful flame, setting fire to the beams and under part of the deck. The ship was immediately run ashore on a mud-bank not far from the Chapman Beacon, while Captain Claxton, Captain Hosken (the commander), and Mr. Pearne (the chief engineer) endeavoured to extinguish the fire.

Captain Claxton went below through the engine-rooms, and forward between the boilers to the fore-hatch, and in a stifling atmosphere of burning paint and felt he directed the nozzle of the fire-hose against the flames. While he was at work, something heavy fell on him from above. On recovering from the blow, he stooped down, and found the body of a man, who was lying insensible, with his head covered to the ears with the water which had collected on the floor. Captain Claxton called for a rope, and the almost lifeless body was hauled up. It was not till he went on deck some time afterwards that he learnt that the person who had fallen on him was Mr. Brunel, and that he had saved the life of his friend.

It appeared that Mr. Brunel was going down to Captain Claxton’s assistance by the long ladder which reached from the fore-hatch to the keelson, and put his foot on a burnt rung. He fell about 18 feet, striking an iron bar in his descent. Had he not fallen on Captain Claxton he must have struck the keelson or floor and been killed, and had not his head been raised at once he would have been suffocated by the water into which he fell. He was so severely hurt that he could not move, and he was laid on a sail on deck until the fire was extinguished, and then lowered into a boat, and landed on Canvy Island, where he remained some weeks. Although his sufferings were very great, he was able, within three days of the accident, to dictate a long letter to Captain Claxton on the state of the ship and engines.

The fire was soon got under, the ship resumed her voyage to Bristol, and anchored at Kingroad in the afternoon of Monday, April 2, to the great surprise of the good people of Bristol, who had heard that she had been burnt in the Thames. Their astonishment was increased by finding no outward signs of the disaster; but, as a fact, the deck above the boiler was charred a fourth of its thickness, and so remained till the ship was broken up.

The ‘Great Western’ started on her first voyage to New York on Sunday, April 8, at 10 A.M.,[124] and struck soundings off Newfoundland on the ninth day. She arrived at New York at 2 P.M. on Monday, the 23rd, having consumed three-fourths of the coal she had taken on board.

She found that the ‘Sirius’ had arrived before her; but under all the circumstances the palm was due to the ‘Great Western,’ for the ‘Sirius’ had left Cork eight hours before the ‘Great Western’ left Bristol (which lies a whole day’s run further from New York), and had only arrived at New York in the morning of the day in the afternoon of which the ‘Great Western’ came in; and, what is after all the most important point for comparison, the ‘Great Western’ had nearly 200 tons of coal left, while the ‘Sirius,’ when she dropped her anchor at Sandy Hook, had not only consumed all her coal, but also all the combustible articles which could possibly be thrown on the fire, including (to repeat the well-known anecdote) a child’s doll!

The ‘Great Western’ was received at New York with well-deserved honour. According to the journal of one of her passengers, ‘Myriads were collected, boats had gathered round us in countless confusion, flags were flying, guns were firing, and cheering rose from the shore, the boats, and all around loudly and gloriously, as though it would never have done. It was an exciting moment, a moment of triumph.’

The ship started on her return home on May 7, 1838, with sixty-eight passengers on board. She made the voyage in fourteen days, although twenty-four hours were lost by a stoppage at sea.

After this she ran regularly between Bristol and New York till the end of 1846. In April 1847 she was sold to the West India Mail Steam Packet Company, and became one of their best vessels.

At length in 1857 she was broken up by Messrs. Castle, of Vauxhall. Among those who went there to take a farewell of her before she finally disappeared was Mr. Brunel; thus he saw the last of his famous ship.

NOTE (p. 235).

CHAPTER IX.

STEAM NAVIGATION. THE ‘GREAT BRITAIN’ STEAM-SHIP.

A.D. 1838—1847. ÆTATIS 33—42.

THE Directors of the Great Western Steam-Ship Company, encouraged by the success of the ‘Great Western,’ determined shortly after her first return to England to lay down a second ship of not less than 2,000 tons burden. As they did not at that time contemplate the use of iron, a portion of the timber was purchased, and drawings were put in hand for a wooden ship. The proposed vessel was intended to be in all respects a companion ship to the ‘Great Western;’ only she was to be of larger dimensions, as it was found that additional cargo space would be remunerative.

In October 1838, Mr. Guppy (one of the Directors) communicated to the Board the results of some calculations Mr. Brunel had made relative to the cost and efficiency of iron vessels as compared with wooden ones. Mr. Brunel then suggested that Captain Claxton and Mr. Patterson, accompanied by one of his assistants, should make a voyage to Antwerp and back in the ‘Rainbow,’ an iron steam-boat of 407 tons burden, and report on the subject. On receiving their report, which was revised by Mr. Brunel, and which was strongly in favour of the adoption of iron, the Directors resolved to build their ship of that material, and of not less than 2,000 tons measurement, the same size as that which they had intended for their wooden ship. They also determined to erect the shops, and provide the tools for building her themselves.

As in the case of the ‘Great Western,’ the details of construction were settled by the Building Committee—Captain Claxton, Mr. Guppy, and Mr. Brunel—who were assisted by Mr. Patterson.

The preparation of the design occupied some time. In each succeeding drawing an increased size was proposed; at length the fifth design, showing a ship of 3,443 tons burden, was finally approved of. On July 19, 1839, the flat keel plates were laid, and the construction of the hull was commenced.

It will be necessary to enter with some detail into the history of the construction of the engines of the ‘Great Britain,’ as it has often been stated that it was on Mr. Brunel’s recommendation that the Company built their own engines. It appears, however, that Mr. Brunel repeatedly urged upon the Directors the utmost caution and economy, and that they ultimately acted ‘against his suggestion.’

When the Directors determined, in May 1838, to build a second ship, they did not entertain any idea of undertaking so great a responsibility as the manufacture of the engines; nor had they any intention of doing so, even when, towards the end of the same year, they resolved to build the ship themselves, and to construct her of iron.

The dimensions of the proposed paddle engines (for at this date the use of the screw propeller was not contemplated) were sent, in November 1838, to Messrs. Maudslay and Field, Messrs. Hall, and Messrs. Seaward.[125]

Messrs. Maudslay declined to tender, and the negotiations seem to have fallen through at the time; but they were renewed in April 1839, when estimates for engines (with cylinders of 100 inches diameter and seven feet stroke) were again invited from several makers.

The contest lay eventually between Messrs. Maudslay and Mr. Humphrys (whose patent for trunk engines was worked by Messrs. Hall). At Mr. Brunel’s desire they prepared designs for engines with cylinders of 120 inches diameter. He twice induced the Directors to postpone coming to a decision on the subject, in order that Messrs. Maudslay might mature their new patent for double-cylinder engines.

When their tender was placed before the Board, the Directors were of opinion that it largely exceeded the estimate of Mr. Humphrys. Mr. Humphrys’ estimate, however, had been more than once sent back to him for revision, at the suggestion of Mr. Brunel, who expressed doubts as to the possibility of Mr. Humphrys being able to construct his engines within the sum named by him.

Messrs. Hall stated that if they tendered for the supply of engines on Mr. Humphrys’ plan, large tools would have to be purchased by them, and the cost charged on the one pair of engines; they therefore strongly recommended the Company to become their own engine makers.

Influenced by these considerations, the Directors determined to adopt the plan of Mr. Humphrys, and to construct their own engines; and they appointed him the superintending engineer of their works.

It appears from a report by the secretary, Captain Claxton, dated March 23, 1840, that ‘previous to coming to this decision, Mr. Brunel succinctly laid before the Directors his views of the matter, and his opinion of the great responsibility they would incur if they made their own engines; and doubtless the Directors would have yielded to his suggestions, but for the report of Mr. Humphrys, showing the utter hopelessness of getting the engines made piecemeal in Bristol.’

The following is the report of Mr. Brunel on the subject:—

The Directors having determined to make the engines, erected shops and fitted them up with proper tools. The services rendered to them by Mr. Brunel at this period were fully acknowledged at the next meeting of the shareholders.[126]

Mr. Brunel’s attention was now anxiously devoted to the consideration of the numerous questions involved in the construction of the ship and her engines; and, in order to obtain reliable information on many points, he sent one of his assistants, Mr. Berkeley Claxton, in the ‘Great Western.’ His sole occupation during six voyages was to note the amount of rolling and pitching, and the exact performance of her engines, with the effect of the use of the expansion valves on her speed, and on the consumption of fuel. These reports furnished Mr. Brunel with information which was of great value, especially when, shortly afterwards, he advised the Directors to adopt the screw propeller instead of paddlewheels.

The circumstances which led to the adoption of the screw propeller in the ‘Great Britain’ instead of paddlewheels were as follows:—

In the early part of the year 1840, the performances of the ‘Archimedes’ steamer began to attract the attention of scientific men. This vessel, which was fitted with the screw propeller patented by Mr. Francis Pettitt Smith, arrived at Bristol in May. A few trips were made up and down the Float, but the advantages of the screw propeller were not fully appreciated by those to whom they were explained.

But Mr. Guppy, who had attended some of these trials, went round in the ship to Liverpool. On his return he made a report to the Building Committee, and the Directors, on Mr. Brunel’s advice, passed a resolution delaying the progress of the engines of the ‘Great Britain,’ and of those parts of the frame which would be affected by any change of plans. Mr. Brunel was also requested by them to give his attention to the question of the adoption of the screw, and to report thereon.

During the next three months experiments were made by Mr. Brunel, assisted by Mr. Guppy and Captain Claxton, on the screw propeller in the ‘Archimedes.’[127] These experiments afforded ample opportunity of trying the performances of several forms of screws.[128]

On October 1, Mr. Brunel attended a special meeting of the Board, and read and explained a report he had drawn up, in which he laid before the Directors at great length the results of the different experiments he had made, and the advantages which he believed would attend the use of the screw propeller.[129] A resolution was passed adopting it for the ‘Great Britain.’

Mr. Brunel at first thought that he would be able to retain the form of engines which had been originally determined on for working the paddle wheels; but, on consideration, this was found impracticable. As the Company had by this time erected complete engine works, there could now be no question as to their undertaking the construction of the new description of engines required for working the screw propeller.[130]

Mr. Humphrys resigned the post of superintendent of the works, and Mr. Harman was appointed assistant engineer under Mr. Guppy, to whom the Directors, on the advice of Mr. Brunel, entrusted the supreme control of their manufacturing establishment.

The duties and responsibilities which devolved on the Building Committee—Captain Claxton, Mr. Guppy, and Mr. Brunel—were most arduous. To design and construct a steam-ship larger than any that had, up to that time, been launched, to make this ship of a material which had but lately been introduced into shipbuilding, and which had never before been employed on a large scale, to adapt to this ship a novel form of propeller which had not previously been used save in a merely experimental steamer, and to build in a newly opened manufactory marine engines of a much greater size than any that had hitherto been contemplated, and of a totally different character, was indeed a bold enterprise. Mr. Brunel had, as has been shown, recommended the Company not to undertake one part of the work, that, namely, of the manufacture of the engines, which he thought would have been better entrusted to the most experienced engine builders. But although the Directors had acted contrary to his advice, this circumstance in no way diminished the zeal with which he and his coadjutors entered upon their task.

A short statement of the principal dimensions of the vessel and engines is given in a note to this chapter; but some of the more remarkable features in the design may be mentioned here.

In the construction of the ‘Great Britain,’ the same care which had been spent in securing longitudinal strength in the wooden hull of the ‘Great Western,’ was now given to the suitable distribution of the metal. Over the transverse angle iron ribs at the bottom of the ship were laid ten deep longitudinal beams (see woodcut, fig. 13, a), which, over the greater part of the bottom of the ship, were covered with an iron deck (b) riveted to their upper edges by angle irons, thus forming a cellular structure which added greatly to the strength of the ship. It does not appear that this deck was designed to be watertight, so that it did not form the same security against accident as the inner skin of the cellular structure which Mr. Brunel afterwards adopted in the ‘Great Eastern.’

The upper part of the sides of the ship, in the middle of her length, were carefully designed so as to give her longitudinal strength. The side plates were thickened, and were riveted to iron shelf-plates three feet broad (c); and two bands of iron, six inches wide and one inch thick, with the joints strengthened, ran along the top of the ship’s side. There were bands of iron riveted to the shelf-plate, and iron deck beams crossed diagonally under the planking of the upper and main decks. Also at the junction of the ship’s side with the shelf-plate there ran longitudinally a tie of Baltic pine timber, 340 square inches in section (d); this being well secured to the shelf-plate and ribs, added considerably to the strength of this portion of the hull.

The ship had five watertight bulkheads, and was thus separated into six compartments.

Fig. 13. ‘Great Britain’ Steam-Ship.
Transverse Section.

She had no keel, as there did not appear to be sufficient advantage gained by such an appendage to make up for the increase of the ship’s draught by the amount of the depth of the keel. There were two side or bilge keels (e), reaching down to the level of the keel plate of the ship, so that when grounded in dock she might rest on three points in her width.

The ‘Great Britain’ had what is termed a balanced rudder, a portion of the rudder (in this case about one third) being in advance of the pivot on which it turned. The result of this arrangement was that, the pressures on either side of the pivot nearly balancing one another, there was no difficulty in putting the helm over rapidly. This rudder was knocked away when the ship ran ashore at Dundrum, and was subsequently replaced by an ordinary rudder.[131]

In the construction of the hull of the ship, instead of a mere imitation of the arrangements of the timber in wooden ships, the proper distribution of the material to receive the strains that would come upon it was carefully considered. In the result, the ship contained, in the structure of her bottom, bulkheads, deck shelves, and longitudinal kelsons, the longitudinal principle of construction which Mr. Brunel afterwards so fully developed in the ‘Great Eastern.’

Apart from their size, the design of the engines of the ‘Great Britain’ necessarily presented many peculiarities. The boilers, which were six in number, were placed touching each other, so as to form one large boiler about thirty-three feet square, divided by one transverse and two longitudinal partitions. This boiler, which was fitted in between the longitudinal bulkheads of the ship, had a double set of furnaces, and therefore of stoke-holes, one at the fore end, and the other at the after end, next the engine room.

It would seem that the boiler was only worked with a pressure of about eight pounds on the square inch.

The feed water for the boiler was passed through a casing surrounding the funnel, in which it was heated before passing into the boiler. This casing was open at the top, and the water flowed thence into the boiler by gravitation. A similar arrangement was adopted by Mr. Brunel in the ‘Great Eastern.’

The condensers were made of wrought iron, being in fact part of the frame of the ship. The main shaft of the engine had a crank at either end of it, and was made hollow, a stream of water being kept running through it so as to prevent heating in the bearings. An important point in the design was the method by which the motion was transmitted from the engine-shaft to the screw-shaft, for the screw was arranged to go three revolutions to each revolution of the engines. Where the engines do not drive the screw directly, this is now universally effected by means of toothed gearing; but, when the engines of the ‘Great Britain’ were made, it was thought that this arrangement would be too jarring and noisy. After much consideration, chains were used, working round different-sized drums with notches in them, into which fitted projections on the chains. The greater part of the length of the screw-shaft consisted of a hollow wrought-iron boiler-plate tube, the metal being thus very advantageously placed for taking torsional strain, and the shaft was in this way made very light. The engines were designed to work expansively, the steam being cut off at one-sixth of the stroke.

The completion of the ‘Great Britain’ was delayed many months, owing to the financial difficulties in which the Great Western Steam-Ship Company had become involved; the profit on working the ‘Great Western’ having been seriously diminished in consequence of the competition of the Cunard steamers.

At length, however, the ship was finished; and she was floated out of dock into the Floating Harbour on July 19, 1843, in the presence of His Royal Highness Prince Albert.

This seems a fitting place to insert the following letter from Mr. Brunel to Mr. Guppy, written at the beginning of August 1843:—

I have been thinking a great deal of your plans for iron-ship building, and have come to a conclusion which I believe agrees with your ideas; but I will state mine without reference to yours. At bottom and at top I would give longitudinal strength and stiffness, gaining the latter by the former, so that all the metal used should add to the longitudinal tie, while in the neutral axis and along the sides, and to resist swells from seas, I would have vertical strength by ribs and shelf-pieces, thus: the black lines being sections of longitudinal pieces, the dotted lines vertical and transverse diagonal plates, throwing the metal as much as possible into the outside bottom plates, and getting the strength inside by form, that is, depth of beams, &c., the former being liable to injury from blows, &c., the latter being protected.

[Fig. 14.]

And now for the screw of which I am constantly thinking, and in the success of which for the ‘Great Britain,’ remember, I am even more deeply interested than you.

If all goes well we shall all gain credit, but ‘quod scriptum est manet,’ if the result disappoint anybody, my written report will be remembered by everybody, and I shall have to bear the storm—and all that spite and revenge can do at the Admiralty will be done! The words ‘better sailing qualities than could be given to the “Polyphemus,”’ which I used in my first report to the Admiralty, I believe have never been forgotten.

Well, the result of all my anxious thoughts—for I assure you I feel more anxious about this than about most things I have had to do with—is first that we must adopt as a principle not to be departed from, that all mechanical difficulties of construction must give way, must in fact be lost sight of in determining the most perfect form—if we find that the screw determined upon cannot be made (but what cannot be done?), then it is quite time enough to try another form; though even then my rule would be to try again at making it....

The ‘Great Britain’ was built wider than the locks through which she would have to pass, as it was supposed that the Dock Company would allow them to be temporarily widened.[132]

After a good deal of discussion, negotiations were satisfactorily concluded, and the requisite alterations were made: the ship passed through into Cumberland Basin, and the upper lock was restored to its original state in a few days.

On December 10, everything was ready for her passing into the Avon through the lower lock. A steam-tug commenced towing her at high water, but, before she had moved half her length in the lock, it became evident to Captain Claxton, who was on board the tug, that there was not an inch to spare; she was touching the lock walls on either side—in fact, she had stuck between the copings. Upon this he gave orders to haul her back again as quickly as possible. This was hardly effected before the tide began to fall; a few minutes later, and the ship would have remained jammed in the entrance.

As the tides had passed their highest, it was necessary immediately to widen the lock, in order not to lose the spring tide; and this was accomplished under Mr. Brunel’s superintendence, just in time to get the vessel through that night.

Mr. Brunel described this occurrence in the following letter, written to excuse himself from keeping an important engagement in Wales:—

The ‘Great Britain,’ after making several experimental trips, sailed for London on January 23, 1845, and, although she experienced very severe weather, made an average speed of 12⅓ knots an hour.

The excitement caused by her arrival at Blackwall was very great. Thousands of persons flocked to see her, and she was honoured by a visit from Her Majesty and His Royal Highness Prince Albert.

She left Liverpool on her first voyage on August 26, and arrived at New York on September 10, having made the passage out in fourteen days and twenty-one hours. She made her return passage in fifteen days and a half.

She started again in October, taking sixteen days and a half across. On her homeward passage, she broke her screw, and got home under canvas after eighteen days of rough weather which fully tested her sailing qualities.

The experience of these voyages showed that the supply of steam from the boilers was defective; the necessary alterations were carried out during the winter months, and the ship was fitted with a new screw.

In the beginning of 1846, everything seemed to promise well for the success of the ‘Great Britain.’ She started on May 9, with her full complement of passengers and cargo, but again an accident happened, which prevented this passage from affording a trial of her steaming power. On May 13, the guard of the after air-pump broke; but up to that time her speed had averaged eleven and three-quarters knots.

She returned from New York in thirteen days and six hours, against adverse winds for ten days, with a speed varying from eight and a half to twelve knots. On one day of her voyage, June 13, she ran 330 knots in the twenty-four hours, or nearly sixteen statute miles an hour. This was said to have been the quickest passage which had, up to that time, been made under similar circumstances of wind and weather.

She left Liverpool again at the beginning of July, and arrived at New York in thirteen days and eight hours, or, deducting stoppages, in twelve days and eleven hours—the shortest passage then and for some time afterwards recorded. Her homeward passage was accomplished in thirteen days, including a stoppage of eighteen hours to repair the driving chains which had been damaged.

She started again from Liverpool on her outward voyage on the morning of September 22, 1846, having on board 180 passengers (a larger number than had ever before started to cross the Atlantic in a steamer), and a considerable quantity of freight. A few hours after her departure, and at a time when it was supposed that she was rounding the Isle of Man, the ship ran ashore, and all immediate efforts to get her off were unavailing. When daylight came, the captain found, to his surprise, that she was in Dundrum Bay, on the north-east coast of Ireland. The passengers were landed safely when the tide ebbed.

Captain Claxton, the managing Director of the Company, went at once to the ship. He found her lying at the bottom of a deep and extensive bay; the ground on which she rested had an upper surface of sand, but underneath this were numerous detached rocks. The ship had settled down upon two of them, and had knocked holes in her bottom. Her head lay NW., leaving her stern and port quarter exposed to a heavy sea, which, at Dundrum, always accompanies southerly gales.

When Captain Claxton got to the ship, he made arrangements for trying to get her off at the next spring tides, which were on the following Monday (September 28); but on the Sunday, a gale of wind from the southward sprung up, and at the night flood-tide the water broke over her; nothing remained to be done but to drive the ship higher up the beach into a position of greater safety. Sails were therefore set, and she was driven forward a considerable distance.

Mr. Patterson was sent by the Directors to Dundrum with Mr. Alexander Bremner (who had had considerable experience in floating stranded ships), and they endeavoured to protect the vessel by breakwaters. These, however, were soon carried away; and, after this misfortune, the Directors seem for a time to have lost all hope of saving their ship.

On December 8, when the immediate pressure of Parliamentary work was over, Mr. Brunel went to Dundrum, having some time before been requested by the Directors and underwriters to examine and report on the ship. He was delighted, he said, in spite of all the discouraging accounts he had received, to find the ‘Great Britain’ ‘almost as sound as the day she was launched, and ten times stronger and sounder in character,’ though at the same time he was grieved to see her ‘lying unprotected, deserted, and abandoned.’

Whatever may have been the misgivings of others, he felt no doubt as to the possibility of saving the ship, by at once protecting her by a breakwater made of fagots; and before he left Dundrum he set Captain Hosken at work at the new arrangements, and he guaranteed the immediate expense in the event of the Directors not sanctioning the measure.

Immediately on his return to town, he wrote the following somewhat vigorous letter to Captain Claxton:—

This letter was a few days later supplemented by the following formal report to the Directors, which was printed and circulated amongst the proprietors.

The Directors adopted Mr. Brunel’s suggestions; and, at his urgent request, they appointed Captain Claxton to superintend the execution of his plans.

Captain Claxton thereupon went to Dundrum, where he took sole charge of all the subsequent operations.

The following is selected from the many letters written by Mr. Brunel to Captain Claxton at this time.

The able manner in which Captain Claxton carried out Mr. Brunel’s plans, and suggested important modifications of them, is acknowledged by Mr. Brunel, in a report to the Directors, written after the successful completion of the breakwater.

The construction of the breakwater will be understood by the following extracts from a report made by Captain Claxton to the Admiralty.

As the summer came on, the mode of lifting and floating the ship had to be decided. On this point Mr. Brunel wrote to the Directors:—

Mr. Bremner and his son, assisted by Captain Claxton, made preparations for releasing the ship. The system followed was that sketched out by Mr. Brunel—namely, that of lifting the ship by mechanical arrangements, and then making good the leaks. The difficulties they had to contend with are graphically described in the reports which were sent almost daily by Captain Claxton to Mr. Brunel, and which were afterwards printed by the Directors at Mr. Brunel’s suggestion.[134]

The principal leak was stopped, and the ship’s head raised 8 feet 7 inches by ramming wedges and stones under her at high water. At last, on August 27, the ship was floated, and Captain Claxton wrote to Mr. Brunel:—

The following day they started for Liverpool. One hundred and twenty labourers were hired to work at the pumps, but only thirty-six came on board, and their services were unavailable, as they spent their time in discussing how much they were to be paid. Consequently, when the ship was taken in tow at 4 A.M. on the 28th there was 6 feet of water in the engine room and 5 feet in the fore hold, and she was making 16 inches an hour. Men from Her Majesty’s ships ‘Birkenhead’ and ‘Victory,’ which had been sent by the Admiralty to assist, were drafted on board, and the influx of water was reduced to four inches an hour. It was evident that Liverpool could not be attempted, so they made for Strangford Lough. A dense fog came on when they were off the entrance, and they pushed on to Belfast Lough, where the ship was grounded. During the night she was cleared of water, and the next day she started for Liverpool. The landsmen who had been hired the previous night to work the pumps were incapacitated by sea-sickness; and the ship was only kept afloat by the exertions of Captain Claxton and the dockyard hands who had been sent to assist in navigating her across. When she arrived at Liverpool she was placed over a gridiron, on which she sank when her pumps were stopped.

Notwithstanding the successful result of the efforts made for her rescue, the stranding of the ‘Great Britain’ in Dundrum Bay led to the ruin of the Company; and she was some time afterwards sold to Messrs. Gibbs, Bright, & Co., of Liverpool, by whom she was repaired, and fitted with auxiliary engines of 500 nominal horse-power. On a general survey being made, it was found that she had not suffered any alteration of form, nor was she at all strained. She was taken out of dock in October 1851, and since that time she has made regular voyages between Liverpool and Australia.

She is known as one of the fastest vessels on that line; and remains to testify to the ability and wisdom of those who, more than thirty years ago, were daring enough to build so large a ship of iron, and to fit her with the screw propeller.

NOTE (p. 255).

CHAPTER X.

STEAM NAVIGATION. INTRODUCTION OF THE SCREW PROPELLER INTO THE ROYAL NAVY.

A.D. 1841—1844. ÆTATIS 36—39.

SOON after Mr. Brunel had taken the bold step of recommending the adoption of the screw propeller in the ‘Great Britain,’ he was asked to send a copy of his report to the Admiralty. He did so; and in the course of a few months was invited to attend the Board on the subject of some experiments their Lordships proposed to make.

An interview took place on April 27, 1841; of which Mr. Brunel gives the following account:—

Within a fortnight of his appointment, Mr. Brunel invited Messrs. Maudslay and Field and Messrs. Seaward to send him designs for the engines: they were to have been of 200-horse power, with a stroke of 4 feet. The engines were to make a smaller number of revolutions than the screw, the motion being communicated from the engine shaft to the screw shaft by drums and straps. This arrangement was adopted in preference to tooth-gearing, in order to facilitate the variation of the number of revolutions, in the experiments with different screws.

The designs ultimately sent to Mr. Brunel for his approval were those of Messrs. Maudslay and Messrs. Forrester. He reported to the Admiralty in favour of Messrs. Maudslay’s engines.

Before drawing up the detailed specifications, Mr. Brunel was desirous of procuring data for estimating the surface of the screw required to obtain the same resistance as that offered by the paddles of a ship similar to the new vessel. With this object he applied to the Admiralty for permission to make an accurate trial of the performances of the paddle steamer ‘Polyphemus’ at various speeds. This permission was granted; the trial, however, was fixed for such an early day that Mr. Brunel had barely time to make the preliminary arrangements, with the assistance of his friend Captain Claxton.

When Captain Claxton arrived at Southampton, the day before the trial, he found that there was no measured mile set out. He immediately hired men, got chains, staffs, and flags, and set out both a nautical mile and a statute mile. They made half a dozen runs each way with the ‘Polyphemus,’ noting carefully all particulars of speed, revolutions, &c.; and the results obtained were considered very satisfactory.

On October 1, Mr. Brunel received information from the Admiralty (now under the administration of the Earl of Haddington) that Messrs. Maudslay and Field’s tender was accepted. The engines were immediately put in hand, under Mr. Brunel’s supervision.

When they were approaching completion, he became anxious to learn something about the progress of the ship which was to have been built for them. Nowhere could she be found. The minutes were searched at the Admiralty, and it was ascertained that the ship was ordered, but that no ship had been laid down. This discovery, as might be supposed, excited considerable surprise. Mr. Brunel was sent for to the Admiralty to see Sir George Cockburn, the First Naval Lord. Almost the first words to him were: ‘Do you mean to suppose that we shall cut up Her Majesty’s ships after this fashion, sir?’—Sir George at the same time pointing to a model of the stern of an old-fashioned three-decker, in which large slices were taken off to give room for the screw, and the whole of the lower deck exposed to view, thus making the application of the screw look very ridiculous. On the model was written, ‘Mr. Brunel’s mode of applying the screw to Her Majesty’s ships.’ Mr. Brunel smiled, and denied its being his idea at all; he had never seen it before, and knew nothing about it. ‘Why, sir, you sent it to the Admiralty.’ This also Mr. Brunel denied having done. While an enquiry was being made as to where the model came from, Mr. Brunel employed himself in effacing the inscription with his knife. When the messenger returned, he reported that the model had come from the office of the Surveyor of the Navy. He was sent for, but did not appear. Mr. Brunel, to terminate this awkward interview, pleaded business, and bowed himself out.

Mr. Brunel often told this anecdote, and spoke of the adverse influence which had been exerted in some department of the Admiralty to prevent the successful issue of these experiments.

Soon afterwards Mr. Brunel was informed that the ‘Acheron’ would be prepared for the screw. He thereupon represented to their Lordships that the ‘Acheron’ could not, from her full after-body and other defects, be converted into such a ship as the Board had originally determined to construct for trying the screw; and, indeed, her unfitness was admitted by the authorities themselves.

To a letter on this subject, in which he stated that the attempt to apply the screw propeller to the ‘Acheron’ would not answer any of the objects which their Lordships had in view, Mr. Brunel received no reply, and for the next four months was kept quite in the dark as to what was going on. At length he made enquiries as to the cause of a treatment which, he said, he had never before experienced from any public body.

These enquiries proving fruitless, he at last wrote to the Admiralty, declining further interference, as it had appeared on investigation that the condition on which he had accepted his position from Lord Minto—namely, that he should have the entire superintendence of the experiments—had not been observed.

On the receipt of his resignation, Mr. Brunel was summoned to the Admiralty. He thus described his interview in a letter to a friend:—

In a few days Mr. Brunel received an official intimation that the ‘Rattler’ was to be adapted for the screw, under his directions.

The ‘Rattler’ was a vessel of 888 tons burden, 176 feet 6 inches between the perpendiculars, and 32 feet 8½ inches beam.[136] She had been commenced for a paddle-wheel steamer shortly before, and was of nearly the same tonnage and midship section as the ‘Polyphemus,’ but she had not the fine lines aft which were so important for the use of the screw.

She was not launched until April 13, 1843, just two years after Mr. Brunel’s first interview with Lord Minto; and she was then delivered to Messrs. Maudslay in the roughest possible state.

Except during the time that Mr. Brunel was prevented from attending to business by the half-sovereign accident, he was in constant communication with the dockyard authorities on matters relating to the construction of the ship, with Messrs. Maudslay as to the multiplying-gear and engines, and with Mr. F. P. Smith as to the forms of the various screws to be tried.

The engines and screw were fitted in the ship, after considerable delay; and, on October 24, 1843, Mr. Brunel reported on them in their completed state. On the 30th, the experiments were commenced.

More than twenty trials were made between that date and the following October, when the ‘Rattler’ went to sea, and Mr. Brunel could not of course any longer personally superintend the experiments; but, except on one or two occasions when his place was supplied by an assistant, all the trials that were made during the first year were conducted in his presence, and he transmitted the results from time to time to the Admiralty.[137]

The performance of the ‘Rattler’ was found to be satisfactory; and the position of the engines and screw being below the water line was so pre-eminent an advantage, that in 1845 the Lords of the Admiralty ordered more than twenty vessels to be fitted with the screw;[138] and since that time it has gradually superseded the paddlewheel for ships of war.

The services which Mr. Brunel rendered to the country during the whole of these proceedings were given entirely without pecuniary recompense, and in the face of opposition and discouragement; but he had the satisfaction of knowing that he had been mainly instrumental, not only in introducing the screw propeller into the mercantile navy, but also in securing its adoption in Her Majesty’s fleet.

CHAPTER XI.

STEAM NAVIGATION—THE ‘GREAT EASTERN’ STEAM-SHIP, FROM THE COMMENCEMENT OF THE UNDERTAKING TO THE LAUNCH.

A.D. 1851—1857. ÆTATIS 46—52.

MR. BRUNEL’S earlier labours in connection with the progress of Ocean Steam Navigation have been described in the chapters on the ‘Great Western’ and ‘Great Britain’ steam-ships.[139] The ‘Great Eastern’ is but the result of the application, under different circumstances, of the same principles which had guided him in his previous under-takings, the practical working out of the ‘idea which he had frequently entertained, that, to make long voyages economically and speedily by steam, required the vessels to be large enough to carry the coal for the entire voyage at least outwards; and, unless the facility for obtaining coal was very great at the out port, then for the return voyage also; and that vessels much larger than had been previously built could be navigated with great advantage from the mere effect of size.’[140]

In 1851, four years after the release of the ‘Great Britain’ from Dundrum Bay, Mr. Brunel became again connected with the construction of steam-ships. In that year he was consulted by the Directors of the Australian Mail Company upon the class of vessels which it would be advantageous for them to purchase, in order to carry out their contract for the conveyance of the mails to Australia. He advised them to have ships of from 5,000 to 6,000 tons burden, in order that they might only have to touch for coal at the Cape.

Some of the Directors would not hear of so startling a proposition; but they nevertheless asked Mr. Brunel to become their Engineer; and he retained the post till February 1853. Two ships were built under his direction by Mr. J. Scott Russell—the ‘Victoria’ and the ‘Adelaide.’

It was, no doubt, his connection with the Australian Mail Company that led Mr. Brunel to work out into practical shape the idea of ‘a great ship’ for the Indian or Australian service, which had so long occupied his mind; and it appears that in the latter part of 1851 and the beginning of 1852 he devoted much time and thought to the subject. He collected facts relating to the trade with India and Australia which demonstrated the advantages to be gained by a rapid and direct communication for the conveyance of passengers and troops, as well as of merchandise. It was with these enlarged views that Mr. Brunel entered upon the construction of the ‘Great Eastern.’ He writes in February 1854, ‘In February and March 1852 I matured my ideas of the large ship with nearly all my present details, and in March I made my first sketch of one with paddles and screw. The size I then proposed was 600 × 70, and in June and July I determined on the mode of construction now adopted of cellular bottom; intending then to make the outer skin of wood for the sake of coppering.’

In the spring of 1852 he communicated the results at which he had arrived to Mr. John Scott Russell, Captain Claxton, and other scientific friends, and also to several Directors of the Eastern Steam Navigation Company.

This Company had been formed in January 1851 for the purpose of establishing an additional line of steam communication by the overland route, for the conveyance of mails, passengers, &c., between England, India, and China, with a branch to Australia. However, in March 1852 the Government determined to grant the contract for the whole service to the Peninsular and Oriental Company. The Directors of the Eastern Steam Company were therefore obliged to report to their shareholders that the object for which the Company had been incorporated could not be carried out.

At about this time Mr. Brunel’s scheme was brought before the Directors, and he submitted to them a detailed statement of his project.

After describing the size and capacities of the vessels then used on the route between England and the East, and the amount and cost of the coals they consumed, he continued:—

A Committee was appointed to confer with Mr. Brunel and with Mr. Scott Russell, ‘who was fully acquainted with all Mr. Brunel’s plans, and had ably assisted him in maturing them.’[141]

The Committee reported to the Directors that they had met on the day after their appointment, when, Mr. Brunel being unavoidably absent, Mr. Russell had attended and entered into a very full explanation of Mr. Brunel’s plans, and that a long investigation of his proposition had taken place; that a few days later they had met again, when Mr. Brunel attended, and that after a further and most satisfactory investigation, they had come to an unanimous decision in favour of the scheme. This resolution was adopted, and Mr. Brunel was appointed Engineer to the Company.

The following extracts from his reports and correspondence carry on the narrative till the date of the next meeting of the shareholders (December 1, 1852), when the details of the project were laid before them:—

Extract from a Letter describing the Scheme.

Letter to J. Scott Russell, Esq., on the Form and Dimensions of the Great Ship.

Report to the Directors on Mode of Proceeding.

Report to the Directors on Enquiries relating to the Draught and Form of the Vessel.

Efforts were made to induce the public to assist in carrying out the project. In February 1853, the Chairman (the late Mr. Henry Thomas Hope) and several of his colleagues formed themselves into a committee for the purpose of communicating with Mr. Brunel on the subject of his plans, and reporting to the Board thereon.

The results of this conference were embodied in the following report which Mr. Brunel addressed to the Directors:—

Report on the Proceedings of the Committee.

Mr. Brunel was authorized to continue his communications with engine-makers and ship-builders, and to invite tenders.

After very detailed and careful calculations of the smallest capacity that would secure the attainment of the objects sought for, the dimensions of the vessel and the power of the engines were finally determined; tenders were received from Mr. Scott Russell, Messrs. Watt and Co., and Messrs. Humphrys and Co. for both sets of engines, and from Mr. Russell for the construction of the hull of the ship and for placing her afloat.

A meeting of the Directors was held on May 18, when Mr. Brunel submitted the various tenders he had received. The Board agreed to adopt his recommendations, and to accept the tenders of Mr. Scott Russell for the ship and paddle engines, and that of Messrs. James Watt and Co. for the screw engines.

The following report, which Mr. Brunel placed before the Directors, gives a detailed account of the steps he had taken to procure the tenders, and the grounds on which he had formed his judgment of them:—

Report on Tenders.[144]

During the next six months Mr. Brunel was engaged in preparing the formal contracts and specifications. These documents were settled with much care, and after frequent communications with the contractors, who consented to the insertion of clauses which gave the full control and supervision over every part of the work to the Engineer, with very large powers of interpretation. They required, however, that, should Mr. Brunel cease to act as Engineer, any disputed point should be settled by arbitration, and not by his successor.

Besides the delay occasioned by the magnitude and novelty of the undertaking, there were other difficulties which helped to postpone the commencement of the works. The Directors were unable, under their charter, to enter into any contracts until a certain amount of their capital was actually paid up; and, as several shareholders had retired when the change of plans was determined upon, it was no easy work to get the shares taken. That this was eventually accomplished was due mainly to the exertions of Mr. Brunel and Mr. Charles Geach, one of the Directors.[146] ‘Could I have foreseen,’ Mr. Brunel writes, ‘the work I have had to go through, I would never have entered upon it; but I never flinch when I have once begun, and do it we will.’

Several times they nearly broke down, but at length the contracts were signed, and on the same day, December 22, Mr. Brunel gave the formal notice to the contractors to proceed with the works. ‘After two years’ exertions (he wrote), ‘we are set going, the contracts entered into, and the work commenced.’

The history of the ‘Great Eastern’ has now been traced up to the date of the contracts for the construction of the ship and her engines.

The following selections from Mr. Brunel’s memoranda illustrate the progress of the design during the early months of the year 1854:—

The extracts from Mr. Brunel’s correspondence which follow, have been selected as containing a definition in his own words of the position he held as Engineer to the Company by which the great ship was built.

Letter to the Secretary of the Eastern Steam Navigation Company.

The works had been commenced in the spring of the year 1854, and the progress of the ship towards completion was eagerly watched, both by scientific men and by the general public.

The newspapers and periodicals of the day frequently contained descriptions of the work, and statements of the anticipated performances of the ship, often very much exaggerated. The writers seem to have been quite at a loss how to convey to their readers any idea of her size, and they generally attempted to do so by comparing her dimensions with those of some of the well-known streets and squares in London.[152]

In the beginning of the year 1855, the longitudinal and transverse bulkheads, which formed the main framework of the ship, were completed for nearly 400 feet of the centre portion, and the plating was being fixed in place.

As the general design was now settled, it was thought that the time had arrived when it would be desirable for Mr. Brunel to describe at some length the nature of the undertaking, and the manner in which it was being carried out.

Report to the Directors of the Eastern Steam Navigation Company.

In the last paragraph but one of this report Mr. Brunel mentions that he proposed to adopt a system for obtaining continuous observations in order to determine the position of the ship.[154]

His first letter to the Astronomer Royal, which is dated as early as October 1852, explains the object with which he began his investigations:—

Mr. Airy entered very warmly into the subject, as did also Professor Piazzi Smyth, the Astronomer Royal for Scotland; and a long and interesting correspondence passed between them and Mr. Brunel. Experiments were conducted, principally with the view of obtaining a stand for astronomical instruments by means of the contrivance known as the gyroscope, the principle of which had been already adopted by Mr. Brunel in a level designed by him in 1829.

In connection with the observers’ department, Mr. Brunel paid much attention to designs of sounding apparatus and means for accurately measuring the speed of the ship. He also intended to have a stream of surface water constantly pumped up through the observers’ cabin, which should, by its change of temperature, immediately indicate the presence of icebergs, instead of the plan of an occasional bucketful being hauled up on to the deck according to the humour of the officer of the watch.

Mr. Brunel made a very curious contrivance for enabling the man on the look-out to keep his eyes open in a gale of wind. This consisted of two sets of vertical plates of tin placed one behind another, diverging from the direction of the wind, with a clear wide passage between the two sets of plates. The wind, entering at the end of the apparatus, became separated by the first two inclined plates, and the residue that passed on in the direct line was again subdivided, so that at the end of the last set of plates there was no rush of air between them, and a man looking through the aperture, with his face to the wind, was in a perfect calm. This was a useful arrangement, the look-out man’s eyes being as well protected as though behind a glass. A glass would not answer the purpose, as it would become obscured with spray.

The unfortunate circumstances which attended the completion of the ship prevented the introduction of these and many other arrangements which Mr. Brunel had originally proposed.[155]

In November 1855, the Directors proceeded to appoint a commander to the ship; and their choice fell upon Mr. William Harrison, one of the most distinguished of the captains of the Cunard Company’s steamers.

This appointment gave Mr. Brunel great satisfaction; he found in Captain Harrison a warm and faithful friend, and an able adviser on all matters connected with the completion and equipment of the ship.[156]

Before they came to a decision, the Directors asked Mr. Brunel to communicate to them his views on the considerations which ought to influence them in their choice.

The memorandum he drew up on the management of the great ship, and a letter on the duties of the chief engineer, are inserted at length, as forming a complete record of the principles which, in his opinion, should be followed ‘in the use of this new machine,’ while employed on the voyages which she was specially designed to make.

Memorandum on the Management of the Great Ship.

Letter on the Duties of the Chief Engineer.

It will be seen from the documents which have been printed in this chapter how ‘deeply and seriously’ Mr. Brunel had considered all the conditions which were, in his opinion, necessary for the economical construction, and the successful employment, of the great ship; but it is hardly possible, by means of extracts from his correspondence, to convey an adequate impression of the amount of labour he expended—from the year 1852 to the last days of his life—on the supervision of every detail of the work. ‘The fact is,’ he said, ‘I never embarked in any one thing to which I have so entirely devoted myself, and to which I have devoted so much time, thought, and labour, and on the success of which I have staked so much reputation.’

Heavy as Mr. Brunel’s duties were in October 1854, when he wrote these words, a far greater amount of labour was subsequently imposed upon him.

During the year 1855 financial difficulties arose which interfered with the progress of the ship; and at last, in February 1856, although Mr. Brunel had done everything in his power to prevent the necessity of such a step, the works were suspended; and they were not resumed till the end of May, after which date they were carried on by the Company under the supervision of the existing staff. It was greatly against Mr. Brunel’s wishes that this was attempted, except as a temporary measure, as he considered it impossible for a company to carry on such a work efficiently and economically.

Notwithstanding all these difficulties, that which seemed at first only a confused mass of iron assumed by slow degrees the graceful proportions of a ‘great ship’; and the hull of the vessel was completed by the end of the summer of 1857, so far as it was desirable to proceed before the commencement of the launching operations.

CHAPTER XII.

STEAM NAVIGATION—THE ‘GREAT EASTERN’ STEAM-SHIP. THE LAUNCH.

A.D. 1857—1858. ÆTATIS 52.

THE mode in which, the great ship was to be launched had necessarily to be determined before she was commenced. In May 1858, when the contract for her construction was entered into, the question was left open, and the contractor was either to launch her, or to build her in a dock ‘if it be found preferable.’ With Mr. Brunel’s full concurrence, Mr. Russell determined to build the ship on the river-bank, broadside to the river.

The reasons which led to this determination were fully described by Mr. Brunel in his report of February 5, 1855. This report has, with the exception of the parts relating to the launching operations, been printed above, p. 315. The passages there omitted are as follows:—

After it was determined that the ship should be built on the river-bank instead of in a dock, and parallel to the river instead of at right angles to it, the next point for consideration was, whether the ship should be lowered gradually to low-water mark, or whether a free launch should be attempted.

In a free launch the ship is allowed by the action of the force of gravity to run down the ways at a considerable velocity. In the case of the ‘Great Eastern’ there were insurmountable objections to this plan. Some of them might have been overcome by mechanical appliances; but these would have introduced complication and additional elements of risk.

In accordance with the opinion which he had from the first entertained, Mr. Brunel determined to move the ship slowly down the ways.

Subsequently to his determination to launch slowly, Mr. Brunel decided to employ sliding-surfaces of iron instead of greased wood.

In ordinary launches the ways are thickly greased, so that there is between the ways and the cradles a thick stratum of grease, which renders the friction very small. The conditions, however, do not remain the same throughout the passage of a ship down the ways; for, when she has moved some distance, the cradle has been rubbing away and squeezing out the grease; and therefore the part of the cradle which supports the middle and bows of the ship meets with increasing resistance from friction. Another and more serious cause of the destruction of the lubrication arises from unevenness in the ways.

The result of the action of the friction between the wooden surfaces after the destruction of the grease is sometimes so great that they become mutually imbedded, the fibres of the wood being rolled up together to such an extent that it has been found difficult afterwards to separate the timbers. The increased friction due to the deterioration of the sliding-surfaces of grease does not often produce failure in ordinary ship launches, because the vessel, while still on the fresh grease, acquires a momentum sufficient to carry it over the lower part of the ways, notwithstanding the retardation resulting from increased friction.

It was from a legitimate fear of the development of a retarding force due to the destruction of the grease, that Mr. Brunel hesitated to employ wooden sliding-surfaces. The ground was far from solid; and the use of piles as a foundation for the ways would not have prevented the possibility of excessive local pressure being brought on parts of the surfaces. The heat produced by undue pressure at any point under the great area covered by the cradles would tend to spread and aggravate the evil; and, had any considerable portion of the sliding-surfaces become wood-bound, the difficulty would have been far less remediable than in the case of an ordinary launch, where the cradles and ways are throughout accessible. But in the case of the ‘Great Eastern’ the space between the ship and the ways, over a considerable portion of the area covered by the cradles, was very confined, and it would have been a most tedious, if not a hopeless, task to get at the injured part so as to repair it properly.

At the end of the year 1856, when the construction of the ways had to be commenced, Mr. Brunel acted upon his views as to the dangers attendant on the use of wooden sliding-surfaces, and adopted iron. By this step, although there might be some fresh difficulties to be encountered, the disastrous consequences were avoided which might have followed from employing wooden surfaces.

Under two places in the length of the ship the ground had been prepared for the reception of the launching ways. These ways or inclined planes were two in number, and reached to low-water mark. They were placed at such positions as best to carry the weight of the ship without straining her. The ways, as originally designed by Mr. Brunel, were each 80 feet wide; but, with the desire of spreading the weight of the ship over a still larger area, he decided to add 20 feet to each side of each way, thus increasing their breadth to 120 feet. The ship’s head pointed down the river; 180 feet of the bow projected beyond the forward way, 110 feet were unsupported between the two ways, and 150 feet of the stern projected beyond the after way. The distance from the starboard side, the side next to the river, down to low-water mark, was about 240 feet; and the actual length of the ways, including the portion under the ship, was about 330 feet.

At the same time that he decided to use iron as the sliding-surface, Mr. Brunel adopted means for ensuring, as far as possible, the even distribution of the weight upon the ways. With this object he did not attempt to make them unyielding, but allowed them to yield slightly, so that, like a cushion, they might adapt themselves to the under surface of all parts of the cradles with a sufficient upward pressure. The ways rested on the river-bank, and piles were used to prevent the earth under the edges of the ways from swelling out at the sides, and yielding more than the ground under the middle portion.

The ground having been prepared to the slope of 1 in 12, a layer of concrete of about two feet in thickness was laid over the area of the ways. On the concrete were placed timbers running at right angles to the ship. These timbers, which were imbedded in the concrete, were 1 foot square, with a space of 2 feet 6 inches between them. Across these timbers, and parallel to the ship, were placed other timbers, with intervals of 2 feet between them; and upon these again were laid rails 18 inches apart, parallel to the ways, and at right angles to the ship. The rails were of the ordinary kind used on the Great Western Railway.

Thus the ways consisted of a network of timber resting on a thin bed of concrete; and on the top of the timber network were placed the rails which formed the actual sliding-surface.

The under side of the cradles consisted of iron bars, which were laid parallel to the ship, and therefore across the rails of the ways. These bars were each 1 inch thick and 7 inches broad, with an interval of 11 inches between the bars. Upon these bars was fixed 6 inches of hard wood planking (see fig. 15, a), and on this again came the framing of the cradles. Tapered timbers (b) were driven in, so as to fill up the wedge-shaped space between the hard wood over the bars and the flat bottom of the ship. On the side next the river, between these timbers and the rounded part of the under side of the ship, were driven in separate wedge-shaped pieces (c), which were secured to the timbers below by long bolts, arranged so as to allow the removal of the wedge-pieces when required. The means of unbolting the wedge-pieces was an essential provision for floating off the ship, as they had to be removed before she could move sideways off the cradles. Resting on the lower timbers of the cradle were stout props (d), which pressed against the ship’s side higher up than the wedge-pieces, and took part of the weight, and spread it over the outer part of the cradle. There were similar props (e) on the landward side of the cradles.

There were 80 rails on each of the ways, and nearly 60 transverse bars under each cradle; so that there were 9,000 intersections of the bars and rails. As the ship and the cradles weighed 12,000 tons, each intersection carried on the average a weight of 1⅓ tons.

After the construction of the ways was settled, the amount of power required to move the ship down had to be determined.

The motive power was not simply the chains, tackle, presses, &c.; but there was also the action of gravity. One motive power, then, was not only available, but was inevitably present; and, as the ways were at an inclination of 1 in 12, the motive power of gravity upon the weight of 12,000 tons was 1,000 tons. The question to be decided was, whether the 1,000 tons of motive force was sufficient to overcome the friction; and, if not, then what additional force would be required to do so.

In January 1857, immediately upon the adoption of iron sliding-surfaces, an experiment was arranged on a considerable scale, in order to form some idea on this important point. Two rails were laid at an inclination of 1 in 12, and upon them an experimental cradle was placed, weighing some 8 tons, and representing a small portion of the actual cradle.

The effect of the friction of iron sliding-surfaces may be summed up very simply. It appeared that the motive power need not, at most, be more than would have been given by placing the ways at an inclination of 1 in 8, and that restraining power could not have been safely dispensed with if the ways had been placed at a greater inclination than 1 in 16; as it was observed that, contrary to received notions, the friction became less as the velocity increased, and that, in case any considerable velocity were attained, a great force would be required merely to overcome the motive power of gravity down the incline, independently of that required to destroy the velocity.[159]

The task of getting the ship from the place where she was built to her moorings in the river divided itself naturally into two parts—the moving of the ship down the ways, and the floating her from off her cradles.

This subdivision of the whole undertaking of the launch into two almost distinct operations is of great importance in considering the manner in which Mr. Brunel conducted them; especially when it is borne in mind that one, the moving down the ways, was capable of being, by careful precautions, rendered almost safe; whereas the other, the floating the ship off, was dependent on the successful issue of various minor operations, in the management of which the fallible human element had a greater share, and where small accidents, though, in their primary effects, productive only of delay, might cause irretrievable disaster.

In the operation of lowering the ship, there had to be provided both power to move her and power to check her motion. In floating, but one force was necessary, namely, that required to pull the ship off if she got jammed on the cradles.

With a desire to provide for the possibility of an extreme amount of resistance on the ways, Mr. Brunel designed a complete hydraulic apparatus, which would have been sufficiently powerful to move the ship down without interruption or delay. It is much to be regretted that he did not persist in carrying out his original intention.

In the operation of floating, chains and tackle were the best means of supplying the tractive force that might be required; and Mr. Brunel decided to have a very large amount of available power. If the weather were fine, and the tide at its calculated height, if no part of the cradles got disarranged, if the calculations as to the ship’s draught of water were correct—if everything went right, there would be no necessity for any great hauling power; a few tug-boats would suffice to take the ship to her moorings. But Mr. Brunel determined that in this critical operation of floating he would not trust to good fortune, when the absence of it might produce grave injury. The power which he thought it desirable to provide in chain purchases for the floating was very considerable, being equal to a pull of 500 tons.

As it seemed probable that the ship would not require much force to move her down the ways, it seemed also probable that the river tackle (as the chains and appliances for hauling the ship off were called) would be sufficient for both purposes. This being the case, it at the time appeared right, in the embarrassed state of the Company’s finances, to dispense with the more powerful and costly apparatus which Mr. Brunel had proposed for moving the ship down; there being no fatal consequences to be apprehended from a defect of power.

Influenced by these considerations, Mr. Brunel resolved to trust to the river tackle alone.

He referred to this decision in a letter to the Secretary of the Company written during the launch:—

The experiments made with the trial cradle had shown the necessity of providing a certain amount of restraining force. As will be seen in the description of the launch, it was only used once, but it must not therefore be supposed that there was no necessity for providing it.[161]

The arrangement of the checking gear was the same at each of the ways. Attached to the land side of the cradle, by means of bolts, was a strong iron framework which held two large horizontal wheels or sheaves. At the upper end of the ways another sheave was fixed in a strong timber framing; and opposite the middle of the upper end of the ways was placed a large windlass or drum.

This drum was a cylinder, about 20 feet long and 6½ feet in diameter, of solid timbers, strongly bolted together, and secured at each end in a broad cast-iron disc, 12 feet in diameter.

To a point in the framing was attached one end of a 2⅝-inch chain cable; this chain was passed round one of the sheaves attached to the cradle, then round the sheave attached to the upper end of the ways, then round the second sheave attached to the cradle; and its end was coiled round the drum. Thus, as one end of the chain was secured, it was necessary, before the ship could move down the ways, that the drum should revolve, and slacken the end of the chain coiled round it.

Round the discs of the drum were wrought-iron straps; these, when tightened by levers, formed brakes by which the revolution of the drum could be retarded. Gearing was provided with a train of toothed wheels, so that the drum could be turned round by handles, and the chain wound on to it.

The following paragraph is from the commencement of a memorandum by Mr. Brunel on the launching arrangements, written about five weeks before the launch began:—

The apparatus which Mr. Brunel prepared for performing the double duty of moving the ship down the ways and hauling her off the cradles was as follows:—At each end of the ship was a powerful chain tackle. One end of a chain cable was secured to a mooring in the river, and it was passed round a large sheave attached to the ship, then round a sheave fixed on a barge about 300 feet from the ship, and the end brought on shore, where it was hauled on by a chain tackle worked by a steam crab. The sheave attached to the ship at the bow was slung by chains about 80 feet from the stem. The sheave at the stern was fixed on the end of the screw shaft. These purchases were intended to be good for 80 and 100 tons respectively, and were to be able to follow up the ship quickly if she moved.

In addition to these purchases, Mr. Brunel desired to have ‘the means of bringing a considerable strain to bear in the event of the ship sticking at starting, or at any subsequent time, and particularly at the last;’ and he considered that ‘nothing under 250 or 300 tons would be of any use for the purpose.’ This power he desired to apply to the centre of the ship between the two cradles by means of double crabs and treble purchase blocks on four barges.

One of the double crabs was mounted on each of the four centre barges, and was placed on a platform, elevated so that the blocks of the chain tackle could pass underneath it. This tackle was made fast to a chain attached to the ship; and the mooring chain extending across the river was hauled on by the tackle.

Each of these four crabs and tackle was to be capable of working up to a strain of 80 tons. The strain which Mr. Brunel intended to be able to put on the ship by the river tackle, in the form of a good continuous pull, was in all 500 tons.

Two hydraulic presses were also provided, one at each of the cradles, to overcome adhesion in first moving the ship. Each of these presses should have been able to exert a strain of 300 tons. Therefore, including the force of gravitation, the power which Mr. Brunel hoped to have to start the ship was 2,100 tons, or more than one-sixth of the weight to be moved; and for a continuous steady pull to keep her moving, 1,500 tons, or one-eighth of the weight.

It was at one time thought possible that the launch might be effected in October. But it was found that it would be impossible to be ready before the spring-tides at the beginning of November; and even then, when the time came, there was considerable hurry, and important matters were, as will be seen, insufficiently attended to.

The cradles were put together and wedged up under the ship, and every effort was made at low water to extend the ways as far as possible; so that, by moving her further down the slope, a greater margin might be obtained, to allow for any falling off in the expected level of the tide, or for any miscalculation in the ship’s draught.

In the memorandum already referred to on the launching arrangements Mr. Brunel instructed Captain Harrison to superintend the moorings for the river tackle, and to satisfy himself of their sufficiency. A few days afterwards he wrote to Captain Harrison on the subject:—

Frequent enquiries were now made relative to the time of launching; and the number of applications which poured in for admission to the yard led Mr. Brunel to write the following letter to the Directors of the Company, and it was published by them in the newspapers. In it he not only removed current misapprehensions as to the nature of the proposed operations, but he also took the opportunity of pointing out that there would be no risk to the ship in the mode of launching adopted, and that, although it might at first be unsuccessful, further power could be applied, and the ship safely launched.

Throughout October an immense amount of work had to be done, and the multiplicity of matters to be attended to pressed heavily on Mr. Brunel and his assistants.

With the check tackle he had reason to be content. The chains, which were the ship’s cables, had been very carefully made; and, in addition to the usual tests, pieces had been taken at hazard, and were found to bear a good breaking-strain.

The river tackle was not so satisfactory. In operations that have to be conducted afloat unexpected delays arise, and all the work may be suspended by bad weather, and it is moreover frequently dependent on tides. In the present case the work to be done was not easy. Heavy chain cables had to be laid out, and moorings picked up and connected to the tackles; one work having often to wait for the completion of another.

Mr. Brunel had determined that each purchase should be tested by being strained to the utmost stress for which it was intended; but, owing to the delays which had occurred in preparing the river tackle, this was not done.

A few days before the launch Mr. Brunel addressed the following memorandum to all who were to take part in the operation:—

General Arrangements and intended Mode of Proceeding.

In a memorandum of ‘Particular Instructions,’ dated the next day, October 31, there is the following passage:—

In another part of these ‘Instructions’ Mr. Brunel again shows that he was not, as has sometimes been supposed, under the impression that the friction would be so small that the only important thing to be thought of was to check the ship from rushing too fast.

On the contrary, he foresaw the possibility of her not moving at all, even with the presses, that is to say, with a force of 1,100 tons over and above the action of gravity. If after moving she stopped, and then required the presses again to move her, this would show that the operation could not be properly carried out, and that the work must be suspended till more motive power was applied. If, again, the river tackle were sufficient to move her, then the work was to proceed, but the friction might even then be so great as to render it desirable to remove all retarding force. He says, in another passage in his ‘Instructions:’—

The best day on which to begin the launch was Tuesday, November 3, as it left two or three days of the high full moon spring-tides for the operations, should they be prolonged.

On Monday, November 2, the chief work remaining to be done was stowing kentledge or iron ballast on the cradles, to prevent the timbers floating when the ship should be moved off them. All the appliances were ready, and, except the river tackle, had been carefully examined. This, as has been already said, had not been tested.

It was now for Mr. Brunel to consider whether, in consequence of the river tackle not having been properly tested, he should postpone the launch till the following month.

It was most important for the Company that the ship should be afloat as soon as possible; and, as any defects which might exist in the river tackle would almost certainly declare themselves in the earlier part of the operation, when nothing worse than delay could be apprehended, Mr. Brunel, after a careful review of all the circumstances, determined to attempt the launch.

On the morning of November 3, the work of putting kentledge on to the cradles was completed by firelight, and the rails were rubbed over with a mixture of oil and black-lead. All the shores and props which supported the weight of the ship had been removed, and she was now resting entirely on the cradles.

Later on in the morning the brakes of the drums were tightened down, and the dogshores were removed from the ways in front of the cradles. Mr. Brunel, who had been engaged from an early hour in examining all the preparations, superintended this operation, and, having satisfied himself that all was clear and ready, returned to the upper part of the yard.

By this time it was crowded with people. The Directors, contrary to Mr. Brunel’s expressed wish, and without informing him of their intention, had issued a large number of tickets of admission. A few days before, Mr. Brunel had suggested that four policemen should be obtained, thinking that all they would have to do would be to contend with trespassers. The police force actually present were ignorant of the portions of the yard to be kept clear, and Mr. Brunel had himself to go and assist in ordering visitors away from the neighbourhood of the path prepared for the tackle of the stern hauling gear. The crowd soon became so great that it was almost impossible for the men in charge of the hauling-engine at the stern to see the signals given from the middle of the yard, or for those in the middle of the yard to see what was happening at the stern.

At about half-past 12 o’clock the fastenings of the ship at the bow and stern were let go, and Mr. Brunel ordered a small amount of slack to be given off from each drum. This was done by men turning the handles of the gearing which had been provided for winding the chain on to the drums. The order was then given to haul on the bow and stern tackle, and to pump at the hydraulic presses. It is doubtful what amount of strain was put on by the tackle and the presses, but it was probably not very great.

Presently a shout from the forward cradle announced that it was moving, and almost immediately the stern cradle also started with what appeared to be a considerable speed. The men who had been engaged in turning the handles of the gearing had remained leaning against them. As soon as the ship had moved a few inches, she took up all the slack chain. This made the drum revolve, and the handles of the gearing spun round very rapidly, striking the men, and throwing them into the air. The men who were at the brake-handle next to the gearing ran away. Mr. Brunel, who was standing near the drum when the accident happened, shouted to the men to hold on to the brakes, and ran to the spot. The men who had remained at the other brake-handle hauled it down with the tackle. A great restraining force was thereby brought upon the ship, and her progress ceased; the forward cradle having moved 3 feet, and the after cradle 4 feet 3 inches.

Five men were injured. On the death of one of them it was stated at the inquest, by the foreman of the drum, that, after the slack had been paid out, he had ordered the men to stand clear. Be this as it may, it cannot be denied that the handles should not have been used after the securing chains had been let go; and indeed Mr. Brunel said at the inquest, ‘I may blame myself, for I did not anticipate that the handles would have revolved so rapidly.’

After this accident, Mr. Brunel determined to wait till high water before recommencing the operations. In the meantime the gearing was removed from both drums.

A more important change was also made in the arrangements. When the ship moved, the men on the four middle barges became frightened, thinking she was about to overwhelm them; a rush was made, and one man, jumping into a small boat, shoved off, leaving the rest to their fate. A report was at once sent to Mr. Brunel that the men were untrustworthy, and that they would not remain; and that, as the barges would be of no use without the men, the chains had better be dropped and the barges removed. To this Mr. Brunel consented.

It would, however, have been sufficient to take the men off, leaving a tug-boat and a few steady men to keep the barges out of the way of the ship; they would then have been available if required. Mr. Brunel, a short time after he had given the order, ran round the bow with Captain Harrison to countermand it; but it was too late, as it had been already acted upon. As events turned out no harm was done, as the centre barges alone would not have been sufficient to go on with, after the rest of the tackle failed.

The result of these changes was that when the operations were recommenced, the only hauling gear was the bow and stern purchases; the hydraulic presses were also available to start the ship.

At a little after 2 o’clock the signal was given to haul on the bow and stern tackle, the presses being at the same time pumped up. The brakes of the drums were slackened, but kept all ready for tightening.

Not long after the strain had been brought on the tackle, several of the teeth of one of the wheels of the bow steam crab gave way, and the chief anchor at the stern began to drag, so that no efficient strain could be obtained. On this being reported, the operations were discontinued; and, as there was no possibility of getting things ready by the next day, the launching operations were postponed till December 2, the next full moon spring-tides.

As soon as this was known the visitors rushed in on the works, crowding about the cradles and ways; and Mr. Brunel had to postpone those investigations which he wished to make at once.[163] The whole yard was thrown into confusion by a struggling mob, and there was nothing to be done but to see that the ship was properly secured, and to wait till the following morning.[164]

The next day was devoted to an examination of what had gone wrong, and to the consideration of what should be altered before another attempt was made.

At the stern mooring the anchor was bedded into the ground on the further side of the river.

The difficulty with regard to the four centre barges was got over by placing the four crabs with their tackles in the yard, on the landward side of the ship. The four chains attached to the ship, which had before been hauled on directly from the barges, were now passed round sheaves on the barges, and brought back under the ship’s bottom to the tackles in the yard.

The chief alteration, however, was in the arrangement of the hydraulic presses. On November 3, there were, as has been said, two presses. Two additional presses were now provided; each of these consisted of two 7-inch cylinders, and was equivalent to a 10-inch press.

With the object of being able to employ the presses continuously during the descent of the ship, they were arranged to point down the ways at an inclination of 1 in 12. The four presses were placed one on either side of the check tackle at the two ways, and were supported by abutments of timber-work. These abutments each consisted of four rows of piles, one behind the other at intervals of about 8 feet. The press abutted against the row of piles nearest to the ship, which were connected by wooden struts to the piles behind them. Long balks of timber of various lengths were prepared to transmit the pressure to the cradles.[165]

The four presses might be considered equivalent, at their full power, to a force of 800 tons; this was so much in excess of the small force that had moved the ship on November 3, that, even making every allowance for the advantage of the fresh lubrication in the first instance, it seemed reasonable to suppose that with this force the ship could be moved down easily.

As the process of moving the ship with the presses would naturally be a slow one, Mr. Brunel determined to proceed with the operations as soon as everything was ready. On November 19 the work was commenced.[166] The bow tackle was hauled upon first, as the forward cradle was more than a foot behind the after one, and the men at the forward presses were set to work. After a short time the timber backing of the presses began to crack and ‘cry out’; and, without much stress on them, the abutments were forced back some 3 or 4 inches. The mooring chain of the bow tackle also gave way, although there was not any excessive strain on it. On examining the abutments, Mr. Brunel saw the cause of their failure, and ordered the strain to be taken off. The number of piles was sufficient, but the way in which the strain was communicated to them did not enable them to exert the proper amount of resisting power.

This defect was cured by tying the heads of the rearward piles with bolts to the foremost piles. The ship being secured, each press was tested to a full strain, and the adequacy of its abutments ascertained.

It was different, however, with the river tackle. The chain which had parted was an old river mooring-chain of great size. Much delay in replacing it was caused by dense fogs, which made it almost impossible to work on the river. Moreover, there seemed a fatality about every attempt to get a regular trial of any part of the tackle. When, at last, a trial took place, and a strain was put on, a mooring-chain gave way; then this had to be fished up from the bottom of the river, and pieced together, the accident being ascribed to a defective link in the chain. The trials were, therefore, so few that it was only proved by degrees that all the regular moorings were worthless; although they had large chains which ought to have been good for three times the strain put on them.

The stubbornness of the ship on November 19 gave Mr. Brunel great anxiety; not from any fear of being unable to apply sufficient power to move her, but because, on continued consideration of the subject, he apprehended that a serious difficulty might arise, if there should be a prolonged delay at a particular part of the ship’s progress.

It has been explained that Mr. Brunel, with a view of obtaining uniformity of bearing over the surface of the ways, had not attempted to support them rigidly on piles, but had rested them on the river-bank. As, however, the foundation of the building slip was comparatively rigid, he feared lest an unequal subsidence might cause injury to the ship, if she were stopped for any length of time before she had completely left the ground on which she was built. He thought that if the ways sank at this point they would assume a slightly convex form, and tend to force upwards the flat bottom of the ship. The main part of the ship’s bottom, between the longitudinal bulkheads, could bend in slightly under a heavy upward pressure; but this action could not take place at the transverse bulkheads, as they would not yield without injury. Mr. Brunel shrank from proceeding with the launch without having in reserve such an amplitude of power as would prevent the ship’s being stopped at this critical point. This consideration, together with the continued failure of the river tackle under such tests as were applied to it, led him to address the following communication to the Directors:—

Mr. Brunel at the same time determined to obtain, on a large scale, a measure of the deflection that might be expected from the weight of the ship coming on the ways. More than 100 tons of kentledge was piled on a portion of the ways 10 feet square, in such a manner as to give a pressure thereon of about double that which would be produced by the weight of the ship.

It was necessary that this test should not be tried on too small a scale, as a weight resting on an isolated patch would receive support from the surrounding ground, which it could not of course do if that ground was equally loaded. The ways sunk so little under the test as completely to reassure Mr. Brunel, and to show that no serious evil need be contemplated in the passage of the ship from off the place where she was built on to the newly made ways, even though she might be again stopped for some time. He therefore determined to go on at once with the launching operations.

The result of the test was very satisfactory to him, and it enabled him to carry on the work with the same confidence as he had at the first felt—‘that the ship may stop halfway or not move at all ... but no injury to the ship can result from any failure in the course of proceeding in this mode of launching.’

Shortly before the second attempt to move the ship, on November 19, the experimental cradle had been again put up with a view of obtaining some additional data as to the hauling strain that might be required. The deductions made from them were the same as those obtained in the commencement of the year, and encouraged the hope that the motive power required would not be excessive.[167]

By Saturday, November 28, the four presses had been got ready; and the river tackle, though still far from being beyond reproach, had been got into place, and partly tested.

The brakes were eased, and a small amount of slack was overhauled on the check-tackle chains by the men stationed on the ways for that purpose. As on the previous occasion, the pressure was to be first put on the presses at the foremost cradle.

Arrangements were made for promptly following up the ship if she moved freely. A black board was placed on each cradle for recording the progress of the ship.

Mr. Brunel stood on a low platform in the centre of the yard, as a convenient position from which to watch and command the operations. A little before ten he gave the order to commence pumping, and the men at the hydraulic presses got to work. When the pressure came on the timber framing which formed the abutments, there was considerable noise of creaking and crushing as the several parts subjected to strain came in to their proper bearing. The men soon changed from the large plunger handle to the small one which put on the full pressure; the timbers of the abutments kept on crying out, but it was evident that they were not yielding as they had done before. Presently, while the noise of the timber-work was still attracting attention, the man in charge of the measuring apparatus recorded on his black board a movement of one inch; the ship was again in motion.

She moved steadily, but slowly, under the force of the presses, at a rate of about one inch a minute, and as soon as the forward cradle had been moved about a foot in this way, the presses at the after-ways were set to work, and the river tackle was put into operation, first the bow and stern tackle, and then the four middle purchases. All went well with the presses, but the strain had not been put on long, when the stern mooring-chain and one of the two chains at the bow broke; an anchor at the bow had also begun to drag.

Later in the day part of the moorings of the centre barges also gave way. Captain Harrison set to work to repair these defects as fast as they occurred; in no way dismayed that, as he was at work remedying one mishap, the news of another was brought to him. Barges had to be got into place, the broken ends of cables fished up or under-run and pieced together, and this often in the dark; for it must be remembered that the work was going on at the end of November, when the sun rose, invisible for fog, at half-past seven, and set at half-past four.

With the exception of the river tackle, all had gone well; the presses and their abutments had acted efficiently, and the ship had been moved easily down the ways about 14 feet before work was suspended at night.

Though the progress had not been great, there still seemed a reasonable hope that, by pushing on, the ship might be got down to the bottom of the ways in time for floating her off at the next spring-tides, namely, on December 2. Mr. Brunel therefore decided to go on with the operation on the Sunday. Early in the morning the presses and crabs were again set to work. The river tackle soon gave way; and, indeed, there was no reason why it should be superior to that used the day before, as almost all that could be done in the night was to piece together the broken chains, and to replace the anchors. The moorings at the bow and stern began at once to drag, and two of the mooring-chains amidships parted. The hydraulic presses were then the only available power; and, although the full pressure was put on, the ship did not move. This was very disheartening; it was, however, thought that the resistance was due to some exceptional adhesion. Every effort was therefore made to get together the means of giving the ship a first start.

It was not till the afternoon that a large number of screw-jacks and hydraulic jacks which had been procured were got into place; they were then screwed up hard, and the hydraulic presses being set to work, the ship began to move in a manner very similar to that of the day before. There was not, however, much daylight left; and, when night came on, the distance traversed was only about 8 feet. The comparative facility with which the ship moved when once started gave hopes that good progress might be made the next day.

On Monday morning the ship moved without more difficulty than when she had stopped the evening before, and the work went on quite satisfactorily. She continued to move slowly, and by dinner-time had gone about 8½ feet. Three feet an hour was not much, but still if it could be kept up it would suffice to get the ship down by the next spring-tides. Arrangements were therefore commenced for lighting up the ways and pumping machinery, so that the work might be continued through the night. The repairs of the river tackle were pushed on, the ship’s anchors, which had just been finished and tested, were laid down for part of the moorings, and some of the chains were replaced with chains lent by the Government and by Messrs. Brown and Lenox.

When work was recommenced after dinner the ship made a short slip of about 7 inches. On pressure being again applied the 10-inch press at the forward cradle burst. This put an end to all work for the day, and it was then determined to replace the broken press and to add two more presses to each cradle, before proceeding with the launch.

The preparations for the new presses were pushed on vigorously, but it was not till the afternoon of Thursday, December 3, that things were again ready for a start.

The pumps were set to work and the tackle hauled upon. The ship made several short slips of a foot or so, and then moved more than 5 feet at one slide. When darkness set in she had moved about 14 feet, in slips of greater or less length.[168]

On Friday, December 4, all was ready early, and during the morning everything went as well as on the day before; but in the afternoon increased difficulty was found in getting the ship to move, and the 14-inch press at the after cradle burst, as did also a 7-inch cylinder of one of the coupled presses.

Notwithstanding the delay due to the bursting of the presses, the ship was moved some 30 feet; but there was no longer any chance of getting her afloat at the spring-tides, and the increased adhesion gave cause for the fear that still more power would have to be applied.

On the next day, Saturday, December 5, the ship made a short slip; but, although the pressure was kept constantly on, no further advance was made until late in the afternoon. Mr. Brunel then tried suddenly letting go the strain on the stern tackle. The sudden relief of the side-way strain on the end of the ship sent a tremor through the hull, which served to destroy the adhesion, and she slid several inches. This operation was several times repeated, and although there were a number of vexatious delays from pushing-pieces giving way and other mishaps, she was moved by the evening a distance of about 7 feet, the resistance due to adhesion being very great.

On Sunday some of the presses farthest from the cradles were moved down the ways nearer to the ship, so as to avoid the necessity of using long pushing-pieces, which required much attention to prevent their bulging sideways. The river tackle now consisted of the bow and stern steam-engine purchases, and two crabs and tackle, one at each end of the ship. The moorings opposite the centre of the ship having proved worthless, it was necessary to lay down new moorings, and it was found more convenient to lay them opposite the ends of the ship.

The next day, Monday the 7th, after the commencement of operations, considerable delay was caused by the failure of some of the feed pipes of the presses. These defects were not cured till after dinner-time, when the operations were resumed, and before dark the ship was moved about 6 feet.

On the following morning several short slips were made, and the ship had been moved about 4½ feet; but, at 10 o’clock, a dense fog came on, and rendered it impossible to proceed. The next day was occupied in re-arranging the tackle and presses.

These were not ready till the morning of Thursday, December 10; when, on the presses being again set to work, and one of the chains being as before suddenly slackened, the ship made one slip of a little over a foot; but, on the strain being again applied, two of the anchors began to drag. As it was now essential to have the river tackle, in order by shaking the ship to destroy the adhesion, and by the drag of the catenaries to increase the length of the slides, Mr. Brunel determined to dispense with the anchors, and to attach the chain cables to piles connected by framework. These abutments or pulling points for the chains were now constructed on the other side of the river, opposite the bow and stern of the ship.

The launching operations last described, namely, from December 3 to December 10, were full of incident. Nor was the scene wanting in that animation which agreeably interests a bystander, the more so if he is not thoroughly conversant with the meaning of all he sees and hears, so that he mistakes a loudly spoken word, loudly spoken merely that it may be plainly heard, for a prompt and urgent command.

The labourers at the pumps relieved the monotony of their work, and shook off the cold, by taking a lively and talkative interest in the progress of the launch, and echoed the orders given them to pump with the ‘big plunger,’ or ‘little plunger’ of the pumps, or to ‘fleet’ the press. This and the singing of the gangs, which were constantly at work moving chains for the repair of the river tackle, or rolling logs of timber on to the ways to serve as pushing-pieces for the presses, gave plenty of life to the operations; and then when the pressure had been got on the presses, and shouts from the bow and stern of the ship passed the word that the river tackle was hauled taut, the order would be given to ‘let go’ the chain at one end of the ship. Immediately the rattling noise announced that this had been done, and, after a second or two of anxious watching, the ship slid off, the timbers, abutments, and pushing-pieces creaking and groaning as the strain was suddenly relieved. While the ship was in motion, the whole of the ground forming the yard would perceptibly shake, or rather sway, on the discharge of the power stored up in the presses and their abutments. The appearance of the ship moving sideways in these short slips, when seen from the ways, was very imposing.

All these somewhat striking surroundings of the operations were naturally heightened in effect, when the work was being carried on in the early morning or late in the afternoon; and when the timber-framing and the groups of men at work were illuminated by the glare from the open fires which were kept burning near the pumps and presses.

The preparations already described were not completed till December 15. In the meantime Mr. Brunel had been joined by his friend Mr. Robert Stephenson. Mr. Stephenson had not been aware of many vexatious circumstances which had even prevented Mr. Brunel from making full use of his own staff of assistants. Mr. Stephenson expressed to a common friend his regret that Mr. Brunel had not invited him down to the ship, and said that he should have gone down uninvited, but that he thought Mr. Brunel had reasons for not wishing it. On the state of affairs being explained to him, Mr. Stephenson said, ‘I’ll go down to him at once;’ he did so, and his arrival at Millwall was very welcome to Mr. Brunel.[169]

Mr. Stephenson agreed with Mr. Brunel as to the expediency of suspending operations until an ample excess of power was applied. Fortified by the support of Mr. Stephenson, Mr. Brunel was prepared to advise the Directors to adopt this course; but, as the preparations for recommencing the work were just completed, it was determined to make a trial on the afternoon of December 15. The presses were all pumped up, and the river tackle hauled on; but, although the force applied was at least 300 or 400 tons greater than that which had last moved her, the ship did not yield, and the attempt was abandoned. After a careful consultation on the depressing result of this day’s work, it was determined to make another attempt the next morning, in order to see if any new form of difficulty had arisen; and that after this operations should be suspended, and an ample number of additional presses provided.

The following day, December 16, as soon as Mr. Brunel and Mr. Stephenson had arrived, the pressure was again put on the presses, and the river tackle having been hauled taut, the chains at the bow were let go, and, to the great satisfaction of all present, the ship made a short slide. The record of her movement showed that, although the adhesion was much greater, the retarding force of friction was about the same as before, and that therefore there was no reason to assume the existence of any special obstacle. Another short slip was made; but, in getting up the pressure again, a press was burst, and the work was then stopped.[170]

Mr. Brunel’s decision to suspend the launching operations at this point was approved at a meeting of the principal shareholders held the next day. His report to the Directors, and a memorandum of a verbal statement which he made to the meeting, are as follows:—

Memorandum of a verbal Report made to the Directors, and a small Meeting of the Principal Proprietors.

A large number of presses were obtained, the owners for the most part lending them free of charge. Among these presses was the large one, with a 20-inch cylinder, which had been used for lifting the tubes of the Britannia Bridge.

On each of the ways were placed nine presses. The total sectional area of the cylinders at the forward cradle was 1,066 circular inches, and that of the cylinders at the after cradle was 1,358 circular inches; but the Britannia press was not to be worked to its full power, so the total area of the cylinders may be taken as 2,300 circular inches, or 1,800 square inches. The presses might be considered as good for at least 2½ tons on the square inch; this gave a power of 4,500 tons, which, with the 1,000 tons due to gravity, gave 5,500 tons, or equal to nearly half the weight of the ship. The presses were now coupled together in groups, in order to ensure that an equal pressure should be brought on them; and to each of these groups an accurate pressure gauge was attached.

All the presses having been tested, it was determined to recommence the actual operation of launching on Tuesday, January 5.

So much of the water in the pipes had been frozen that it was eleven o’clock before the order was given to the men to pump. When at one group after another the pressure was shown to be one ton on the circular inch, the pumps were stopped. As the backing of the presses continued to yield slightly, a stroke or two of the handles had to be made from time to time, to keep up the required strain. For six minutes there was perfect silence, and then the ship moved, sliding down about 3 inches.

The same process was repeated at the stern cradle once or twice, and then at both cradles. After this the order was given that the pumps should be kept going till she moved. This was accordingly done, and when the pressure amounted to 1¼ ton on the circular inch the ship made a slide of about 4 inches. In this manner she was moved about 5 feet before work was stopped in the evening.[171]

On January 6, there was a singular change in the behaviour of the ship. During the whole of the forenoon she moved gradually, yielding to the pressure at a rate of about an inch in four minutes. In the afternoon, however, she moved in short slides.

During this and the three following days her progress was about 10 feet each day. After this the ship, being to a considerable extent waterborne, was moved with greater ease, and on Tuesday, January 12, 20 feet was accomplished in less than four hours.

By Thursday, the 14th, the ship had traversed a distance of 197 feet at the forward cradle, and 207 feet at the after cradle. It was thought unwise to advance further till the coming spring-tides on the 19th of the month were past, lest an exceptionally high tide might come unexpectedly, and partially float her. As soon as the spring-tides had passed, she was moved on cautiously, a short distance at a time, and the depression of the ways was carefully observed. This was found to be inconsiderable, and the cradles were gradually pushed 25 feet off the ways. As the spring-tides came on, water was run into the ship, to prevent her from floating prematurely.

The upright struts of the cradle on the side next to the river were all removed, and the wedge-pieces had chains fastened to them, with the ends brought on deck; so that, if any of the wedge-pieces got jammed and did not come out when the ship floated, they might be hauled out by the chains.

The river tackle now consisted of two purchases at the bow and two at the stern. To keep the ship, when she floated, from being drifted by the tide or wind, chains were carried from the bow and stern to moorings, by which her movement up and down stream might be regulated. Four tugs were in attendance to tow the ship to her berth, and a floating fire-engine was also ready to pump water into her, should this be necessary owing to any sudden postponement of the launch.

Nothing now remained but to watch carefully for a suitable tide.

It was determined that, if the weather were favourable, the floating should be effected on Saturday, January 30. The tides had been below the average, and on the Friday matters did not look promising; the tides had continued low, and the weather was bad. A careful watch was kept on the tide, observations being taken every half hour, and plotted on a diagram so as to show at a glance the probable height to which it would rise.

The tides showed signs of improvement, and they commenced to pump water out of the ship on Friday night; but, as time went on, the weather did not mend, and the wind was blowing from the south-west against her broadside; therefore in the early morning Mr. Brunel, who was in person attending each turn of affairs, ordered water to be pumped in by the fire-engine. There was hard rain and strong wind; and telegrams which, according to arrangement, were being frequently sent from Liverpool and Plymouth, showed similar weather. This continued throughout the Saturday, and the tide was low; but, when it began to rise in the evening, it gave indications of being a very high one. As soon as the tide reached the Kingston valves, Mr. Brunel had water run into the ship. Although she rested uneasily on the cradles, she remained safely in her position.

In the evening the rain came down in torrents; nevertheless, after midnight the weather mended, and the wind went round to the north-east. As the telegraph gave the same report from Liverpool, Mr. Brunel, encouraged by every sign of fine weather, and having the good promise given by the high tide of the night before, determined early on the morning of Sunday, January 31, to float the ship on that day.

The pumps were immediately started to discharge the water from the ship. The bolts securing the wedge-pieces of the cradles were unfastened at daybreak, and the ship was then ready.

The morning broke with great splendour after the gloom of the previous days, and the tide, as soon as it had turned, began to rise with unusual rapidity. It had been arranged that all the men should be at their posts at the presses and crabs by eleven o’clock; but the tide was not only very high, but exceptionally early; and, although a considerable margin had been allowed, it was not sufficient. Mr. Brunel and his assistants hurried the men to their places, the presses were set to work, and the ship was put in motion down the ways for the last time.

At a little before one o’clock observations taken by levels showed that the ship had ceased to descend, although she was still being pushed forward. Shortly afterwards Captain Harrison, who had gone on board, sent Mr. Brunel word that all the wedge-pieces had floated up on the outer side of the ship; and at twenty minutes past one the stern was seen to be afloat. Mr. Brunel had been loath to haul out the ship by the river tackle, lest the wedge-pieces might get jammed; but, as soon as he was informed that they had floated up, he sent orders for a strain to be put on the bow tackle. This was at once done, and by twenty minutes to two the bow rose from the cradle.

Mr. Brunel then ordered the checking gear to be secured, that the ship might be sooner hauled clear of the cradles, and he went on board. He had scarcely done so when a serious difficulty arose. It has been already said, that in order to keep the ship from moving up or down stream, cables had been carried out to moorings ahead and astern; and both these chains had been hauled up tolerably taut, at least the slack had been taken out of them, so that if required they might be at once available. Now when Mr. Brunel had given the order for the bow out-haul tackle to be hauled upon, Captain Harrison, in order to supplement it, ordered the tug-boats to haul the bow off. This order was by some one conceived to have been given with the object of hauling the ship ahead; and to facilitate this the stern mooring-chain was let go.

By this time, though the tide was still running up the river, its strength was much diminished; and the drag of the chain at the bow of the ship was sufficient to pull her forward against the tide. The paddlewheel on the shore side then came in contact with the upright timbers of the forward cradle. Mr. Brunel ran down from the ship into a boat and examined the place where the wheel was fouled. He then hurried back on board, where, as through some blunder the stern outhaul had also been let go, he had now little but the tug-boats to depend upon. They were of course of but small value for a dead pull as compared with the chain tackle. He had the bow chain veered out and the tugs all set to work, assisted by the tide, to haul the ship up the river.

In about twenty minutes time, the paddlewheel was got clear of the cradle, and this great difficulty was overcome. Fortunately, the tide was an extraordinarily high one, and the time of available high water was long.

The ship had not been moved far towards her berth when another mishap delayed her progress. The barge of the bow purchase came foul of the starboard paddlewheel, and the only way of freeing the ship was to scuttle the barge. When this was done it sank away clear of the wheel, and the ship proceeded to her berth on the Deptford side of the river.[172]

By about seven o’clock she was safely moored; and the cheers of the men, as Mr. Brunel went down her side, announced that the launch of the ‘Great Eastern’ was at length accomplished.

NOTE A (pp. 348, 368, 372).

Experiments and Observations on Friction.

NOTE B (p. 384).

Letter from Mr. Brunel to W. Froude, Esq.

CHAPTER XIII.

STEAM NAVIGATION—THE ‘GREAT EASTERN’ STEAM-SHIP.

COMPLETION AND SUBSEQUENT HISTORY.

A.D. 1858-1859: ÆTATIS 52-54.

A.D. 1859-1870.

SOON after the launch of the ‘Great Eastern,’ efforts were made to obtain funds for finishing her, and Mr. Brunel proceeded to prepare designs with the view of obtaining tenders for the execution of the decks, skylights, fittings, rigging, &c. He obtained advice from persons thoroughly conversant with this class of work; and a specification was carefully prepared, providing for the completion of the ship in a perfect manner.

Meanwhile it had been considered that, large as the ship was, she might be profitably employed in the American trade, and that it might be expedient to run her on that line for a few voyages before placing her on the Eastern route. Captain Harrison went to America to examine the harbour at Portland, and brought back a favourable report of it.

All efforts to raise the funds for finishing the ship proved unavailing; and it was determined to reconstitute the company.

The new company, which was called the ‘Great Ship Company,’ was formed towards the end of the year 1858. In the beginning of December, Mr. Brunel was compelled by ill-health to go to Egypt for the winter. On leaving England, he strongly urged the Directors on no account to fail to make a strict contract, distinctly defining the work to be done, and the manner of its execution, as provided for by the specifications he had drawn out. But his advice was not followed.

After Mr. Brunel’s return to England in May 1859, he continued to give the greater part of his time to the ship. The difficulties which he had to encounter were certainly neither fewer nor less vexatious than those which had arisen at earlier periods in her history; but they were the last with which he had to contend.

On September 5 he left her in the morning, feeling the commencement of the illness which ten days afterwards terminated fatally.

The ship left her moorings on September 7, and with the assistance of several tugs steamed down the river. She stopped for a night at Purfleet, and again at the Nore, and then left for Weymouth.

On the voyage a serious accident happened, which was made the subject of much misrepresentation.

Round each of the funnels of the paddle engines was what was termed a water-casing, or jacket, consisting of an outer cylinder, about 6 inches from the inner cylinder which formed the funnel. The top of the annular space between the cylinders was at about the level of the deck. From it a stand-pipe was carried up, which, after rising to a certain height, was turned over, and the end brought down into the stokehole. The object of this arrangement was to heat the feed-water before it entered the boiler, and at the same time to keep the saloons cool, through which the funnels passed. The arrangement of the stand-pipe gave this advantage, that when the head of water in the heater and stand-pipe together became equivalent to the pressure in the boiler, the water could be run into the boiler by gravitation. The stand-pipe at the same time, being open to the air at the top, formed a safety-valve to the water-heater.

For the purpose of testing the joints of the jacket with water pressure, while the ship was being finished, a stop-cock had been placed on the stand-pipe, which unfortunately had not been afterwards removed. While the ship was proceeding down Channel, the donkey feed-pumps were not working well, and to ease them it was thought better to cut off the water-heater, and to force the water direct into the boiler. The communication of the water-heater with the boiler was therefore cut off; and, as was afterwards ascertained, the stop-cock at the top of the water-heater had been also closed. The water confined in the heater soon produced steam, and when the ship was off Hastings the casing exploded. The funnel was thrown up on to the deck, and a body of boiling water and steam was driven down into the boiler room, severely injuring several of the firemen, who afterwards died.

That the effects of this accident were confined to one compartment of the ship, was due to the complete protection afforded by the transverse bulkheads.

After she arrived at Weymouth the funnel was repaired; but as an outcry was raised against the water-heaters, it was thought desirable, from deference to public opinion, to discontinue their use; although this accident had not in any way proved them to be objectionable, and they are now generally adopted.

While the ‘Great Eastern’ was at Weymouth Mr. Brunel died.

Many visitors went in the ship when she left Weymouth on a trial trip to Holyhead. At Holyhead she lay in a somewhat exposed situation; and the sudden storm came on in which the ‘Royal Charter’ was lost. The great advantage of having both paddle and screw was now, for the first time, felt. A portion of the temporary staging erected by the contractor at the breakwater was carried away, and drifted down upon the ship. During the gale her engines were kept going, in order to relieve the strain on the cables. The timbers of the staging got foul of both paddlewheels and screw; but, as it was always possible to keep one of the engines at work, the ship was saved from drifting.

The season being now too far advanced for a profitable voyage to America, the ship left Holyhead and went to Southampton Water for the winter, where several alterations and additions were made.

In Mr. Brunel’s report of February 5, 1855, printed above, at p. 315, he describes the leading features of the ‘Great Eastern’ as she was then being constructed, but a more detailed account of them will fitly precede the history of her career as a passenger-ship.

The main arrangements of the ship are shown in the woodcut (fig. 16, p. 397).[173]

The ship is 680 feet long, 83 feet wide, and 58 feet deep. Her gross tonnage is 18,915 tons. She is divided into water-tight compartments by ten bulkheads (a and b), all of which, except two (b), extend completely across the ship, and up to the upper deck. These two are complete to 6 feet above the 28-foot water line. In addition there are partial bulkheads (c), which form the ends of coal bunkers, and aid materially in strengthening the flat bottom of the ship. The more remarkable parts of the construction of the ship will be understood by means of the transverse section. The bottom is made double, and between the two skins are webs, running longitudinally. Mr. Brunel considered that the double skin would greatly diminish the chance of such an accident occurring as would cause any of the compartments to be filled with water. The material being arranged in the direction of the length of the ship is all capable of taking part in the strains that are thrown on the bottom, as well as on the top, by forces tending to bend the ship.

Mr. Brunel also made the upper deck cellular, in order to resist the compressive strain that would come on it when the ship was heavily loaded in the middle of her length. Great additional strength to the ship, considered as a girder, is given by two longitudinal bulkheads, 36 feet apart, extending for 350 feet. These bulkheads, with the sides of the ship, form the vertical web plates of the girder. Her structure resembles the tubes of the Britannia bridge; the cellular top flange being connected with the cellular bottom flange by plate-iron webs.

The two skins of the ship, with the web plates between them, forming the cellular bottom of the great girder, may also be considered as a number of smaller girders placed side by side, each resisting the excess of the pressure of the water over the load that may happen to be resting on it inside the ship. The difference of pressure or upward strain is transmitted by the cross bulkheads (a, b, c) from the bottom of the ship to the sides and longitudinal bulkheads.

The double skin extends up to about 6 feet above the water level throughout the whole length of the ship, with the exception of the extreme ends.

The foremost compartment next the bow has two cable decks (E), with capstans and all the necessary riding-bitts, stoppers, and other appliances for working the cables. These arrangements answer well, and the 3-inch chain cables are worked with great facility. The capstans were originally driven by a shaft from the paddle auxiliary engines, but this was found inconvenient, and a small independent engine has been put to work them. The cables are stowed in chain lockers on a deck (F) below the cable decks, and below this (G) are ice-houses and store-rooms. The next compartment of the ship (H) is intended for cargo. It is at present occupied by the forward cable tank.

The main part of the ship, 350 feet in length, up to the level of the lower deck, 34 feet above the bottom, is occupied with her engines, boilers, and coal bunkers. The space above the lower deck was occupied with saloons and cabins for passengers, except at the paddle engine room (J). The boilers, four in number, two in each boiler room (I), which supply steam to the paddle engines, are placed forward of the engines; and forward of the boiler rooms is a coal bunker (K), 20 feet long; and abaft of the paddle engines are the six boilers, two in each boiler room (M), that supply steam to the screw engines (N). These three boiler rooms are separated by coal bunkers (K), 20 feet long. On either side of the boilers and engines, and also upon plate iron arches above the boilers, are bunkers for coal. This will be seen on the transverse section of the ship. Between the paddle engines and boilers is a water-tight compartment, 10 feet long (L), in which are placed a pair of auxiliary engines of sixty horse-power, which pump water out of the ship and also work fire-pumps. There are two other auxiliary engines of sixty horse-power in a compartment (O) aft of the screw engines, intended to keep the screw propeller turning round, either when the ship is at anchor, to relieve the strain on the cables, or when, for any reason, she is only using her paddle engines. They also work bilge-pumps and fire-pumps. Each set of auxiliary engines has two independent high-pressure boilers. Throughout the bottom of the ship there are two bilge-pipes, fitted with valves, with branch-pipes leading to the various compartments of the double skin. These bilge-pipes can be connected with either of the auxiliary engines, and so the water can be pumped out of any part of the ship.

The paddle engines, of 1,000 nominal horse-power, consist of four inclined oscillating cylinders, 14 feet stroke and 6 feet 2 inches diameter, each pair of which work on to a single crank. There are means for disengaging either paddlewheel from the engines.

The screw engines, of 1,600 nominal horse-power, consist of four fixed horizontal cylinders, 4 feet stroke and 7 feet diameter, the two cylinders of each pair working opposite to each other on one crank.

In each boiler room are two donkey engines for supplying the boilers with water, and the main engines are also fitted with feed-pumps. Each of the donkey engines is capable of pumping water out of the ship, and of being used in case of fire.

The screw shaft passes along what is termed a screw alley (P). The weight of the screw rests on the bearing where the screw shaft passes out through the stern-post of the ship. To prevent the water that leaks in through this bearing from penetrating into the screw alley, there is a bulkhead with a stuffing-box round the screw shaft, a short distance forward of the stern-post. To enable access to be gained to the bearing, a tube was provided leading down from the main-deck. This was intended to be fitted with appliances for pumping air in so as to drive the water out, and to admit men to get at the bearing under air pressure.

Another arrangement was also provided for the same purpose. On the after side of the stern-post was placed a ring of india-rubber; and, by pulling in the screw-shaft, the screw was pressed tightly against the india-rubber ring, which prevented the water from entering. By means of this arrangement the stern-bearing was examined and repaired at Southampton.

The screw propeller has four blades, and is 24 feet in diameter and 44 feet pitch. The paddlewheels were 56 feet in diameter, with 30 floats, each 13 feet broad and 3 feet deep.

Over the boiler rooms run two tunnels; one of them (V) serves as a passage to enable the engineers to pass from one compartment to another throughout the part of the ship occupied by the boilers and engines. The openings leading from the tunnel to the engine or boiler rooms are provided with watertight doors, which can be shut in the event of any of the compartments getting full of water. The other tunnel (W) serves as a passage for the steampipe, which leads from the boilers to the engines. Though the boilers are divided into two sets, one for the paddle engines and one for the screw, the steampipes are connected, so that the whole of the ten boilers, or any of them, may be used to supply steam for either of the engines.

In one point a deviation was made from Mr. Brunel’s arrangements. It was his intention that there should be no apertures in the water-tight bulkheads except at the tunnel (V), from which the various boiler and engine rooms were to be entered by openings, to be closed by water-tight doors. The tunnel was placed high up, so that in the event of a leak there might be ample time to close the door. The inconvenience of ascending and descending by ladders was, however, considered an evil; and it was found necessary at times to carry coals from one compartment to another. For these reasons, upon the requirement of the Board of Trade, doorways, fitted with sliding doors, which can be closed by handles on the upper deck, have been cut in the bulkheads between the boiler rooms. This arrangement exists in other ships; and in the ‘Great Eastern,’ even without closing these doors, there are eight watertight compartments.

At the stern of the ship (Y) on the main-deck are arrangements for working cables, similar to those at the bow.

These appliances are required when the ship has to be moored so as not to swing with the tide; and they would allow of the ship’s riding by the stern instead of by the bow, which it might often be useful for her to do in narrow waters. On the lower deck (Y), at the stern of the ship, is a spare tiller and wheel for working the rudder, in case anything goes wrong with the main tiller, which is on the upper deck. The weight of the rudder is carried on the lower deck by a grooved collar, resting on a ring of cannon balls.

The compartment (X) immediately aft of the screw engine room is for cargo.

The saloons and cabins are all in the middle of the length of the ship, where there is least motion. The usual plan of putting the first-class passengers at the stern was not adopted, and they were placed forward. As the smoke generally drifts towards the stern of a ship, the first-class passengers in the ‘Great Eastern’ are not annoyed by the smoke, or by the dust and smell from the boiler and engine rooms.

The transverse section shows the arrangement of the cabins.

Mr. Brunel intended that the upper saloons (T) should be used as sitting-rooms, and the lower saloons (S and U) as dining-rooms. These were to be lit and ventilated by shafts on either side of the upper saloons, rising up to the skylights on deck. The smell of dinner was thus to be kept away from the sitting-rooms. The cabins (Z) on either side were to be approached from the saloons by passages and steps, as shown on the section. The saloon marked (Q) is the first-class, and (R) the ladies’ saloon.

The ship is rigged with six masts. The arrangements of the masts and rigging were especially intended for the Eastern voyages. At the extreme bow and stern are low masts, which carry trysails and staysails. The sails on these masts were chiefly intended for manœuvring the ship. She also has three large masts, the lower masts being of iron. The two foremost of these are square-rigged, and all three of them have trysails and staysails. The aftermost of the three was also made strong enough to be fitted with square yards, in the event of its being desirable to rig it in that manner. Aft of the three principal masts is a large mast, only intended to be rigged with fore-and-aft canvas. The ship has no bowsprit, the stay of the foremost mast being attached to the stem inside the bulwarks.

In the beginning of June 1860, the ship made a trip from Southampton down the Channel, as far as the Start Lighthouse and back, to try her engines; and on June 17 she sailed for New York, under the command of Captain Vine Hall, who had succeeded Captain Harrison. She arrived there, after a prosperous voyage, on June 28, and was received with great enthusiasm. The ship left New York on August 16, and, having called at Halifax, arrived at Milford Haven on August 26.

In the course of these two voyages the stern-bearing of the screw-shaft, which was in white metal, had worn down between two and three inches. With the view of allowing for any depression of the stern-bearing, the lengths of the screw-shaft were not rigidly connected throughout, but the end length, attached to the screw, was coupled to the remainder of the shaft by a universal joint, consisting of two double cranks. Thus the two shafts might be, to a considerable extent, out of line, and yet revolve efficiently.

When the ship returned to Milford Haven, a gridiron was prepared on the beach, and she was grounded on it; and the screw-shaft was drawn in. By this time it had become the general opinion that a shaft cased with brass, and running in lignum-vitæ bearings, was the best. A lathe and machinery for making the shaft revolve were provided, and fixed in the stern of the ship; the shaft was turned, and brass collars shrunk on. The bearing was made with lignum-vitæ, and the brass-covered shaft replaced in it. It has since worked well, and has shown no signs of wear.

The ship, commanded by Captain William Thompson, left Milford Haven for New York on May 1, 1861, and returned to Liverpool from New York on June 4, having made an average speed of 13¾ knots on the outward and 14 knots on the homeward voyage.

At this time the Government determined to send her out with troops to Quebec, and she was fitted up for that purpose. She took upwards of 2,500 troops, and about 40 passengers. There were, altogether, about 3,000 persons on board, and 200 artillery horses. Scarcely any of the troops were placed in the regular passenger part of the ship, as they were accommodated in the cargo departments (H, X). Thus a much greater number of men might have been carried in her with perfect comfort. She was commanded on this voyage by Captain James Kennedy, of the Inman service. She left Liverpool on June 27, and arrived at Quebec on July 7. She returned to Liverpool with about 500 passengers in August.

By this time her superiority had become recognised by the regular travellers between England and America. Those who had been in her found that, while they passed other ships rolling and pitching in the sea, the deck of the ‘Great Eastern’ was so steady that it was difficult to believe that there was a gale blowing;[174] and when, after a continuance of heavy weather, she began to roll, the motion was so slow and easy as to be comparatively unimportant.

When she left Liverpool again, there were a considerable number of passengers, and it seemed as if her success was ensured. She started under the command of Captain James Walker, on September 10, and three days afterwards encountered a severe Atlantic gale.

The ship was behaving well, when one of the boats, which hung on davits outside the ship forward of the paddlewheels, got adrift on the weather side. Fears were entertained that it might foul the paddlewheel, and the captain determined to cut it away. The direction of the ship was altered, in order that the boat might float clear. The ship then resumed her course; but shortly afterwards fell off, with her broadside to the sea.

Relieving tackles having been put to assist the men at the wheel, the tiller was kept hard over, to bring the ship’s head to the wind; but with no effect. Towards evening, as the seas beat heavily against her side, first one paddlewheel and then the other was destroyed, being completely torn away from the central bosses. During the night she lay in a helpless condition. The gale had been of some duration, and the waves being large and long, the ship was placed in a very unfavourable position to receive them; and she rolled considerably.

The next morning, when an officer went to examine the auxiliary tiller on the lower deck, he discovered that the rudder-head was twisted short off, just above the point where it entered the ship. The rudder was still in its place. The accident had most likely happened on the previous evening, when the ship fell off her course. It had not been noticed by the men at the helm, perhaps because there were so many of them at the wheel and relieving-tackles that they held one against the other; and the broken parts of the rudder-head, grinding together, threw jerks on to the tiller. The fracture of the rudder-head was caused by the badness of the workmanship in the interior of the forging.

Attempts were made to get sail on the ship, but without much success; and with the hope of bringing her head to wind, the screw engines were reversed.

As soon as the ship was driven astern by the screw, the rudder, being uncontrolled, was forced round by the rush of water, and it knocked away the after stern-post.[175] No other harm was done, as the rudder is secured by a pin into the heel of the ship, and by a collar round the rudder-head, attached to the hull above water.

Steps were then taken to get command over the rudder. Chains were wrapped round the stump of the rudder-head inside the ship, and a certain amount of control was thus obtained. A more effective plan was at the same time carried into execution. A man was lowered by a rope from the stern of the ship, who hove a piece of wood, with a line attached to it, through the screw-opening. The wood with the end of the line was caught with a boat-hook; and a rope, and afterwards a hawser, and then a piece of the ship’s chain cable were passed through behind the rudder. The two ends of the chain cable were brought together at the stern of the ship, and a large shackle put round both parts of the chain, and shaken down till it held them together. In the edge of the rudder-blade a notch had been made by the rudder striking against the screw, and into this notch the shackle was made to drop. In this way two chains or pennants had been attached to the back of the rudder. One of these was brought to each side of the ship, and they were hauled on by means of the stern capstan.

The ship then turned homeward, and the weather having moderated, she arrived off Cork harbour on the afternoon of September 17. By this time the chains round the rudder had shifted, and were of little service; and before night it began to blow heavily towards the shore. It was dangerous for the ship to remain on a lee shore; and, although the steering-gear was out of order, the captain wisely determined to take advantage of the ship’s head pointing in the right direction, and steamed out to sea.

Three days afterwards the ship, assisted by several small steamers, was got safely into Cork harbour, a temporary tiller was attached to the stump of the rudder-head, and she proceeded to Milford Haven, where she was placed on the gridiron, and her after stern-post and paddlewheels replaced. The accident had proved that the original paddlewheels might with advantage have been made stronger, and in the new wheels the bracing was increased.

The ship, under the command of Captain Walter Paton, left Milford Haven for New York on May 7, 1862, and returned to Liverpool on June 11. She left again on July 1, and returned on August 6. Besides the number of passengers the ship accommodated, she carried a considerable amount of cargo; she brought over large quantities of grain and provisions. The custom of carrying this class of freight in steam-ships received a great impulse from the success of the ‘Great Eastern’ in the traffic. As it was found that the shallowness of the bar at Sandy Hook prevented her taking full advantage of her carrying power, she had on this voyage followed the route along Long Island Sound, so as to arrive close to New York in deep water, and on her return voyage she brought as much as 5,300 tons of cargo in bulk, which with 4,350 tons of coal gave her a mean draught of 28 feet.

She left Liverpool on August 17, and arrived off Montauk Point, at the entrance to Long Island Sound, at about two in the morning of the 27th, to take in the pilot. While stopping, a loud rumbling noise was heard, and presently the ship heeled slightly over to one side. The pilot, when he came on board, said that the ship had passed over a reef of sunken rocks, which was not marked on the charts.

It was at the same time found that many of the spaces between the double skins were full of water. The ship went on to New York, and most of the passengers landed in ignorance of an accident which in any other vessel would have been fatal.

Steps were at once taken to examine the damage, and the divers reported a large fracture in the outer skin 80 feet long and about 10 feet broad. They also discovered afterwards several smaller fractures. It was considered that this damage might be mended while the vessel was afloat, and a very skilful arrangement, contrived by Messrs. Renwick, of New York, was adopted. A large wooden barge was made with a gunwale shaped to fit the ship’s side, and two wooden passages leading down into the barge. It was placed so as to cover the large fracture, and was secured by chains passed round the bottom of the ship. The joint between the gunwale of the barge and the ship’s side was made water-tight; the water was pumped out, and men and materials passed down through the shafts. By the exertions of those engaged in this difficult operation, the great fracture was repaired, and the ship returned to England in the beginning of 1863.

A gridiron was made at Birkenhead; the ship was placed on it, and the repairs were proceeded with under the direction of Mr. Brereton, who at Mr. Brunel’s death succeeded him as engineer to the Great Ship Company. On examination, it was found that fractures had been made in ten separate places in the outer skin.

The ship started again in May 1863, and made three voyages to New York and home. At this time, however, there was a severe competition with other vessels, and the Company could not afford to run the ship unremuneratively for any length of time. In 1864 she passed into the hands of a new company, which consisted almost entirely of those who, from their belief in the capabilities of the ship, had found the money for starting her again after each of her successive misfortunes.

The ship lay idle for some months, and was then chartered by the Telegraph Construction and Maintenance Company.

The ‘Great Eastern’ had in the course of the four years from 1860 to 1863 made nine voyages across the Atlantic and back. Though this was not the route for which she had been intended, it had given her many opportunities of showing her merits. Adverse fortune had added to these opportunities, and had at the same time demonstrated the necessity of many of the precautions which Mr. Brunel had taken to ensure her safety.

The construction of the hull of the ship has been proved by experience to possess the advantages anticipated by Mr. Brunel.

Its strength as a whole has been proved by the absence of all signs of weakness in the heavy weather she encountered on several occasions, and especially in the gale of 1861, when her rudder was disabled. The strength of the ship has since been fully tested by the enormous loads she has carried while on telegraph cable expeditions.

The importance of the double skin was shown on the occasion of her grinding over the rocks at Montauk Point, when so large a number of leaks were made in all parts of her bottom that no ordinary system of bulkheads would have saved her from foundering. Moreover, the space between the two skins was sufficient to allow of the outer skin and the webs being crushed to the extent of three feet, while they at the same time acted as a buffer and prevented the inner skin from coming in contact with the rock.

The engines have not had any opportunity of working at high speed in the long voyages for which they were intended, but in the rapid and comparatively short passages made by the ship across the Atlantic they worked with great regularity and success. Although they were commenced seventeen years ago, they are still fine specimens of marine engines, and bear witness to the care taken by their builders in their design and manufacture.

Of the points on which Mr. Brunel laid stress, and which, as he remarked, ‘involve no other risk than that of being useless; they cannot do mischief,’ many have now come to be considered essential parts of good marine engines. He thought it of great importance that the steam cylinders should be jacketed, especially at the ends; and it was intended that the high-pressure steam for this purpose should be taken from the auxiliary boilers. This plan was, however, not adopted.

Mr. Brunel was also anxious that the steam should be heated immediately before it entered the cylinders, and that fresh water should be supplied for the boilers by using the same water over again. Arrangements for effecting these objects have since been brought into general use.

The advantage of having several cylinders to each engine was shown while the ship was running to America. Part of the valve-gear of one of the paddle-engine cylinders gave way, the engines were stopped for four hours, and the ship was propelled by the screw alone. The cylinder was disconnected and turned back out of the way, and the engines worked efficiently with three cylinders for four passages across the Atlantic.

The average speed of the ship on those voyages in which her performances were fairly tested was about 13½ knots. On two occasions she made the voyage from New York to Liverpool at an average speed of 14 knots; and she maintained her speed in rough weather and head winds to a much greater extent than is the case in smaller vessels.

By having two sets of engines, the ship was saved from serious disaster at Holyhead, and again in the gale of September 1861.

The great handiness of the ship is one of the many beneficial results of the use of both paddles and screw. By working the paddlewheels astern and the screw ahead, she can be kept from moving forward or backward, and at the same time the stream of water from the screw, acting on the rudder, makes her answer her helm and turn round on her centre. By modifying the speed of the two engines, she may be made to creep slowly forward; and as the rudder is in the full rush of the water driven back by the screw, the ship has practically as much steering power as she has when moving rapidly. The importance of this power of controlling her when passing through narrow channels, in entering and leaving port, can scarcely be over-estimated.

The career of the ‘Great Eastern’ since the formation of the present Great Eastern Steam-Ship Company, has been prosperous.

In the commencement of the year 1864, when Mr. Cyrus Field had succeeded in reviving the project of laying the Atlantic cable, the Telegraph Construction and Maintenance Company took the contract for laying it, and hired the ‘Great Eastern.’ She was brought round to Sheerness, where the cable tanks were fitted into her. One tank was placed in the forward cargo compartment, and another in the after cargo compartment; and the largest tank was placed over the middle screw boiler room, the funnel being removed. Therefore, during the cable-laying expeditions, the ship only used eight of her boilers.

The history of the laying of the Atlantic cable is well known. The ‘Great Eastern’ started from Valentia on June 23, 1865, under the command of Captain (now Sir James) Anderson, and the cable was laid more than half way across the Atlantic; but, on hauling in to recover a fault, it was broken, and dropped to the bottom of the sea.

The grappling tackle was not sufficiently strong. The cable was three times partially raised, and each time lost; and the expedition returned to England defeated, but with the knowledge that ultimate success was certain.

The engineers and scientific men on board the ‘Great Eastern’ drew up a memorandum as to the results of this expedition, and, among other things, stated—‘That the steam-ship “Great Eastern,” from her size and constant steadiness, and from the control over her afforded by the joint use of paddles and screw, renders it safe to lay an Atlantic cable in any weather.’[176]

Sufficient additional cable was made to lay a second one and to finish the old cable when it should be recovered. The ship started again on July 13, 1866, and laid the cable across the Atlantic without the slightest mishap. She then returned, and after three weeks of hard work, the end of the cable which had been lost the year before was picked up, and completed to Newfoundland.

On her return to England there did not seem to be any immediate employment for her in cable laying, and the tanks were taken out. In the following year a company was formed in France to charter the ship, and to work her between New York and Brest during the French Exhibition. She made one voyage from Liverpool to New York and back to Brest and Liverpool; but the undertaking was a commercial failure.

She remained at Liverpool till October 1868, when it was proposed to lay a cable from France to America; and she came round to her former berth at Sheerness. Tanks were made in the fore and aft cargo spaces, and a very large tank, 75 feet in diameter, was placed amidships. The bulkheads were cut partially away to make room for it, the ship being strengthened above and below. She started on this expedition from Brest under the command of Captain Robert Halpin, and encountered very heavy weather. The cable was laid successfully.

The ship then returned to England, and was fitted out for the greatest adventure she has yet undertaken. She was to proceed with a full cargo of cable round the Cape of Good Hope to Bombay, to lay it thence to Aden, and from Aden a portion of the way up the Red Sea. With her cable and coals, on leaving England, she drew 34 feet 6 inches, with the enormous displacement of 32,724 tons. She laid the cable with perfect success, and returned to England.

Throughout all these cable-laying expeditions, and especially in the work of picking up the Atlantic cable of 1865, the good qualities of the ship have been fully exhibited.

The later voyages of the ‘Great Eastern’ were undertaken for the accomplishment of a work in which Mr. Brunel had felt a great interest.

In 1856, Mr. Cyrus Field came over to this country in order to consult English engineers and scientific men upon his project of an Atlantic cable. It is stated in a work written by Dr. Field,[177] that—

It appears, however, from drawings in Mr. Brunel’s sketch-books that at this time, and again in 1858, he thought that it would be better to have a vessel specially built for the work.

He was throughout sanguine as to the ultimate success of the undertaking, as is shown by the following extract from a letter written in December 1856:—

The ‘Great Eastern’ has not yet been engaged on the work for which she was originally designed by Mr. Brunel; but her employment in the promotion of great scientific enterprises has been an occupation worthy of her connection with his name.

NOTE (p. 395).

CHAPTER XIV.

DOCK AND PIER WORKS.

A.D. 1831—1859. ÆTATIS 26—54.

MR. BRUNEL’S dock and pier works are interesting, not only in their general features, but also in the details of their construction; and the plans he made for large docks at Monkwearmouth in 1831, which he carried out on a smaller scale shortly afterwards, were among the earliest of his independent designs.

With the exception of the gates of this dock, which are of timber, all the dock gates Mr. Brunel constructed are of wrought iron. This material had been employed in ship-building before Mr. Brunel adopted it for the gates of the new lock at Bristol, and it was also beginning to be extensively used for bridge girders.

At the same time that he introduced the use of wrought iron into dock gates, he constructed them with a large amount of buoyancy, in order that they might be moved easily, while being opened and shut.

The dock and pier works which he constructed are at Monkwearmouth, Bristol, Plymouth, Briton Ferry, Brentford, and at Neyland, Milford Haven. They will be described in this order, which is nearly that of the dates of their construction.

Monkwearmouth Docks.

The town of Monkwearmouth is situated at the mouth of the river Wear, on the north side, and opposite to the towns of Sunderland and Bishopwearmouth, which extend for about a mile along the south side. In order to improve the entrance of the river, and to diminish the sand-banks which lay near its mouth, piers were proposed as early as the middle of the last century, and were partly built on both sides of the river before the year 1800. From that date until 1831, although the question of making docks had been considered, and designs proposed by different engineers, no steps had been taken for their construction, and the only works executed for the improvement of the port were the extension and alteration of the piers already existing. In 1831 designs for docks to accommodate the increasing traffic were made simultaneously by Mr. Brunel and Mr. Giles. Mr. Brunel’s docks were to have been on the north side of the river, and to have had an area of 25 acres, with quays, warehouses, &c. Mr. Giles’s were to have been on the south side.

Neither of these schemes was approved of by Parliament; but shortly afterwards a private company was formed for the construction of a dock on a plan designed by Mr. Brunel, though on a much smaller scale than his scheme of 1831, the dock being only about 6 acres in area, with a tidal basin of about an acre and a half. The company encountered considerable opposition from the authorities of the town of Sunderland, but succeeded in obtaining a royal charter for the construction of the dock. They subsequently obtained an Act of Parliament empowering them to make the entrance from the dock to the river. The dock was constructed, and eventually became the property of the North Eastern Railway Company, to whom it now belongs; they have erected coal drops along the quay, and have made it a shipping place for collieries connected with their railway.

The work was begun in 1834, and the dock and tidal basin occupy part of the site chosen by Mr. Brunel for his larger scheme of 1831.

The quay wall was built with a curved batter, the chord line joining the top and bottom having an inclination of 1 in 5. The masonry was carried up in courses, and made solid by filling every part thoroughly with mortar. A course at the face and at the back of the wall was built up; an abundance of mortar was then spread in the heart of the wall, and the stones built in the mortar. Thus no crevices could be left in any part of the work, and the back of the wall was soundly built throughout.

The entrance to the dock is 45 feet wide, with side walls of the same profile as the quay wall. Except at the gate floors, there is a segmental invert of dressed stone of such curvature that it is 6 feet 6 inches lower in the middle than at the side walls. The gate floors are formed with inverts, curved to correspond with the under sides of the gates.

The masonry of the entrance was executed within a four-sided coffer-dam, the sides of which were slightly convex outwards. This coffer-dam was constructed in the usual way, there being two rows of close piling with puddle between them; and it was strengthened by internal horizontal shores which connected the opposite sides, and by diagonal bracing. The piles were driven until they met with so much resistance as to render it unsafe to drive them farther. When the ground inside the coffer-dam was excavated, it was found that the piles had been driven into sand and gravel, and that, to enable the masonry to be built on a good foundation, it would be necessary to excavate about 7 or 8 feet below the piles. They were therefore driven down gradually, as the ground was removed from the inside, until the requisite depth was obtained. The whole coffer-dam was thus an immense caisson, the sides of which were lowered by gradual driving, instead of being simultaneously forced down by weights.

The masonry of the walls of the tidal basin is similar to that of the walls of the dock; some parts of the foundation were laid by means of a diving-bell.

In the entrance between the dock and the tidal basin there is a pair of gates pointing inwards, which serves to retain the water in the dock during the fall of the tide, and there is also a pair of storm gates pointing outwards, which protects the inner pair from the force of the waves.

The construction of both pairs of gates is similar.

The two leaves of each pair meet at an angle of 125°. Each leaf is about 30 feet long; the bottom beams are curved to the form of the segment of a circle; the height at the meeting-post is 27 feet, and at the heel post 22 feet (see woodcut, fig. 17). This arrangement is, to a greater or less extent, followed in the dock gates Mr. Brunel afterwards constructed. By raising the pivot, the gate floor can be made of ample strength, and the cills and heel-posts are free from mud and deposit. The gates are constructed of horizontal beams of yellow pine timber, 21 inches thick, placed close together for a height of 12 feet above the bottom. Above this there are beams of timber and of cast iron at intervals. The whole is planked over on the inner side with 4-inch planking. The heel-post and meeting-post are socketed into cast-iron uprights, which also receive the ends of the horizontal beams. To preserve the gate from any change of form, a diagonal iron tie-bar extends from the top of the heel-post to the timber beams forming the lower part of the gate.

Nearly under each meeting-post is placed a bevelled cast-iron wheel, 18 inches in diameter, which supports part of the weight of the gate.

There are four sluices in each leaf, placed in pairs, with a small interval between them. Each pair of sluices counterbalances the weight of the other pair by being attached to opposite ends of a lever at the top of the gate. A screw works in the segment of a large worm-wheel formed on the end of the lever, and, being turned round, opens and shuts the sluices. After the timber work of the gate had been fitted together, it was taken to pieces, and subjected to the preserving process called Kyanising, which consists in immersing the wood in a solution of corrosive sublimate. This process has been so successful, that when the gates were recently taken out for examination the timber was found to be nearly perfect, only slight surface repairs being required in one or two places.

The great bulk of light wood at the bottom of these gates gives them a certain amount of flotation at all times of tide. After the gates had been in use many years it was found that one of the wheels had been detached for some time, but the buoyancy of the gate had prevented any mischief resulting. The buoyancy of the lower part of the gate is somewhat analogous to that of the air-chamber which Mr. Brunel introduced afterwards in his wrought-iron dock gates.

Bristol Docks.

About the year 1804 that portion of the river Avon which flows in a serpentine course through the city of Bristol was enclosed, and the water in it retained at a constant level, a new cut or shorter channel being made for the river. The portion separated, called the Floating Harbour, or Float, is about two miles long and 100 yards broad. At its lower end it is connected with the river by the Cumberland Basin, a half-tide basin, with two locks, and at its upper end by a feeder, which brings the water of the Avon into it, the river in dry weather being stopped from passing into the new cut by the Neetham Dam, About half-way up, the Float is entered on the north side by the river Frome; and, a little above this junction, it is crossed by the Prince’s Street drawbridge, which divides it into two parts. About 170 feet above the bridge the Float is connected with the new cut by another basin with a lock, called Bathurst Basin.

Mud and other deposits had accumulated to such an extent in the Floating Harbour, that at the end of the year 1832 the directors of the Dock Company employed Mr. Brunel to suggest remedial measures.

In order to effect his object at the least possible cost, he proposed certain works, together with an improved system of managing the water of the river, so as to allow more of it to pass through the Floating Harbour, by means of which great benefit might fairly be anticipated.[178] He remarked that,—

It should be observed that the yearly scourings, which became so objectionable to the trade, were not introduced by Mr. Brunel, but were part of the original arrangements of the docks.

After the reception of Mr. Brunel’s report, the Dock Company executed the works which he required, namely, the Sluice, Trunk, and Drag-Boat; but his other recommendations, as to scouring and increased supply of water, were only acted upon to a limited extent.

In 1842 the Directors again asked Mr. Brunel to report, in conjunction with Captain Claxton, upon ‘what further measures are requisite for keeping the Floating Harbour more clear of mud than it has been for a few years.’

Mr. Brunel thereupon made a report to the Directors. After having referred to his previous reports of 1833 and 1834, he remarked that ‘the efficiency of the whole system then recommended and adopted, and subsequently partially carried out, depended entirely and was founded on the supposition of the then existing mud-banks and shoals being first removed, and the Float deepened at once to the full extent required,’ according to the plans which he had pointed out; and that ‘the increasing the supply of water through the Float was one of those means on which he had most insisted’ as necessary for keeping it clean and preventing its becoming a settling reservoir. He then continued,—

The recommendations contained in this report were not adopted.

In 1839 Mr. Brunel, in a report to a Committee of the Council of the City of Bristol, suggested several improvements connected with the Port, almost all of which have since been undertaken. He proposed to straighten and widen the course of the river, and to make new locks, both from the river to Cumberland Basin and from that basin to the Floating Harbour, or, as an alternative, to construct docks at Sea Mills, a creek on the Avon, about two miles below Bristol.

He also proposed to construct a large pier at Portishead. The rise of tide is there sometimes 45 feet, and the velocity of rise or fall as much as 10 feet per hour. There is also a great deposit of mud by the Severn. Mr. Brunel considered that these circumstances rendered a fixed structure undesirable, and he therefore recommended a floating pier. He said:—

In 1847, after an Act had been obtained for making a railway from Bristol to Portishead, with a pier at the latter place, Mr. Brunel designed the pier on the plan described in his report of 1839; but the project was not carried out.

As has been already mentioned, the communication between the lower part of the Floating Harbour and the river Avon is through the Cumberland Basin; between this basin and the river were two locks, made at the time that the Floating Harbour was constructed.

Owing to the increased size of merchant vessels, it had long been in contemplation to enlarge the entrance. At the time when the ‘Great Britain’ was built, the northern lock was so narrow that a portion of the upper masonry had to be removed in order to give room for the ship to pass from the basin to the river on a spring tide. It was then felt that the enlargement of one of the locks could no longer be delayed, and Mr. Brunel was asked to adapt the narrower or southern entrance lock to the passage of the largest vessels.

Between the two locks was a pier, from which vessels were guided, and the gates opened or shut. The elongation of the lock was limited by the length of this pier, as it could not be extended towards the river without diminishing the area of entrance, nor could it be extended upwards without lessening the area of Cumberland Basin. Mr. Brunel, although hampered by this restriction, succeeded in obtaining a lock of considerable length. He constructed the gates of a single leaf, and placed the upper gate outside the lock so as to shut against the upper end of the middle pier, and to swing back when opened into a recess in the side wall of the Cumberland Basin. He thus avoided the necessity of finding room on the pier for the machinery to open one of the leaves of the upper gate. Had the gate been in two leaves, the lock would have been shortened from 30 to 40 feet. At the lower end he placed the gate as near the river as possible; and, lest the end of the middle pier should not be strong enough to withstand the pressure, he secured the quoin stones, against which the gate closed, by horizontal wrought-iron bars at different levels, built into the side wall of the lock.

The lock is 262 feet in length between the gates, and 54 feet wide at the narrowest part.

The masonry is of plain character, all the part below the ashlar coping being of ordinary fitted rubble of great thickness, solidly built with hydraulic lime mortar. The ground behind the wall consisted of a wet silty clay, causing a great pressure against the masonry. The under part of the body of the lock is formed to a semi-oval cross, section.

The works were commenced by the construction of coffer-dams at each end. In 1846, when the masonry was approaching completion, a very high tide took place, and a portion of the upper dam gave way. As some work still remained to be done at the sill and apron of the lower gate, Mr. Brunel decided to make a brick dam in the middle of the lock, where the masonry had been completed. This brick dam was a horizontal arch built on the bottom of the lock, up to the level of the water in the Floating Harbour. The abutments were formed by the masonry of the lock walls, which was notched to receive the bricks of the arch rings. The dam was 28 feet high, only 8 feet thick at the bottom, and 3 feet thick at the top. It was set in Roman cement, and was completely water-tight. It was easily and rapidly made, and the cost was small, as compared with what would have been the cost of repairing the upper dam.

In this lock the chief point of interest consists in its being the first in which wrought-iron gates were introduced, these gates being at the same time made buoyant.

Floating caissons had been previously used at the entrances to graving docks, and in similar situations; indeed at Bristol, a caisson had long been employed at Prince’s Street Bridge, to separate one part of the Floating Harbour from the other. The buoyant gates of the Bristol Docks differ essentially from these vessels, inasmuch as, instead of requiring to be floated into their places, they turn on a hinge, and do not rise or fall vertically.

The gates are provided with wheels, but only a small part of the weight rests on them, as the gates are rendered buoyant by large air-chambers, formed in the lower part of them.

The upper and lower gates are alike in construction and dimensions, so that it is only necessary to describe one of them. (See woodcut, fig. 18.)

The extreme length of the gate is 58 feet, and the extreme height 29 feet. In the middle it is about 10 feet wide, the width diminishing to 3 feet at the top. In plan it is curved to resist the pressure of the water. The gate when closed is not at right angles to the direction of the length of the lock, but is at an angle of about 12°. The length is thus scarcely increased, while the travel in being opened and shut is much reduced. The top is at the level of the water in the Floating Harbour; so that, when the tide falls, the water in the Cumberland Basin may be retained at the same height as in the Float.

The air-chamber is formed by two water-tight decks of wrought-iron plating, one at the level of half-tide, the other a short distance above the bottom of the gate. Above the deck forming the top of the air-chamber, the water, as the tide rises, flows freely into the interior of the gate, through openings in the face next the dock, so that when the water is level with the top of the gate, the part above the air-chamber is full of water, which flows out again if the level of the water falls.

In ordinary working the gate only needs to be opened or shut when the water is above the level of half-tide, and therefore at these times the whole of the air-chamber is immersed. To whatever height the water rises above this level, the buoyancy remains almost the same, the only change being caused by the displacement of the iron of the upper part. This displacement, when the water is level with the top of the gate, amounts to about six tons.

The size of the air-chamber is so arranged that when the water is level with the top of the gate it is just afloat; and at half-tide, when the water is at the level of the top of the air-chamber, there is a weight of about six tons on the wheels.[179]

The gate is provided with a sluice, by which water may be admitted into the air-chamber, or allowed to escape when the water outside is at a lower level; there is also a pump, by which leakage water may be extracted. The volume of the air-chamber may thus be altered at will, and the buoyancy may be modified so as to counteract the effect of the weight of any mud which may be deposited upon the decks of the gate.

There are in each gate two very large double sluices, which are used for working the lock, and for lowering the water in the Cumberland Basin to meet the tide. They are also used for scouring away the mud. The shutting pieces of the gates, which bear against the granite masonry and form a water-tight joint, were made of Honduras mahogany, a very durable wood for the purpose. The timber is bedded in creosoted felt and bolted to the gates; and the pieces are still sound, after the lapse of more than twenty years.

Underneath the gate are two wheels, slightly conical, 3½ feet diameter and 1 foot wide, which travel on level cast-iron rails let into the masonry of the gate floor. There is no heel-post such as is usual in dock gates, but the gate is hinged to the masonry by wrought-iron collars and a wrought-iron pin about 8 inches diameter, which is passed through them. Any portion of the weight of the gate which is not supported by the flotation of the air-chamber is borne entirely by the wheels, the arrangement at the hinge being merely for the purpose of retaining the gate in its position and guiding it in opening or shutting. The gate is moved by chains, which are attached to the barrels of powerful crabs, and conveyed through passages formed in the masonry; at the lower ends of these are chain rollers or broad sheaves, round which the chains pass. The sheaves are fluted on the circumference, to ensure their turning readily. When the gates are nearly afloat, they can be moved with great ease; but at the time of their construction it was considered essential to provide machinery sufficiently powerful to open and close them at low water, when the whole weight of each gate, nearly one hundred tons, rests on the wheels. The crabs and chains were therefore made much stronger, and were more difficult to move, than if they had been merely designed to work the gate under ordinary conditions.

The gates were constructed in Bristol at the Great Western Steamship Works in 1847. After the lower gate had been tested and proved to be water-tight, it was launched, and floated with the front surface nearly level. The positions it would assume under different conditions had been calculated beforehand. Before it was fixed, the gate was made to float nearly upright by the admission of water; it was then towed to its place, and brought into correct position. The hinge-pin was dropped through the collars, and by admitting water into it, the gate was sunk, so that it rested upon its wheels. This operation had to be performed at high water, which only lasted for a short time.

In fixing the upper gate, the water was kept up to the proper level by the lower gate, and therefore there was no need to do the work quickly.

Plymouth Great Western Docks.

As it was considered probable that, on the completion of railway communication, mail packets and other large ocean steamers might make Plymouth their port of departure, a company was formed in 1846 for the construction of a dock in Mill-bay, a large inlet in Plymouth Sound near the entrance to the Hamoaze.

The bay was already protected from the prevailing winds by a pier at its eastern side constructed by Mr. Rendel.

It was decided to form a wet dock and graving dock at the inner end of the bay, and to make quay walls along the side of the outer part, to join the existing pier. A floating pier for large vessels afterwards became part of the scheme. In 1847 preliminary trials were made as to the best means of excavating in deep water the limestone rock of which part of the bottom of the bay consisted; some quay walls were also constructed and made use of by the shipping.

At the end of 1851 a contract was entered into for the execution of the whole of the works remaining to be completed; the most important of these were the entrance, the graving dock, and the completion of the floating basin.

The progress of the undertaking was much facilitated by Mr. Brunel giving his sanction to the proposal of the contractors to form a stone and earth embankment across the mouth of the bay, instead of employing the usual timber coffer-dams. This embankment, which completely answered its purpose, was finished by the middle of 1853.

The works now proceeded steadily until they were completed, and at the end of the year 1856 the dock was opened.

The middle of the embankment was cut through, and an entrance channel dredged to a level of 8 feet below low water. The remainder of the dam, being partly protected by masonry walling, was used as a quay, and served for the protection of the outer basin.

Mr. Brunel had prepared the foundation, and had intended to build a pier to shelter the entrance gate from the sea, and to assist in pointing long vessels. The want of this shelter was felt in the gale of October 1857, when the gates were thrown down. In order to avoid any future casualty, storm gates, or framed struts reaching down to low water level, were placed immediately behind the entrance gates, so as to support them against heavy seas.

The dock, which is of oblong shape, has an area of 13 acres, and a length of quay wall of 3,490 feet. The greater part has a depth of 22 feet below high water at spring tides, or 16 feet at neap tides; the remainder is 4 feet deeper, or the same depth as the channel in the outer basin.

The walls are 8½ feet thick at bottom, and 3½ feet at top, and are built to a curved batter. They reach generally to a depth of 5 feet below low water, and rest on concrete 12½ feet thick, carried down until a rock foundation is reached, which in some places is as much as 40 feet below the bottom of the dock.

To accommodate the larger paddlewheel steamers, the entrances to the basin and graving dock were made 80 feet in width.

The dock is entered through a short passage, the sill being 13 feet below low water. The masonry of this entrance has curved battering sides, with a segmental invert.

The entrance is closed by a pair of wrought-iron buoyant gates, which meet at an angle of 127°. Each gate is 48 feet long, and weighs seventy-five tons, the breadth being 8 feet in the middle, curving to 2 feet at the ends. There are six horizontal decks and four vertical bulkheads. The depth at the heel-post is 22 feet, and at the meeting-post 35 feet (see woodcut, fig. 19).

In each gate is an air-chamber, the top of which is at half-tide level; and its volume is such that when the gate is wholly immersed there is a small downward pressure.[180]

Under each gate, near the meeting-post, is placed a wheel, which supports part of the weight. This wheel is so arranged that it can be easily removed for repair. The heel-posts are of cast iron, planed and ground in place against the polished surface of the granite hollow quoins so as to form a water-tight joint.

There are large scouring culverts behind the side walls of the entrance; but for the purpose of regulating the level of the water in the dock, and of discharging a large volume of water readily, without having to overcome the friction of ordinary sluice valve faces, each gate is furnished with a cylindrical valve, of the following description:—

From an opening in the side of the gate next the dock there is a large curved pipe or sluice-way, which terminates inside the body of the gate, with a circular horizontal orifice about 5 feet in diameter. The opening is covered by a short length of vertical pipe of the same diameter, reaching above high water, the bottom edge making a water-tight joint. This pipe can be raised or lowered by a screw at the top of the gate. When raised a short distance it allows the water from the dock to flow out between the bottom of the movable pipe and the orifice of the sluice-way into an isolated compartment of the gate, and to escape by an opening provided in the outer face. The movable pipe is guided by rollers, and from the construction the pressures on it are balanced.

The entrance to the graving dock, 80 feet wide, is closed by a pair of gates of the same dimensions and construction as those of the entrance. This dock is 380 feet long, 92 feet wide, and has a depth of 28 feet over the sill.

The floating pier was erected in Mill-bay in 1852, to accommodate the steam-shipping trade. It consists of a pontoon with a bridge leading to it.

The pontoon is a large wrought-iron vessel of nearly rectangular cross-section, 300 feet long, with 40 feet breadth of beam, and a depth of 17½ feet. It is loaded so as to draw 10 feet of water, and is capable of storing 4,000 tons of coals. To connect the pontoon with the shore there is an iron bridge, working upon hinges, in two spans of 125 feet each. The connection between the two spans was supported on a timber pier, and was made so as to be movable vertically, and capable of being adjusted by a crab and counterbalance weights. By means of this arrangement a uniform gradient over the whole length of the bridge could be obtained at any time of tide, for the convenience of heavily laden carts passing to and from the pontoon.

Briton Ferry Docks.

In 1846 a company was formed to establish docks in Baglan Bay at Briton Ferry, near the mouth of the river Neath; but nothing was done until 1851, when the necessary powers were obtained under an Act of Parliament. From the vicinity of the proposed docks to the South Wales and Vale of Neath Railways, a large amount of trade was anticipated; and in 1853 an Act was obtained for the South Wales Mineral Railway, which was intended to terminate at the docks, and was expected to bring a large traffic in coals and other minerals.

The dock works were begun soon afterwards, but the earthwork was not completed, nor the construction of the gate commenced, until the year 1858. The docks were completed, after Mr. Brunel’s death, by Mr. Brereton, and were formally opened on August 22, 1861.

They consist of an outer tidal basin of about 7½ acres, and an inner floating basin of about 11 acres, with a depth of water of 27 feet at spring tides, and 16 feet at neap tides. The two basins are connected by a passage or entrance of 50 feet in width, with curved battering walls and an invert, closed by a gate of a single leaf. An important advantage of single gates is that the sill and quoins may be in one plane, and that the troublesome and costly fitting of the hollow quoins is avoided. The sill was laid 6 feet below what was then the low-water level, as it was thought that future improvements might reduce the bar at the entrance of the river Neath to that level. This has already been nearly accomplished.[181] The total length of the docks is a little over half a mile, and the average breadth is about 400 feet. They are connected with the South Wales Railway by branch railways.

With the exception of the walls dividing the two basins near the entrance gate, the sides of the dock are not constructed with masonry quay walls, in the ordinary manner, but are formed in a very inexpensive manner of slopes pitched with furnace slag, obtained from the copper smelting works on the Neath river, with jetties at intervals for the shipping. Besides being suitable for the soft clay in which the dock is made, this plan is specially adapted for mineral traffic, as the work of loading or discharging a cargo of minerals can only be properly carried on at the point where fixed machinery is provided for the purpose. This machinery may be placed as conveniently on projecting jetties as on a dock wall. The traffic, which consists mainly of coals and metals, is accommodated at the jetties, which are furnished with cranes for loading and unloading the vessels employed in the metal and iron ore trade, and with tipping-frames, which discharge the coals into the ships. These cranes and tipping-frames are worked by hydraulic machinery.

In order to facilitate the entrance of vessels from the river Neath to the tidal basin, and to protect it from the sea, two pier-heads were built, one at each side of the basin at the point where it joins the river. These piers are of timber piling and framework, filled in with copper slag; the entrance between them is 300 feet wide. They were constructed after Mr. Brunel’s death.

The gate is a wrought-iron buoyant gate, with five vertical partitions or bulkheads and six decks. The length is 56 feet; the depth in the middle is 31 feet 6 inches, and at the sides 26 feet 6 inches. The breadth in the middle is 9 feet, and is curved to 2½ feet at the ends (see woodcut, fig. 20).

The air-chamber, which is similar to that of the Plymouth gates, is placed so that the top is at the level of high-water neap tides, about half-way up the gate.

There are two sluices at low-water level, each having an area of 8 square feet.

The entrance invert being subject to the influx of sand from the outer basin, and to the deposit of coal rubbish dropped into the dock, Mr. Brunel decided in this gate not to use wheels, but to make the hinge and heel-post strong enough to carry the whole weight of the gate, even if it were unsupported by the buoyancy of the air-chamber.

The heel-post is a massive piece of cast iron; the bottom part is bored out, and into it is fitted a cast-iron cylindrical pin, 1 foot 6 inches diameter and 7 feet 6 inches long. On this are ground discs of steel, lubricated with oil, whereon the gate rests and turns. Thus the surfaces exposed to friction are above the sand or grit at the bottom of the dock. The lower end of the pin fits into a cast-iron socket fastened to the masonry, and is prevented from turning round by being made hexagonal. The sides of the hexagon have sufficient play to enable the gate to adjust itself, when shut, to the masonry sill, so as to be water-tight. The top of the heel-post works in a brass bush, 18 inches diameter and 15 inches broad, enclosed in a massive wrought-iron collar, which is strongly fastened by anchor chains to the masonry. After the gate was completed the strength of the hinge was tested by moving the gate before the water was admitted into the dock. The only resistance to the motion of the gate is the slight friction at the hinge.

No coffer-dam was used in the construction of this work, but advantage was taken of a large bank of slag and earth enclosing a portion of the site of the dock. This was extended and raised, and a sea dam formed. The dam was cut through when the works were completed, and a channel dredged to the depth of 6 feet below low water.

Brentford Dock.

In 1855 an Act was obtained for making a dock on the Thames at Brentford, and a railway to join the Great Western Railway at Southall. The dock has an area of about 3½ acres.

The works were begun in July 1856, and were completed, and the dock opened, three years later.

The walls are founded in the London clay, which here underlies a bed of gravel of some thickness; from this there was a considerable influx of water.

The chief peculiarity of the dock is the form of construction adopted for the sides. Piers of brickwork, 10 feet long and 2 feet 3 inches thick, are placed at right angles to the sides of the dock at intervals of 26 feet. The backs of these piers are connected by horizontal arches, carried up with a curved batter. The piers are about 20 feet high, and arches are turned upon them, which support the front part of the quay, and meet the horizontal arches at the backs of the piers. Thus the sides of the dock consist of a series of vaults, arched over at the top, and also at the back towards the pressure of the earth.

The thickness of the horizontal arches which form the bulk of the wall is only 3 feet, but these are so strengthened by the piers in front, that a wall strong enough to resist the pressure of the earth behind it was obtained by means of a very small quantity of brickwork.

Along one side of the dock the piers are 31 feet long, in order that coal barges may lie with part of their length in the vaults between the piers while their cargo is being put on board. By this arrangement the barges have their longest dimension at right angles to the side of the dock, and a much greater number can be accommodated than if each occupied a space alongside the quay wall. The contents of the coal trucks are tipped into the barges through sloping shoots.

The entrance has a clear width of 30 feet, and is closed by a single wrought-iron buoyant gate, which, like the Bristol gates, is, when shut, not quite at right angles to the entrance.

The gate is 33 feet long, 19 feet high, 2 feet 6 inches wide at the middle, curved to 1 foot 6 inches at the sides, and weighs sixteen and a half tons. It is divided into compartments by four decks and two vertical bulkheads. The air-chamber occupies the whole space below one of the decks, 7 feet 6 inches above the bottom (see woodcut, fig. 21); and there are two sluices, each having an opening of 4 feet by 2 feet. This gate, like that at Briton Ferry, has no wheel under it, the weight being carried upon the pivot.

In order to avoid side strains upon the pivot and top collar, a counterbalance arm is fastened on the top of the gate. This is formed of two cast-iron girders, bolted together and enclosing weights between them. The ends of these girders project beyond the heel-post over the quay, as in canal lock gates, and carry the machinery by which the gate is turned, as there are no crabs, chains, or chain rollers. Instead of these, a cast-iron circular rack is fixed on the top of the masonry, in which a pinion works, turned by gearing fixed to the end of the counterbalance.

This gate turns with remarkable freedom, and the current of water running into the dock on a spring tide opens it completely.

Pier at Neyland, Milford Haven.

The South Wales Railway was originally intended to terminate at Fishguard, on the north coast of Pembrokeshire, with the view of securing a large quantity of Irish traffic, the distance across the channel to the Irish coast at Wexford being only 60 miles, less than the distance from Holyhead to Kingstown.

It was, however, ultimately decided to form a terminus, which would accommodate the ordinary Irish traffic, and would not require such an extensive outlay on harbour works as would have been necessary on the northern coast.

With this object, the inlet or natural harbour of Milford Haven was examined, and the South Wales Railway was carried to Neyland Point, opposite Pembroke, where the position is sheltered, and there is deep water at all times of tide for the largest vessels.

The pier at Neyland, or New Milford, which was made in 1857, consists of a timber viaduct, with a pontoon at the end, 150 feet long and 42 feet beam, loaded so as to draw about 7 feet. There is a depth of 16 feet alongside it at low water, and it is connected with the shore by a landing bridge. The pontoon is made of wrought iron, and has three transverse and two longitudinal bulkheads. It is moored by chain cables, which pass through two large hawse pipes, extending from the bottom nearly up to the deck, with cast-iron mouthpieces at their lower ends. The cables passing through these are anchored firmly to the ground at a considerable distance from the pontoon.

The pontoon was intended to be the centre of several others, which were to be moored in deeper water.

The rise of tide being sometimes as much as 25 feet, it was necessary that the landing bridge should be of considerable length, in order that there should be a moderate inclination at all times of tide. It is accordingly made in one span of 205 feet. It consists of two plate-iron side girders, of the uniform depth throughout of 14 feet, and width of 2 feet 6 inches. These are placed 12 feet 6 inches apart, the roadway being between them. The ends of the girders which rest on the pontoon are provided with cast-iron wheels, 1 foot 6 inches in diameter.

The pier has since been extended by additional pontoons, which were those used in the floating of the Saltash Bridge.

CHAPTER XV.

MISCELLANEOUS WORKS.

THERE are several matters of importance in which Mr. Brunel was engaged, which could not under any system of classification be introduced into the preceding chapters; these are therefore collected under one head of ‘miscellaneous works.’

The first of these is his connection with the Great Exhibition of 1851. He was from the beginning one of the most zealous supporters of this undertaking, and was appointed a member of the Committee of the Section of Machinery, whose duty it was to classify the objects to be exhibited in that department.

Upon the question of awarding prizes to exhibitors, Mr. Brunel held a very decided opinion adverse to the plan ultimately adopted. In a letter to the Chairman of the Committee, dated March 11, 1850, he writes:—

Mr. Brunel’s views found no favour at the time; but subsequent experience has convinced those best able to form a sound judgment in the matter, that ‘no prizes of any kind should be awarded’ in International Exhibitions.[182]

Mr. Brunel was also a Member of the Building Committee; and he accepted the office of Chairman and Reporter of the Jury for Class VII., on Civil Engineering, Architecture, and Building Contrivances.

He took a very active part in the proceedings of the Building Committee. Designs were invited, and two hundred and forty-five were sent in. None of these were considered satisfactory by the Committee, and they submitted to the Royal Commission a design of their own, the principal feature of which was a dome 200 feet in diameter.

Mr. Brunel was responsible as a member of the Committee for the plans prepared by them, and as regards the dome may be said to have designed it himself, but he expressed strong objections to the substantial and expensive buildings which it was proposed to erect in brickwork. His idea was that the building should be in what he called the ‘railway shed style;’ and he wished to produce effect rather by the construction of the roofs, &c., than by any architectural elevation.

When, therefore, the plans of the Building Committee failed to meet with public approval, and the late Sir Joseph Paxton submitted his well-known design, Mr. Brunel gave it his cordial support, and defended it against its detractors. He thus spoke of it in the report of the Jury of Class VII.

The award of Council Medals (the highest prize given) was recommended to Sir Joseph Paxton, and to the contractors, Messrs. Fox, Henderson and Co.

In a later part of the report, in announcing the recommendation of a Council Medal to His Royal Highness Prince Albert, for the model dwelling houses which were erected near the Exhibition building, and exhibited by the Prince, Mr. Brunel spoke in emphatic language of the magnitude and importance of the results which would follow from the introduction of improved dwellings for the working classes.[183]

When the Crystal Palace Company was formed in order to purchase the Exhibition building and erect it, with additions, at Sydenham, Mr. Brunel took a great interest in the project, and frequently went down to examine the progress of the building and gardens, and the beautiful architectural courts which were to be the chief attraction in the interior of the Palace. The water towers, which are so conspicuous a feature in the building, were designed by him.

The towers are 284 feet high, and carry near the top tanks 47 feet in diameter and 38 feet high, holding 1,200 tons of water.

The foundations required great care in their construction. The tanks had to be placed at a height of more than 200 feet, and the towers, which, with their load, weighed fully 3,000 tons each, had to rest on the sloping side of a clay hill. There was also the possibility that by the bursting of a pipe a large quantity of water might be suddenly discharged, and so cause a slip in the surrounding ground. Mr. Brunel carried the foundations down to a considerable depth, forming a large base of Portland cement concrete, and placing on it a cone of brickwork in cement, rising up to the ground level. The towers are twelve-sided, with two hollow cast-iron columns at each angle. The height of the building below the tanks is divided into ten stories, and at each floor there is a strong wrought-iron diaphragm, or shelf, 5 feet wide. The columns are also connected by strong diagonal bracing in the sides of the tower.

The tanks are made of wrought iron, and the water pipes are placed in the interior of the tower. Mr. Brunel did not think it would be prudent to form any of the columns of the towers into pipes, lest the expansion due to the temperature of the water should cause unequal support to be given to the tanks.

In July 1855, the pipes were proved, and the towers were completed shortly afterwards.

The remainder of this chapter will relate to matters which have but little in common with the subjects of the earlier part of it; but the change is hardly less marked than that which took place in the nature of the questions which occupied public attention within a few years of the close of the Great Exhibition.

Polygonal Rifle.

In October 1852, Mr. Brunel consulted Mr. Westley Richards, of Birmingham, as to the manufacture of a rifle ‘for the purpose of determining whether there was anything in a crotchet he had upon the subject.’ The rifle was made by Mr. Westley Richards according to Mr. Brunel’s directions, and finished in May 1854. Many experiments were tried with it, at Birmingham and at Manchester, in the spring of 1855, and afterwards at Woolwich; and its performances obtained great notoriety.

The history of this rifle, and the objects Mr. Brunel had in view in its design, will be understood from the following letters to Mr. Westley Richards:—

I.

Gunnery Experiments.

In 1854 Mr. Brunel took up warmly the question of improvement in large guns, which was then attracting the attention of several scientific men.

The friendship which had for some years previously existed between him and Mr. (now Sir William) Armstrong, of Newcastle-on-Tyne, gave Mr. Brunel opportunities for discussing these matters, with a view to their being carried into practical effect.

The following extracts from a letter written by Mr. Brunel, in April 1855, to Mr. James Nasmyth, explain generally his opinions at that time upon the construction of large guns:—

The scheme of making a gun with the barrel wrapped round with wire, which is referred to in this letter, was one which Mr. Brunel and Mr. Armstrong were very desirous of making the subject of actual experiment. Whether or not it would under their hands have become practically successful, could not be ascertained, as they were obliged to abandon the project, in consequence of the wire covering being patented, in May 1855, by Mr. Longridge.

The following letter to Mr. Armstrong relates to the same subject, and is interesting not only as showing Mr. Brunel’s correct appreciation of a principle which is the essence of the coil system of constructing guns, but as further illustrating his objections to the patent laws:—

Mr. Brunel had also considered the advantages of making the bore of the gun polygonal, with a projectile shaped to fit it. He had a portion of cannon tube and a projectile made by Mr. Armstrong in the beginning of 1855, but he did not himself pursue the question further.

Indeed, after the middle of the year 1856, when the works of the ‘Great Eastern’ steam-ship began to occupy a large portion of his time, Mr. Brunel was unable any longer to take part in gunnery investigations; but he watched with unabated interest the proceedings of those friends who have continued their experiments, with the great practical success of which he lived to see only the beginning.

Floating Gun-Carriage.

The plan of a gun-boat, or, as it would be more correctly called, a floating gun-carriage, which Mr. Brunel designed for an attack on Cronstadt and other Baltic forts during the Russian war, is clearly described in the following memorandum, which he drew up for the information of the Admiralty:—

Mr. Brunel had matured these plans in September 1854, and they were then brought under the notice of the Admiralty; but no steps were taken to test the practicability of the scheme.

He was, however, induced to make a further representation to the Admiralty in the following July. He wrote,—

Although the want of efficient gun-boats was then severely felt, this letter appears to have produced no effect upon the Board of Admiralty. But the friend who had originally brought the matter under the notice of the Board took the bold step of writing to Lord Palmerston, and acquainting him with what had passed.

Lord Palmerston at once saw the importance of investigating the subject, and sent for Mr. Brunel, who explained the plans to him. Lord Palmerston then asked him to see the officials at the Admiralty. Mr. Brunel did so; but great delay followed. It was, however, unimportant, as hostilities soon afterwards terminated, and there was no further need of gun-boats, good or bad.

This project did not exist only in the outline in which it is described in the memorandum given above. Mr. Brunel had worked out all the calculations of displacement, &c., and had made designs and models for the boat and its various appliances, and had been for some months in constant communication with Mr. W. G. Armstrong upon the form and construction of the gun.

This will be a fitting place to mention that in 1855 Captain Cowper Coles, C.B., showed Mr. Brunel the designs for his shot-proof raft, the principle of which was afterwards developed in the turret ship. Mr. Brunel gave Captain Coles the benefit of his advice on the various questions involved, and allowed him to use the services of his principal draughtsman, and to have the drawings got out in his office without expense.

Captain Coles, in a lecture which he delivered at the United Service Institution on June 29, 1860, warmly acknowledged the obligations he was under to Mr. Brunel for this act of kindness and generosity, and said that it had greatly encouraged him to persevere in bringing his plans into public notice.

Renkioi Hospital.

In February 1855, after the first winter of the allied armies in the Crimea, Mr. Brunel was asked by the War Department to undertake the design and construction of hospital buildings for the East.

He replied (on the same day that he received this application, February 16) that his ‘time and best exertions would be, without any limitations, entirely at the service of Government.’

He was accordingly appointed as engineer, and proceeded to design and superintend the manufacture of the required buildings and all their internal arrangements. They were sent out under his supervision, and erected at Renkioi, on the Dardanelles. All use for the buildings was ended with the conclusion of peace; but, for the seven months during which they were occupied, they added much to the comfort of more than thirteen hundred sick and wounded soldiers.

Many of the special arrangements adopted at Mr. Brunel’s suggestion have been since brought into general use; and the success of these buildings was, to a considerable extent, influential in leading the Americans to construct similar hospitals during their civil war. These are now (1870) being copied in the German armies.

The history of the Renkioi hospital buildings is a striking instance of the zeal with which Mr. Brunel entered into any undertaking which had a claim upon his assistance, of the varied experience and fertility of invention which he could bring to bear upon any subject, however remote it might seem to be from his ordinary occupations, and of the minute personal attention he was accustomed to give to every detail, as the only certain means of ensuring success.

Mr. Brunel entered upon his duties on February 16, and reported to the War Office on March 5 that he had not lost any time nor spared any exertion or any means in his power to forward the important business he had undertaken. He stated that he availed himself freely of the advice and assistance of all persons to whom he could apply with any prospect of advantage; and he added, ‘It is most gratifying to be able to state that from everybody I have received the most zealous and cordial assistance, and found it sufficient to mention the object of my enquiries to obtain immediately every assistance I could possibly require.’

An experimental ward was erected a few days afterwards on the premises of the Great Western Railway at Paddington, and was carefully criticised by competent persons; and, the plans having been approved of, specifications were made, with drawings of the various parts, and tenders were invited for the construction of the buildings.

The following paper gives a description of the buildings, and was written by Mr. Brunel in order to satisfy the curiosity of his friends:[l]—

As the buildings were completed the work of transport was commenced; and twenty-three steamers and sailing-vessels were despatched, containing altogether about 11,500 tons measurement of materials and stores. The first vessel arrived out on May 7, 1855, and the last on December 5, in the same year.

Meanwhile the important question of the site for the hospital buildings was being determined by Dr. Parkes, the Medical Superintendent, with the assistance of Mr. Brunton, who was in constant communication with Mr. Brunel on the subject.

After visiting various places, Dr. Parkes finally selected a spot near the village of Renkioi, on the Dardanelles. In a report which he addressed to the Secretary of State for War upon the formation and general management of the hospital, he thus describes ‘the nature of the site, and the means which were used in the formation of the hospital:’—

On the working of the system, Dr. Parkes says in his report:—

CHAPTER XVI.

MR. BRUNEL’S PROFESSIONAL OPINIONS AND PRACTICE.

IT is proposed in the earlier part of this chapter to describe, principally by extracts from Mr. Brunel’s correspondence, the position occupied by him in regard to the Companies which he served, and to the various classes of persons with whom he acted in the discharge of his duties as engineer to those Companies. These selections are followed by extracts relating to questions of general professional interest.

The first point to be considered is, his relations with the Companies which employed him as their engineer, and with the Directors who formed the governing body.

Mr. Brunel conceived that he was, by virtue of his appointment as engineer, the sole and confidential adviser of the Company in all matters relating to the construction and mechanical working of the undertaking. He did not permit any one to be associated with him in the supreme control over those matters which were in his department; and the moment he thought that confidence was no longer placed in him, he was prepared at every sacrifice to resign his office. But, as long as he was supported by the Directors, he thoroughly identified himself with their cause, and he never allowed considerations of health or convenience or pecuniary advantage to interfere with the performance of any service which he could render them. The fearless independence of his position, combined with his absolute devotion to the interests of his employers, was no doubt the secret of the immense influence he acquired, and of the affectionate esteem with which he was regarded by those whom he served.

On the Direction of Railway Works.

On the Position of Joint Engineer.

On the Position of Consulting Engineer.

On the Position of the Engineer in Relation to the Contractors.

On the Relations between the Engineer and the Directors.

I.

II.

III.

It is, from the nature of the case, impossible by any extracts from Mr. Brunel’s correspondence to give an adequate idea of the position which he occupied in relation to his assistants. There was so much personal intercourse between them that letter writing was but little resorted to.

His relations with them were of the most affectionate and intimate kind, and were maintained without any ostentation or outward show. He was in the habit of placing entire confidence in his subordinates as long as he considered that they deserved it; and, while he preserved his own proper position, he was always ready to shield them from the interference of others. The letters which are printed below are evidence of this. When, on the other hand, anything occurred to displease him in the conduct of his assistants, he was eager to give the offender a chance of retrieving his position; and he was always ready to help them in any difficulties.

On Interference of Directors with the Assistant Engineers.

I.

II.

III.

A few words may here be added on Mr. Brunel’s practice in reference to taking pupils.

Although many of his assistants had been his pupils, he did not encourage young men to come to him with the object of learning their profession in his office. He never absolutely declined to take pupils; but he endeavoured, by fixing a high premium, to reduce the number of applicants.

He did not profess to do more for his pupils than to give them the opportunities of seeing work, afforded by his office, and the chance of being afterwards employed as his assistants. He attached much importance to private study of mathematics and other branches of science.

Passing on to the position assumed by Mr. Brunel in his relations to the profession at large;—it may be stated in a few words, that he was desirous on all occasions of promoting its welfare by encouraging friendly intercourse among its members, by healing strife, by suppressing as far as he could all cant or pretension, and by setting his face steadfastly against all attempts to fetter the freedom of invention or to lessen the independence of engineers by State patronage or control.

It may appear strange to affirm of one who was foremost in almost all the professional contests of his time, that he was zealous in healing strife; but it is nevertheless true that Mr. Brunel, while he was a bold and uncompromising advocate of his own schemes, was at the same time untiring in his exertions to limit the area of controversy, to confine it strictly within its proper bounds, and to divest it of all personality or of anything which could lead to unpleasant feeling or annoyance.

His endeavours to this end were greatly helped by the friendly relations which he maintained at all times with his professional brethren. He never allowed any divergence of opinion to interfere with private friendship; and, even in the height of controversy, he was glad to give, and ready to ask for, advice on matters connected with the scientific departments of civil engineering.

It is but seldom that extracts have been made from Mr. Brunel’s private journals; but it may be permitted, in illustration of what has been said on this point, to give the following passage, written during the great contests of the year 1846.

Mr. Brunel’s opinions on the working of the patent laws will be given below, as following more fitly after extracts from his correspondence relating to the position of his profession in regard to the Government; but, before entering upon that subject, a few words may be said in reference to a class of persons who formed a very large proportion of his correspondents—the class of ‘Inventors.’

He used to receive numerous applications from persons who had invented, or who thought they had invented, some useful contrivance, from a locomotive which would save fifty per cent. in fuel over those then in use, to a machine which, as Mr. Brunel assured its inventor, ‘would not even have a tendency to move.’ He was always ready to encourage inventions which seemed likely to produce good results, and to enquire into their merits, if they were patented; but not otherwise, lest it should be said that confidence had been placed in him.

The following is one of the many letters he had to write in answer to requests of this nature.

Upon the important question how far, if at all, the practice of civil engineers should be subject to State control, Mr. Brunel held very decided views. He was strongly opposed both to any interference on the part of the State with the freedom of civil engineers in the conduct of their professional work, and to the recognition of merit by the bestowal of honours or rewards.

On the Royal Commission on the Application of Iron to Railway Structures.[191]

On a Proposal to obtain the Recognition in England of Decorations conferred at the Paris Exhibition of 1855.

On the question of the patent laws, Mr. Brunel held the opinion that the system of protecting inventions by means of letters patent was productive of immense evil. The prominent part which he took in all discussions upon this subject exposed him to much adverse criticism, which was perhaps the more freely bestowed, because it was felt that he was a very formidable opponent, not only from the force of his arguments, but also from the authority with which he spoke.

He was, from the necessity of his position as a civil engineer, himself an inventor; he had in his staff and among those with whom he acted many inventors; he did not, therefore, underrate the benefits conferred on science by those who, by inventing, add to its resources. He was continually being trammelled and thwarted in his various undertakings by patents, and he therefore could judge of their evil effects upon the progress of practical engineering; and, lastly, he had the best possible means of judging of their effects upon the inventors themselves, both from his opportunities of becoming acquainted with the fate of others, and from his own experience. His father, Sir Isambard Brunel, had taken out patents for most of his inventions, and, as Mr. Brunel stated before the House of Lords Committee of 1851, with very unfortunate results, especially in the case of the carbonic-gas engine (see Note B to Chapter I); where, if they had not been obliged to work secretly, in order to conceal the process before the patent was granted, they could have obtained valuable advice, which might either have led to an earlier abandonment of the project, or to its improvement in those points in which it failed.

Mr. Brunel drew up the following statement when asked to give evidence before the Select Committee of the House of Lords in 1851. His evidence will be found at p. 246 of the Minutes of Evidence (ordered to be printed July 1, 1851).

Memorandum for Evidence before the Select Committee of the House of Lords on the Patent Laws, 1851.

Extract from Observations on the Patent Laws made by Mr. Brunel at a Meeting of the Society of Arts.

CHAPTER XVII.

PRIVATE LIFE.

UNDER any circumstances, and by whomsoever made, the attempt to describe Mr. Brunel’s home life must fail to satisfy those who knew him, and who remember him in the midst of his family or among his friends.

But those who did not know him, except as a professional man, or who are only acquainted with his works, will expect to find in these pages some account of his private life, and of the manner in which he spent those brief intervals of relaxation which he permitted himself to enjoy.

Although Mr. Brunel was never an idle man, he was able, until he obtained business on his own account, to enjoy many amusements from which in after life he was completely debarred.

This arose partly from his work under his father being near his own home and his friends, and partly from the power he possessed, and which never deserted him, of being able to throw aside cares and anxieties and to join with the utmost zest in passing amusements.

The following letter, relating to this time, is written by one who was Mr. Brunel’s constant companion during the period to which it refers:—

The events of the year 1835 brought with them, not unnaturally, other changes. At the beginning of 1836, he removed to 18 Duke Street, Westminster, a large house looking on St. James’s Park, and now (1870) the last in the street, next to the new India Office.

In July of the same year he married the eldest daughter of the late William Horsley, and granddaughter of Doctor Callcott. Of this marriage there was issue two sons and a daughter, all of whom survive him.

Although, as will be presently mentioned, he afterwards bought some property in Devonshire, the Duke Street house was always his home. He spent his life there, having his offices on the lower floors.

He had no wish to enter Parliament, although it had been more than once suggested to him to do so, and his work prevented his taking an active share, as an inhabitant of Westminster, in the concerns of his neighbourhood.

The only occasion on which he took a prominent part in local affairs was as a special constable in April 1848, when he acted as one of the two ‘leaders’ of the special constables in the district between Great George Street and Downing Street.

He was not without experience of the duties of a special constable, as he had been sworn in during the Bristol riots of 1830, and on that occasion saw active service. Happily, matters were better managed in London, and no actual collision took place between the constables, or the military, and the mob.

The extent to which Mr. Brunel kept his works in his own hands, and under his own superintendence, made it necessary for him to have a large amount of office accommodation; and the inconvenience of having branch offices in the streets near his house led him, in 1848, to enlarge his offices: with this object he added the adjoining house, 17 Duke Street, which he rebuilt. A large room on the ground floor, looking on the Park, was thenceforward his own office, and the room above was made the dining-room. It was decorated in the Elizabethan style, and was to have contained a collection of pictures illustrative of scenes in ‘Shakespeare,’ painted for him by the principal artists of the day. This project was never completely carried out, but several pictures (about ten in all) were painted and hung up, among them the ‘Titania’ of Sir Edwin Landseer. These subjects are again referred to in the following letter:—

Within less than a year of Mr. Brunel’s return from his visit to Italy, a strange accident happened to him, which placed his life in great jeopardy.

On April 3, 1843, he was amusing some children at his house by the exhibition of conjuring tricks, when, in pretending to pass a half-sovereign from his ear to his mouth, the coin he had placed in his mouth slipped down his throat. After a few days he began to suffer from a troublesome cough, and on April 18 Sir Benjamin Brodie was consulted.

The nature of the accident and the course of treatment adopted are described in the following letter from Mr. Brunel’s brother-in-law, the late Dr. Seth Thompson, which was published in the ‘Times’ newspaper of May 16, 1843:—

During the time that Mr. Brunel was in danger the public excitement was intense. His high professional position, the extraordinary nature of the accident, and the greatness of the loss, were the result to prove fatal, made his condition and the chances of his recovery an engrossing topic of conversation; and, when the news was spread that ‘it is out,’ the message needed no explanation.

That the result was successful was due, not only to the skill of the surgeons engaged, and to the anxious care with which those who nursed him left nothing undone to ensure his safety, but also to the remarkable coolness which Mr. Brunel himself displayed throughout. From the first he took part in the consultations which were held on his case, and assisted materially in determining the course of treatment which should be pursued.

The ten years which followed were the most prosperous in Mr. Brunel’s life; he had attained to great eminence in his profession, and was still in the enjoyment of robust health. But the results of the gauge controversy and the fierce contests which followed it, and, above all, the failure of the Atmospheric System on the South Devon Railway, caused him grave anxiety and sorrow. Critics have erred greatly in representing him as a man who, in order to accomplish some vast design, thought but little of the distress which follows want of success in commercial enterprises. So far from its being true that Mr. Brunel was indifferent to the interests of his employers, his private journals show that throughout (to use his own words) ‘the incessant warfare in which he was engaged’ he was earnestly desiring peace and endeavouring to secure it, and that in times of difficulty, such as the trial of the Atmospheric System and the launch of the ‘Great Eastern,’ his chief thoughts were for those who would suffer through the failure of his plans.

In the midst of his professional occupations he was able occasionally, though rarely, to enjoy the society of his friends. After the session was over, in 1844 and 1845, he went to Italy on business, and in 1846 to Switzerland for a short holiday. In 1847 the South Devon Railway was occupying his attention, and he determined to take a house at Torquay. While there, the important character of his railway works in Devonshire and Cornwall led him to think of making a more permanent settlement in that part of the country.

After a good deal of hesitation between various places, he fixed upon a spot at Watcombe, about three miles from Torquay, on the Teignmouth turnpike road. He made his first purchase of land in the autumn of 1847; and from that time to within a year of his death the improvement of this property was his chief delight.

He had always a great love and appreciation of beautiful scenery, and in his choice of a place in which to plant and build he provided amply for his complete gratification.

The principal view, which, if the house had been built, would have been the view from the terrace, is one of the loveliest in that part of Devonshire. On one side is the sea, and on the other the range of Dartmoor, while in front is spread undulating country, bounded by the hills on the further side of Torbay, the bay itself looking like a lake, being shut in by the hills above Torquay.

When Mr. Brunel bought this property it consisted of fields divided by hedgerows; but, assisted by Mr. William Nesfield, he laid it out in plantations of choice trees. The occupation of arranging them gave him unfailing pleasure; and, although he could seldom spare more than a few days’ holiday at a time, there can be little doubt that the happiest hours of his life were spent in walking about in the gardens with his wife and children, and discussing the condition and prospects of his favourite trees.[193]

He could not, of course, take a prominent part in the affairs of the parish, but he was always ready to assist in any work that had been taken in hand. He will be long remembered there by his friends in every rank of life.

In purchasing this property in Devonshire, Mr. Brunel had looked forward to retiring gradually from active professional life, ‘to draw in and make room for others,’ and to spend a greater portion of his time in the country.

It may well be questioned whether he would have been happy in giving up work while yet in middle life; but the wisdom of his resolve was not to be put to the test.

From the beginning of the year 1852 the ‘Great Eastern’ steam-ship began to occupy his time and thoughts. As the works progressed he was more and more tied to London; and the large pecuniary investment he had made in the shares of the company caused him to hesitate before proceeding with the building of his house.

Thus the hopes he had formed for making his home in Devonshire faded gradually away, and were at length extinguished by the failure of his health.

Many things had happened in the earlier part of 1857 which gave him pleasure. In June he received, in company with Mr. Robert Stephenson, the honorary degree of Doctor in Civil Law from the University of Oxford.[194] In the summer he paid several visits to Devonshire, and at the beginning of September the floating of the first truss of the Saltash bridge was successfully accomplished.

The history of the launch of the ‘Great Eastern,’ which was commenced in November, has been already told. Throughout all the disappointments he then endured Mr. Brunel took comfort from the sympathy of valued friends, and from those higher sources of consolation on which it was his habit to rely. He paid for his exertions a heavy price, for they left him broken in health and already suffering from the disease of which in a little more than eighteen mouths afterwards he died.[195]

In May 1858 Mr. Brunel went to Vichy, and thence to Switzerland, returning home in the autumn by way of Holland. When at Lucerne he went up the Righi, and was so charmed with it that, instead of spending only a night there, he remained a week, working at the designs for the Eastern Bengal Railway.

It was on his return to England in September that the alarming nature of his illness was ascertained. After anxious consultation with Sir Benjamin Brodie and Dr. Bright, he was ordered to spend the winter in Egypt, in the hope that he might return in the March or April following in restored health.

He was very unwilling to be so long absent from England, especially as a new company had just been formed to finish the ‘Great Eastern,’ and the contracts for her completion were about to be let.

However, it was thought that very serious consequences might follow if he remained at home; and in the beginning of December he left for Alexandria, with his wife and younger son.

Having stayed there a day or two, they went on to Cairo, where they found Mr. Robert Stephenson. He and Mr. Brunel dined together on Christmas Day.

On December 30 the journey up the Nile commenced. On January 21 they arrived at Thebes, and spent some days there. Mr. Brunel was able to ride about on a donkey, and made some sketches of the celebrated ruins in the neighbourhood.[196]

They reached Assouan on February 2, and made preparations for ascending the cataracts. They went as far as Dakkeh, and got back to Assouan on February 19.

The following letter from Mr. Brunel to his sister, Lady Hawes, describes some of the scenes through which he passed:—

After leaving Egypt, Mr. Brunel went to Naples and Rome, where he spent Easter, and he returned to England in the middle of May.

When abroad, Mr. Brunel made sight-seeing a pleasure rather than a business; thus in Egypt he preferred to visit frequently the same places, and rather to enjoy that which he knew gave him pleasure, than to hurry about with the object of seeing all that was to be seen. At Philæ he stopped more than a week, and at Thebes he spent more time in a small outlying temple near Karnac than in the great ruin itself. So also at Rome he went frequently to the Colosseum, and he spent many hours in the interior of St. Peter’s.

Shortly after his return to England he went to Plymouth, and over the Saltash bridge and other parts of the Cornwall Railway, which had been opened during his absence abroad.

Although it had by this time become certain that the disease under which he laboured had assumed a fatal character, he continued to give unremitting attention to his various professional duties; and in order to be nearer the ‘Great Eastern,’ he took a house at Sydenham, and removed there with his family in the beginning of August.

Almost every day he went to the great ship and superintended the preparations for getting her to sea. She was advertised to sail on September 6, and Mr. Brunel had intended going round in her to Weymouth.

He was on board early on the morning of the 5th, and his memorandum book has, under that date, an entry of some unfinished work which had to be looked after. Towards midday he felt symptoms of failing power, and went home to his house in Duke Street, when it became evident that he had been attacked with paralysis.

At one time it seemed possible that he might recover; but on the tenth day after his seizure, Thursday, September 15, all hope was taken away. In the afternoon he spoke to those who watched around him, calling them to him by their names; as evening closed in he gradually sank, and died at half-past ten, quietly and without pain.

The funeral was on September 20, at the Kensal Green Cemetery.

Along the road leading to the chapel many hundreds of his private and professional friends, his neighbours among the tradespeople of Westminster, the Council of the Institution of Civil Engineers, and the servants of the Great Western Railway Company, had assembled, and, with his family, followed his body to its place of burial, in the grave of his father and mother.[198]

It would be improper here to attempt to enter into a general criticism of Mr. Brunel’s works, or to determine the position which he is entitled to occupy among civil engineers. That task has yet to be accomplished, and must be undertaken by those who can claim to be impartial judges. It has been the object of this book to provide, as far as possible, the materials on which a just judgment of his career can be based.

But it may be permitted, in conclusion, to place on record the following testimony to the high position held by Mr. Brunel in the esteem of his contemporaries.

On November 8, 1859, at the first meeting of the Institution of Civil Engineers after the death of Mr. Brunel and of Mr. Robert Stephenson, Mr. Joseph Locke, M.P., the President, rose and said—

‘I cannot permit the occasion of opening a new session to pass without alluding to the irreparable loss which the Institution has sustained by the death, during the recess, of its two most honoured and distinguished members.

‘In the midst of difficulties of no ordinary kind, with an ardour rarely equalled, and an application both of body and mind almost beyond the limit of physical endurance, in the full pursuit of a great and cherished idea, Brunel was suddenly struck down, before he had accomplished the task which his daring genius had set before him.

‘Following in the footsteps of his distinguished parent, Sir Isambard Brunel, his early career, even from its commencement, was remarkable for originality in the conception of the works confided to him. As his experience increased, his confidence in his own powers augmented; and the Great Western Railway, with its broad-gauge line, colossal engines, large carriages, and bold designs of every description, was carried onward, and ultimately embraced a wide district of the country.

‘The same feeling induced, in steam navigation, the successive construction of the “Great Western” steamer, the largest vessel of the time, until superseded by the “Great Britain,” which was in its turn eclipsed by the “Great Eastern,” the most gigantic experiment of the age.

‘The Great Ship was Brunel’s peculiar child; he applied himself to it in a manner which could not fail to command respect; and, if he did not live to see its final and successful completion, he saw enough, in his later hours, to sustain him in the belief that his idea would ultimately become a triumphant reality.

‘The shock which the loss of Brunel created was yet felt, when we were startled by an announcement that another of our esteemed members had been summoned from us.[199]

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

‘It is not my intention at this time to give even an outline of the works achieved by our two departed friends. Their lives and labours, however, are before us; and it will be our own fault if we fail to draw from them useful lessons for our own guidance. Man is not perfect, and it is not to be expected that he should be always successful; and, as in the midst of success we sometimes learn great truths before unknown to us, so also we often discover in failure the causes which frustrate our best directed efforts. Our two friends may probably form no exception to the general rule; but, judging by the position they had each secured, and by the universal respect and sympathy which the public has manifested for their loss, and remembering the brilliant ingenuity of argument, as well as the more homely appeals to their own long experience, often heard in this hall, we are well assured that they have not laboured in vain.

‘We, at least, who are benefited by their successes, who feel that our Institution has reason to be proud of its association with such names as Brunel and Stephenson, have a duty to perform; and that duty is, to honour their memory and emulate their example.’

.’

APPENDIX I.

(See Chapter V. on the Broad Gauge, p. 99.)

Report to the Board of Directors of the Great Western Railway Company.

August 1838.

GENTLEMEN,—As the endeavour to obtain the opinions and reports of Mr. Walker, Mr. Stephenson, and Mr. Wood, prior to the next half-yearly meeting, has not been successful, I am anxious to record more fully than I have previously done, and to combine them into one report, my own views and opinions upon the success of the several plans which have been adopted at my recommendation in the formation and in the working of our line; and in justice to myself and to these plans, and indeed to enable others to arrive at any just conclusion as to the result which has been attained, or as to the probable ultimate success or advantages of the system, it is necessary that I should enter very fully, I fear even tediously, into a recapitulation of the circumstances, peculiar to this railway, which led to the consideration and the adoption of these plans, which some call innovations and wide deviations from the results of past experience, but the majority of which I will undertake to show are merely adaptations of those plans to our particular circumstances.

It will be necessary also that I should refer to all the numerous difficulties which we have had to encounter, which have necessarily prevented the perfect working of these plans in the first instance, but which have been overcome, or which are gradually and successively diminishing; and, finally, I am prepared to show that, notwithstanding the novelty of the circumstances, and the difficulties and delays which at the outset invariably attend any alteration, however necessary, or however desirable, from the accustomed mode of proceeding, and notwithstanding the violent prejudices excited against us, and the increased difficulties caused by these prejudices, the result is still such as to justify the attempt which has been made, and to show that in the main features, if not in all the details, the system hitherto followed is good, and ought to be pursued.

The peculiarity of the circumstances of this railway, to which I would more particularly refer, and which have frequently been mentioned, consists in the unusually favourable gradients and curves which we have been able to obtain. With the capability of carrying the line upwards of fifty miles out of London on almost a dead level, and without any objectionable curve, and having beyond this, and for the whole distance to Bristol, excellent gradients, it was thought that unusually high speed might easily be attained, and that the very large extent of passenger traffic which such a line would certainly command would ensure a return for any advantages which could be offered to the public, either in increased speed or increased accommodations. With this view every possible attention was paid to the improvement of the line as originally laid down in the parliamentary plans. We ultimately succeeded in determining a maximum gradient of 4 feet per mile, which could be maintained for the unusual distance, before mentioned, of upwards of fifty miles from London, and also between Bristol and Bath, comprehending those parts of the line on which the principal portion of the passenger traffic will be carried. The attainment of high speed appeared to involve the question of the width of gauge, and on this point accordingly I expressed my opinion at a very early period.

It has been asserted that 4 feet 8 inches, the width adopted on the Liverpool and Manchester Railway, is exactly the proper width for all railways, and that to adopt any other dimension is to deviate from a positive rule which experience has proved correct; but such an assertion can be maintained by no reasoning. Admitting, for the sake of argument, that, under the particular circumstances in which it has been tried, 4 feet 8 inches has been proved the best possible dimension, the question would still remain—What are the best dimensions under the circumstances?

Although a breadth of 4 feet 8 inches has been found to create a certain resistance on curves of a certain radius, a greater breadth would produce only the same resistance on curves of greater radius. If carriages and engines, and more particularly if wheels and axles of a certain weight, have not been found inconvenient upon one railway, greater weights may be employed and the same results obtained on a railway with better gradients. To adopt a gauge of the same number of inches on the Great Western Railway as on the Grand Junction Railway, would in fact amount practically to the use of a different gauge in similar railways. The gauge which is well adapted to the one is not well adapted to the other, unless, indeed, some mysterious cause exists which has never yet been explained for the empirical law which would fix the gauge under all circumstances.

Fortunately this no longer requires to be argued, as too many authorities may now be quoted in support of a very considerable deviation from this prescribed width, and in every case this change has been an increase. I take it for granted that, in determining the dimensions in each case, due regard has been had to the curves and gradients of the line, which ought to form a most essential, if not the principal, condition.

In the Report of the Commissioners upon Irish Railways, the arguments are identically the same with those which I used when first addressing you on the subject in my Report of October 1835. The mechanical advantage to be gained by increasing the diameter of the carriage-wheels is pointed out, the necessity, to attain this, of increasing the width of way, the dimensions of the bridges, tunnels, and other principal works, not being materially affected by this; but, on the other hand, the circumstance which limits this increase being the curves on the line, and the increased proportional resistance on inclinations (and on this account it is stated to be almost solely applicable to very level lines); and, lastly, the increased expense, which could be justified only by a great traffic.

The whole is clearly argued in a general point of view, and then applied to the particular case, and the result of this application is the recommendation of the adoption of 6 feet 2 inches on the Irish railways. Thus, an increase in the breadth of way to attain one particular object—viz. the capability of increasing the diameter of the carriage-wheels without raising the bodies of the carriages—is admitted to be most desirable, but is limited by certain circumstances, namely, the gradients and curves of the line, and the extent of traffic.

Every argument here adduced, and every calculation made, would tend to the adoption of about 7 feet on the Great Western Railway.

The gradients of the lines laid down by the Irish Commission are considerably steeper than those of the London and Birmingham Railway, and four and five times the inclination of those on the Great Western Railway; the curves are by no means of very large radius, and indeed the Commissioners, after fixing the gauge of 6 feet 2 inches, express their opinion, that upon examination into the question of curves, with a view to economy, they do not find that the effect is so injurious as might have been anticipated, and imply therefore that curves, generally considered of small radius on our English lines, are not incompatible with the 6 feet 2 inch gauge; and, lastly, the traffic, instead of being unusually large, so as to justify any expense beyond that absolutely required, is such as to render assistance from Government necessary to ensure a return for the capital embarked. As compared with this, what are the circumstances in our case?

The object to be attained is the placing an ordinary coach body, which is upwards of 6 feet 6 inches in width, between the wheels. This necessarily involves a gauge of rail of about 6 feet 10½ inches to 6 feet 11 inches, but 7 feet allows of its being done easily; it allows, moreover, of a different arrangement of the body: it admits all sorts of carriages, stage-coaches, and carts to be carried between the wheels. And what are the limits in the case of the Great Western Railway, as compared to those on Irish railways? Gradients of one-fifth the inclination, very favourable curves, and probably the largest traffic in England.

I think it unnecessary to say another word to show that the Irish Commissioners would have arrived at 7 feet on the Great Western Railway by exactly the same train of argument that led them to adopt 6 feet 2 inches in the case then before them.

All these arguments were advanced by me in my first Report to you, and the subject was well considered. The circumstance of the Great Western Railway, and other principal railways likely to extend beyond it, having no connection with other lines then made, leaving us free from any prescribed dimension, the 7-feet gauge was ultimately determined upon. Many objections were certainly urged against it: the deviation from the established 4 feet 8 inches was then considered as the abandonment of the principle: this, however, was a mere assertion, unsupported even by plausible argument, and was gradually disused; but objections were still urged, that the original cost of construction of all the works connected with the formation of the line must be greatly increased; that the carriages must be so much stronger; that they would be proportionally heavier; that they would not run round the curves, and would be more liable to run off the rails; and particularly, that the increased length of the axles would render them liable to be broken: and these objections were not advanced as difficulties which, as existing in all railways, might be somewhat increased by the increase of gauge, but as peculiar to this, and fatal to the system.

With regard to the first objection, namely, the increased cost in the original construction of the line, if there be any, it is a question of calculation which is easily estimated, and was so estimated before the increased gauge was determined upon. Here, however, preconceived opinions have been allowed weight in lieu of arguments and calculations; cause and effect are mixed up, and without much consideration it was assumed at once that an increased gauge necessarily involved increased width of way, and dimensions of bridges, tunnels, &c.

Yet such is not the case within the limits we are now treating of: a 7-feet rail requires no wider bridge or tunnel than a 5-feet; the breadth is governed by a maximum width allowed for a loaded waggon, or the largest load to be carried on the railway, and the clear space to be allowed on either side beyond this.

On the Manchester and Liverpool Railway this total breadth is only 9 feet 10 inches, and the bridge and viaducts need only have been twice this, or 19 feet 8 inches; 9 feet 10 inches was found, however, rather too small, and in the London and Birmingham, with the same width of way, this was increased to 11 feet by widening the interval between the two rails.

In the space of 11 feet, allowed for each rail, a 7-feet gauge might be placed just as well as a 5-feet, leaving the bridges, tunnels, and viaducts exactly the same; but 11 feet was thought by some still too narrow: and when it is remembered that this barely allows a width of 10 feet for loads, whether of cotton, wool, agricultural produce, or other light goods, and which are liable also to be displaced in travelling, 13 feet (which has been fixed upon in the Great Western Railway, and which limits the maximum breadth, under any circumstances, to about 12 feet) will not be found excessive.

It is this which makes the minimum width, actually required under bridges and tunnels, 26 feet instead of 22 feet, and not the increased gauge.

The earthwork is slightly affected by the gauge, but only to the extent of 2 feet on the embankment, and not quite so much in the cuttings; but what, in practice, has been the result? The bridges over the railway on the London and Birmingham are 30 feet, and the width of viaducts 28 feet; on the Great Western Railway they are both 30 feet; no great expense is therefore incurred on these items, and certainly a very small one compared to the increased space gained, which, as I have stated, is from 10 to 12 feet. In the tunnels exists the greatest difference; on the London and Birmingham Railway, which I refer to as being the best and most analogous case to that of the Great Western Railway, the tunnels are 24 feet wide. On the Great Western Railway the constant width of 30 feet is maintained, more with a view of diminishing the objections to tunnels, and maintaining the same minimum space which hereafter may form a limit to the size and form of everything carried on the railway, than from such a width being absolutely necessary.

Without pretending to find fault with the dimensions fixed, and which have, no doubt, been well considered, upon the works on other lines, I may state that the principle which has governed has been to fix the minimum width, and to make all the works the same, considering it unnecessary to have a greater width between the parapet walls of a viaduct, which admits of being altered, than between the sides of a tunnel which cannot be altered.

The embankments on the London and Birmingham Railway are 26 feet, on the Great Western 30 feet, making an excess of about six and a half per cent. on the actual quantity of earthwork.

The difference in the quantity of land required is under half an acre to a mile. On the whole, the increased dimensions from 10 to 12 feet will not cause any average increased expense in the construction of the works, and purchase of land, of above seven per cent.—eight per cent. having originally been assumed in my Report in 1835 as the excess to be provided for.

With respect to the weight of the carriages, although we have wheels of 4 feet diameter, instead of 3 feet, which, of course, involves an increased weight quite independent of the increase of width, and although the space allowed for each passenger is a trifle more, and the height of the body greater, yet the gross weight per passenger is somewhat less.

Being an average of 594 lbs. on the two carriages.

This saving of weight does not arise from the increased width, and is notwithstanding the increased strength of the framing and the increased diameter and weight of the wheels; I have not weighed our second-class open carriages, but I should think the same proportion would exist.

As to the breaking of axles or running off the line, the practical result has been that, from some cause or other, we have been almost perfectly free from those very objections which have been felt so seriously on some other lines. Far from breaking any engine axles, not even a single cranked axle has been strained, although the engines have been subjected to rather severe trials. One of our largest having, a short time back, been sent along the line at night, when it was not expected, came in collision with some ballast waggons, and was thrown off the line nearly 6 feet; none of the axles were bent, or even strained in the least, although the front of the carriage, a piece of oak of very large scantling, was shattered. After ten weeks’ running, one solitary instance has occurred of a carriage in a train getting off the line and dragging another with it, and which was not discovered till after running a mile and a half. As the carriage was in the middle of the train, and one end of the axle was thrown completely out of the axle guard, there must evidently have been some extraordinary cause—possibly a plank thrown across the railway by a blow from the carriage which preceded, and which might have produced the same effect on any railway; and at any rate it was a strong trial to the axle, which was not broken, but merely restored to its place, and the carriage sent on to London. The same mode of reasoning which has by some been used in favour of the 4 feet 8 inches gauge, if applied here, would prove that long axles are stronger than short, and wide rails best adapted for curves. All that I think proved, however, is this—that the increased tendency of the axles to break, or of the wheels to run off the rails, is so slight that it is more than counterbalanced by the increased steadiness from the width of the base, and the absence of those violent strains which arise from irregularity on the gauge and the harshness of the ordinary construction of rails. In fact, not one of the objections originally urged against the practical working of the wide gauge has been found to exist, while the object sought for is obtained, namely, the capability of increasing at any future period the diameter of the wheels, which cannot be done, however desirable it may hereafter be found, with the old width of rail. This may be said to be only prospective; but, in the meantime, contingent advantages are sensibly felt in the increased lateral steadiness of the carriages and engines, and the greater space which is afforded for the works of the locomotives. And here I wish particularly to call your attention to the fact that this prospective advantage—this absence of a most inconvenient limit to the reduction of the friction, which, with our gradients, forms four-fifths or eighty per cent. of the total resistance—was the object sought for, and that, at the time of recommending it, I expressly stated as follows:—‘I am not by any means prepared at present to recommend any particular size of wheel, or even any great increase of the present dimensions. I believe they will be materially increased; but my great object would be in every possible way to render each part capable of improvement, and to remove what appears an obstacle to any great progress in such a very important point as the diameter of the wheels, upon which the resistance, which governs the cost of transport and the speed that may be obtained, so materially depends.’

These advantages were considered important by you, they are now considered so by many others; and certainly everything which has occurred in the practical working of the line confirms me in my conviction that we have secured a most valuable power to the Great Western Railway, and that it would be folly to abandon it.

The next point I shall consider is the construction of the engines, the modifications in which, necessary to adapt them to higher speeds than usual, have, like the increased width of gauge, been condemned as innovations.

I shall not attempt to argue with those who consider any increase of speed unnecessary. The public will always prefer that conveyance which is most perfect, and speed within reasonable limits is a material ingredient in perfection in travelling.

A rate of thirty-five to forty miles an hour is not unfrequently attained at present on other railways in descending planes, or with light loads on a level, and is found practically to be attended with no inconvenience. To maintain such a speed with regularity on a level line, with moderate loads, is therefore quite practicable, and unquestionably desirable. With this view the engines were constructed, but nothing new was required or recommended by me.

A certain velocity of the piston is considered the most advantageous.

The engines intended for slow speeds have always had the driving wheels small in proportion to the length of stroke of the piston. The faster engines have had a different proportion; the wheels have been larger, or the strokes of the piston shorter. From the somewhat clamorous objections raised against the large wheels, and the construction of the Great Western Railway engines, and the opinions rather freely expressed of my judgment in directing this construction, it would naturally be supposed that some established principle had been departed from, and that I had recommended this departure.

The facts are, that a certain velocity of piston being found most advantageous, I fixed this velocity, so that the engines should be adapted to run thirty-five miles an hour, and capable of running forty—as the Manchester and Liverpool Railway engines are best calculated for twenty to twenty-five, but capable of running easily up to thirty and thirty-five miles per hour; and fixing also the load which the engine was to be capable of drawing, I left the form of construction and the proportions entirely to the manufacturers, stipulating merely that they should submit detail drawings to me for my approval. This was the substance of the circular, which, with your sanction, was sent to several of the most experienced manufacturers. Most of these manufacturers, of their own accord, and without previous communication with me, adopted the large wheels, as a necessary consequence of the speed required. The recommendation coming from such quarters, there can be no necessity for defending my opinion in its favour; neither have I now the slightest doubt of its correctness. As it has been supposed that the manufacturers may have been compelled or induced by me to adopt certain modes of construction, or certain dimensions, in other parts by a specification—a practice which has been adopted on some lines—and that these restrictions may have embarrassed them, I should wish to take this opportunity to state distinctly that such is not the case. I have indeed strongly recommended to their consideration the advantages of having very large and well-formed steam passages, which generally they have adopted, and with good results; and with this single exception, if it can be considered one, they have been left unfettered by me (perhaps too much so) and uninfluenced, except indeed by the prejudices and fears of those by whom they have been surrounded, which have by no means diminished the difficulties I have had to contend with.

The principal proportions of these engines being those which have been recommended by the most able experimentalists and writers, and these having been adopted by the most experienced makers, it is difficult to understand who can constitute themselves objectors, or what can be their objections.

Even if these engines had not been found effective, at least it must be admitted that the best and most liberal means had been adopted to procure them; but I am far from asking such an admission. The engines, I think, have proved to be well adapted to the particular task for which they were calculated—namely, high speeds—but circumstances prevent their being beneficially applied to this purpose at present, and they are, therefore, working under great disadvantages. An engine constructed expressly for a high velocity cannot, of course, be well adapted to exert great power at a low speed; neither can it be well adapted for stopping frequently and regaining its speed. But such was not the intention when these engines were made, neither will it be the case when the arrangements on the line are complete; in the meantime, our average rate of travelling is much greater than it was either on the Grand Junction or the Birmingham Railway within the same period of the opening. I have but one serious objection to make to our present engines, and for this, strange as it may seem, I feel that we are mainly indebted to those who have been most loud in their complaints—I refer to the unnecessary weight of the engines. There is nothing in the wide gauge which involves any considerable increased weight in the engine. An engine of the same power and capacity for speed, whether for a 4-feet 8-inch rail, or for a 7-feet rail, will have identically the same boiler, the same fire-box, the same cylinder and piston, and other working gear, the same side frames, and the same wheels; the axles and the cross-framing will alone differ, and upon these alone need there be any increase; but, if these were doubled in weight, the difference upon the whole engine would be immaterial. But the repeated assertion, frequently professing to come from experienced authorities, and repeated until it was supposed to be proved, that the increased gauge must require increased strength and great power, was not without its indirect effect upon the manufacturers. Unnecessary dimensions have been given to many parts, and the weight thereby increased—rather tending, as I believe, to diminish than to add to the strength of the whole. I thought then, and I believe now, that it would have been unwise in this case to have resisted the general opinion, and taken upon myself the responsibility which belonged to the manufacturers; but I need not now hesitate to say that a very considerable reduction may be effected, and that no such unusual precautions are necessary to meet these anticipated strains and resistances—such being, in fact, imaginary. It cannot surprise anybody that, under such circumstances, attention was more occupied in endeavouring to meet these imaginary prejudiced objections, than in boldly taking advantage of the new circumstances, and that a piece of machinery constructed under such disadvantages was not likely to be a fair sample of what might be done. I am happy to say, however, that the result of the trials that have been made has entirely destroyed all credit in these alarmists with the manufacturer, and that we may hope in future to have the benefits of the free exercise of the intelligence and practical knowledge of engine-manufacturers.

The mode of laying the rails is the next point which I shall consider. It may appear strange that I should again in this case disclaim having attempted anything perfectly new; yet regard to truth compels me to do so. I have recommended, in the case of the Great Western, the principle of a continuous bearing of timber under the rail, instead of isolated supports—an old system recently revived, and as such I described it in my Report of January 1836; the result of many hundred miles laid in this manner in America, and of some detached portions of railways in England, was quite sufficient to prove that the system was attended with many advantages; but since we first adopted it these proofs have been multiplied—there need now be no apprehension. There are railways in full work, upon which the experiment has been tried sufficiently to prove beyond doubt, to those willing to be convinced, that a permanent way in continuous bearings of wood may be constructed, in which the motion will be much smoother, the noise less, and consequently—for they are effects produced by the same cause—the wear and tear of the machinery much less. Such a plan is certainly best adapted for high speeds, and this is the system recommended by me and adopted on our road. There are, no doubt, different modes of construction, and that which I have adopted as an improvement upon others may, on the contrary, be attended with disadvantages. For the system I will strenuously contend.

But I should be sorry to enter with any such determined feeling into a discussion of the merits of the particular mode of construction. I would refer to my last Report for the reasons which influenced me, and the objects I had in view in introducing the piling; that part which had been made under my own eye answered fully all my expectations. Here the piles did answer their purpose, and no inconvenience resulted from their use. The difficulties which we have since encountered, the bad state in which the line was for a considerable time, and which is only recently improved, have undoubtedly been aggravated, if not caused, by these piles; but not, as I believe, from a defect in the principle as applied in our case, where the line is mostly in cutting, or on the surface, but from defective execution; for, notwithstanding the determination to allow sufficient time for this most important operation, yet, to make up for previous delays and loss of time, it became necessary at last to force forward the work more rapidly than was at all consistent with due care in the execution; and during the whole of this period I was most unfortunately prevented by a serious accident from even seeing the work almost until the day of opening, when I ought to have personally superintended the whole. I do not mean that the work was neglected by those whose duty it was to supply my place—far from it; but in such a case, a new work cannot be properly directed except under the eye of the master. Following exactly the plan which had succeeded on the first piece completed, several serious faults were committed. A much greater density and firmness of packing is required than was previously supposed; the mode of packing adopted, and the material selected, in the first instance, have proved defective elsewhere; and over a great extent in the line, particularly in the clay cuttings, and where the work was at last most hurried, it has been badly executed. But many parts have stood well from the commencement; others are fast improving; and I have the satisfaction, although a very painful one, of seeing that if, in the first instance, a foundation of coarse gravel had been everywhere well rammed in before the timbers had been laid, and the packing formed upon this, we should, from the outset, have obtained as solid a road as we have now over a great part of the line. What we have been able to effect since the opening of the line has necessarily been a slow, expensive, and laborious operation. We have been compelled to open the ground, and excavate it to a depth of 18 inches under the longitudinal timbers, and this without interrupting the traffic: to remove the whole of the material thus obtained from off the line, and to replace it by coarse ballast; and not having the means of sufficiently consolidating this ballast by ramming while the timber is in its place, the packing has to be repeated once or twice after it has been compressed by the passing of the trains. This new packing, however, does stand, and in a few weeks I expect the line will be in a very different state from that in which it has been, or indeed now is. From what I have described as the result which can now be, and might have been, obtained from the commencement, it will be inferred that I am disposed still to defend the system of piling. I certainly could not abandon it from conviction of its inefficiency, for I see proofs of the contrary; and I feel that under similar circumstances I could now prevent the mischief which has occurred. Upon that portion of the line where the permanent way must next be formed, piling could not be resorted to, the ground being a solid hard chalk for many miles. I had intended, however, recommending the same principle, but in a different form, holding down the longitudinals by small iron rods driven into the chalk; but the same objection could not exist, because the chalk cannot yield under the timbers like clay, or even gravel. But I should wish most anxiously to avoid anything like an obstinate adherence to a plan, if the object which I believe essential can be obtained by other means, particularly when, that plan being my own, I may be somewhat prejudiced in its favour. I find that the system of piling involves considerable expenses in the first construction, and requires perhaps too great a perfection in the whole work, and that if the whole or a part of this cost were expended in increased scantling of timber and weight of metal, that a very solid continuous rail would be formed.

For this as a principle, as for the width of gauge, I am prepared to contend, and to stand or fall by it, believing it to be a most essential improvement, where high speeds are to be obtained. I strongly urge upon you not to hesitate upon these two main points, which, combined with what may be termed the natural advantages of the line, will eventually secure to you a superiority which, under other circumstances, cannot be obtained.

As regards the expense of forming the permanent way on this principle, I am quite prepared to maintain what I have on a former occasion advanced: that even on the system which we have adopted between London and Maidenhead, the total cost does not materially exceed that of a well-constructed line with stone blocks. I did not make in the outset an exact estimate of the cost of either mode; I was unable to obtain the cost which has actually been incurred on other lines; but a comparative estimate was made, and the result of that comparison led me to state that the one might exceed the other by 500l. a mile. The actual cost of our permanent way appears, by the detailed account which has been made out, to have been above 9,000l., including expenses of under-draining and forming the surfaces which cannot be included in the cost given in other cases, because that drainage (although I believe generally forming part of the plan) is not yet constructed. This sum includes the sidings at the stations, switches, joints, and other contingencies, and also the expenses incurred during the first month of working the line, and which, as I have before stated, consisted in removing and replacing work which had been improperly executed. These items will make a considerable reduction; and besides these, larger reductions may be effected in parts of the work which were new, and, from the circumstances naturally attending a first attempt, were not so economically conducted as they might be, or indeed, as they were towards the close of the works, when the different parts were let by contract. Taking the prices at which the work was latterly actually executed, 8,000l. per mile would be a liberal allowance for our future proceeding, even adopting the same system; and with a modified system, such as that suggested of simple longitudinal bearers of large scantling, and a rail of fifty-four pounds per yard, at the present high price of iron, the cost, calculated upon our actual past expenditure, would not exceed 7,400l. per mile. This, I am aware, is a larger sum than that which has usually been assumed as the cost of the permanent way. I cannot prove that others have cost more, or even so much as this, as I have nothing but the published accounts to refer to; but this I can state, and prove if necessary, that rails and blocks, such as are now being adopted on the Manchester and Liverpool Railway, would upon our line cost at least as much.

The prime cost of rails and chairs delivered on the line would alone amount to half the money; and nothing is, perhaps, more certain than that the experience of other lines within the last two or three years has proved that this part of the construction of a railway is unavoidably much more expensive than was ever calculated for at the time our estimates were made.

I am, gentlemen, your obedient servant,
(Signed)        I. K. BRUNEL.

APPENDIX II.

(See Chapter IX. on the ‘Great Britain’ Steam-Ship, p. 254.)

Report to the Directors of the Great Western Steam-Ship Company.

October 1840.

GENTLEMEN,—I have now the pleasure to lay before you the result of the different experiments which I have made, and of the best consideration I have been enabled to give to the subject of the screw propeller.

The observations which I have to make are naturally divided under two principal heads, namely: first, the simple question of the applicability and efficiency of the screw considered merely as a means of propelling a vessel, compared with the ordinary paddlewheel; and, secondly, the general advantages or disadvantages attending its use.

The consideration of the comparative efficiency of the screw as a means of propelling, of course embraces the whole question, not merely of the effect produced, but also that of the proportionate power absorbed in producing that effect.

With respect to the mere effect of a screw, the performance of the ‘Archimedes’ has proved, in a satisfactory and undeniable manner, that a screw acting against the water with a surface even much smaller than that offered by the paddle-boards of a well-proportioned paddlewheel, will propel the ship at a very fair speed, but at what expense of power this effect has been produced is not so evident.

I shall first examine into the principal cause of what amounts practically to a loss of power, and which is common in a greater or less degree to all modes of propelling a vessel by exerting a pressure against the water as against a fixed point.

The resistance, whether to the surface of a screw, or of a paddle-board, or of the blade of an oar, or any other propelling body, offered by the fluid against which it acts, is of course not perfect, and there is a certain amount of yielding, commonly called the slip, of the paddlewheel; the amount thus slipped causes a considerable waste of power, inasmuch as the full power of the engine is expended through the entire space passed over by the paddles or other propelling surface, while the useful effect produced is only equal to the same power expended over the space through which the vessel passes: this loss frequently amounts to one-quarter, and even one-third, of the whole power employed. To investigate theoretically the amount of slip due to any given form and quantity of surface, involves much more complicated calculations than have generally been applied, and would indeed require data which we hardly possess; but fortunately we have had the means of making experiments, the results of which enable us to determine the comparative slip of the paddle and of the screw, with sufficient accuracy for all practical purposes.

The screw in use on board the ‘Archimedes’ is 5 feet 9 inches diameter, with a pitch of 8 feet—that is to say, in making one revolution the thread of the screw advances 8 feet; the area of the screw, considered as a disc of the same diameter, or the extent of the surface of water which is acted upon in the direction of the axis of the vessel, is therefore about 26 feet, without deducting the section of the shaft-bearing, &c. The midship section of the vessel when I experimented upon her was, according to Mr. Patterson’s estimate, 122 feet; the ratio of the resisting surface to the midship section being therefore as 1 to 4·7, which is a small proportion; and the form of the vessel is by no means peculiarly good as a steamboat. This proportion of propelling surface to midship section is much smaller—that is, the area of the screw is much less in proportion to the size of the vessel than is the area of paddle-boards immersed in steamboats generally.

The average paddle-board immersed and really effective is rather difficult to estimate, as allowances must be made for the disturbance of the water, when the wheel is in motion; but this average in the ‘Great Western’ measured perpendicularly—that is, allowing for the obliquity of the paddle—cannot be less than 180 to 200 feet, say only 180, while the midship section averages about 462 feet; the surface of paddle is therefore about 1/2·56 of the midship section.

I will now give the comparative effects of these different propelling surfaces in these two cases.

I have made very accurate experiments upon the comparative rate of the ‘Archimedes,’ and of the space passed through by the screw, and was enabled to determine this ratio with great certainty.

The average of a number of trials gave the following results:

Rate of ship, 50,867 feet per hour, or about 8⅓ knots.

Space passed through by screw due to the number of revolutions, 65,685 feet.

The average rate of vessel being to that of screw therefore as 1 to 1·2913.

In the performances of the ‘Great Western,’ upon an average of 20 voyages the ratio has been as 1 to 1·2997; but, separating from these 20 such voyages as were unusually short or long, and taking only such as, occupying 14, 15, or 16 days, may be considered as giving a fair average of the speed of the ship when not adversely affected by the wind or heavy seas, the average of these 13 voyages give 1 to 1·283; and leaving out again those of 16 days, and taking only 8 voyages of 14 and 15 days, the average gives a ratio of 1 to 1·27187.

The last three, however, were short passages and homeward, when the currents and winds have been in favour, and consequently we may safely say that the ratio must be above 1 to 1·239; and after making every allowance for the effect of swell and other impediments (the experiments upon the ‘Archimedes’ being made in smooth water), the average of the 8 (5 of which were homeward voyages with favourable current and wind and the vessel in good trim), giving a ratio of 1 to 1·27, may be taken as a fair average.

The comparison between the ‘Archimedes’ and the ‘Great Western’ will therefore stand thus—

Showing an amount of slip in the ‘Great Western’ very nearly equal to that of the ‘Archimedes,’ while the ratio of the propelling surface to the midship section in the case of the screw is little more than half that of the paddle-boards in the ‘Great Western.’

In taking the average of the eight voyages of the ‘Great Western’ with favourable winds as I have done, I believe I have made full allowance for the different circumstances of smooth water and sea; but there is ample room in the above comparison to make even greater allowance for these circumstances, and still to leave a result which would prove that with similar areas the screw would meet with at least equal, if not a greater resistance, and consequently will slip as little or less than the ordinary paddle-board.

I subjoin a table also, taken from a well-known work on the steam-engine (Tredgold’s), of the slip of a number of vessels, of which in every case the surface of paddle immersed is far greater in proportion to the midship section than that of the screw in the ‘Archimedes.’

Rate of Paddle, that of Ship being 1.

This list shows that the result in the ‘Great Western,’ with which ship I have made the comparison, is in itself a favourable one, and that compared with many others the ‘Archimedes’ would stand much better.

This apparent superiority of the screw over the paddle as regards the resistance offered to it by the water may at first appear startling, but there is a great mistake committed in assuming that the action of the screw is a very oblique action, tending rather to drive the water laterally with a rotatory motion than to push it steadily backwards.

Having witnessed and carefully observed the degree and the nature of the disturbance in the water caused by the screw, and comparing this with the violent displacement of the water by the action of paddle-boards, even under the most favourable circumstances, I no longer feel surprised.

The mass of water pushed backwards by the action of the screw appears to be very large, spreading from the screw probably in the form of an inverted cone, but there is little or no appearance of any rotatory motion, and the surface of the water is not put into rapid motion as in the case of the paddlewheel, which may be observed to impart a considerable velocity to the water, probably for a small depth only, but over a very large space.

As regards the oblique action also, a great mistake appears to have been generally made, and very naturally made, by most persons when first considering the working of the screw. It is generally assumed that the inclined plane formed by the thread of the screw strikes the particles of water at that angle and with the velocity of the revolution of the screw, but it is forgotten that the screw is moving forward with the ship, and therefore that the angle at which the water is struck by the plane is diminished by all that much that the ship with the screw advances—indeed, it is evident that if the ship advanced the whole amount of the pitch of the screw, the screw, oblique as it appears, and rapidly as it revolves, would not strike the water at all, but simply glide through.

The angle at which any given part of the screw does in fact strike the water is only equal to the difference between the angle to which that part of the screw is formed and the angle or direction in which it moves by the compound motion of the revolution of the screw and of the forward motion of the ship and screw; and, contrary to one’s hastily imbibed notions of the action of the screw, this angle at which the plane of the screw is driven against the particles of water, is in such a screw as that of the ‘Archimedes’ very nearly equal over the greater portion of the surface, diminishing to nothing at the centre; and the motion imparted to the water, although perpendicular to the plane of the screw in point of direction, is small in extent or velocity, being also nearly the same over the whole surface of the screw, except close to the centre, where it is infinitely small.

In the ‘Archimedes’ screw, which appears to the eye so oblique, and the centre part of which would appear to act flat against the water, only causing it to revolve, the outer circumference being 18 feet and the slip 1 foot 8 inches, the angle at which this outer edge acts upon the water is only one in 11½.

The total amount of motion imparted to the water at right angles to the plane of the screw by one entire revolution even at the outer edge is not quite equal to the slip, being only 1·67 foot. The rotatory motion is still less, the total distance to which any particle of water is displaced laterally, or at right angles to the axis of the ship, by one entire revolution of the screw being at the outer edge only 0·69 foot, and the maximum distance being in any screw only equal to half the slip, and occurring at that part of the screw where the circumference is equal to the advance of the ship due to one revolution. This maximum of lateral motion is 0·9 foot, and takes place at 0·99 foot, or about 1 foot from the centre. In this mode of considering the direction at which the particles of water are acted upon by the plate of the screw I have taken no notice of the effect of the friction upon the surface of the screw, which, causing to be carried with it a film of water, will modify more or less according to the degree of smoothness of the surface the effect of the screw upon the water; and towards the centre this friction, however smooth the surface may be made, will gradually become equal to, and at last greater than, the propelling effect of that part of the screw; but this defect applies only to a very small portion of the whole area of the screw, and the absence of any very violent impulse to the water in a direction approaching to a right angle with the axis of the vessel, and which has always been assumed as an unavoidable evil in the screw, will account for the absence I have observed upon of any apparent rotatory motion.

I would not pretend, however, to advance these circumstances which I have observed, or these reasonings, as arguments whereon to found an opinion of the action of the screw, the facts as proved by the experiments are what I rely upon; but it is satisfactory to be able to account for the results by circumstances actually observed, and the reasons which suggest themselves.

The effect of a propelling surface in the form of a screw, and moving at a certain velocity, as compared with an equal surface moving at the same velocity but applied in the shape of paddle-boards, having been ascertained, it remains to determine the comparative power required to give motion to that surface.

The difficulty of determining this with any degree of accuracy from any experiments which we could make on board the ‘Archimedes’ was very great, but considering such results as I could obtain in conjunction with experiments which I have since made in our own works, and with the results upon steamboats recorded by others, and of those of experiments made by Colonel Beaufoy on the resistance of bodies in water, I think we may arrive at approximate conclusions sufficiently accurate for our purpose, and which may safely be relied upon.

In the case of the ‘Archimedes’ the engines were certainly not effective well-working engines, the proportions of the gearing or wheel-work between the engine and the screw was bad—such that the engine could not attain its proper speed—the friction of the gearing (which, whether it be a source of resistance necessarily attending the use of the screw or not, I shall consider afterwards) was very great, and the surface of the screw itself, which I had an opportunity of examining out of water, was so rough as necessarily to create very much more friction than would be caused by a tolerably smooth metallic surface. With all these sources of resistance, and under these unfavourable circumstances, the power calculated for the effective pressure on the piston and without deduction for friction or other causes, which, for the sake of distinction hereafter, I shall call the gross power, was about 145 horses, the speed of the vessel being about 8⅓ knots per hour, as actually measured by the land, and full 9 knots as measured with great care by heaving the common log, the midship section being, as before stated, 122 feet, and the lines of the vessel not so good as those of fast boats; comparing this with the gross power of the ‘Great Western’ engines when propelling that vessel at the same velocity, with the advantage of better lines and the other advantages arising from greater dimensions, there does not appear any such discrepancy as to indicate any loss of power by the use of the screw in the ‘Archimedes’; on the contrary, the power expended in the ‘Great Western’ is actually as great as that in the ‘Archimedes,’ as compared with their relative midship sections—and if any great allowance is to be made for the circumstances which I have referred to of larger dimensions and better lines, there would appear to be actually less power expended in proportion to the dimensions and form of the ‘Archimedes’ than in the ‘Great Western.’

The results obtained with the ‘Great Western,’ which as regards speed are similar to those of the ‘Archimedes,’ are necessarily taken from experiments made when she was rather deep, and the speed thereby reduced to 7·9 knots; but I have compared these with results reduced by calculations from experiments at higher speeds, and I find them agree satisfactorily—indeed, at the draft and consequent immersion of paddles when in this state, I consider the ‘Great Western’ as very nearly at her best as regards economy of power and effect produced. I should observe that the particular experiments from which the following calculations are deduced were made with the ‘Great Western’ in smooth water in the Severn. I have added also some calculations deduced from data given by Tredgold as to the performance of the ‘Ruby,’ a good boat with immense surface of paddle-board.

The comparison stands thus:

The speed being the same, viz., 7·9 knots, the power expended is as nearly as possible the same in the three, and equal to one horse-power gross to one foot of midship section; while the relative propelling surface in the ‘Archimedes’ is equal to only half that of the ‘Great Western,’ and one-fifth that of the ‘Ruby.’ This gross horse-power, it will be observed, is about equal to one-half a nominal horse-power.

I have made several comparisons with recorded observations made on board the ‘Great Western’ at different times, and with experiments made in other vessels, and I find the same result; in estimating the powers used more particularly in some comparisons with the ‘Great Western,’ I have taken the mean pressure as ascertained on both sides of the piston, while in the ‘Archimedes’ I only obtained that on the top of the piston, which appears generally to be the best, and consequently the estimate is made unfavourably to the ‘Archimedes.’

Such general results are all that I could obtain from the experiments on board the ‘Archimedes,’ but since that time I have made some experiments upon the friction of a plate of metal in water, and have compared these results with the experiments of Colonel Beaufoy, and the conclusion I have come to is that the power absorbed by friction in a well-made screw, apart from all question of the means adopted for working it, would not be such as to interfere with its beneficial application.

The resistance created by the screw itself arises principally from two sources—the resistance to the cutting edge and the tail-edge, and the friction of the surface in contact with the water. The amount of the first may of course be reduced to an unlimited extent by having a fine edge, and practically such edge ought to be much finer than that of the screw of the ‘Archimedes.’

The friction upon the surface will of course materially depend upon the smoothness of that surface, and in the ‘Archimedes’ it was very rough, the iron being corroded at many places, with exfoliations and small holes—the corrosion arising apparently from the galvanic effect produced by the iron and the ship’s copper.

The great number of revolutions required in the screw as compared with those of the paddlewheel, leads a person to assume, without much consideration, that a very high velocity is given to the cutting edges and to the surface of the screw, and consequently that great friction must be produced—this velocity is not, however, nearly so great as it at first appears.

In the present screw of the ‘Archimedes’ the velocity of the extreme point, following its oblique or spiral course, is only about three times that of the vessel, while the average velocity of either of these knife edges or of the surface is not twice that of the vessel.

Now without determining what the actual amount of these resistances may be, we can at once satisfy ourselves that it cannot be very considerable, by comparing it (which we have the means of doing) with the resistance caused by the cutwater and any given portion of the ship’s bottom. The resistance of a knife-edge will be about as the square of the velocity, and if we assume the surface friction to increase in the ratio determined by Colonel Beaufoy—namely, at the 1·75th power, or as the 4th root of the 7th power of the velocity—then the resistance of the knife-edge will be equal to the resistance of a similar edge of about five and a-half times the length of the diameter of the screw moving at the same rate as the vessel, and the surface friction will be equal to that of a piece of the ship’s bottom about six and five-eighth times the area of the screw—or, in the case of the ‘Archimedes,’ the additional power absorbed by the friction of the screw would be about equal to that absorbed by the friction of little more than twice the space of the dead wood which had been cut out to receive the screw—while the knife-edges would be about equivalent to three knife-edges immersed in the water, of the same depth as the ship’s stem.

The actual amount of power absorbed in driving the ‘Archimedes’ screw was probably about twenty horse-power gross, or from ten to twelve nominal horse-power; but I have no doubt that a screw of similar diameter and in good condition would not absorb half that power: and this amount may be still further, and very much reduced, by increasing the relative size of the screw to that of the ship, and thereby reducing the slip, and proportionately reducing the number of revolutions required.

The great extent to which this is capable of being carried will at once be seen when I state that if the ship’s progress were made to be 7 feet instead of 6 feet to each revolution of the screw, which a very slight increase of diameter and pitch of screw would effect, the power absorbed in driving the screw would be diminished in the ratio of the 6²⁴ √6⁷ to 7²⁴ √7⁷—that is, as 6¹⁵/₄ to 7¹⁵/₄, or about as 3 to 2.

I must repeat here the observation I have previously made, and remind you that these calculations are not introduced as proving, but merely as explaining, that which appears to me proved by the general results of the experiments on the ‘Archimedes’—namely, that the effect produced was, considering all the circumstances, fully proportionate to the power expended, while the experiments and calculations which I have since made also satisfy me that these results may be very much improved upon.

As regards the first of the two heads under which I stated that I proposed to consider the subject, namely, the mere efficiency of the screw as a propeller, I think but one conclusion can be drawn from the results of the experiments quoted, and that is, that as compared with the ordinary paddlewheel of sea-going steamers, the screw is, both as regards the effect produced, and the proportionate power required to obtain that effect, an efficient propeller.

I limit the comparison to the ordinary paddlewheels of sea-going steamers, first, because those are the circumstances which we have alone to consider; and, secondly, because it is possible, by increasing the diameter and breadth of the paddles, which, for the attainment of an adequate object is practicable to any extent in a mere river boat, to render the action of the common paddle all but perfect, and probably more effective than any other propeller.

In considering the advantages and disadvantages likely to attend the use of the screw propeller, I will, commencing with the latter, consider such objections as have been advanced by others, as well as those which may have occurred to myself.

The only objections, however, which I think worth consideration are:—

First. The necessity of a peculiar form of vessel.

Secondly. The situation of the screw under water, and consequently to a certain extent unseen and inaccessible, and the liability to injury from its position from grounding or in other ways.

Thirdly. The probability of its being lifted out of water when the ship pitched deep.

Fourthly. The difficulty of getting up the required number of revolutions, and the great defects of the mode employed in the ‘Archimedes,’ and the shaking caused by the machinery.

As regards the form of vessel, undoubtedly a shallow boat, intended for shallow waters, would be very unfit for the application of the screw, which would probably require a greater depth of water than the whole draft of the vessel; but I see no defect or difficulty of this description in the vessel now under consideration, nor can I anticipate any in any vessel this Company is likely to be interested in; a clean run is the most essential condition, and I should suppose no ship was ever built in which this principle of form was carried to a greater extent than in our new iron ship. Her present form I believe to be excellent for the screw, and with a very slight dropping of the keel towards the stern, which can easily be done now without any expense, assisted by the different trim, which, as I shall presently show, will be effected by the use of the screw, the required draft of water will be attained.

It may, perhaps, be as well to mention here, that the diameter of the screw, if in the same ratio to the midship section as in the ‘Archimedes,’ would be only 12 feet 3 inches, my friend Captain Claxton having made a mistake upon this point in calculating it at 16 feet, and that if increased only to 14 feet 4 inches, the diminution referred to in a former part of my Report of one-third in the power lost in working the screw would be effected; considering the speed we wish to attain, probably 15 feet 6 inches would be a good diameter. Upon the whole I think the vessel is as well fitted for a screw as she is for paddles, and much better adapted for either than the ‘Archimedes;’ but if originally intended for a screw, possibly some trifling modification in the form and construction, principally of the keel near the stern, might have been introduced which would have rendered the whole a more perfect job than she would now be if altered—but the absence of this would in no way lessen the efficiency of the screw, and I cannot think that any alteration we might now be obliged to make would exceed in cost the sum of 200l.

Secondly, the inaccessibility of the screw and liability to damage; this appears to me the objection most plausible, but I cannot say that I attach much weight to it, particularly in the case of a vessel intended for long voyages and across the ocean. During the whole passage in deep water I consider the screw far less exposed to injury than a paddlewheel, and that the chances of injury are so remote that even if it were quite inaccessible it would still be altogether safer than paddles, which are so much exposed; but it is by no means inaccessible, the screw may be rendered stationary at any time or during any weather, when it would be barely safe to stop the engines with common paddles, and when it would be very difficult to do anything to the paddles even if the engines were stopped, while the whole of the screw, bearings, &c., may easily be examined and felt from above, and, if necessary, men sent down with common diving jackets and hoods to replace bearings, or attach tackle to move the screw, or clear away any obstacle entangled in it. When in port I still think the chances of injury very remote; an inspection of our model will satisfy you that from the form and size of her midship section the vessel cannot lay in any position in which the screw would touch the ground, while at that time the whole screw may be very easily examined and replaced without any necessity for going into dock.

Thirdly, the probability of its being lifted out of water when the ship pitches deep.

This appears at first to be a very natural and an unavoidable objection, but the result of observations proves that the motion of vessels, of steamers at least, is not such as to cause the apprehended difficulty. Among the observations made on board the ‘Great Western’ steam-ship by Mr. Berkeley Claxton, under my direction, were measurements of the angles of rolling and pitching, and from these it was evident that the vessel never pitches to so great an angle as that to which she rises; such a result might indeed have been anticipated by considering the form of the vessel forward and aft, and the circumstance that a steamer is almost invariably meeting or passing the seas, or, if overtaken by them, is still going at a good rate, which reduces the relative speed of the sea; consequently, although the vessel may be frequently thrown up very violently forward, yet the stern, which has no displacement under water, settles down quietly and heavily upon the surface; or, considering it in another way, the variation of displacement at the stern is very rapid, falling off almost to nothing at a few feet below the water-line, and spreading out to a great extent at a few feet above, whilst forward the difference of displacement is comparatively small, the centre of motion, therefore, is thrown very far aft, and while the bows, which are also opposed to the first shock, are thrown alternately high out of water or plunged deeply into it, the stern floats nearly steady, the vessel resting on its broad counter nearly as the centre of motion: whatever may be the explanation such is the operation, not only as measured by instruments, but more particularly as observed since, practically.

In the ‘Great Western’ the whole cutwater and, it is said, a considerable length of keel, is frequently seen out of water from the bowsprit, while astern it is very doubtful whether more than half the stern part was ever seen; marks have been made by my direction on the rudder to observe this; as yet the 9-foot mark is the lowest seen, and this occurring rarely, and for very short intervals.

In the ‘Archimedes,’ during a voyage performed in her by Mr. Guppy from Bristol to Liverpool, and during which they were exposed on more than one occasion to violent pitching, the screw (which can be watched from the deck) never was uncovered; and Mr. Smith and others on board the ‘Archimedes,’ whose whole conduct was such as to inspire unusual confidence in all information obtained from them, assured me that such was always the case.

In the voyage to Oporto and back, in which I sent Mr. Berkeley Claxton, he made the same observation; these facts, in conjunction with previous and subsequent observations on board the ‘Great Western,’ convince me that nothing is to be feared on this head; but even if the screw were occasionally to be partly exposed, I know of no evil consequences likely to ensue, as I shall clearly point out when referring to the advantages of this propeller over the common paddle.

Fourthly, the difficulty of getting up the required number of revolutions, and the great defects of the mode employed in the ‘Archimedes.’

Upon this point certainly the ‘Archimedes’ offers but a miserable example, and the result is almost enough to prejudice the mind of any person against the whole scheme; the proportions of the gearing, as I have before stated, are so bad that the engines appear, even to the eye, to labour ineffectually to get up their speed. The required speed of the screw is not nearly attained, while the noise and tremor caused by the machinery is such as to render the vessel uninhabitable, and perfectly unfit for passengers, I should almost say for a crew. I never attached much importance to these circumstances, because I felt convinced that such a mere mechanical difficulty would by some means be overcome, if, as I confess I did not then at all anticipate, the screw itself should prove efficient.

The most simple and effectual means of overcoming all objections on these heads always appeared to me to be by the use of straps instead of gearing; and all my experience, and I have seen a great deal of the working of machinery by straps and ropes in the numerous works executed by my father, led me to the conclusion that there existed no difficulty whatever in sending the necessary power through a rope or hemp strap, but I was hardly prepared to find the result so entirely satisfactory as it has proved to be.

In an experiment made in your works at the yard, I have sent through two small whale lines, a power equal to about one-thirtieth of that which would be required in the strap if used in the new ship, and this without any slip or straining of the rope which would be injurious in practice, and without any peculiar means of ensuring adhesion to the drums; so that we have ascertained beyond doubt that sixty such whale lines upon a drum of only 4 feet 3 inches diameter is adequate to our wants, but if we suppose seventy lines of superior manufacture to that used in the experiments with a perfect mode of tightening and working upon a drum of 6 feet diameter, all of which can easily be had, it will ensure the perfect and easy working of a mode of obtaining the required number of revolutions of the screw without noise or tremor. The strap in question would be only about 3 feet or 3 feet 3 inches broad, easily replaced piecemeal, and even, if necessary, without stopping the engines.

All the difficulties enumerated under the fifth head may be considered as entirely overcome, or rather as ceasing to exist; and so far from the working of the screw involving difficulties and unavoidable friction, noise, or tremor, it may be worked with unquestionable and perfect facility, and as compared even with the best-made paddles in smooth water, the whole machine will be noiseless.

It is almost unnecessary that I should say that the screw, apart from the gearing in use on board the ‘Archimedes,’ cannot and does not produce the slightest tremor or noise—it was with some difficulty, and at least only by attentively listening, that the revolutions of the screw could be counted, even when disconnected and free from the noise of the engine or gearing and the vessel being towed, and then only from some defect in the bearings or the shaft of the screw causing a slight beat.

In thus answering the objections supposed to have been urged against the use of the screw, I may probably have appeared to see everything in a favourable light; unhesitatingly I admit that it is so, and that both formerly when I was completely sceptical as to the mere efficiency of the screw as a propeller, and since my doubts on that head have been removed, I always felt that upon all other points the screw possessed every superiority that could be desired over a common paddlewheel for a sea-going vessel.

I shall now proceed to point out the principal advantages peculiar to the use of the screw; they are—

First. A considerable saving of weight, and that principally top weight.

Secondly. The admitting of a better and simpler form of vessel, having greater stiffness with the same quantity of material, and offering less resistance to head wind and seas, and affording more available space within.

Thirdly. The operation of the screw being unaffected by the trim or the rolling of the vessel, and allowing of the free use of sails, with the capability of entirely disconnecting the screw or of varying the multiplying motion so as to adapt the power of the engine to the circumstance either of strong adverse winds or scudding.

Fourthly. Perfect regularity of motion and freedom from the possibility of violent shocks to the engines.

Fifthly. The singularly increased power of steering given to the vessel—and

Sixthly. The great reduction in the breadth of beam.

I have gone into some detail in calculating the weights of the parts which are not common to the two systems, and I find that the difference, or actual diminution in weight in favour of the screw as applied to our new ship, is upwards of ninety-five tons; but that a much greater weight even than this is transposed from the top of the ship to the bottom—no less a mass than one hundred and sixty tons is removed from the level of the paddle-shaft or from about 10 feet above the water-line, and replaced by sixty-five tons at about 7 feet below the water-line; not only is buoyancy, and consequently proportionate space for cargo, gained to the extent of the difference, but the relief to the labouring of the vessel in bad weather from the change of position must be immense. If the reverse were under consideration, if in a vessel fitted for sea, however stiff in trim or form, it were suggested to remove sixty-five tons of her ballast, and to place one hundred and sixty tons upon her deck, and thus navigate her across the Atlantic in all weathers, it would probably be considered, not merely as highly dangerous, but as actually impossible. Although such an opinion as that it would be impracticable we now know would be incorrect, yet the extent of the beneficial change is much more striking when considered in this way. As regards the trim of the ship, about one hundred and forty-five tons would be removed from nearly the centre of flotation, and the balance of fifty tons added and distributed over the after part, principally quite aft.

I have not calculated the exact effect of this upon her trim; it would only bring her down by the stern, and this is a defect which there seems, as we too well know, never any difficulty in remedying.

Secondly. The simplifying and improving the form of the ship—both as regards strength and mass exposed to the wind and sea.

The necessity of contracting the midships of a steamer, and making her completely wall-sided, and forming a sort of recess to receive the paddles, interferes considerably with the framing of the ship. In a wooden ship of the size of our new one the whole beam of the ship would have to be contracted in order to carry the planking through in a direct line and obtain the requisite fore and aft tie as has been done in the ‘Great Western’; in the new ship the almost infinite resources afforded by the material used, enabled us to expand the sides and obtain breadth of beam for cabin room, both before and abaft the paddles, and contract the sides at the paddles as seen upon the plan; but in order to strengthen this part, so evidently weak by form, much contrivance and much material was required. By dispensing with paddles, the best form of ship is left free to be adopted; perfect lines may be preserved, more equal strength obtained with increased space, and the whole mass of paddle-boxes and their accompanying sponsons and deck-houses swept away, and the resistance of these huge wings to head winds or seas entirely avoided.

The space gained by avoiding the contraction is calculated by Mr. Patterson to amount to two hundred tons measurement; this would be entirely gained, and would not even involve increased dues or tolls, as it would be added to the engine-room; it would therefore perhaps counterbalance any loss of room caused by the shaft conveying the movement from the engine to the screw, but I believe this nominal increase at one part would not be so great, while in fact the ship would really be more compact, and, though to a very small extent, a smaller ship, as the sponsons would be removed.

The third point of advantage named is perhaps the most important. With paddles, the action is materially affected by the depth of immersion; when the vessel is deep, and consequently the paddles deep, their action is impeded, a greater part of the power of the engine is absorbed in driving the paddle, the speed of the engine is reduced and the effect diminished; when too light also the paddles do not take sufficient hold of the water, the amount of slip increases and power is wasted; in rolling the same effects are produced, and thus at those times when the greatest effect is required, namely, with deep immersion or in bad weather to overcome the increased resistance offered to the vessel, the propelling power is least effective, and Captain Hoskins actually estimates this loss as occasionally equal to two-thirds the whole power.

The bad effects of one paddle being immersed too deeply, and the other not sufficiently, also prevents the free use of the sails; and it must often occur that the impediment thus offered to the working of the paddles more than counterbalances the good effects of a tolerably fair wind. With the screw the effect is constant, at least unaffected by the position or motion of the ship, whether deep or light the screw acts nearly the same, and as to rolling or heeling over, the screw would work equally well (as long as it be immersed) if the vessel were on her beam-ends or bottom upwards.

The screw therefore leaves the ship free to be used as a sailing-vessel to any extent that other circumstances will admit of, and as long as the sails draw there can generally be no doubt that the wind is assisting the ship. The screw may also be thrown in and out of gear at any time and during any weather, either in case of accident to the engines, or in the event of her scudding before a gale of wind, when the engine would be useless; this last, however, I do not consider a probable occurrence, particularly if another arrangement of which the screw is susceptible be taken advantage of.

If the motion be conveyed by a strap, as I have recommended, there is no difficulty in having two or even three drums on the screw-shaft of different diameters, and thus when the resistance to the ship is very much increased by strong head winds, deep draught, and other causes, to use the slow motion and obtain an increased propelling force, or when, on the contrary, the vessel is running before the wind to use the quick motion—by which, in both cases, a great increase of speed would be attained.

This is in fact obtaining at once and by simple means all those advantages, and to a much fuller extent, which are aimed at in the reefing-paddles.

Fourthly, great regularity of motion is naturally consequent upon the screw being unaffected by the rolling of the ship, and upon its being immersed and not exposed therefore to blows from the sea, and except in the case of its being lifted out of water, the resistance is perfectly uniform and perfectly smooth.

An engine could not have a work less capable of causing any jar or shock as to the effect; even if lifted partially out of water the variation of resistance would be as easy or soft, to use a mechanical term, as possible, while the extent of the variation could never approach to that to which paddles continually expose an engine. A heavy sea or a deep plunge will occasionally bring the engines nearly to a stand; while at other moments, if the engineers are to be believed, the paddles are left free and the engines run away at a fearful speed. I am inclined to think this description of the effects somewhat exaggerated; but certainly the screw cannot by possibility be exposed to the same variations as the paddles—it cannot be stopped by the action of the sea, indeed, being wholly immersed, the resistance cannot be increased at all, while under no circumstances can it be relieved to the extent to which paddles are, which may both on some rare occasions be quite out of the water; and therefore whether the resistance of the screw is so constant as I believe it to be, or not, yet as compared with that offered by paddles, it is certainly all but perfectly constant.

Fifthly, the effect upon the steerage is singular, the mass of water put into motion by the thrust of the screw is thrown directly upon the rudder, and the consequence is not only that when the ship is going at any given rate, the rudder is passing through the water at a greater rate, and consequently is more sensible, and acts more powerfully upon the ship; but even when the ship has no way, but the screw is at work, the rudder is acted upon by water moving perhaps at two or three knots per hour, and the vessel is still under command—this must be a most important power to possess in a ship, and must materially diminish many of the greatest dangers arising from a strong head wind and sea, and at the same time and under the same circumstances must increase the speed by improving the steerage.

And lastly, her diminished breadth of beam. Important as this alteration would be to any vessel, it is peculiarly so as connected with Bristol; the total breadth, including paddle-boxes, would be at least 78 feet; with the screw, and taking all the increased beam that might be convenient, it would be under 50—very nearly 30 feet of difference. One of the principal objections to her coming up the river would be removed, and the dock gates might easily be made to receive her.[201]

There are many other points upon which comparisons may be drawn, but I am not aware that any very important differences exist.

As regards first cost I believe there would be little difference—if any, it would be in favour of the screw; as a reduction of ninety-five tons of iron can hardly fail to cause some saving, although some portion of the substituted machinery may be more costly per ton.

As regards wear and tear I can have no doubt that some considerable saving would be effected; the paddles are a constant source of trouble and expense, and seem never to be capable of being kept in good repair; indeed, they are huge and comparatively light frameworks subjected to extraordinary and constantly repeated shocks, each arm receiving direct about 260,000 very sharp blows per voyage, independently of the more violent shocks from heavy seas, while the screw can be subjected to no such constant source of mischief.

From all that I have said it must be evident to you, gentlemen, that my opinion is strong and decided in favour of the advantage of employing the screw in the new ship; it certainly is so. I am fully aware of the responsibility I take upon myself by giving this advice, I am also fully sensible of the large amount we have at stake, and I have not forgotten the nature and tone of the observations which have on more occasions than one been so freely made by individuals upon the course we have hitherto pursued; although, and I have pleasure in referring to the fact, this course has in every instance where results have been obtained proved successful; but my conviction of the wisdom, I may almost say the necessity, of our adopting the improvement I now recommend is too strong, and I feel it is too well founded, for me to hesitate or to shrink from the responsibility.

I think I have hardly advanced an opinion which I have not supported, and in most cases preceded, by a statement of facts, leaving no doubt as to the correctness and safety of relying on these opinions; still it would be too much to hope that my mode of laying before you these facts which I have collected and the opinions I have formed could produce as strong a conviction in your minds as the consideration of them has in my own; but if you bear in mind that the actual results of the fair and full trial of the ‘Archimedes’ for several months has completely established the fact of the efficiency of the screw as a propeller; that the experiments I have made, as well as the general and apparent results of her working, have equally satisfactorily explained the fact of the power required being no greater in proportion to the effect produced than in the ‘Great Western’ steam-ship, and many other good steamboats; and that these results are satisfactorily explained by theory, you cannot fail to draw the same conclusion that I have done as to the general question of at least the equal efficiency of the screw.

As to the comparisons I have drawn between the general and what I may call the indirect advantages of the one mode of propelling over the other, they seem to me so evident that I am disposed to apologise to you for having occupied your time in pointing them out, and we have the satisfaction of knowing that they are now very generally admitted, particularly by practical men.

In conclusion, I must observe that much more detailed information and recorded results than appear on the face of this Report have been required to enable me to form correct comparisons, and to reduce to calculation and to actual figures and amounts many results observed; and that it would have been impossible for me to have given you such clear and positive facts on many most important points without the very detailed observations made and recorded by Mr. Berkeley Claxton in the several voyages of the ‘Great Western,’ and also in one on board the ‘Archimedes.’

The information obtained from these logs has been, and may still be, of the greatest importance to us in our future working, and I have much pleasure in adding that the manner in which my directions were carried out was highly creditable to Mr. Berkeley Claxton, who, I think, has conferred a great benefit on the Company by his labours. I have to express also my thanks to my friends Captain Claxton and Mr. Guppy for their assistance in the various experiments which have been made, and in working out the results.

I am, Gentlemen,
Yours very faithfully,
(Signed) I. K. BRUNEL.

INDEX

A, B, C, D, E, F, G, H, I, K, L, M, N, O, P, Q, R, S, T, U, V, W.

‘Adelaide’ steam-ship, built under Mr. Brunel’s directions, 290
Admiralty, Mr. Brunel’s connection with the, respecting the screw propeller, 283.
Communication with the, on floating gun-carriage, 459
Airy, G. B., Astronomer Royal, member of the Gauge Commission, 117.
Correspondence with Mr. Brunel on astronomical observations for the ‘Great Eastern,’ 321
Angarrack, viaduct at, 189
‘Archimedes’ steamer, the screw propeller used in the, 253.
Experiments made in the, 254
Armstrong, Sir W. G.
His hydraulic machinery at Paddington station, 85 note.¹
Engaged with Mr. Brunel on gunnery investigations, 452.
Letter to, 454, 461
Atlantic cable expeditions of the ‘Great Eastern,’ 412.
Loss of the first cable, 412.
A second one laid, and the first recovered, 413.
The French cable of 1869, 413
Atmospheric system of propulsion on railways, 131.
Description of this method of traction, 134.
History of its introduction prior to 1844, 136.
Mr. Brunel’s views respecting it, 137.
His report recommending its adoption on the South Devon Railway, 138.
Grounds of his recommendation, 142.
Select Committee on, 144.
Working of the system, 153.
Imperfections of engines, 154, and longitudinal valve, 157.
Mr. Brunel’s report on the failure of the Atmospheric apparatus, 159.
Abandonment of the system, 164
Australian Mail Company, Mr. Brunel appointed engineer of the, 290

Barlow, Professor P., member of the Gauge Commission, 117
Barlow, W. H., 57
Bath, station at, 84
Bath, bridges at, 175, 179
Bathford, bridge at, 175
Beamish, Richard, his account of Sir Isambard Brunel’s block machinery at Portsmouth, quoted, 3.
Joins the Thames Tunnel works, 21
Bennett, Joseph, Mr. Brunel’s secretary, 92
Berks and Hants Railway, 88
Birmingham and Oxford Junction Railway, 90
Birmingham, Great Western extension to, 124
Birth of Mr. Brunel, 1
Blake, H. W., consulted by Mr. Brunel on the ‘Great Eastern,’ 297
Block machinery at Portsmouth, Sir Isambard Brunel’s, 2
Bourbon, Ile de, Sir Isambard Brunel’s suspension bridges for the, 5.
Description of them, 40
Bourne viaduct, 181
Box Tunnel, 70 note¹, 72, 81.
Criticism as to its safety, 81.
Letter from Mr. Brunel on the, 81
Bremner, A., 263, 280
Brentford, dock at, 440
Brentford, extension of the Great Western Railway to, 86
Brereton, Robert Pearson, chief of Mr. Brunel’s engineering staff, 92, 210, 215 note¹, 217 note¹, 223, 225, 437, 438 note¹
Brickwork, use of, 59.
Bridges in, 172
Bridges, suspension, Sir Isambard Brunel’s: in the Ile de Bourbon, 5, 40; designs for the Serpentine, and for the Thames at Kingston, 5.
Mr. Brunel’s: at Clifton, 46; Charing Cross, 59
Bridges, railway, 171.
1. Brickwork and masonry bridges, 172.
Flying bridges, 176.
Skew bridges, 177.
Letter from Mr. Brunel on bridge construction, 178.
2. Timber bridges and viaducts, 179.
3. Cast-iron bridges, 190.
4. Wrought-iron bridges, 192.
Girder bridges, 193.
Opening bridges, 195.
Trussed bridges, 199.
Extracts from letters on bridges of large span, 212 note¹.
Experiments on matters connected with bridge construction, 227
Bristol, Mr. Brunel’s early connection with, 58, 64.
Station at, 84.
Bridges at, 175, 195.
Floating Harbour, 422.
Proposed improvement of the port, 426.
New lock at, 427
Bristol and Exeter Railway, 86
Bristol and Gloucester Railway, 90
Bristol and South Wales Union Railway, 90
Briton Ferry Docks, 437
Broad Gauge. See Gauge
Brunel, Sir Marc Isambard, birth of, 2.
Arrives in England, 2.
Marries Miss Sophia Kingdom, 2.
Designs the Block machinery at Portsmouth, 2.
Veneering machinery, 5.
Shoe machinery, 5.
Designs suspension bridges for the Ile de Bourbon, 5, 40.
Experiments on carbonic acid gas, 5, 42.
Proposes the Thames Tunnel, 5.
Extracts from his Journal relating to the Rotherhithe shaft, 10.
Extracts from his Journal relating to the works at the Thames Tunnel up to January 1828, 16.
His death, 39.
Hoop iron introduced by, in brickwork, 177.
Designed a large timber bridge to cross the Neva, 211 note²
Bullo Pill opening bridge, 197

Caermarthen, opening bridge at, 198
Carbonic acid gas, experiments on, by Sir Isambard Brunel and Mr. Brunel, 5, 42
Cast-iron bridges, 190.
Mr. Brunel’s views as to the use of cast iron in bridge construction, 190, 192
Cheltenham and Great Western Union Railway, 88
Chepstow bridge, 203.
Mode of forming piers, 203.
Description of superstructure, 206.
Floating and erection, 209
Clarke, Seymour, 117
Claxton, Captain, 57.
Assists Mr. Brunel at the floating of the Chepstow bridge, 210.
And the Saltash bridge, 222.
Appointed Managing Director of the Great Western Steam-Ship Company, 234, 242, 247.
Letter to, from Mr. Brunel, on the ‘Great Britain,’ 264.
Goes to Dundrum to carry out Mr. Brunel’s plans for the protection of the ‘Great Britain,’ 272.
Letter to, from Mr. Brunel, on the breakwater, 272.
Report of, on breakwater, 274.
Superintends floating of the ‘Great Britain,’ 280.
Consulted by Mr. Brunel on the ‘Great Eastern,’ 291, 297.
Floating Harbour, Bristol, 424
Clifton Suspension Bridge, origin of the, 47.
Mr. Brunel’s designs, 47.
Rejected by Mr. Telford, 51.
Mr. Telford’s own design, 52.
Second competition, 52.
Mr. Brunel successful, and appointed engineer, 53.
The site described, 54.
Description of the design, 55.
Architectural features, 56.
Commencement of the work, 56.
Completed, 57
Coles, Captain Cowper, 461
Construction of works, letter on, 178
Continuous girders, 208
Cork and Youghal Railway, 91
Cornwall Railway, 87.
Viaducts on, 185
Crystal Palace at Sydenham, water-towers of the, 448
Cylinders, of Chepstow bridge, method of sinking the, 204.
The great cylinder of the Royal Albert Bridge, 214

Dalkey Railway, Atmospheric System on, 131
Dartmouth and Torbay Railway, 87
Death of Mr. Brunel, 520
Dock and pier works:
Monkwearmouth, 418;
Bristol, 422;
Plymouth, 433;
Briton Ferry, 437;
Brentford, 440;
Neyland, 443
Draught, Mr. Brunel’s paper on, 101 note¹
Dublin, railway to Wicklow from, 91
Dundrum Bay, stranding of the ‘Great Britain’ in, 263

Early life of Mr. Brunel.
He goes to school at Chelsea, 4; at Brighton, 4; at Paris, 5.
Employed in his father’s office, 5.
Engaged at the Thames Tunnel, 6.
References by Sir I. Brunel to his exertions, 17, 19, 21, 22, 25, 33.
Appointed resident engineer, 25 note¹.
First irruption of the river, 29.
Second irruption, 35.
Accident, 36.
Visit to Plymouth, 46
Eastern Bengal Railway, 91, 195, 517
Eastern Counties Railway, gauge adopted on the, 105
Eastern Steam Navigation Company, formation of the, 291.
See ‘Great Eastern’
Egypt, visit to, 517
Electric telegraph, application of the, in connection with railways, 155
Engineer, Mr. Brunel’s view of the position of, 475.
Of joint-engineer, 476.
Of consulting engineer, 477.
Of the position of the engineer in relation to the contractors, 477.
To the Directors, 478.
Remarks on interference of Directors with assistant engineers, 481.
On State control over engineering works, 486
Experiments:
Strength of timber, 182, 227.
Cast-iron girders, 190, 191.
Wrought-iron girder, 193.
Riveting, 194, 228.
Continuous beams, 209, 229.
Bridge construction, 227.
Ropes and chains, 228.
Friction, 348, 368, 385

Faraday, M., his experiments on the liquefaction of gases, 42.
Consulted by Mr. Brunel on the Kyanising process, 189
Field, Cyrus, 411, 414
Field, J., consulted by Mr. Brunel on the ‘Great Eastern,’ 297
Floating gun-carriage, 454
Floating harbour at Bristol, 422
Floating pier, proposed at Portishead, 426.
In Mill Bay, 436
Florence and Pistoja Railway, 91
Flying bridges, 176
Ford, Captain Robert, consulted by Mr. Brunel on the ‘Great Eastern,’ 297
Friction, experiments and observations on, 348, 368, 385
Froude, W., letter to, describing floating of the ‘Great Eastern,’ 389

Gathampton, bridge at, 174
Genoa, Novi, and Alessandria Railway, 91
Gauge of railways, difference between the broad and narrow, 99.
Origin of the ordinary gauge, 99.
Adoption of the broad gauge on the Great Western Railway, 101, 106.
Reasons for its adoption, 102.
Attacks on, 106.
Reports of Mr. Wood and Mr. Hawkshaw on, 107.
Report by Mr. Brunel on, 107.
Northern extension, 116.
Inconveniences of a break of gauge, 116.
Royal Commission on the gauge question, 117.
Report of the Commissioners, 117.
‘Observations on the Report,’ 119.
Report of the Board of Trade, 122.
Act for regulating gauge, 122.
The mixed gauge, 124.
Summary of the advantages of the broad gauge, 127.
Partial abandonment of the broad gauge, 127, 129.
Report on the broad gauge, 525
Gilbert, Davies, appointed referee in the second competition for the Clifton Suspension Bridge, 52.
Recommends Mr. Brunel’s design, 53
Girder bridges, 193
Glennie, W., 215 note¹
Gloucester, opening bridges near, 196
Gloucester and Dean Forest Railway, 88
Gooch, Sir Daniel, 117, 119.
Experiments by, 125
Gravatt, William, an assistant engineer at the Thames Tunnel, 26
‘Great Britain’ steam-ship, commencement of the, 247.
Report on the engines, 249.
Adoption of the screw propeller, 254.
Principal features of her design, 255.
Arrives in the Thames, 261.
Her voyages, 262.
Stranded in Dundrum Bay, 263.
Letter from Mr. Brunel on the subject, 264.
His reports to the Directors, 267, 273.
Construction of breakwater, 274.
Floating of the ship, 280.
Her subsequent history, 282.
Dimensions of ship and engines, 282
‘Great Eastern’ steam-ship, origin of the project, 291.
Memorandum by Mr. Brunel to the Directors of the Eastern Steam Navigation Company, 292.
He is appointed engineer, 293.
Letter on the form and dimensions of the ship, 294.
Report on mode of proceeding, 296.
On enquiries relating to the draught and form of the vessel, 297.
On the dimensions, 299.
Tenders invited, 300.
Report on tenders, 301.
Commencement of the work, 304.
Extracts from Mr. Brunel’s memoranda, 304, 310.
Letters on his position as engineer, 311.
Report describing the ship, 315.
Letter to the Astronomer Royal, 321.
The observers’ department in the ship, 322.
Captain Harrison appointed to the command, 323.
Memorandum on the management of the ship, 324.
Letter on the duties of chief engineer, 335.
Suspension and resumption of the works, 339.
Reasons for launching the ship broadside to the river, 340.
Adoption of iron sliding-surfaces, 343.
The ways and cradles, 345.
Motive power, 348.
Checking gear, 351.
River tackle, 352.
Letter to Captain Harrison on the river tackle, 354.
Letter to the Directors respecting the operation of launching, 355.
Memorandum of arrangements and intended mode of proceeding, 356.
Particular instructions, 358.
Final preparations, 359.
Commencement of the launch, 360.
Accident at one of the drums, 361.
Failure of the first attempt, 362.
Second attempt, 364.
Report on operations, 366.
Progress of the launch, 368.
Suspension of operations, 376.
Report and memorandum, 377.
Re-commencement, 379.
Floating of the ship, 382.
Experiments and observations on friction, 385.
Letter to Mr. W. Froude, describing the floating, 389.
Formation of the Great Ship Company, 393.
Progress of the works to Mr. Brunel’s last illness, 393.
Completion of the ship, 393.
Voyage to Weymouth, 393.
Explosion of water-heater, 393.
Storm at Holyhead, 395.
Description of the ship, 396.
Her first voyages to New York, 403.
To Quebec, with troops, 404.
Accident to rudder, and loss of paddlewheels, 405.
Voyages in 1862, 407.
Accident off Montauk Point, 407.
Formation of Great Eastern Steam-Ship Company, 409.
Remarks on performance of ship, 409.
Employed in laying Atlantic cables, 412.
The Indian cable, 414.
Dimensions of ship and engines, 416
Great Exhibition of 1851, Mr. Brunel’s opinion respecting prizes to exhibitors, 445.
His part in the work of the Building Committee, 446.
Supports Sir Joseph Paxton’s design, 447
Great Western Hotel, 86
Great Western Railway, origin of the, 63.
Mr. Brunel appointed engineer, 64.
Survey of the country, 65.
Bill for a line from London to Reading, and Bath to Bristol, read a second time, and referred to a committee, 66.
Opposition to the Bill, 67.
Plan of entering London, 68.
Mr. Brunel’s cross-examination, 69.
The Bill passed by the Commons, but thrown out in the Lords, 70.
A Bill for the whole line introduced, read a second time, and committed, 71.
Evidence taken before the Commons’ Committee, 72.
Evidence before the Lords’ Committee, 73.
The Bill receives the Royal Assent, 74.
Construction of the line, 80.
Opening from London to Bristol, 80.
Levels and inclines, 80, 104.
The Box Tunnel, 81.
The Bath and Bristol stations, 84.
Paddington station, 84.
Branches and extensions of the railway, 86, 88, 90.
Adoption of the broad gauge, 106.
The permanent way, 108, 111.
Meeting of shareholders on broad gauge, 111.
Extension of the Great Western system, 116
‘Great Western’ steam-ship, formation of the company, 233.
Details of the construction of the vessel, 234 note².
Report on the selection of the builders of the engines, 235.
Controversy with Dr. Lardner, 237.
Launch of the vessel, and voyage to London, 241.
Return to Bristol, 242.
Fire on board, and accident to Mr. Brunel, 242.
First voyage to New York, 243.
Subsequent history, 244.
Dimensions of ship and engines, 245
Gunnery experiments, 452
Guppy, T. R., 148, 233, 234, 247, 253, 254.
Letter to, on iron-ship building, 259

Hammond, J. W., 65, 92
Hanwell, bridge at, destroyed by fire, 190
Hanwell viaduct, 172
Harrison, Captain, 223.
Appointed commander of the ‘Great Eastern,’ 323.
Letter to, on the river tackle, 354.
At the launch, 362, 370, 382, 392
Haverfordwest, opening bridge at, 198
Hawkshaw, J., 57.
Report on broad gauge and permanent way, 107
Henley branch of the Great Western Railway, 86
Hungerford Suspension Bridge, 57, 59

India, railway works in, 91
Indian Cable expedition of the ‘Great Eastern,’ 414
Institution of Civil Engineers, 516 note², 521
Inventors, communications with, 485
Ireland, railway works in, 90
Italy, Mr. Brunel’s railway works in, 91, 510
Ivybridge viaduct, 182

Kennet, bridge over the river, 175
Kidwelly, opening bridge at, 198
Kyanising process, 189, 421

Landore, viaduct at, 183
Lane, Michael, 29
Lardner, Dr., 114 note¹.
Opinions respecting ocean steam navigation, 237
Llansamlet, flying arches near, 176
Llynvi Valley Railway, 89
Locke, Joseph, 62, 74.
His address on the death of Mr. Brunel, 521
Locomotive power, comparison of, with stationary power, 142, 166
Loughor, opening bridge at, 197

Maidenhead bridge, 96, 173
Masonry, bridges in, 172
Maudslay and Field, 15, 148, 236, 284
Milford Haven, 88, 443
Monkwearmouth, docks at, 417, 418
Moulsford, bridge at, 174

Nasmyth, James, his steam hammer designed, 252 note¹.
Letter to, on gunnery experiments, 452
Neath, improvement of river, 438 note¹
Newport viaduct, 185, 199
Neyland, pier at, 443

Ocean steam navigation, Mr. Brunel’s connection with, 231, 313
Opening bridges, 195
Oxford, Mr. Brunel created a Doctor in Civil Law at, 516
Oxford and Rugby extension of the Great Western Railway, 90, 116
Oxford branch of the Great Western Railway, 86
Oxford, Worcester, and Wolverhampton Railway, 90, 116

Paddington station, 84
Paris Exhibition of 1855, letter on decorations conferred at, 489
Parkes, Dr., medical superintendent of Renkioi Hospital, 468.
Report of, on hospital buildings, 468
Patent laws, Mr. Brunel’s opinions on the, 212 note,¹ 450, 451, 454, 485, 489, 497
Patterson, W., 234, 247, 263
Paxton, Sir Joseph, his design for the Great Exhibition building, 447
Permanent way on the Great Western Railway, 108, 535
Plymouth Great Western Docks, 433
Polygonal rifle, 449
Portishead, proposed pier at, 426
Prince Consort, H.R.H. the, opens the Royal Albert Bridge, 226.
Present at floating of the ‘Great Britain,’ 259
Private life of Mr. Brunel, 499.
Early reminiscences, 500.
Removal to Duke Street, and marriage, 505.
His taste in art, 506.
First journey to Italy, 508.
Half-sovereign accident, 511.
Purchase of property in Devonshire, 514.
Life at Watcombe, 515.
Failing health, 516.
Journeys to Switzerland and Egypt, 516.
Letter from Philæ, 517.
His last illness, 520

Quaker’s Yard, viaduct at, 89

Railways, sketch of, in England prior to 1833, 61.
Extent of Mr. Brunel’s, 79.
Great Western, 80.
Branches to Oxford, 86.
Windsor, 86.
Wycombe, 86.
Uxbridge, 86.
Henley, 86.
Brentford, 86.
Bristol and Exeter Railway, 86.
South Devon, 87.
South Devon and Tavistock, 87.
Cornwall, 87.
Branch lines now incorporated with Great Western Railway:
Berks and Hants, 88.
Wilts and Somerset, 88.
Cheltenham and Great Western Union, 88.
Gloucester and Dean Forest, 88.
The South Wales, 88.
The Taff Vale, 89.
The Vale of Neath, 89.
The Llynvi Valley, 89.
The South Wales Mineral, 89.
Bristol and South Wales Union, 90.
Bristol and Gloucester, 90.
The Oxford and Rugby, 90.
Birmingham and Oxford Junction, 90.
Oxford, Worcester, and Wolverhampton, 90.
Ireland, 90.
Italy, 91.
India (Eastern Bengal), 91
Railway Structures, letter on the Royal Commission on the Application of Iron to, 192, 486
‘Rattler’ steam-ship, trials with the, 287
Rendel, J. M., 211, 433
Renkioi, hospital buildings at, 461.
Description of the buildings, 463.
Dr. Parkes’s report on the formation and general management of the hospital, 468
Rennie, G. and J., 148
Richards, Westley, letters to, on polygonal rifle, 450
Riveting, experiments on, 194, 228
Ropes and chains, experiments on, 228
Rotherhithe shaft of the Thames Tunnel, construction of the, 9
Royal Albert Bridge at Saltash, 211.
Plans for crossing the river Tamar at Saltash, 211.
Trial cylinder for centre pier, 213.
Report on making bridge for a single line, 214.
Mode of construction of centre pier, 214.
Description of superstructure, 218.
Floating of first truss, 221.
Lifting of first truss, 224.
Floating and lifting of second truss, 225.
Opening by H.R.H. the Prince Consort, 226
Royal Society, 516 note¹
Russell, J. Scott, builds the ‘Victoria’ and ‘Adelaide,’ 290.
Assists Mr. Brunel in maturing designs of the ‘Great Eastern,’ 291, 292, 297.
Letter to, on the form and dimensions of the ship, 294.
Tender accepted for hull and paddle-engines, 301

St. Mary’s viaduct, 181
St. Pinnock viaduct, 186
Saltash bridge. See Royal Albert Bridge
Samuda, J., 131, 134, 148, 160
Saunders, C. A., 92, 117, 119
Screw propeller, the, adopted for the ‘Great Britain,’ 254.
Communications on, with the Board of Admiralty, 283.
Trials with the ‘Polyphemus,’ 284.
With the ‘Rattler,’ 287.
Report recommending adoption of, 539
Shield, Thames Tunnel, the, 11, 12
‘Sirius’ steam-ship, 241
Skew bridges, 177
Smith, F. P., the screw propeller, 253, 287.
Consulted by Mr. Brunel on the ‘Great Eastern,’ 297, 298
Smith, Sir F., member of the Gauge Commission, 117
Smyth, C. Piazzi, Astronomer Royal for Scotland, correspondence with Mr. Brunel on astronomical instruments for the ‘Great Eastern,’ 322
Sonning Cutting brickwork bridge, 175.
Timber bridge, 179
South Devon and Tavistock Railway, 87.
Viaducts, 188
South Devon Railway, 87.
Course of the line, 132.
Atmospheric System adopted on the, 138.
Viaducts, 182
South Wales Mineral Railway, 89
South Wales Railway, 88.
Viaducts, 183, 194
Standard drawings, 172 note²
Stationary and locomotive power, comparison of, 142, 166
Statue of Mr. Brunel, 520 note¹
Stephenson, George, 61, 62, 70, 74, 99
Stephenson, Robert, 62, 106, 107, 134
Atmospheric System, 136, 137 note¹, 138, 144.
Conway and Britannia bridges, 221, 223.
Launch of the ‘Great Eastern,’ 375, 376, 377, 378, 384 note¹, 485, 516, 517, 521
Stonehouse viaduct, 181

Taff Vale Railway, 89, 104 note¹
Tamar, plans for crossing the river, 5 note², 46, 211
Telford, T., appointed referee to decide upon the plans for the Clifton Suspension Bridge, 51.
Rejects Mr. Brunel’s plan, 51.
Designs one himself, 52.
His plan described, 52
Thames Tunnel, project of, first occupies Sir Isambard Brunel’s attention, 5.
Plans suggested for the construction of a tunnel, 6.
Borings, 7.
Remarks on borings, 8 note¹.
Commencement of the work, 9.
Construction of the Rotherhithe shaft, 9.
Description of the shield, 12.
Journals of Sir I. Brunel of the progress of the work, 10, 11, 16.
Mr. Brunel appointed resident engineer of, 25 note¹.
First irruption of the river, 29.
Second irruption, 35.
Works suspended, 37.
Resumed, 38.
The Wapping shaft, 38.
Completed and opened, 39.
Its subsequent history, 39 note¹
Thompson, Dr. Seth.
Letter on the half-sovereign accident, 511
Timber bridges and viaducts, 179
Timber, experiments on strength of, 182, 227
Torquay branch of the South Devon Railway, 87
Trussed bridges, 199

Uxbridge branch of the Great Western Railway, 86

Vale of Neath Railway, 89.
Viaducts, 171
Vick, Alderman William, his bequest for a bridge at Clifton, 47
‘Victoria’ steam-ship, built under Mr. Brunel’s direction, 290
Vignoles, C., 74

Walker, J., 107
Walkham viaduct, 189
Wapping shaft of the Thames Tunnel, construction of the, 38
Watcombe, Mr. Brunel’s life at, 514
Watt, James & Co., 148.
Tender accepted for screw engines of the ‘Great Eastern,’ 301
West Cornwall Railway, 87.
Viaducts, 189
Westminster Abbey, memorial window in, 520 note¹
Wilts and Somerset Railway, 88
Windsor branch of the Great Western Railway, 86
Windsor bridge, 200.
Description of superstructure, 200.
Mode of forming piers, 201
Wire gun, 453
Witness, Mr. Brunel’s reputation as a, 69, 93, 505
Wood, Nicholas, 101.
Report on broad gauge and permanent way, 107
Wrought-iron bridges, 192
Wrought-iron girder, experiments on, 193
Wyatt, Sir M. D., 84
Wycombe extension of the Great Western Railway, 86