“Oh—my shoulder!” the man cried out in sudden anguish. (Page 93)

THE
HAUNTED HANGAR

By VAN POWELL

THE SAALFIELD PUBLISHING COMPANY
Akron, Ohio New York

THE HAUNTED HANGAR

CHAPTER I
“SUSPICIOUS SANDY”

Neither sixteen-year-old Larry Turner nor Dick Summers, a year his junior, had any more fear than had Sandy Maclaren, hardly thirteen and seated just back of the pilot who, in flying the four-place, low-wing airplane, had called back reassuringly.

“Jeff’s a war ace and knows his stuff,” Larry mused, “and the engine couldn’t have died in a better spot. We are high enough and within gliding distance of that old, abandoned private field.”

Dick, who saw something to make light of in any situation, turned with his plump face cracked by a broad grin.

“I always said whether you fly a crate full of passengers or handle one full of eggs, you get a good break sometimes!”

Only the youngest member of the trio, as the craft nosed into a gentle glide and banked in a turn to get in position to shoot the private landing spot on the old estate, took the occasion as anything but a lark.

Sandy Maclaren, with narrowed eyes and an intent frown, bent his gaze on the pilot’s back and muttered under his breath.

“That engine didn’t die. I saw what Jeff did. He was as quick as a cat—but he didn’t fool me.”

“But why did he shut off the ignition and pretend the engine had stopped—so handy to this old, abandoned estate?”

No answer rewarded his agile thoughts as Jeff skilfully shot the small field, compelled to come in to one side because of tall trees directly in their line of flight, over which his dead engine made it impossible to maneuver. Nor did he get a solution to his puzzle as Jeff cleverly side-slipped to lose momentum, and to get over the neglected, turf-grown runway down which, a little bumpily but right side up, he taxied to a standstill.

“Well,” Jeff said, with a grin, swinging around in his seat and drawing off his helmet, “here we are!”

“If I ever get the money to take flying lessons,” Larry said, “I know the pilot I’m going to ask to give me instruction! When I can make a forced landing like that one, Jeff, I’ll think I’m getting to be a pilot.”

“If ever I get taken into my uncle’s airplane passenger line,” Dick spoke up, “I know who’ll be Chief Pilot—until Larry gets the experience to crowd Jeff out.”

The tall, slim pilot, grinned at the compliments and then went on working his jaws on the gum he habitually chewed.

“Guess I’ll have to trace my gas line and ignition to see if a break made this trouble.” Jeff began removing his leather coat. “Say! By golly! Do you know where I think we’ve set down?”

“Yes,” Sandy spoke meaningly. “This is the old Everdail estate—the one that’s been in the newspapers lately because the people around here claim the hangar is haunted.”

“I believe it is!” agreed Jeff. “Why don’t you three take a look. Yonder’s a hangar and the roll-door is lifted a little. Maybe you’d spot that there Mister Spook and clear up the mystery while I work.”

“I’d rather go down by the water and see if it’s cooler there,” Sandy said, trying to catch Larry’s eye. “Since we got down out of the cool air it’s the hottest day this June.”

“I’m for the hangar!” voted Dick. “If there’s any specters roaming through that hangar you’ll get more chills there than you will by the Sound.”

“I could stand a shiver or two,” commented Larry, leading the way toward the large, metal-sheathed building at the end of the runway.

Facing them was a wide opening, sufficiently spacious to permit airplanes to be rolled through: in grooved slots at either side the door, made of joined metal slats working like the old-fashioned roll-top desk, could be raised or lowered by a motor and cable led over a drum.

Sandy gave in, and as they walked toward the hangar they discussed the stories that had come out in the news about queer, ghostly noises heard by passers-by on the state road late at night, accounts of the fright the estate caretaker had received when he investigated and saw a queer, bluish glow in the place and was attacked by something seemingly uncanny and not human.

The door, when they arrived, was seen to be partially open, lifted about three feet.

“There’s an airplane in there—it looks to be an amphibian—I see pontoons!” Larry stated.

Larry and Dick straightened and stared in surprise. It was very plain to be seen that Sandy was not joking.

“Think back,” said Sandy. “When school vacations started and we began to stay around the new Floyd Bennett airport that had opened on Barren Island, Jeff had his ‘crate’ there to take people around the sky for short sight-seeing hops, didn’t he?”

“Yes,” admitted Larry, “and we got to be friendly because we are crazy to be around airplanes and pilots, and Jeff let us be ‘grease monkeys’ and help him get passengers, too.”

“Surely he did! But when we brought them to go up with him, did he take their money and fly them around, the way others did? Or——”

“No,” Dick admitted. “He generally had something wrong with the crate, or the wind was too high, or he had stubbed his left foot and met a cross-eyed girl, or saw a funeral passing, and thought something unlucky might happen from those signs.”

“Do you really believe anybody can be as superstitious as Jeff tries to make us believe he is?”

“Yes. Lots of pilots are—they think an accident will happen if anybody wears flowers in their ‘planes——”

“He said, this morning, we had helped him a lot and he didn’t have money to pay us,” Larry answered. “He offered us a joy-ride.”

“But why did he come so far out on Long Island, and then get a dead stick so handy to this old estate that hasn’t been lived in for years and that has everybody scared so they won’t come near at night?”

“‘Then get a dead stick!’” Larry shook his head. “Why, Sandy! I know you read detective stories until you think everything is suspicious——”

“But we read to try to guess the answers to the mystery,” Dick declared. “You’ve got the idea that real life is like those wild stories. Everything looks as if it had some hidden mystery behind it—I know what will be your new nickname——”

“That’s good,” Larry smiled. “Suspicious Sandy thinks a pilot gets a dead stick to make us land near a haunted hangar——”

“I know I did—and, what’s more, here we are at a spot where nobody comes because of the ghost story—and he tells us to go into the hangar and—the door is left up a little way——”

“Ho-ho-ho-ho! That’s good. Suspicious Sandy—is that somebody inside the hangar?” Dick changed his tone suddenly, dropping his voice to a whisper as he stooped and saw something move behind the old amphibian at the back of the building.

“I thought I saw—but it’s gone!” Larry retorted, lowering his voice also.

By a common impulse of curiosity they stooped and went in. Sandy, his own impulse following theirs, was inside almost as quickly.

“There isn’t anybody!” Larry’s eyes became used to the duller light that filtered through the thick dust on the roof skylight.

To their startled ears came a muffled clang, a queer, hollow sound—and as they turned to run back under the rolled-up door, it slid rapidly down in its grooves, dropping into place with a hollow rumble.

CHAPTER II
GHOSTS, GUM—AND GEMS

For a long minute Dick, Larry and Sandy stood in a compact group, feeling rather stunned by the sudden springing of the trap, as they considered the closed hangar.

“Even if Jeff did want to catch us and demand ransom to let us go,” he remarked quietly, “he wasn’t outside that rolling door—and I don’t think he could pull it down anyhow.”

“No,” Dick agreed, seeing no fun in the situation for once. “See! There is a motor connected to a big drum up in the top of the hangar, and the door is counterbalanced so that turning the drum winds up the cable that pulls it up. I suppose the motor reverses to run it down and——”

They heard the strange, hollow sound again, seeming to come from the metal wall, but impossible to locate at once because of the echo.

“Not somebody—something!” corrected Sandy. “The same ‘something’ that worked the door and shut it!”

“Gracious-to-gravy!” exclaimed Larry, “you don’t believe in ghosts, do you, Sandy? Not really!”

“I think it did!” challenged Larry. “We thought we saw somebody at the back of the hangar—that’s why we came in! I’m going to see where he is, what he’s doing and why he’s trying to fright—frighten us!”

He broke his sentence in the middle of a word because the queer knocking repeated itself, but with quick presence of mind he completed his phrase to steady Sandy, whose face was growing drawn with dismay.

“There’s a big, closed can for waste and oily rags,” he commented, “but anyone would suffocate who hid in that!”

“Well, there’s a clothes cupboard—in the back corner,” Dick said. “Let’s look in that, you and I. Sandy, you stay back and keep watch.” Dick, quick to see Larry’s attitude toward Sandy, wanted to have a dependable chum at his side as he investigated while he hoped to give Sandy more confidence by leaving him in the lighted part of the building, under the smudged, dusty skylight.

With Dick he walked boldly enough to the built-in wooden cupboard, protected from dust by a heavy burlap hanging.

“It’s peculiar,” Larry said doubtfully. “Nobody here—but—” a new idea struck him. Quietly he gestured toward the amphibian, old, uncared for, looking almost ready to fall apart, its doped wings stained with mould, its pontoons looking as if the fabric was rotting on them.

Dick, instantly catching Larry’s notion, went to the forward seat, while Larry took the second compartment behind the big fuel tank.

“Nobody here,” he reported, and investigated, by climbing in the vacant part of the fuselage toward the tail.

“Oh!”—Sandy almost screamed the word as the dull, hollow knocks came again.

Larry leaped from the wing-step, sent his sharp gaze rapidly around the enclosure and, of a sudden, gripped Dick’s arm so tightly that the plump youth winced and grew chilly with apprehension.

At once he saw Larry’s amazed, relieved expression and followed the older comrade’s eyes.

With an instant return of his old amused self he threw back his head and let out a deep howl of delight.

“You got us all worked up and worried,” he told Sandy, “with your suspicions. And all the time——”

“Ho-ho-ha-ha! All the t-time, we were like mice racing around a treadmill.” Dick had to speak between chuckles. “All the time we ran around in circles so fast we didn’t see the end of the cage. Sus—suspicious Sandy! Thinking we would be trapped and held for ransom! Ho, golly-me! Look around you, Sandy!”

“Oh!” His voice was sheepish. “You mean the switch for the motor over by that small metal door they use when they don’t want to run up the big one?”

“That runs the motor,” Larry agreed. “The cable must have slipped on the drum and let the door go down——”

“But,” Sandy clung obstinately to his theories, “why did Jeff pick this haunted place and cut the ignition—and why was the door up in the first place?”

“What do we—ho-ho—care?” Dick chuckled. “Another thing—even if the electric current is off and the motor doesn’t work—look at that small, hinged door—do you see that the knob of the spring lock—is on—our—side!” He broke out in a fresh cackle of laughter.

For reply Larry strode over to the metal door set in the wall for use when anyone chose to enter or leave the hangar.

“Took you long enough to answer!” grumbled Jeff. “What made you fool with that door and shut yourselves in?”

“What made you cut the ignition!” snapped Sandy, working on the idea he had read in so many detective stories that a surprise attack often caused a person to be so startled as to reveal facts.

The older pilot, staring at his accuser for an instant, as though hesitating about some sharp response, suddenly began to chuckle.

“That-there is one on me!” he admitted. “You must have mighty quick eyes.”

“None of us do!” Dick caught the spirit of Sandy’s accusing manner. “I know you’ve been here before, too. There are lots of chunks of old chewing gum stuck around in that front compartment of the amphibian—and someone has been working on it, too. I saw the signs.”

“Chewing gum?” Jeff was startled. Swiftly he strode across the dimly sunlit floor, got onto the forward step, peered into the cockpit.

“That-there certainly is queer,” he commented. “You’re right. Gum is stuck every place, wads of it.”

“And you chew gum!” snapped Sandy, unwilling to be left out of the suddenly developing “third degree” he had begun. Jeff made a further inspection, touched a bit of the dried gum curiously, stepped down and stood with a thoughtful face for a moment.

Presently he walked to an old soap box holding metal odds and ends, washers, bolts and so on. This he up-ended. He sat down, his lean jaws working as he chewed his own gum slowly. Around him, like three detectives watching the effect of a surprise accusation, stood the chums.

“I guess I better explain,” Jeff decided. “I didn’t think you was so suspicious and quick or I’d of done different.”

“Well, didn’t you make friends with us and let us work on your crate and help get passengers that you never took up? Didn’t you say you’d give us a joy-ride, then come straight here, cut out your ignition and make believe you had a dead stick, land and then try to get us into this haunted hangar?” Sandy ran out of breath and stopped.

“Yes, I did all that—and I guess I will explain. I meant to, anyhow—or I wouldn’t have brought you here.”

“I never dreamed you’d be suspicious of me! I made friends with you all and tried you out to be sure you were dependable and honest and all that—and I did bring you to this place because it is so far from telephones and railroads. But I didn’t think you’d get the wrong idea. I only wanted you in a place it would take time to get away from if you refused to help me.”

“Help me save the most valuable set of emeralds in the world from being—destroyed!”

CHAPTER III
THE SKY PATROL ORGANIZES

“I don’t think so—but I don’t know for sure who it is. But I do mean to ask you if you’d like to help me, and I don’t think it would be against robbers but against somebody that wants to destroy the Everdail Emeralds.”

“The Everdail Emeralds!” Larry repeated the phrase sharply. “Why, Jeff! I’ve read a newspaper story about them, in a Sunday supplement. That’s the matched set of thirty emeralds——”

“Matched stones—and priceless,” added Larry. “The paper said they were a present to one of Mr. Everdail’s ancestors by one of the most fabulously rich Hindu Nabobs who ever lived.”

Jeff drew a bulky, registered envelope from his coat, displayed the registration stamps and marks, and his name and address typed on the envelope. Drawing out a half dozen hand written sheets in a large masculine “fist,” he showed the signature of Atley Everdail at the end.

“This-here is what got me going,” he stated. “Want to read it or will I give it to you snappy and quick?”

“You said we couldn’t get away to tell anybody anyway,” Sandy said, but he was compelled to admit to himself that although anyone might write such a letter—even Jeff!—the postmark was Los Angeles and the enclosure had every appearance of sincerity.

“Never mind old Suspicious Sandy,” urged Dick. “Let him read that, but you tell us.”

“Suits me!” Jeff crossed his legs, leaning against the metal wall, as he related an amazing and mystifying series of events.

“I’m pretty close to one of the richest men in America,” he began. “You see, we both enlisted in aviation units when the big war tore loose and got Uncle Sam mixed up in it. We were buddies, Atley and me. Well, after we came back I stayed in aviation, knocking around from control jobs to designing new gadgets like superchargers and all. But when he went to California and began to organize some passenger flying lines, I stayed East in a commercial pilot’s job.”

“Atley Everdail sold out stocks and stuff here and went West to work out some pet ideas about passenger transport,” he told Dick and Larry. “Of course he bought a big place out there and closed up this estate—put it up for sale. Hard times kept it from selling, the same reason made him hang onto that-there swell yacht he owned.”

“She is that!” Jeff agreed. “Well, as Sandy must be reading, about where he’s got in that letter, Mrs. Everdail, who goes in for society pretty strong, got a chance to be presented, this Spring, before the King and Queen of England at one of their receptions.”

“And how!” Jeff nodded. “Now, that-there Everdail necklace that was in his side of the family for generations—that wasn’t took out of the safe-deposit box once in a lifetime, hardly. Most generally the missus wore a good paste imitation.”

“It says, here, she took the real necklace, on the yacht, when she went to England!”

Sandy had lost his suspicious look. His interest, as much as that of his older chums, was caught and chained by the coming possibilities and he put down the letter to listen to Jeff.

“She did take the string, as the letter says,” Jeff nodded. “It was a secret—they didn’t broadcast it that the necklace was in the captain’s cabin, locked up in his safe. Nobody knew it, not even the lady’s personal maid, as far as anybody supposed.”

“He was too busy routing air lines and working out cost, maintenance and operation plans for his big Western lines,” explained Jeff. “But they took all the care in the world of those emeralds. Even on the night of the reception, the imitation string was taken to the hotel Mrs. Everdail stayed at. That-there real necklace was brought to the hotel, in person, by the captain.”

“That-there is what started things,” Jeff told Dick. “The missus was in her private suite, in the dressing bowdoir or whatever it is, with nobody but her French maid to help, and all the jewels in a box in the room, hid in her trunks.”

“She was all but ready, dolled up like a circus, I guess,” Jeff grinned, and then became very sober. “All the jewelry was spread out to try how this and that one looked, with her clothes, separate and in different combinations.”

“There comes a banging on that-there suite door to the hall and a voice hollered, like it was scared to death, ‘Fire! Fire—get out at once!’”

“She didn’t have time to think. That French maid went crazy and started to hop around like a flea in a hot pan, and yelling, and it upset the missus so much she forgot all about a fire escape on the end window of the suite, and rushed out, snatching up all the strings of beads and pearls and the pins she could carry. But, because she knew it was only imitation and there wasn’t anybody else around anyway, she didn’t bother about the emerald necklace.”

“All she found was a paper of burnt matches outside in the hotel corridor that had been set off so when she opened the door she’d smell smoke. Of course she ran back—and——”

As he reached for the letter, and searched on the fourth page, all three of his listeners were holding their breath in suspense.

“Here it is,” he declared, and they crowded around. “Read it, so you’ll see just what I learned about when she went back.”

“Some strong, pungent liquid had been poured on the green necklace,” the letter from the millionaire stated. “No alarm was given. My wife did not want to broadcast either the fact that she had the real gems or the trouble in the hotel. But people had heard the ‘fire!’ cry and doubtless some suspected the possible truth, knowing why she was getting ready.

“Captain Parks came up later with the real stones and while he waited for my wife to finish her costume, he examined the fire escape window and was sure that someone had entered and left by that.

“Now Jeff,” the letter concluded, “my caretaker on Long Island has sent me clippings about a ghost scare on the old estate, and somehow I connect that with the attempt to destroy the emeralds. I can’t imagine any motive, but there are fanatics who do such things from a warped sense of their duty or from spite and hatred of rich folks. For old times’ sake, drop everything, get down to bedrock on this thing at your end—do whatever you think best, but get in touch with the yacht, learn their plans, cooperate with Captain Parks and my wife to bring that necklace back to the vaults, and—I count on you!”

Jeff explained. He had sent a radiogram to the yacht, and as its owner had already sent one identifying Jeff, he was given the information that the real necklace was being brought back, extra heavily insured in a London company, by the captain himself.

“I located and rented this crate we flew here in,” he went on. “I played joy-ride pilot by day at the airport and hopped here of nights. But I couldn’t get a line on anything. I didn’t notice that chewing gum until you, Dick, Larry and Sandy—all of you—started your third degree and showed it to me. But I did think—if anybody was playing ghost here, they might be planning to use the old amphibian for something—maybe to get away to get away with the emeralds if they could get hold of them—in case anybody thought the yacht was due to lay up here.”

“Not exactly. But it came over me that at night I didn’t get anywhere and I thought I’d try coming in the daytime—and being that the yacht is due to make Long Island this afternoon, I thought I might need some help with a plan I’ve worked out.”

“I’ve sent the caretaker here—he’s as dependable as sunrise!—to a place out near Montauk Point lighthouse, with Mr. Everdail’s fast hydroplane boat and I’ve sent a radio message to the yacht captain to be on the watch to meet the hydroplane pretty well out to sea, and transfer the necklace to the boat. Then, the yacht will come on and make harbor here, as though nothing had happened—and all the time the emeralds will be on the way, down the Sound and East River, to a wharf where I’ll have a motor car, with a dependable chum of mine, to take charge and carry the package to safe deposit, get a receipt—and there you are!”

“I mean to hop out in the airplane, sort of oversee the business of the transfer, and escort the hydroplane till she lands the emeralds, and then circle around till my friend, with the receipt, goes up onto the bank roof—it’s pretty high up—fourteen stories—and wig-wags an O.K. And I’d like dependable observers——”

“I’m one!” cried Sandy, his suspicions swept away. “Number two is named Larry.” “Dick is a dependable third!”

“We’ll be a regular Sky Patrol!” exulted Sandy. “And watch what goes on while you do the control job—and, that way—nothing can go wrong!” “Not with the Sky Patrol ‘over’-seeing!” Dick, too, spoke overconfidently.

CHAPTER IV
MYSTERY OVER THE OCEAN

Three youths, thrilled by the prospect of a mysterious adventure, and a war pilot, intent on a friendly service, discussed plans for protecting the Everdail Emeralds.

“I don’t know,” Jeff spoke dubiously, uncertainly. “We’ve gone over all the things we can think of that might go wrong—but——”

“I had a fortune teller read the cards for me,” Jeff told him. “The nine o’ spades—the worst card of warning in the pack—was right over me and that means trouble—and the ace of spades, a bad card——”

“Crickety-Christmas!” Larry was amazed. “Are you really telling us you believe in all that?”

“You’ve twisted things that happened to fit what you wanted to believe,” argued Larry.

“Oh, well,” Jeff did not want to discuss his superstitions, “maybe it won’t come out so bad. I met a pair of colored twins yesterday. That’s a good-luck sign——”

“Look here!” Dick began to chuckle. “We’ve got a queer combination to work with—our Sky Patrol has! Suspicious Sandy—and—Superstitious Jeff!” Sandy grinned ruefully, a little sheepishly. Larry smiled and shook his head, warning Dick not to carry his sarcasm any further, as Jeff frowned.

“I fixed up Atley’s old short-wave radio, in the old house—and I’ve been getting dope from the yacht the last couple of nights. In about an hour we’ll take off, fly out beyond the lighthouse and patrol.”

“Had some delivered in cans early this morning—down at the boathouse,” Jeff told him. “We can fill up the main tank and get a reserve in my small wing-tanks—enough for ten hours altogether.”

Only when Jeff was warming up the engine, checking carefully on his instruments, taking every precaution against any predictable failure, was there time for a moment together and alone.

“Now what do you think of your suspicions?” Dick demanded. Sandy shook his head.

“Most of the time I think I was letting imaginitis get the best of me—but every once in awhile I wonder—for one thing, why doesn’t the yacht sail right on to the New York wharf and let the captain take those emeralds to safe deposit?”

“For another thing,” Sandy went on, “anybody could write that letter Jeff showed me—and who is Jeff, when all is said and done?”

“Well, then, let that go. But—he chews gum and there’s gum stuck all over in this amphibian—he’s been here, nights——”

“Suspicion may be all right,” Larry commented, “but what does it bring out, Sandy? What is your idea——”

“This is my idea! Nothing is what it seems to be. Jeff pretends to be a joy-ride pilot, but he never takes up passengers—hardly ever. The engine dies, only it’s Jeff stopping the ‘juice.’ This old amphibian crate looks as though it’s ready to come to pieces and yet, somebody has been working on it—that chewing gum wasn’t stale and hard, because I made sure. Well—suppose that Jeff was in a gang of international jewel robbers——”

“Next you’ll be saying the letter was in a registered envelope from California and was written in Cairo!” laughed Dick.

“Jewel robbers,” Larry was serious. “I don’t think that holds water, Sandy. First of all, Jeff claims to know that the emerald imitations had acid poured on them—acid to destroy them. That must be some chemical that corrodes or eats emeralds. Now, robbers wouldn’t——”

“Why not?” Sandy was stubborn. “Suppose they had gone to all that trouble to get into the suite and discovered the false emeralds? What would you do?”

“I might rip them apart—but do you think robbers carry acids along to eat up emeralds if they think they are going to profit by taking them?”

“Suspicious Sandy,” Dick began to chant a rhyme he invented on the spur of the moment, “Suspicious Sandy, Suspicious Sandy, he thinks everything is like April-Fool candy! Nothing is what it seems to be and soon he’ll suspect both Larry and me!”

Sandy turned away, hurt, and strolled to the amphibian with its retractable wheels for land use and its pontoons for setting down on water.

Jeff called and signaled that all was ready. Larry summoned Sandy but the latter lingered, while Dick, a little sorry he had taunted so much, followed Larry toward the waiting airplane. But Sandy, scowling, hesitated whether he would go or be angry and refuse to join the Sky Patrol. Then, as he clambered onto the forward bracing of the under wing and leaned on the cockpit cowling, his face assumed a startled, intent expression.

“Jeff chews gum,” he mused. “He pretended not to know any was in this amphibian. But it’s gone! Well,” he told himself, “I’ll watch and see what he’s up to. He’ll give himself away yet!”

Assuming an air of having forgotten all about Dick’s rhyme, he went to his place in the seat behind Jeff and the instant his safety belt was snapped Jeff signaled to a farmer who had come over to investigate and satisfy himself that the airplane had legitimate business there; the farmer kicked the stones used as chocks from under the landing tires and Jeff opened up the throttle.

With wind unchanged the trees which had complicated their landing were behind them. Jeff’s only problem, Larry saw, was to get the craft, heavier with its wing tanks full, off the short runway and over the hangar.

“If he gets a ‘dead stick’ here,” Larry mused, “it will be just too bad!”

He had no trouble lifting the craft and flying for seconds just above the ground to get flying speed after the take-off, then giving it full gun and roaring up at a safe angle to clear the obstruction.

They were—off on an adventure that was to start with a mad race and terminate—in smoke!

Down the backbone of Long Island, not very high, they flew. The farms, landscaped estates and straight roads of the central zone were in striking contrast to the bay and inlet dented North Shore with its fleets of small boats, its fishing hamlets, rolling hills and curving motor drives and the seaside with its beach resorts, yellow-brown sand and tall marsh grass clustered between crab-infested salt water channels.

Passing over the fashionable Summer homes of wealthy people at Southampton, they held the course until Montauk Point light was to the left of the airplane, then Jeff swung in a wide circle out over the desolate sand dunes, the ooze and waving eel-grass of marshes and the tossing combers of the surf.

“There’s the hydroplane!” Dick, leaning over the left side, made a pointing gesture. Larry, watching seaward, had not been looking in the right direction. Sandy, alert to pass signals, touched Jeff and received a nod from the pilot.

The first step of the plan was taken. They had made contact with the small, speedy craft which, on a later signal that they had “picked up” the incoming yacht, would speed out to sea to meet her.

Climb they did, until the sea dropped down to a gray-green, flat expanse and only the powerful binoculars Larry was using could pick out the cruising hydroplane slowly verging away from the shore in an apparently aimless voyage.

“This isn’t such a bad scheme, at that,” Dick concluded mentally. “If there should be anybody on the lookout—robbers or somebody who wants to see what’s going on—no one will see any connection between us passing here and then climbing to get a good wind for a run down the coast toward Maine, and a hydroplane that’s acting as if it had some engine trouble.”

Higher and higher they went, probably out of sight of anyone without strong field glasses, and while they swung in a wide circle, Larry’s binoculars swept the horizon.

“Smoke!” He turned the focusing adjustment a trifle. “Too soon to signal—it may be an oil-burning steamer and not the yacht—or a rum-runner of a revenue patrol—it’s thick, black oil smoke, the sort the yacht would give—it is a small boat—yes——”

His signal, relayed through Dick and Sandy to Jeff, shifted the gently banked curve into a straighter line and swiftly the lines of the oncoming craft, miles away, became clear.

Larry verified his decision that the low, gray hull, with its projecting bowsprit, the rakish funnel atop the low trunk of the central cabin, and the yacht ensign, identified the Tramp.

“Now we’ll dive to where the hydroplane can see us, and the dive will signal the yacht that we’re the airplane they’ll be watching for,” Dick decided.

The maneuver was executed, ending in a fairly tight circle after Jeff had skilfully leveled out of the drop.

“Smoke was trailing over the yacht’s stern,” Sandy murmured. “Now it’s blowing off to the starboard side. She’s swinging toward us.”

Through his glasses Larry saw the hydroplane awaken the sea to a split crest of foam, saw a cascade of moiling water begin to chase her, and knew that the tiny craft was racing out to the meeting.

Sandy did not smile. Instead, as they swung, he scanned the sky. That was not his instructions, but it was his determined plan.

“I’ll see the amphibian Jeff was working on, nights,” he mused. “It ought to be in sight now——”

Convinced that both the hydroplane and the yacht would have located the spot on the sea where they would meet, Jeff broke the tedium of his tight circle by a reverse of controls, banking to the other side and swinging in a climbing spiral to the right.

Closer and closer together came the swift turbine propelled yacht and the surface-skimming hydroplane.

“I was right!” shouted Sandy, unheard but triumphant—and also a little startled that he had so closely guessed what would happen.

He swung his head, signaled Dick, waved an arm, pointing. Dick and Larry stared, while Sandy poked Jeff and repeated his gestures.

On the horizon, coming at moderate speed, but growing large enough so that there could be no error of identification, came the amphibian. Its dun color and its tail marking were unmistakable.

“I wonder who’s in it?” Dick mused as Jeff cut the gun and went into a glide, the better to get a look at the oncoming craft low over the seashore.

No glass was needed to show him the yacht, swiftly being brought almost under them by its speed and theirs. A quarter of a mile away was the hydroplane, coming fast. A mile to the south flew the approaching amphibian. And in every mind—even Jeff’s, had they been able to read it—was the puzzled question, “Why?”

Jeff began to climb in a tight upward spiral to keep as well over the scene of activity as he could without being in the way.

“And to be high enough to interfere if something has slipped,” Larry decided on the purpose in Jeff’s mind. Then, as the amphibian came roaring up a hundred yards to their left, and in a wide swing began to circle the yacht, Sandy screeched in excitement and pointed downward.

Swiftly Larry threw his binoculars into focus as he swept the length of the yacht to discover what caused Sandy’s cry, for with a wing in his way he did not see the stern. They swung and he gave a shout of dismay and amazement.

“No—but there’s a life preserver in the water—it was thrown over but the yacht isn’t stopping.” His glasses swept the bridge, the deck.

Turning away, back to his view, in a dark dress, a woman who had been at the extreme after rail was racing out of sight behind the cabin.

“There’s a life preserver in the water!” Dick could see it without glasses. Sandy looked.

Fast and high, in a swift glide, coming like a hawk dropping to its prey, a light seaplane, skimming the edge of an incoming fog bank, showed its slim, boatlike fuselage and wide wingspan, with two small pontoons at wingtips to support it in the surf.

There was a swift drop of their own craft as Jeff dived, came into a good position and zoomed past the yacht, close to it.

Wildly, as those on the bridge came into clear view, Sandy, Larry, Dick and Jeff gesticulated, pointing astern. Bells were jangled, the yacht was sharply brought up by reversed propellers and a tender was swiftly being put down from its davits, an excited sailor working to start its engine, even as it was lowered.

Then, helpless to take active part because they had no pontoons, the Sky Patrol witnessed the maddest, strangest race staged since aviation became a reality. And the prize? A mysteriously flung life preserver!

CHAPTER V
MYSTERY IN THE FOG

While Sandy watched the amphibian and Dick stared at the rapidly approaching sea plane, Larry gazed at the swift hydroplane and noted the feverish attempt on the yacht to get its tender going as it struck the surging water.

Swiftly he snapped the binoculars to his eyes as they receded from the yacht in the onrush of their zoom.

But there was a woman on the bridge with the white uniformed captain and a navigating officer. She was in dark clothes! But she had been there all the time. He suddenly recalled the French maid Jeff had mentioned in the hotel. That answered his puzzled wonder. He knew who had thrown that life preserver, at any rate. It could not be the mistress. It left only the maid to suspect.

“She’ll get there—they see the life preserver!” he cried, looking past the tilting wing as they executed a split-S to turn to head back the quickest possible way.

“The amphibian can set down on the water and she’ll pass the place—already there’s somebody climbing out of the front cockpit onto the wing—to grab the thing as they pass!” Sandy muttered.

“That seaplane is coming fast!” mused Dick. “What a race! It will be a wonder if there isn’t a smash when they all come together!”

With a warning cry that was drowned by their engine noise, Larry saw that the amphibian was in such a line of flight that it must be crossed by the course of the hydroplane—and from the respective speeds, as well as he could judge, there might be either a collision or one of the craft must alter its course.

“The seaplane is almost down on the water—and coming like an arrow toward that white preserver!” gasped Dick. “Will its wings hit the yacht?”

Evidently Jeff either caught his thought or decided on a course through his own quick wit.

Opening the throttle full-on, he kicked rudder and depressed his left wing. Around came the airplane. Skidding out of her course from the momentum and the sharp application of control, she moved sharply upward and sidewise.

Flying fast, in a steep descent, they went across the nose of the amphibian, and in the turmoil of their propeller wash she went almost out of control, and before her pilot caught up his stability the hydroplane raced across her path in a slanting line and made for the small round object bobbing in the trough between two swells.

Quick to take it, dipping a wing and kicking rudder, the seaplane’s pilot swerved a little, leveled off, and set down in a smother of foam, and on his wing also a man climbed close to the tip!

He had no time to pay attention to that situation. The imminent culmination of the race chained his gaze.

“The tender is almost there—oh!” gasped Sandy, “the seaplane must be rammed by the tender!”

But the yacht’s boat, with its motor hastily started, and cold—lost way as the engine sputtered and died!

Slackening speed, the seaplane raced along until, with a hand clinging to a brace and his body leaning far over the dancing waves, its passenger on the wing scooped up the life preserver.

The tender, its engine missing badly, turned its attention to the man in the water, but before it could get to him or near him Sandy, Dick and Larry saw that he caught the tail assembly of the amphibian and scrambling over the fuselage as the craft picked up speed, fell flat on his stomach just behind the pilot’s place and clung tightly while the craft got “on the step” and went into the air in a swift moil of foam and a roaring of its engine.

Outgeneraled, the hydroplane cut speed and swung toward the yacht, followed by the tender.

Kicking rudder and dipping a wing, almost wetting it in the spray of a breaking comber, he flung his airplane into a new line of flight, reversed controls, giving opposite rudder and aileron, got his craft on a stable keel and gave it the gun as he snapped up the flippers to lift her nose and climb after the retreating ’plane.

Far behind them in their swift chase, with every ounce of power put into their engine and their whole hearts urging it to better speed, the Sky Patrol saw the amphibian swerve toward shore and give up the try for whatever that precious life preserver had attached to it.

That something had been cast overboard, tied to the float, was obvious to Larry, Dick and Sandy.

What a chase! Speed was in their favor, because the seaplane, fast as it was, lacked the power of their engine which they learned later that Jeff had selected for that very quality.

Their problem was to get above it, to ride it down, force it to take the sea or to come down in a crackup on shore if that must be—before it could lose itself in that dull, gloomy, lowering bank of fog ahead.

“Climb, Jeff!” Sandy begged, hoping their pilot could ride down the craft ahead.

But Jeff held a level course. He had to, in order to maintain the advantage of speed. He thought he could get alongside their quarry before the mist swallowed it, hid it, ended the pursuit.

Hardly more than two hundred feet behind, they felt the cold, clammy fingers of the cloud touch their shrinking faces.

Where was the seaplane? Would it climb above the murk, glide straight through it and down, swerve and glide—or dive out and risk leveling off and setting down just beneath the bank so that its rapidly coming folds, and the silent sea would make a safe and comfortable concealment?

Slowly, almost in a “graveyard” glide, so flat was the descent, to hold flying speed and stay as high as they could, their airplane moved along. They listened.

“This can’t last long, for us,” thought Larry. “We’ll be down to the water before we know it!”

“They must be listening for us, in the seaplane,” Sandy decided. “I know there was a pilot and the man who got the life preserver. I wish I could have gotten a good look at either one, but the pilot had goggles and his helmet to hide his face and the other man had his back turned to us. Where can they be? What are they doing?”

Through a thin cleft in the heavy mist, not far below them the dark outlines of eel-grass, flanking two sides of a channel in the swampy shore line stood out, for an instant, clear and menacing.

Dick echoed the cry. Jeff had already caught the threat of that swamp below them. They could not risk going a foot lower. The pilot opened his throttle, picking up climbing speed to the roar of his engine.

Not only had they given in. Jeff, it appeared, had given up. In thickening mist the risks were too great.

Jeff was climbing for the top of the bank, where he could come into the clear, get some idea of his location and return to report defeat to the yacht whose captain probably lay-to, waiting for news.

“Oh, well,” Dick was always hopeful, “maybe we’ll get a ‘break’ sooner or later.”

With suddenly thinning rifts parting overhead they shot out into the clear sunlight. Beneath, stretching up disappointed fingers of murk lay the bank of fog.

CHAPTER VI
THE END OF THE CHASE

Having heard their own engine, the pilot of the seaplane had decided to risk a dash out of the fog and to try to escape.

When they climbed above the lower shoreward mist the cry from Sandy drew their attention to the seaplane, even higher than they were, and going fast across the narrow end of the island.

Jeff dropped a wing sharply—kicking rudder at the same time. Onto the trail swung their craft. Righting it Jeff gave the engine all it would take, climbing.

Larry, more conversant with flying tactics, decided that Jeff meant to get to a higher level than they occupied, to outclimb the less flexible seaplane, so that he could swoop upon it with the advantage of elevation to help him overtake it.

“Now we must be higher than they are!” Larry muttered. “Jeff—for crickety-Christmas’ sake—catch them!”

Jeff leveled and their engine roared. In a quartering course, evidently making in an airline for some point on the Connecticut side of Long Island Sound, the seaplane held its way.

Gaining in a very flat descent, calculated, as Sandy could see, to bring them either alongside or—if fortune favored them—onto the tail of the other craft, Jeff drew closer.

The seaplane sheered to one side in a violent slip as her pilot evidently tried to bank and kick rudder and lost control.

The seaplane wavered, caught itself in a steadier line. In the pursuing airplane three youthful faces grew intent.

Down, almost like a hawk falling to its prey, the seaplane went through the still air.

Trembling with excitement Larry caught up the binoculars. They were still too far behind for clear vision unaided by glasses.

Silhouetted against the northern blue of the sky, with a tiny white circle showing sharply in the sunlight, the leaping person fell clear of the diving seaplane, while Larry, shaking with excitement, tried to focus his glasses and train them on the falling object.

“He’s harnessed to a parachute—there goes the ripcord!” Sandy would have leaped to his feet but for his restraining safety belt.

“The life preserver snapped out of his hand!” Larry muttered, giving up his effort to locate the moving objects in the glass and using his unaided eyes to view the tragedy—or whatever it would prove to be.

The life preserver was jerked away by the jar when the parachute arrested the fall sharply, making it impossible for a handgrip to retain the rope of the swiftly plunging white circle.

“Why doesn’t the other one jump clear!” Dick’s heart seemed to be tearing to get out through his tightening throat. Which one was under the parachute? Which stayed in the falling seaplane—and why?

An arm of mist, swinging far over the land, intervened between their vision and the shore line.

More deliberately, settling down, first the hanging bulk of the unknown man, then the spreading folds of the parachute drifted into mist—and mystery.

CHAPTER VII
THE SWAMP GIVES UP A CLUE

“We can try to drop down into the fog,” called Larry to Dick as their pilot, with closed throttle, nosed down to get closer to the scene of the tragedy.

“But we can’t set down or do anything—and we can’t see much for the fog,” objected Dick. “I think we ought to go back and drop a note onto the yacht, telling the people to come here in a boat.”

Larry agreed with this sensible suggestion and Dick, scribbling a note, passed it to Sandy. After a glance the younger of the trio gave it to Jeff. The pilot nodded when he read it.

Again the engine roared as they swung around, laying a course to take them above the rolling mist, toward the end of the island around which—or beyond which—the yacht should be cruising or waiting.

“It will be hard to find the yacht in this fog,” Sandy mused, but as they flew along he, with the others, scanned the low clouds for some open rift through which to catch a possible glimpse of the water craft. A slantwise gust of wind crossed the cockpits, giving them new hope. If a breeze came to blow aside the mist they might have better chances to see the yacht.

In steadily increasing force, and gradually coming oftener, the puffs of moving air increased their confidence.

With the breeze from the new direction, as they steadily got closer to the end of the island, coming over a spot where a break in the cloud showed brown-yellow sand and rushing white surf beyond the wide level beach, Sandy’s alert eyes caught sight of something for an instant. Prodding Jeff, he indicated the object.

As Jeff swooped lower, inspecting, Dick caught a good glimpse of the tilted, quiet focus of Sandy’s gesture.

“There’s the amphibian,” Dick muttered. “Stranded—cracked up, maybe. But—if we could get down and land, we could use her, two of us could, to go to the swamp and see what’s there—before anybody else gets to the life preserver the jewels must have been tied to.”

Jeff agreed, made his bank and turn, as Sandy saw the drift of a plume of smoke on the horizon, to get into the wind.

“It looks safe for a landing—pretty solid beach,” Larry concluded, and evidently Jeff felt the same way for he climbed in his turning bank, got the wind right and came down, using his engine with partly opened throttle to help him settle gradually until the landing wheels touched when the tail dropped smartly, the gun was cut, and the sand, fairly level and reasonably well-packed, dragged them to a stop.

Hurriedly the youthful Sky Patrol tumbled onto the sand, digging cotton plugs out of their ears now that the roar of the motor no longer made them essential.

“It’s the amphibian, and no mistake!” Larry cried, running down the beach toward the titled craft.

“If she isn’t damaged,” he told Dick, “you and Jeff, or Jeff and I could fly to the swamp in her.”

“You go.” Dick was generous to the friend he admired, and who was almost a year older. “It would need a cool, quick head to handle whatever you might find in the swamp. You go.”

That also was Sandy’s opinion when, after a rapid inspection, they agreed with Jeff that the amphibian, set down with only a strained tail skid and a burst tire in the landing wheel gear, was usable.

“But there’s no gas,” objected Larry, noting the indicator in the control cockpit. “See, the meter says zero!”

“It was that way when I looked before,” Sandy said. “That was why I didn’t think anybody meant to use it——”

“Easy to fool you on that,” Jeff declared. “It’s been disconnected. I wouldn’t be surprised if that-there tank wasn’t nearly half full. They had it all fixed and ready——”

“Let’s go, then,” urged Larry. “Dick, look over the pontoons for strains, will you? She may have struck one of them—she has tipped over part way, maybe hit one of the pontoons.”

Dick, examining with the thoroughness of an expert, with Jeff’s and his chum’s life perhaps depending on his care, stated that he saw no damage to the waterproofed coverings of the water supports. Declaring that they would stand by and watch the airplane, Sandy and Dick watched Larry and Jeff get settled, Dick spun the propeller to pump gas into the still heated cylinders, Jeff gave the “switch-on—contact!” call, Dick, pulling down on the “prop,” sprang aside to avoid its flailing blades, and the amphibian’s engine took up its roar.

Acting as a ground crew, Dick righted the craft by thrusting up the wing which was evidently not seriously damaged, while Sandy, as the motor went into its full-throated drone, shook the tail to lift the skid out of the clogging sand. His eyes shielded from the sand, blasted back by the propeller wash, he leaped sidewise and backward as the elevators lifted the tail and the amphibian shook itself in its forward lunge, lifted, flew within two inches of the sand, and then began to roar skyward.

“They won’t be any good, with that burst tire—he’ll have to set down in water anyhow,” Dick explained. Sandy nodded.

Waving to his two watching comrades as they grew smaller to his peering eyes, Larry turned his attention to the work of scanning, from the forward place, all the indented shore line, north, that the mist had uncovered.

To their left, as they sped on, the lighthouse poked its tower out of the drifting, dispelling fog.

Soon Jeff dropped low, diminished the throb of the engine, cruising while Larry kept watch.

Jeff, peering, located the wing of the seaplane, the fuselage half submerged in muddy channel ooze, the tail caught on the matted eel-grass.

In the mouth of a broad channel they touched water and ran out of momentum with the wings hovering over the grassy bank to either side.

Already Larry had his coat and shoes off. Stripping them off, and with no one to observe, removing all his clothes, he lowered himself onto a pontoon and thence to the water, chilly but not too cold on the hot June afternoon.

Striking out with due care not to get caught by any submerged tangle of roots or grasses, Larry swam the forty feet.

“The pilot’s in his cockpit—” he gasped. “He’s—he isn’t——”

“Get that collapsible boat on the back of the tank, there!” urged Jeff, “and come back for me.”

It took inexperienced Larry some time to open and inflate the tubular rubber device used for supporting survivors of any accident to the seaplane while afloat.

“He’s—I think he’s alive,” Jeff declared fifteen minutes later. “That’s a bad slam he’s had on the forehead, though.” He lifted the silent pilot’s bruised head, put a hand on his heart, nodded hopefully and bade Larry dash water in the man’s face.

“His parachute isn’t loosened or unfolded,” he responded, working to get the spark of life to awaken in the man he bent over. “No, Larry, from the looks of things—somebody hit him, while they were away up in the air, and jumped—with that life preserver.”

“Where is he now? If only I could get my hands on him. I wonder who it was?”

“Never mind,” Larry urged. “Can you get him into the boat, somehow, Jeff? You ought to land him at a hospital—or at the nearest airport. There’s a medical officer at every one—for crack-ups. Or, fly and telephone for help!”

Without further words or conscious movements from the silent pilot they managed to get him unhooked from his belt and parachute harness, to lower him, precariously limp, into the rubber boat, which Larry held onto as Jeff, half supporting his inert co-pilot, propelled it to their own craft.

As they moved slowly along Larry, fending off a clump of tough grass into which the breeze sought to drift their rubber shell, caught sight of something dimly white, far in among the muddy grass roots.

He left his support, swam across the smaller channel, carefully, and secured the life preserver which had dropped into a heavy clump of the grass and then had floated free of the mud, held only by the end of a tangled string—and the skin of an empty, oilskin pouch, torn and ripped to tatters, that hung to the cord.

When Larry rejoined Jeff, he flung the life preserver into the space behind the control seat of the amphibian, leaving it there without comment as he helped Jeff to lift and drop the still unconscious man into his own forward place.

Then, pushing off in the rubber boat, he sat still, his dry clothes in a compact bundle in the boat thwarts, while Jeff let the wind and tide-run carry his amphibian out of the channel to where he could get sea space for a start, to get the amphibian pontoons “on the step” from which, with his silent cargo of human tragedy, Jeff lifted into air and went out of sight, southbound.

“Well,” he reflected, “its something, now, anyway. We can look for a Frenchman—and learn if there’s one named Gaston.”

He sculled back to get under the shading, up-tilted wing of the seaplane, studying what he saw of its half submerged after place.

CHAPTER VIII
SANDY MEETS A “SUSPECT”

Sandy and Dick, standing by the airplane on the beach, whirled to see a short, stoutish man in regulation flying togs come unexpectedly into view from behind an inshore hillock of sand.

Sandy discerned instantly that he was looking at the pilot who had handled the control job on the amphibian during the recent excitement.

The stranger had a pleasant, round face, with eyes that twinkled in spite of the creases around them that showed worry. No wonder he was worried, Sandy thought: having deserted the craft they had foiled in its attempt to get the gems, the man had returned from some short foray to discover his craft replaced by another.

“Howdy!” Dick greeted the stranger and replied to his exclamation. “No, sir, you’re not seeing things! At least you’re not if you mean the airplane near where the amphibian was——”

Sandy wanted to nudge his comrade, to warn him to be careful. There was no chance; the man was observing them intently.

“Amphibian? You know the different types, eh? May I ask if you belong around here, and if not, how you got here—and who took the ‘phib’?”

Unable to check Dick, his younger chum had to stand, listening while Dick related some of their most recent adventures.

“As I live and breathe! So you’re two of the lads who were in the other ‘crate’. Where’s the third—and was that Jeff with you? I thought it must be.”

Dick judged the man to be both friendly and “all right,” from his pleasant, affable manner and his evident knowledge of their pilot’s identity.

This man might be “in cahoots” with Jeff, and Sandy was determined not to take Jeff, or anyone else, at face value too readily.

Jeff had falsified the true reason for the landing in the Everdail field. He might falsify other things—his real reason for flying out to the yacht. This man might be his partner in some hidden scheme. Even the Everdail Emeralds, Sandy decided, might be just “made up.”

“Nothing has been what it seemed to be,” he mentally determined. “I wish Dick would be careful what he says.”

Since Dick had already given the man a sidelight on Jeff’s character by mentioning his superstitions, it occurred to Sandy that he might learn, from the stranger’s reply, how well he knew Jeff.

His expression, as Sandy watched narrowly, became one of amusement, he smiled broadly, threw back his head and as he answered Dick’s phrase about superstitions and all, he laughed.

“He must have walked under a ladder, from the way things have turned out,” he said, amusedly.

“Me? Oh—” Did the man hesitate, Sandy wondered. It seemed to be so before he continued. “I’m Everdail.”

“Mr. Everdail?” Even Dick, questioning as he repeated the name, was a little doubtful. “Why, I thought Mr. Everdail was in——”

“California? So I was. But one of my air liners brought me across in record time.”

Anybody could have learned that the millionaire was in California, Sandy reflected; it would be easy for a clever jewel robber, one of a band, to impersonate the man when he was caught off guard by their exchange of aircraft.

“If you boys were with Jeff you must be all right,” the man advanced, hand extended.

Sandy’s grip was less cordial, but he played the part of an unsuspecting youth as well as he could by finishing the handshake with a tighter grip and a smile.

“I thought Jeff might be in the ship, yonder, until he nearly threw us out of control with his propeller wash. Then I thought—he might be——” he hesitated.

“He thought you might be—” Dick smiled as he made the response, winking broadly.

“As long as you’re not, and I’m not—what neither of us cared to say,” he turned toward the airplane, “let’s get together! I’m here because my passenger, a buddy of mine, wrenched his shoulder climbing back into the ‘phib’ and we set down here so I could leave him at the fishing shack, yonder, and go back to see what was what. He was in too bad shape to take chances if I felt called on to do any stunts—I thought I could take the air in time to catch that seaplane coming out of the fog, but it fooled me. I already know why you’re here,” he added, “suppose we hop off in Jeff’s ‘crate’ and give a look-see if your friend and my war buddy need any help.”

“You can’t set down if they do,” objected Sandy, his confidence in the man’s possible guilt shaken by his knowledge of Jeff’s war record. “I don’t see, for my part, why Jeff didn’t use the amphibian in the first place!”

“I wondered about that when I got in at the estate, soon after you’d left,” Mr. Everdail—or the man who claimed to be the millionaire—asserted. “I could see he had been working on it, getting it ready—even had the tank full up, but he had disconnected the fuel gauge to fool anybody who might be looking around, I guess.”

“Maybe he landed and changed his mind about using it,” Dick suggested. “On account of taking us in—we organized a sort of Sky Patrol, to oversee things—but everything went wrong.”

“That accounts for it. I didn’t know he was going to make the hop or I might not have come myself—but now—well,” the man broke off his phrase and started to clamber into the control seat, “let’s get going.”

Sandy, who had spoken, felt his suspicions returning at the reply. Could there be any reason why they must not identify the other man? Might he be the ringleader, or have some outstanding mark that they had seen before and might recognize?

Dick performed the “mech’s” duties for the pilot in getting the engine started again, then he clambered into his old place. Sandy was already behind their new pilot.

“Whoever and whatever he is,” Sandy mused, “he knows how to lift a ‘crate’ out of the sand.”

The man claiming to be Mr. Everdail made a skillful getaway from the beach, and it took them very little time to get over the marsh, already free of fog.

Dick located the crack-up, Sandy indicated the spot and the pilot dropped so low that his trucks almost grazed the waving eel-grass.

“There’s no amphibian in sight, though!” Dick murmured. “I wonder——”

Larry, in his rubber boat, just having given up trying to explain how a number of bits of chewing gum had transferred themselves from the amphibian, where last he saw them—or some like them—to the seaplane, gestured and pantomimed to try to tell them his news.

The new pilot waved a reassuring glove at Larry and swerved back toward the end of the island. Larry wondered who he was and what his comrades were doing with him; but Larry, always practical, let the questions wait for their eventual answers and continued to study the half-sunken seaplane.

No new clues offered themselves. He detached one of the hard, adhering chunks of gum and dropped it into his pocket, “just in case,” he said, half-grinning, “just in case they transfer themselves somewhere else. I’ll leave twenty-nine of them—and see.”

The supposed Mr. Everdail scribbled a note which he handed back to Sandy, who caught his idea of dropping instructions on the deck of the yacht.

Their pilot was skillful at coursing in such a direction and at such a height that he could skim low over the water craft’s radio mast and come almost to stalling speed while Sandy cast the note overside.

Dick, who had caught up Larry’s abandoned binoculars, saw as they zoomed and climbed that a sailor had rescued the note before it bounded over the cabin roof and deck into the sea.

At once the hydroplane was manned and sent away, the yacht took up its own course, and Mr. Everdail—to give him his own claimed title—pointed the airplane’s nose for his estate. Sandy occupied the time of the flight by trying to piece together the strangely mixed jig-saw bits of their puzzle—or was it only one puzzle?

By the time they sighted the hangar and field, he had all the bits joined perfectly. Sandy’s solution fitted every point that he knew, and was so “water tight” and so beautiful that he landed with his face carrying its first really satisfied, and exultant grin.

The beautiful part of it, to Sandy, was that he could sit by and watch, do nothing, except “pay out rope and let them tie themselves up in it.”

“Let them guy me and call me ‘Suspicious Sandy,’” he murmured as he followed Dick toward the wharf on the inlet by the shore of the estate. “If I untangle this snarl the way I expect to, I may not bother to go in for airplane engineering. There might be as much money in a private detective office.”

“Well—hm-m!” he remarked to Dick, “feels good to be on the old place again. First time I’ve set foot on it for three years.”

“And he told us, on the beach, he’d been here this morning,” Sandy whispered to himself.

“Look here, boys,” he said earnestly, “don’t say a word to her about me! I won’t be here when she lands—and I don’t want it known I’m in the East. There’s a good reason——”

CHAPTER IX
JEFF ENCOUNTERS A “JINX”

Turning with a confidential air and addressing Dick, for whom he seemed to have the greater liking, Mr. “Everdail” spoke.

“I’ve just thought of a good scheme. Has Jeff—er—taken you into his confidence any?”

Sandy, helpless to interfere, heard Dick give the substance of what they had learned from the superstitious pilot. The man continued:

“That lets me snap right down to my plan. Now we don’t know where those emeralds are. We don’t know which people used the seaplane, or whether the man who jumped has them and has gotten away or not. But if I should fade out of sight, and no one but my dependable Sky Patrol knows I’m around——”

“Your dependable Sky Patrol!” Sandy thought. “Going to try to use us now. Well——”

“If no one else knows I’m around—I can watch and see a lot that others might miss. I’m going to have that seaplane brought here—and then I’ll be around, watching to see who comes snooping—if anybody does. As I live and breathe, I think that’s a great idea, don’t you?”

“All right, then. You can tell your other comrade—Larry, you said you call him, Dick. I’ll leave a note for Jeff. Now I’ll go on up to the house and write it and make a couple of telephone calls—and then I’ll drop out of things—but you’ll hear from me off and on till we get those emeralds safe in our hands. Then—even while we’re waiting—if you can get your parents’ consent to stay, which I think can be arranged by Jeff—Larry can take some flying navigation—you, Dick, can study engines and construction, or navigation—whatever you like.”

He put a hand on Sandy’s shoulder and the latter managed not to wince or draw away.

“Sandy can have the run of my library, full of books on engineering and mechanics—and you’ll be learning while you help me get those emeralds and find out who flew the seaplane and who helped them on the yacht.”

“I know I can get my father’s consent to ‘visit you’ here,” Dick said eagerly. “And I like the plan,” he added heartily.

Sandy, watching their confidant stroll toward the closed mansion, turned a cold face to Dick.

“You’re a fine Sky Patrol,” he grumbled. “You swallowed everything he said, like a big softie! And told him everything you knew,” he continued, bitterly.

“All right,” Dick agreed cheerfully. “But don’t start in earning your nickname all over again,” he warned.

The drone of an incoming airplane took them racing to the landing spot where Jeff came down to report that he had taken the unconscious seaplane pilot to a hospital where it was declared that he had a bad blow on his temple and might not recover his mental clearness for many days.

“And I’m glad I’m done with this-here amphibian,” he added. “Had more trouble than I ever had before. I think the crate’s hoodooed.”

“Maybe the ghost haunting the hangar ‘put a spell’ on it,” Dick chuckled. “Well—don’t, worry, Jeff. You’re down safe, and——”

Sandy shook his head. Let them take Jeff up to the house, he decided, and watch the two men when they met. Dick, not comprehending the idea behind Sandy’s headshake, nevertheless, did not finish his sentence.

The roar of a motor boat began to attract their attention and as they went to the wharf again, Jeff wanted explanations of how they got in with the airplane.

“No,” Dick agreed. “I didn’t. You’ll find the man who did up at the house.”

Jeff swerved aside on a graveled path, leaving them to aid the caretaker and his mechanic to bring the hydroplane to its mooring and let Larry jump out to join them.

They compared notes eagerly. Dick and Sandy could hardly forego interrupting one another as they brought their story up to the minute after hearing how Larry had helped to get the pilot to the amphibian, discovering and rescuing the life preserver on the way.

“Now, Larry,” Dick said, finally, “Mr. ‘Everdail’ said we could take you into our confidence, and he’s probably telling Jeff everything. Suspicious Sandy has a theory all worked out. I suppose Jeff is a double-dyed villain, and this Mr. ‘Everdail’ will turn out——”

“It’s no joking matter,” Sandy spoke sharply. “You listen to my idea and see what you think.”

Jeff, the so-called Mr. “Everdail,” and the pilot and passenger of the seaplane, as well as the presumably injured man whom they had not seen—all these were members of an international band of robbers, Sandy claimed.

“The man who jumped with the parachute and life preserver must be named Gaston—from what the pilot said to you, Larry,” he went on.

“Wait till I get to that,” urged Sandy. “Well, they learned, somehow, that Mr. Everdail was in California and his wife was taking the emeralds to London. They didn’t have any conspirator on the yacht—then—or else they would have gotten the real emeralds long ago. So there was just those five in the band—Jeff, Mr. ‘Everdail,’ Gaston, the man we haven’t seen, and the injured pilot.”

“There might have been two gangs, one of three, one of two—or three bands—one of two, one of two, one of one——”

“Thanks, Larry,” Sandy was grateful. “All right, then, the band planned the work in London, at the hotel—that’s how Jeff knew the emeralds were imitations they poured acid on.”

“Did they carry acid just in case?” Dick could not restrain his tendency to tease.

“I think it was something they meant to throw on anybody who tried to stop them.”

“Anyhow, they discovered the false emeralds and tried to destroy them.” Sandy was more confident at Larry’s acceptance of his ideas.

“They managed to get somebody on the yacht,” Sandy guessed, “and then to be sure that there was no hitch, divided into three groups—Jeff, possibly the ringleader after all, in his airplane, two in the seaplane, the other two in the amphibian.”

“The confederate on the yacht was to secure the gems, somehow, and they must have had a radio somewhere to get messages,” Larry was beginning to see daylight and to concur with Sandy’s opinions.

“But Jeff interfered with the amphibian,” objected Dick, “and you forget to account for the two men in the hydroplane.”

“I think it came out the way it does in books,” Sandy declared. “Each set wanted those emeralds, and they tried to outdo one another—and maybe the hydroplane was the honest one of the lot, with Mr. Everdail’s—the real one’s—caretaker, summoned by the captain.”

“I know how that fits,” Sandy spoke earnestly. “The hydroplane men were honest, and Jeff worked into their confidence and offered to help them—to discover the plan!”

“We know what happened. Jeff signaled, but he knew the amphibian was coming, and the seaplane, to make sure neither would break down and leave him helpless—while he supervised,” Sandy had good going now, “the seaplane got the life preserver, and then Jeff decided that they might get away, tried to follow—and while the seaplane was flying, its passenger got the emeralds free of the life preserver, and then——”

“The passenger, while they were high up, threw something and hit the pilot, the seaplane went out of control, the man jumped—and then cut free his parachute, cut the sack holding the emeralds, and hid in the swamp.”

“Why, Dick! Wait till everybody was gone, then take to the rubber boat, get himself picked up——”

“If the boat isn’t there when they bring up the seaplane, I’ll think you’ve hit the nail on the head,” Larry conceded.

“He says you know all about him, but he was gone when I got this-here note.” He failed to display the missive, to Sandy’s disappointment. It would have provided a fine chance to compare the writing with what he had seen in the letter supposed to have come from California. And—if he was really flying East, why had Mr. Everdail written? A letter, by mail, would be slower than an airplane flight!

“I don’t like this plan a-tall, a-tall,” Jeff went on, dubiously. “That seaplane is jinxed.”

“I don’t care, Larry. Listen—she cracked up and her pilot got a bad smash—from something! And—the emeralds vanished!”

“We recovered the life preserver, anyhow,” chuckled Dick. “And here comes the yacht so we can return that much property. I tell you, the Sky Patrol has accomplished something!”

“He says for me to shove my crate in the hangar, stay here, get your parents to let you make a visit and Larry learn flying and so on, but if I put my crate in that hangar—it haunted and now the jinxed seaplane to come in—any instruction I give will be at your own risk.”

“And say—here’s a queer one.” Jeff changed the subject. “I notice them chunks of gum wasn’t in the amphibian! Did you take ’em out when you stayed back in the hangar, Sandy?”

“No—or, if he did, somebody else put the same kind in the seaplane.” As Larry spoke he withdrew from his pocket a dark, hard object.

He tore at the hard substance with finger-nails, working it flatter, and then, with an exultant screech, boy-like but not good practice for an amateur detective, he pointed to something dark, green, glowing.

CHAPTER X
LARRY’S CAPTURE

“How did you ever guess the gem was in the gum?” Dick stared admiringly at Sandy, exultantly at the green light flashing from that hidden emerald as Sandy scraped aside the clinging substance from it.

“First the gum was in the amphibian,” Sandy said, trying to be as modest as the discovery would let him, “then it was gone. We thought we saw somebody in the hangar when first we went in—but he got away somehow. Then we saw the amphibian flying and it flashed over me that whoever we had seen before had been working on the amphibian and had chewed up all those pieces of gum—but I didn’t see why he had left it there. Then, when we found out that the man calling himself ‘Everdail’ didn’t look for or miss the gum, I guessed that he hadn’t been the gum chewer—but who had, then, I wondered. And why. It must have been for some reason, because if he had found the gum when he came to play ghost, keep everybody away from the estate by scaring them, and get the amphibian ready, he’d have throw any gum he found into the waste can.”

“The gum was there for some reason,” agreed Dick. “This is one time when being suspicious has paid,” he added.

“Yes,” Sandy admitted. “When the life preserver was found and no gems were in the oilskin tied to it, and Dick showed me the gum, the reason for the big chunks of old gum came to me. The passenger had been getting it ready. He had to chew a great lot to get enough.”

“We mustn’t waste any more time,” cried Larry, eagerly. “There are twenty-nine more chunks in the seaplane. Let’s fly there, Jeff, and get it.”

“That-there is good sense.” Jeff started toward the flying field. “The fellow we didn’t find might come back for the emeralds.”

Going with them, to help out, Dick told Larry that he proposed to go at once to the various airports and flying fields, to learn, if he could, who had engaged the seaplane.

“The new Floyd Bennett field is the best chance,” argued Jeff. “They have got water and seaplane facilities there. It’s on Barren Island, and that’s where a man could have gone, in about the time between your seeing the ‘spook’ and the time the seaplane got where the yacht was.”

“I’ll wait for the yacht,” Sandy said, accompanying them. “Mrs. Everdail will be glad to see what I discovered.”

Dick had no difficulty in learning, when he got the executives of Bennett field interested that the seaplane was an old one belonging to a commercial flying firm operating from the airport.

“The pilot who handled the control job,” the field manager told him, “was a stunt man who has been hanging around since he stunted on our opening day. I’ve questioned some of the pilots for you, but no one seems to know who the pilot had with him. A stranger, one says.”

Sandy had even less success. Although in the short time since his disappearance the supposed impersonator of Mr. Everdail could not have gone far, he was not to be discovered by any search Sandy could make.

Farmhouses had no new “boarders.” The house on the estate, searched with youthful vim and alert thoroughness, revealed no observable hiding places. Sandy finally gave up.

The arrival, anchoring and debarkation of its people by the yacht allowed him to meet and to reassure Mrs. Everdail and Captain Parks.

Besides these two he met the almost hysterical French maid, Mimi, also Mrs. Everdail’s companion and cousin, who had traveled with her, a quiet, competent nurse and attendant whose lack of funds compelled her to serve as a sort of trained nurse for the millionaire’s wife, who was of a very nervous, sickly type.

In spite of everybody’s relief when Sandy displayed the emerald, the elderly trained nurse and companion insisted that Mrs. Everdail must retire, rest and recover from her recent exciting experience.

Landing the amphibian, at almost the same spot they had set down before, Jeff looked around for the rubber boat they had left tied to a sunken snag.

“I guess Sandy’s ideas were right, after all,” decided Larry as he saw that the small water conveyance was not there. Sandy had claimed that if the missing seaplane passenger had hidden during the recent search of the seaplane, the boat would aid him to escape from the otherwise water-and-swamp-bound place.

“If the rubber boat’s gone,” Jeff commented, “the twenty-nine other emeralds of the thirty on the necklace—they’re gone, too.”

“I’ll have to swim over again and see.” Larry stripped and made the short water journey.

Jeff, who had kept his engine idling, decided to risk a closer approach in the amphibian whose lower wingspan barely cleared the tops of grass clumps.

“I guess there aren’t any snags to rip the pontoons,” Larry assured him. To get closer would save Larry many trips to and fro in the water.

“Fine!” Larry commented as the amphibian, moving cautiously, came close enough for him to catch a rope and put a loop around the closest truss of the submerged seaplane. Thus he was able to pass the chunks of gum to Jeff, who had his clothes on and pockets for storage.

While the transfer was being made the amphibian’s engine died with unexpected suddenness.

“Can’t tell by the gauge.” Ruefully Jeff upbraided his stupidity in forgetting to see if they had to gas up before the take-off from the estate.

Larry, too, saw a number of difficulties—perhaps more than did Jeff, because, from Larry’s point of view, due to Sandy’s suspicion of the superstitious pilot, Jeff must not go free with the gems in his pockets, nor did Larry dare be the one to go. If he did, Jeff might be playing a trick, let him get beyond chance of return in time, use some reserve gas and fly away.

“I can’t swim,” Jeff began, considering the ways of escape to some place where they could secure a supply boat with fuel.

“I wouldn’t chance swimming all the way down the swamps to the nearest village on shore,” Larry said quietly.

“This-here is a fix that is a fix,” morosely Jeff summed up the situation. “Here we are with a pocketful of emeralds—and no gas and no way to get to any—and if anybody knows the gems are in this gum—we’d be helpless if they wanted to take them.”

One thing that kept coming into his mind was the strange fact that if the disappearing passenger of the seaplane had taken the rubber boat he had not also taken the hidden jewels.

“He must have known something about them—or guessed,” he reflected. “If they were put in the gum while they were flying—unless it was done while they were in the fog. But, even then, he knew all that excitement meant something. I don’t understand it—he did know, because he must have hired the pilot and the seaplane to get the emeralds.”

Still, in that case, he mused, if the man had known where the gems were, why hadn’t he inflated the rubber boat and taken them all, in the first escape?

Saying nothing to Jeff he bent his whole power of thinking on the more important discovery of a way to get fuel.

Climbing onto the amphibian and dressing, he considered that matter without arriving at any workable solution.

His eyes rested for a moment on the upthrust wing of the submerged seaplane. His face changed expression. An idea flashed across his mind.

“Jeff,” he cried, “do you suppose we could make a gas line from the brass tubing on the seaplane?”

“See that wing?” he pointed. “It sticks up, and it’s higher than our own tank—and if there’s a wing-tank, and I think a seaplane would have them——”

“Why didn’t I think of that?” grinned Jeff. “I wouldn’t be surprised if that-there is right.”

He carefully climbed out onto the amphibian’s lower wing till he could grip a guy wire on the seaplane. By agility and a good deal of scuffling with some damage to the doped fabric of the seaplane, he got into the partly sunken pilot’s seat and from that, climbing up, sent a quick glance over the cockpit, tracing the fuel lines.

“Right as can be!” he called. “Now if I can find a wrench and get loose some brass tubing——”

“Stay where you are,” he called. “Two might push the crate down into the mud too fast for safety. She’s half a foot deeper in than when we were here before. I’ll manage.”

Shutting off the governing valve, Jeff began unscrewing the pipe lines, rejoining lengths of piping until, with a section from the carburetor to give the needed length, he passed over a makeshift path for the wing-tank gas to flow by gravity into their own craft.

“All ready!” called Larry, bending the end of the line so its flow went into the central tank of the amphibian.

“We’ll get enough to hop down the shore to a fuel supply, anyhow,” Jeff said.

The gauges were out of commission and they had to figure the amount they secured from the size of the pipe and time that the gas flowed.

“I guess that’s all—about seven gallons,” said Jeff as the last drops fell into their tank. Larry threw aside the useless pipe, sent home the tank cap and dropped down into the after seat to be sure the ignition was off before Jeff swung the propeller sturdily to suck the gas into the cylinders.

So intent had they been on the business of the gas transfer that as Jeff swung the “prop” both were taken by surprise when a curt voice came from close under the amphibian’s tail assembly.

A man, coming silently from some concealment, in a dory, undetected in their busy absorption, held something menacingly businesslike and sending sun glints from its blue steel. Its hollow nose covered both at the range he had.

“Now!” remarked the stranger, pulling the dory around without losing his advantage, “both turn your backs and clasp your hands behind you!”

“Wait!” said Larry, suddenly, earnestly. “I’ll give you the jewels without making any trouble—if you’ll let me put my hand in my pocket I’ll throw the emeralds down to you.”

Larry had no emeralds and was well aware of it. Jeff still made his pockets bulge with the packed chunks of gum.

But Larry had seen a chance that they might turn to their own advantage if once the man’s eyes could be diverted from Jeff. Just before he had clambered onto the forward bracing to spin the amphibian’s propeller, Jeff had laid down the sturdy wrench he had used for bending the pipes; evidently he meant to transfer it to his own tool kit but had wished to start the amphibian’s engine first.

The wrench, within his reach, could be used as a weapon. Larry had caught Jeff’s flash of the eyes toward it as his hands had been elevated. From Jeff’s expression Larry saw, out of the corner of his eye, that the older pilot caught the younger comrade’s purpose.

“All right,” the man had recovered his surprised wits and was closely watching Larry. “Which pocket?”

“This one!” Larry, carefully keeping fingers spread wide, tapped one side of his coat.

“It’s stuck!” Larry began to tug, with his hand in his inside pocket where he pretended the jewels were.

Jeff’s hand flashed down, the wrench, with a twisting, underhand fling, spun through the air. Jeff dropped into the cockpit. The wrench struck, hitting the man’s arm and deflecting the muzzle of his weapon as it exploded—but he did not drop it.

In that split minute of time Larry was on the cockpit seat—and plunged, in a swift, slantwise leap, down upon the man in the dory.

His unexpected assault was executed so rapidly that the man had not time to recover from the surprise and get his weapon trained, before Larry was on him, sending him sprawling backward.

Larry, startled, seeing the pain in the face just under his own, relaxed for an instant, only being sure that his quick grip on the wrist holding the weapon in its hand was not released.

“Oh!” the man groaned, and dropping his weapon, he began to nurse his shoulder.

Larry suspected some trick, but there was none. The man tamely surrendered. As he nursed his painful muscles, a sudden misgiving came over Larry.

The man, he recalled, in pulling with his arm, had winced, before he got the dory where he wanted it. His cry, his subsequent favoring of his shoulder, told Larry the truth.

“You’re the man who was in the amphibian when Mr. Everdail flew it!” he said. “How did you get here, with your injured shoulder?”

“Tide brought me through a channel. I felt better, saw a spare dory and watched some debris on the water and reckoned the tide would get me to where I could see where the amphibian set down. I saw it hop off the beach, saw it disappear, heard it and saw it coming back—and was curious—but how did you know about Mr. Everdail—and who was in the seaplane, and in the other crate I saw?”

“Here comes the tug and floating crane, to salvage the seaplane,” said Jeff. “You’ll have to stay in the tug deckhouse, till we get the straight of this—and for holding a gun on us. You can explain to the police, maybe—as for us, we don’t need to explain!”

And, as later, he and Larry resumed their places in the amphibian, Larry’s captive remained under guard on the tug.

CHAPTER XI
“POP! GOES OUR MYSTERY!”

Before the lowered landing wheels of the amphibian touched the private landing field, after a flight delayed by the need of more fuel, Larry saw his chums waiting by the hangar.

As the aircraft taxied to the end of the runway he saw that their expressions were doleful.

“Our adventure is over and done with,” Dick said. “It has gone ‘poof’ like a bursted soap bubble.”

“But Jeff and I have caught the man who was with the one claiming to be Mr. Everdail——”

“Claiming to be,” Sandy said disgustedly. “I was wrong. He is Mr. Everdail.”

“He wrote the note for Jeff, and then called up the hospital where the pilot was taken,” Dick stated. “They said the man seemed to be coming out of his sleep and Mr. Everdail went out to the road while we weren’t especially watchful, and got a passing car to take him to the next village. Then he took a taxi to the hospital.”

“Carbon monoxide—deadly fumes that blew in from the exhaust of the engine—it was an old crate, and the engine didn’t have perfect combustion, he said,” Sandy gave the explanation.

“The direction they flew,” Dick added, “across the wind—the fumes blew into his cockpit. It was set low, you know. Well, before he knew what was what, he felt himself going. Then he thought he could snap out of it, loosened his safety belt, tried to lift himself for a breath of pure air—the seaplane dived, and he fell against something that knocked him out!”

“No. He didn’t throw anything. The pilot explained all that,” Dick said, while Jeff formed an interested fourth of the group. “You recall, Jeff, the captain of the yacht took out extra insurance on the emeralds?”

“The English company became suspicious,” Dick went on. “They sent a man—we’ve called him ‘the passenger’—to this side, suspecting that some effort was on foot to hide the gems or get rid of them till the insurance was paid—it’s a trick that has been worked.”

“I begin to understand,” said Larry. “The man from England hired the stunt pilot to fly him out to meet the yacht—but how did he know when it would arrive?”

“I can,” said Jeff. “That English fellow was that-there ‘spook.’ Maybe he ‘listened in’ on the short wave set in the big house yonder.”

“That’s probably it,” Dick retorted. “Anyway, he flew out, and when he saw the amphibian and the small hydroplane and our airplane, he jumped to the idea that either one or more gangs of robbers had somebody on the yacht to get the jewels and throw them out, or else——”

“That’s so,” said Dick. “Let’s go up to the house and see what Mr. Everdail says.”

“Oh, his wife would know any impersonator,” argued Dick. “So will Jeff.”

That the millionaire was genuine, “in person and not a caricature,” as Dick put it, was evident. Both the nurse, his relative, and his wife, were chatting with him as Jeff delivered the heavy packed ball made up of the gum.

“That’s simple enough,” responded the rich man, breaking the exhibit into its separate pieces. “The special agent from England, watching here, had seen Jeff making his nightly hops over from the airport. He thought, quite naturally, Jeff was working with some jewel robbers.”

“This will. The agent from London thought it likely that some attempt would be made to get the jewels. He proposed to see whether it would be made by professionals or by some one working for me. He thought my wife or I had the intention of robbing ourselves—making the gems disappear until we could collect the insurance. When he couldn’t make up his mind which was most likely—professionals or amateurs hired by us—he thought of trying to get the jewels—and that meant——”

“A safe hiding place if he was followed, until he could get to a vault and notify his firm,” Sandy broke in, eager to declare how mistaken he had been by giving the true facts.

“And how about the man who was with you?” Larry turned to Mr. Everdail, while Mrs. Everdail with a little grimace of disgust, drew Sandy’s first discovery of the gem in the gum closer to look at.

“He’s one of my divisional managers in the transcontinental tourist airlines,” stated the millionaire.

“Then we’d better get him off that wrecking tug,” and Larry gave the story of the man’s appearance and capture, giving Jeff the credit which Jeff, generously and promptly, returned to him with interest.

“Well,” concluded Mr. Everdail, “here are the emeralds, minus the chain, which can easily be duplicated. And you know who’s who, and why the hangar seemed to be haunted, and all about the gum. Is there anything you don’t understand?—before Larry starts taking flying instructions from Jeff and you others join my wife and I for a cruise to Maine where I will leave Mrs. Everdail.”

“Yes, sir,” Larry responded. “We saw that parachute the man in the seaplane had come down with—the harness was unbuckled, so he wasn’t hurt in the drop. What I want to bring up is this: why did he desert the stunned pilot—and not appear when we landed there?”

“I wonder,” the millionaire was thoughtful. “I wonder what you would do if you had to make a ’chute jump and then, after the excitement discovered that the pilot was ‘out’ and had a blow on the temple—and with concealed jewels in his cockpit——”

“But why were the chunks of gum put in the pilot’s cockpit and not in the passenger’s?” Larry persisted.

“The passenger was not an aviator,” the rich man retorted soberly. “He put them where he thought he would sit—in the wrong place, it happened. So, when they got the jewels, it was simpler to put them where the pilot could hide them, where the gum was.”

“Another reason would be,” Jeff said, “pilots use gum and it would look more natural for it to be stuck around where he did his control job than up forward, where the special agent had it in the amphibian.”

“Atley,” she said, excited and nervous. “Look here!” The man almost raced around the library table, bending close to where her finger touched the dark green showing through the adhesive gum.

The Sky Patrol saw her expression and each grew taut with excitement at her next words.

“Don’t you see? Can’t you?” She raised her voice to a shrill pitch of excitement.

“Glory-gracious-golly!” Larry was agitated enough to couple all the exclamations.

“This isn’t the Everdail Emerald,” the lady was almost screaming, her hands trembled as she pointed. “It is the emerald that I had in the hotel room——”

“I just said, ‘Pop! goes our mystery.’” He had to laugh in spite of the grave situation, the new development, as he added:

CHAPTER XII
THE HOODOOED AIRPLANE

After their exciting day, the next two weeks proved more than dull to the youthful members of the Sky Patrol.

To the surprise of the yacht crew, Captain Parks kept them all busy preparing, the day after Mrs. Everdail’s dramatic discovery, for a run to Bar Harbor, Maine.

That was unusual. After a trip across the Atlantic, the yacht was ordinarily laid up for awhile, giving its crew some shore liberty.

Captain Parks, however, agreed with Mr. Everdail, who trusted him absolutely—if Sandy did not—that it would be wise not to give any person who had been on the yacht during its crossing any chance to get away.

“On the run,” Mr. Everdail told Sandy and Dick, “and while we lay over at Bar Harbor, you two can watch for anything suspicious. My wife won’t let me say that Mimi, the maid, could be guilty—besides, how could she get into Captain Parks’ safe?”

“I think, myself, some man of the crew would be the one to watch,” Dick agreed. “Maybe the steward, who could have a reason for getting into the captain’s quarters.”

“But it was a woman Larry saw, through the glasses, at the stern,” Sandy objected.

“Well, then—there’s the stewardess who attends to the ladies’ cabins,” argued Dick. “We can watch her.”

They did, but no one on board asked for shore leave, either on the day before lifting anchor or during the stay in the Maine waters. Dick and Sandy used ears and eyes alertly; but nothing suspicious looking rewarded their vigilance.

Larry, staying at the old estate home with Jeff, had some compensation, at least, for being separated from his chums. Not only could he keep an eye on things and be ready if Jeff called for an aide; as well, he had his daily instruction in ground school and in the air.

Already “well up” on all that books could tell about engines, types of airplanes, construction methods, rigging and even handling a craft in the air, he got the practical personal experience that is the only real teacher, and the thrill of donning the Gossport helmet, with its ear ’phones and speaking tube through which Jeff, in the second place of the amphibian or the airplane, instructed him, correcting faults or gave hints, was a real thrill.

He learned, first of all, not to start up an engine while the tail of the ship pointed toward a hangar, or other open building, or toward a crowd, in future, on a field.

The propeller blast threw a torrent of dust and as Jeff told him, he mustn’t become that most unpopular of airport nuisances, a “dusting pilot,” whose carelessness flung damaging clouds on airplanes in hangars and people on the fields.

Learning to warm up the engine, to check up on instruments, to keep the ship level while taxiing down the field to head into the wind, to make the turn, either in stiff wind or gentle breeze, so that the wind did not tip the craft and scrape wingtips—these and a dozen other things he acquired in several early lessons.

The second place of the airplane had been fitted with a set of dual controls, rudder bar, throttle and “joystick” so that Jeff, for two successive hops, let Larry put feet on his rudder bar and lightly hold the stick as Jeff manipulated the controls and explained, by use of the Gossport helmet, why he did this or that.

Jeff believed, as does every good instructor, that showing, and explaining, is necessary as a first step, but that a flyer is developed only by practice during which he makes mistakes and is told why they are mistakes and how to correct them, thus gaining confidence and assurance by actually flying.

“That-there time,” Jeff might say, “when the caretaker ‘playing mechanic’ and pulling down the prop till the engine catches, didn’t you open up the throttle too wide? Better to open it just enough to give the engine gas to carry along on—and even cut the gun a bit more to let it run fairly slow till it warms up. Turning her up to full eighteen hundred revs don’t gain while she’s cold, and it throws dust like sin!”

Or, as Larry taxied, learning to manage speed on the ground by use of wider throttle for more speed, cutting down the gas if the craft began going too fast, he would catch an error:

“Did you forget last time to put the stick back and make the blast on the elevators hold the tail down while we taxi? Sure, you did—but you won’t again, because you saw that if you didn’t we might nose over. You ‘over-controlled’, too, and almost nosed over before you caught it—and then, we were going so fast I don’t know what kept this-here crate from starting to hop.

“That’s right—easy movements always—don’t jerk the controls—take it fairly easy. And you are doing right to move the stick back to neutral this time when the tail came up—kick rudder a bit, isn’t she slanting to the right? That’s it, buddy, left rudder and back, and now the right rudder—there she is, headed right.”

Ordinarily cool-headed, he had to be told only once or twice, and reminded almost never that jerky manipulation of the controls was not good practice or helpful to their evolutions. Easy movements, continual alertness and a cool head stood him in good stead.

Seeing those fine qualities, Jeff had Larry thrilling and happy on the fourth day by letting the youthful enthusiast for aviation take over for a simple control job, straight, level flying.

“You’ll want to get the feel of the air, and see how stable the average modern crate is,” Jeff spoke through the Gossport tube. “How does that-there wing look to you—kind of dropping?—remember what I did—that’s the stuff, stick to the left a bit and back to neutral, so the other wing won’t drop! No use teetering back and forth. They put neutral position into a control so you can set ailerons or rudder or elevators where you want them and hold them.”

There was more than Larry had ever dreamed there would be to keep in mind: there was the maintaining of level flight; even in his simplest personal contact with the controls; then there was the job of keeping the horizon line at the right location by watching past a chosen spot on the engine cowling, else they would start to climb or go into a glide. There was the real horizon to distinguish from the false horizon, which an airman knows is, through some trick of the air, the visible horizon that is just a little bit above the true horizon, so that to hold level flight in a forward direction, that false horizon is not held on a line with the top of the engine cowling, but, to hold a line with the true horizon the marking point is held just a trifle below that false, visible horizon line.

Had that been all he had to comprehend Larry’s first control job would have been simple. There was much more to watch—the tachometer, to keep track of engine speed; the air speed was learned by watching the indicator on the wing of that particular type of airplane; the position of the nose with relation to the horizon had to be constantly noted and a tendency to rise or lower had to be corrected: little uprushes or warm air made the airplane tilt a trifle to one side or the other and ailerons had to be used to bring it back, the stick had to be returned to neutral gently at exactly the point of level flight after such correction and not sent to the other side or the craft tipped the other way and opposite aileron had to be applied; then there was the chosen point such as a church steeple, tall tree or other landmark selected as a point on the course to hold the nose on—that must be watched and a touch of rudder given if the craft deviated from its straight line.

Nevertheless, complicated as flying appeared to be on that first handling of joystick, rudder and throttle, Larry knew that the happiest time of his life would be his first successful solo hop, and that the complicated look of the maneuvers and the number of things to watch—level flight, direction, maintaining flying speed, seeing that altitude was maintained, that his own craft was not menacing or menaced by any other in the air, all these would become simple, second nature as soon as the flying hours piled up and gave him more skill and experience.

Quick to learn, retentive of memory, not repeating the same mistakes—even working out some points for himself—Larry, at the end of the fifth day, was gratified to have Jeff, as he slipped off the Gossport, tell him:

“The only trouble about this-here instruction is that I’m scared you’re going to make a better pilot than your teacher.”

“Yes, you can,” the older man’s face became doleful. “You ain’t the kind to let that-there superstition bug bite you.”

“No,” admitted his pupil. “I think superstition is just believing something somebody else tells you until you are so busy watching out for something to go wrong that you aren’t ‘right on the job’ with your own work—or you are so busy waiting for some good thing to ‘happen’ that you don’t see Opportunity when it comes up because you’re not watching Opportunity—you’re watching Luck, or Omens.”

“Don’t I know it!” Jeff was rueful. “I want to kick myself sometimes—but when you know other folks has had their crates ‘jinxed’ by being in the same hangar with one that has got the name for being hoodooed—what would you do?”

“Just what I’m doing now,” Larry grinned. “I know Mr. Everdail paid the company for the ruined seaplane and moved it into the hangar, here. I know your airplane almost touches it, every night. But I don’t let that worry me, because——”

“Well, it worries me. I try not to let it, but the worry is there, no matter what I do. You see, I never thought, out in the marsh, about anything going wrong because I took that big wrench and put it in my tool kit after we salvaged it out of the water. But I dreamt about emeralds, last night, and so I went to a fortune teller gypsy woman and she told me a dream like that meant bad luck in business, and so I said I was a pilot and told her all about the seaplane——”

“You ought to be careful,” Larry interrupted. “If she puts two-and-two together, emeralds and a chase and a wrecked seaplane——”

“They’re awfully quick—the way they guess what’s in your mind proves that.”

“Oh, she won’t think anything about it. Anyhow, she told me not on any chance to touch that cracked up seaplane or anything that ever was on it—and so—I put the jinx on my own crate without meaning to.”

CHAPTER XIII
THE “HOODOO” STRIKES

“Hello, Sandy! How are you, Dick?” Larry met the returning chums as they climbed to the small estate wharf from the yacht tender, and while they strolled up the path he asked eagerly:

“Those emeralds aren’t on the yacht,” Sandy declared. “Captain Parks helped us by sending most of the crew ashore while Mr. Everdail took his wife to their woods camp. We went over the yacht——”

“With a fine-tooth comb!” Dick broke in. “We did make one big discovery, though.”

Dick tried to conceal the twinkle in his eye, but it got the better of him as he explained.

“We found a string of beautiful, perfect emeralds in the stewardess’ cabin, hung up on a nail.”

“Sandy suspected her right away!” went on the jovial one, “but no arrest was made.”

“What have you discovered?” Sandy asked Larry quickly, to cover his impulse toward assaulting the teasing chum.

“Not a thing—except I learned that the injured pilot was able to sit up and I went to see him.” Dick and Sandy waited anxiously for a revelation, but Larry was unable to give one.

“He is named Tommy Larsen,” Larry informed them. “He’s getting well fast. He was glad that his passenger had been wrong in suspecting the Everdails——”

“What did he say to explain about his passenger not helping him, and then taking the boat?”

“The man came while I was there,” Larry told Dick. “He is named Deane, and he’s a nice-looking, quiet chap. It seems that when he landed with his ’chute, he came down and struck some driftwood or an old log, and it knocked the wind out of him. When he got back strength to cut himself loose, he tried to get to the seaplane but his landing, as I explained the location—well, you saw it when you flew over—his landing was made a couple of hundred yards away. I got the gardener to take me to the place, yesterday, in the hydroplane. There was a big, sunken log close to the torn ’chute.”

“No. He tried to swim over, turned sick, crawled onto some mud that was out of water and stayed there. I guess he fainted. When he managed to get there, we had taken Tommy Larsen away—so he’s cleared!”

“Why—Sandy! We left with the pilot—I mean, Jeff did. Then the hydroplane came for me, and when he got there, afterward, don’t you see that if he was guilty of anything, he’d have taken the chewing gum?”

“He might have seen that one chunk was gone, suspected that the hiding place was discovered and left the rest——”

“Suspicious Sandy!” Dick laughed. “With twenty-nine lovely emeralds to recover—and a rubber boat to get away in!”

“As innocent as the man I helped capture—Mr. Everdail’s friend, that man we put on the wrecking tug for five hours.”

“Everybody is innocent,” declared Dick. “Sandy, my advice to you, for your birthday, tomorrow, is to turn over a new leaf and instead of looking for people to suspect, try to think where those emeralds can be.”

“They’re not on the yacht, you say,” Larry said to take away the sting to Sandy’s pride. “They aren’t in the old house. They were taken from the captain’s safe—where did they go?”

“You tell me who knew the way to get into the captain’s safe and I’ll try to get the emeralds.”

“All right, Dick,” Sandy replied to the chum who had just spoken. “You’ve answered Larry’s question.”

“Who else could be safer? He says the emeralds were gone and his word is his bond! Oh, yes!”

“Then the emeralds won’t be found,” concluded Dick. “Captain Parks has been ashore, and away, hours at a time, here and in Maine.”

The millionaire listened gravely to their statement and broke into a hearty laugh.

“As I live and breathe!” he said. “You members of Jeff’s Sky Patrol are working for the wrong side. You ought to be with that London lad, who suspects my wife and her cousin, Miss Serena, and me! Oh—this is great! You’re helping me a whole lot. I think I must increase the allowances for Suspicious Sandy, Detective Dick and—er—Follow-the-Leader Larry.”

“Captain Parks had opportunity—he knew you would take his word—no one else knew his safe combination. Isn’t that common sense, sir?”

“Well, let’s see. Besides Captain Parks, there’s—” his voice trailed off; once he shook his head at some thought; once he scowled; finally he shook his head defiantly.

“As I live and breathe—it looks—but I won’t believe it! Not Billy Parks. He’s——”

“All right, sir,” Larry said. “We thought we ought to report what came into our minds. But we can’t prove anything, of course.”

“All right, my boy. Watch him, trail him, whatever you like. I’ll give you each a thousand dollars if you can prove——”

“Wait—let me finish. A thousand dollars if you’ll prove—Parks is innocent!”

He turned, dismissing them as he greeted his cousin, Miss Serena, who had declared that his wife would be better off alone to rest in the quiet camp in Maine. Miss Serena, with a will of her own, had come back, determined, if the rich man proposed to stay at his old estate, that she would assemble a group of servants and manage the house for him. The three chums sidled out, neither of the three counting on the payment of that, to them, large sum.

Sandy’s birthday dawned hot, but clear, with a good, steady south wind blowing.

The rich man had not forgotten Sandy. A fine set of books awaited him at the breakfast table, a set of engineering books that he would prize and study for many years.

Larry’s remembrance, a radium-dial wrist watch, and Dick’s gift, the set of drawing implements he coveted, delighted him. Jeff’s modest but earnestly presented “luck charm” secured from his gypsy fortune teller was accepted with a grave, grateful word—but Sandy had hard work not to break into a wild laugh.

“Surely it is,” laughed Larry, and then, in a lower tone, he urged, “now, Jeff——”

“You would spoil it!” Larry was unable to keep from being annoyed, almost angry, because Jeff had spoiled a surprise.

“We might as well tell you, Sandy, now that it’s ‘all off’,” Dick said. “We were going to give you another present—a hop over your own house in Flatbush—with Larry for pilot! But——”

“Don’t be silly, Jeff,” Mr. Everdail chided the pilot. “Check over everything and then go up. You know mighty well that accidents don’t come from ‘hoodoos’. They come from lack of precaution on the pilot’s part. The weather charts for today give perfect flying weather. The airplane is in fine shape. Go ahead—give the lads a treat!”

He did not neglect his duty. For all his nonsense about omens and such things, he gave the airplane a careful checkup, warmed up the engine for Larry himself and made sure that everything he could foresee was provided for.

Sandy, thrilled at the prospect of a hop with his own comrade doing the control job, was full of fun and jokes.

Dick, no less eager to see Larry perform his new duties, wasn’t behind Sandy in good humor.

He did not forget to assure himself, by a final look at the windsock indicating the wind direction, that the breeze had not shifted.

Neither did he “dust” the hangar, nor lose his straight course as he taxied across the field at an angle to turn, without scraping wings or digging up turf with the tail skid.

A final test, with chocks under the wheels, the signal for the wheels to be cleared by the caretaker, a spurt of the gun for several seconds to get the craft rolling as the elevators were operated to lift the tail free, a run at increasing speed, picked up quickly because of the short runway—stick back, lifting elevators so the propeller blast drove the tail lower and the nose higher—and they left the ground.

Stick back from neutral, after leveling off for a bare two seconds to regain flying speed, and they climbed, the engine roaring, Jeff nodding but making no comment through the speaking tube he still used. Dick shouted a hurrah! Sandy joined him.

Over the hangar they rose, and Larry, holding a more gentle angle to avert a stall, continued upward until his altimeter gave him a good five hundred feet.

Then, choosing a distant steeple as in direct line with the course he would fly toward Brooklyn, to be out of any airline around the airports, he made a climbing turn, steadied the craft, straightening out, went two thousand feet higher to be doubly safe—and drew back his throttle to cruising speed.

CHAPTER XIV
DICK HANDLES A CONTROL JOB

Flying close to three thousand feet above Oyster Bay, level and stable, the airplane seemed to be in perfect condition.

Jeff, for all his superstition, would have given it as a pilot’s opinion that only some mistake on Larry’s part, or a quitting engine, leaving them with a dead stick, could cause danger.

“There’s where President Roosevelt lies,” Dick, in the last seat, because their places were rearranged by Larry’s position as pilot, indicated to Sandy, just ahead of him, the cemetery beneath them.

Very tiny, in its iron fenced enclosure, the last resting place of a national idol, was almost invisible with its simple headstone; but Dick’s statement was understood by Sandy to mean the location more than the exact spot.

“I’ll get Jeff to ask Larry to spiral down for a better look,” Sandy decided.

“Sandy wants to see President Roosevelt’s place in the cemetery,” Jeff spoke into the tube of the Gossport helmet Larry still used.

“There it is, just off our left wing, buddy. That’s right—stick goes to the left and a touch of left rudder, but when you moved the stick sidewise to adjust the ailerons you neglected that-there bit of forward movement to tip us down into a glide. Remember, it’s the double use of the stick that works ailerons and elevators both.”

Larry had overlooked that point for the instant. It was his only difficulty in flying, to recollect always to control all the different movements together. The joystick, operating the wing-flap ailerons by the left-or-right, lateral movement, also raised or depressed the elevators by forward-or-backward movement. However, in any lateral position, the forward and backward set of the stick worked the elevators and in executing a control maneuver, even as simple as going into a bank combined with a turning glide, or downward spiral, the movement of the stick should be both slightly sidewise, for sufficient bank, and, with the same movement, slightly forward, for depressing the nose into a glide, returning the stick from slightly forward back to neutral to avoid over-depressing the nose into too steep a glide; if not put back in neutral when the right angle was attained, the depressed elevators would continue to turn the forward part of the craft more steeply downward.

Just at the instant that Larry was about to obey Jeff’s instruction a gust of air, coming up warm, tilted the lifted wing more, and as he corrected for that, trying to get the wing up and the nose higher for a flatter spiral, his movement was a little too sharp, and the sensitive controls, working perfectly, but too sharply handled, sent the craft into an opposite bank, rolling it like a ship in the trough of a sidewise wave.

Also, Larry meant to try to draw the stick backward at the same time, coordinating both corrections; but Jeff, a little less calm than usual because of the superstitious fears that kept riding him, neglected to speak the words by which he would inform Larry that he was “taking over” until the correction was made.

By that neglect, both drew back on the stick at the identical instant, and the nose came up much too sharply.

Larry, not aware that Jeff meant to handle the job, almost pulled the stick away from Jeff in his anxiety to get the nose down again, and Dick, in the last seat, thought he felt a sort of thud.

He drew back on the stick for, with the throttle rather wide—because Larry had feared a stall as the nose went up and had thrust the throttle control sharply forward—the craft began to go down in a very steep glide, not quite a dive, but with engine on full gun, sending it in a sharp angle toward earth.

Naturally, when he pulled back on the stick and it did not yield, Jeff shouted through the speaking tube, “Let go!” for he thought Larry had lost his head and was fighting his control.

Larry was not doing anything. He had removed his hand from the stick, his feet merely touched the rudder bar.

Jeff cut the gun swiftly, and came out of the bank pointed toward the wide, shimmering waters of Oyster Bay.

“Stuck. It won’t come back. It’s the jinx! Hoodoo! We’re heading down for the bay and I can’t get the nose up!”

If he did not hear, at least his flying study informed him that something had gone amiss.

The only reason Jeff would swing toward the water and give up working with the stick must be that the stick would not operate the elevators.

Its speed accelerated at the start by the engine the airplane picked up speed rapidly because its nose was steadily going down.

The stick, part of an installed auxiliary control for instruction work, snapped out of its bed.

Larry sat quietly, knowing well that in no time they would be diving toward a wet, deep bay—and the end!

Sandy, not fully aware of the situation, but tense, thought of his ’chute, in the seat-pack. Would there be time? Could he use it? He waited, watching Jeff and Larry.

If the stick was jammed, it might be possible to get into the fuselage. There he might operate the elevator cable by hand enough to get that nose up more, flatten the glide, maybe enough to enable Larry, who alone had a stick, to swing around and come down on land—somehow.

Before his mind flashed the recollection that in construction plans he had seen provision for getting into the after part of the fuselage.

Not wasting a second, he was already free from his safety belt, climbing with agile quickness for all his plumpness, onto the fuselage.

Their speed sent them through the air so fast that the wind was a gale there on the unprotected top fabric of the fuselage.

With his cotton-stuffed ears tortured by the pressure, with the fierce wind tearing at him, Dick clutched the seat top as he tore away the fabric flap covering a sort of manhole back of his place.

Headfirst he plunged in, scrambling, instantly beginning to seek the points where the control cables passed through channeled guides at each side.

He was in a dark, stuffy, closely confined and narrow space, his legs hanging out in the roaring gale, unable to see, half suffocated by the fumes collected in that restricted area.

It was slack. That told his feverishly acute intelligence that it was the cable whose lever did not operate. He had seen that Jeff, when he flung the stick forward to try to free it, had been able to pull it back again without operating the elevators.

Almost as his hand touched the cable and twitched at it, his other hand, as he lay with his weight on his chin, face and chest, contacted something else—a large, roundish object, feeling like a spare landing wheel tire.

He knew as though the light photographed the truth to his eyes, that this tire-like object had moved, shifted, fallen onto the cable, wedging it.

In the dark, he did not know how close the water was. He could not tell if his alertness had been able to give back the use of the elevators in time.

Automatically he tested it. It came back, and the nose began to come up a trifle. He did not dare over-control. He had learned that lesson!

He must not drag the ship out of that dive too swiftly—a wing might be torn off.

But with his nerves taut, by sheer power of his cool will forcing himself to work steadily but not sharply, he brought the nose up, closing his eyes to that wild nightmare of water seeming to be leaping toward the airplane.

Jeff shut his eyes. Then he opened them again. No use to try a jump, no use to do anything but be ready if——

The nose came up steadily—with a fraction of time to the good, they began to come out of the glide to level flight.

Larry braced himself against the slap of the wheels into the surface water. That might offer just enough resistance to nose them in.

He must be ready to open the throttle and pull up the nose—but he must not do it too soon, or do it at all in his strained, excited state—he might go too far.

Level! The airplane skimmed, it seemed to Larry, inches above the slightly ruffled water.

And in that ridiculous position Dick, a hero upside down, came to earth at the end of Sandy’s birthday flight—on the thirteenth, a Friday, as Jeff, white and shaken, hastened to remind them.

“You did the trick, Larry,” he declared. “I only loosened the cables—freed them——”

“Yes,” he said very quietly for him. “The jinx! The hoodoo. I think it’s broken, though—in fact, I know it is.”

“Because.” Dick began to chuckle, “I’ve thought of a sure way to break it.”

CHAPTER XV
A TRAP IS BAITED

“Glad to hear you think the hoodoo is busted,” Jeff commented. “Me, I don’t care. I’ve taken my last hop in that-there crate. I’m shaking like a leaf, even now.”

Dick watched him go along the gravel path, watched him climb to the side veranda of the big house, pausing for a moment to tell the newly installed housemaid about his recent adventure.

Mr. Everdail’s cousin, Miss Serena, evidently hearing the voices, came out on the veranda and listened.

“She’s coming out to ‘make over us,’ as she calls it.” Sandy saw the elderly, stern-faced, but kindly lady descend the steps and come rapidly toward them.

“We had a little trouble,” Dick said. “Somehow the cable for the ‘flippers’ got jammed, but Larry got us out of the trouble like a born flyer.”

“Yes,” laughed Larry. “After Dick guessed what to do so I could work the stick.”

“Oh, I only crawled back to loosen the cable.” Dick tried to make his exploit seem unimportant. “First time I ever flew around standing on my head,” he broke into his infectious gurgle of laughter. “Sandy, did I look like a frog stuck in the mud?”

“Whatever you looked like,” Sandy retorted, “you did a mighty big thing, crawling out onto that open covering in the wind, risking being snatched off or slipping, or having the airplane shake loose your grip!”

“I agree with Sandy,” Miss Serena declared. “It was a very fine thing——”

“I think so,” agreed Sandy. “He gave me one gift for my birthday at breakfast. But just now he made me a present of my life.”

“He did that for all of us.” Larry put an arm affectionately around his chum’s shoulders.

“A very fine thing, Dick.” Miss Serena smiled gently. “Now you had better go and lie down, and I’ll have the maid bring up some hot cocoa and something for you to eat.”

“I think we’d better get this crate into the hangar—we’ll get the gardener and the caretaker and push it in,” Dick suggested. “I always get over a scare quicker if I’m busy doing something to take my mind away from it.”

“Very well,” the lady agreed. “I shall have a good lunch ready when you come in.”

“Jeff is silly,” she said with some annoyance. “There are no such things.”

“I don’t know—” Larry took up the argument. “It is not usual for a cable to jam. It might break, but one shouldn’t get caught.”

“I see. Don’t think for a moment, Lawrence, that it was caused by anything but Jeff’s carelessness, because of his fears.”

“Did I play up to you all right?” Larry asked. “I saw you didn’t want to explain anything.” Dick nodded.

“You did just what I wanted,” he said. “Let’s get the airplane in. Then we can talk.”

As soon as they were alone, Dick climbed up onto the back of the fuselage, dived down into the small space, while Larry waited an agreed signal, in the after seat, and pulled his chum out.

“Great snakes!” cried Sandy, then lowering his voice. “How did that get there?”

Dick, emerging from the fuselage working compartment, displayed a large, fat, round object.

“Oh, no!” declared Larry. “Jeff is a good pilot. He’d never leave anything that could shift about and cause trouble.”

“We all thought it went back to the yacht,” Larry finished his sentence for him.

“It did,” said Dick, seriously. “I know that after Jeff brought it in, the caretaker in the hydroplane took it out—and I’ve seen it at the stern.”

Larry hurried from the open hangar, followed by his two friends. At a trot they went through the grove and down the path, after Dick, dropping the life preserver onto the after seat, jumped down.

“That’s queer,” observed Larry. “I see a life preserver hanging in its regular place. This must be another one!”

The one in the airplane, Dick argued, was “the one”—and the one on the yacht was a substitute.

“I’m trying not to suspect anybody. Instead of doing that I try to believe everybody’s innocent and nothing is wrong. I’m going to let you do the suspecting.”

“That’s turning the tables on you, Dick,” Larry grinned. Sobering again he turned back to Sandy.

“I think Dick is working out something we may be able to prove,” he argued. “I think I see his idea. Captain Parks was the only one who could open the cabin safe. He is a seaman, and he would know that a life preserver isn’t bothered with except if somebody is overboard or in some other emergency. Supposing that he meant to help some one in America to ‘get away with’ the emeralds——”

“He would tie them to a life preserver and throw them over where somebody he ‘expected’ could get them,” agreed Sandy, with surprising quietness. “Only—a woman threw the life preserver.”

“I am working on the notion that Captain Parks agreed with somebody not on the yacht—to get the emeralds. But he made up his mind to get them all for himself!”

“So he hid them in the life preserver.” Sandy spoke without enthusiasm, making the deduction sound bored and commonplace, although it ought to have been a striking surprise, an exclamatory statement. It would have been, Larry thought to himself, if Sandy had made it. Was the youngest chum jealous of Dick, displeased because it was not his own discovery that led to the hiding place of the jewels—if they were right?

“Where else?” he argued. “Captain Parks couldn’t get a better or safer place, right in front of everybody and never noticed. If the life preserver was thrown into the sea—it would be recovered.”

“No, Dick! Why should it? I thought of it. But I’m not telling all my ideas, any more. I’m not ‘peeved,’ but I mean to be able to prove this before I accuse anybody again.”

“No need,” declared Sandy. “I noticed while we were on the way to Maine that a new life preserver was on the stern of the yacht. I saw it hadn’t been cut and sewed up, so the emeralds couldn’t be in that—or in any other one on the yacht. And, when Dick made his discovery, just now, I examined the one he found for cuts and marks of being sewed up.”

“All the same,” Larry commented, “Jeff didn’t put the preserver in his fuselage, and Captain Parks could open his safe and no one else knew how, he declared! There are some things I can’t work out and I wish I could.”

“Let’s make whoever knows anything—er—let’s make them work it out for us,” suggested Dick. “Let’s bait a trap with the life preserver—leave it where it is, get Mr. Everdail to call everybody together, and we’ll tell what we found and what we think is in it—and see what we see.”

CHAPTER XVI
THE “BAIT” VANISHES

His library, that evening, made Sandy think of a “mass meeting of creditors or stockholders who have been tricked.”

The room sheltered a mixed assembly. Jeff was there, and so was the seaplane pilot, Tommy Larsen, and his former “passenger” supposed to be a special agent from London.

Miss Serena, with the yacht stewardess, uneasy but clinging close to the older woman, made up the representatives of the ladies’ side, while Captain Parks, his chef, mate, engineer and their helpers and crew, with the caretaker and all the new servants, filled one end of the room.

“Now you know why there was so much excitement as the yacht came in,” Mr. Everdail completed a long speech in which he told the astonished gathering about the missing emeralds. “That is, those of you know who didn’t know before,” he added meaningly, and went on quickly. “I decided to tell you because somebody on that yacht was ‘in cahoots’ with somebody else, and if any of you know who it is, it will be worth ten thousand dollars to you to point out the right one and help me prove you’re right!”

“That will start something!” mused Larry as many exclaimed, and others looked startled at the disclosure of the large reward.

By agreement Mr. Everdail watched the sailors and servants to note the effect of his story. Sandy, without doing it openly, watched Jeff. Larry’s eyes covertly observed Tommy Larsen and his associate and Dick noted the action and expression of Captain Parks.

“There’s some one who knows something!” Larry decided as he saw the passenger of the cracked-up seaplane bend forward, intent, but without a trace of expression. He had the sort of face that can completely conceal its owner’s emotions.

“I’ve discovered that Captain Parks has a hand in this somehow,” Larry determined, as he saw the mariner’s eyes shift. Larry followed the swift, instantly changed direction of the seaman’s glance.

“Jeff didn’t turn a hair,” Sandy murmured under his breath. “He knew all about it, of course. But—just you wait, Jefferson-boy, till Mr. Everdail ‘springs’ the trap.”

As soon as the sensation created by the large offer was over, everybody looked suspiciously at his or her own neighbor.

The millionaire waited a decent interval for someone to come forward, and Miss Serena finally broke the spell of silence by saying, quietly:

“Because—” She spoke in harmony with her name, pronouncing her words serenely:

“Because—the person who threw the jewels off the Tramp—isn’t here—and wasn’t suspected or seen.”

“As I live and breathe!” The rich man rose, while Dick, Larry and Sandy almost bounced out of their chairs.

“I did not see her,” Miss Serena replied to Sandy while she answered the older man’s question in the same breath. “But I saw a glimpse of dress just afterward.” Her expression showed confident assurance.

“Why, Miss Serena!” Jeff was stunned. “I didn’t know you was one of these-here detectives.”

“I’m a woman and I use my eyes,” she responded quietly. “A woman needs only to catch a flash of a dress to identify it. Mimi’s maid’s outfit has a distinctive cap—and I saw her cap just as she turned into the after cabin—I was on the bridge. I went there immediately but she had gone out through the galley door and I could not locate her.”

“There was no need. She had taken only the imitations—the ones you found.”

“But she knew them,” objected Dick. “She wouldn’t throw over the wrong ones and she couldn’t get the right ones.”

“She—did—not—know—that the real emeralds—had been—hidden—in the life preserver she used!”

“Who put the real ones there?” Larry spoke abruptly in the astonished silence.

“I hid them to keep them secure!” he stammered, turning toward his employer. “I had no wish to take them. I felt—sure—nobody knew the combination of the cabin safe—but I couldn’t say that a clever man, some ‘Jimmy Valentine’ fellow, might not get in. So I decided to hide the real emeralds—and what was safer than a life preserver?”

While eyes were fixed on him, surprised, accusing, unbelieving, he spoke haltingly to his employer:

“I believe you!” Larry spoke earnestly, reassuringly. “It’s a perfectly reasonable explanation.”

“Took off part of the cover, cut the rubber, put them in, wrapped in oiled silk to make a tight pack, then used some rubber patching cement I keep for torn rubber coats or boot patching, and with a hot electric iron I vulcanized the rubber together and put back the covering.”

“Then we’re all right!” Larry leaped to his feet. “We can restore the jewels!”

“Certainly we can!” agreed Sandy. “And Mr. Everdail can telegraph his wife to have Mimi arrested——”

“Now you had better go and get that life preserver, and we’ll cut it open,” suggested Mr. Everdail. “I guess it’s safe enough hidden in the tail of Jeff’s plane—” He was baiting their trap. “Don’t look so surprised, Jeff—that was what caused your ‘hoodooed’ crate to go out of control—but we don’t suspect you of putting it there!”

Reaching the hangar, with Mr. Everdail’s private key they opened the smaller door, and used a flashlight to locate, reach and climb to the tail of the airplane’s fuselage.

CHAPTER XVII
A FIGHT FOR A FORTUNE

Into the waiting assemblage in the Everdail library plunged Sandy with a white, frightened face and his breath coming in gasps after his run.

“I don’t see how—” Mr. Everdail was thinking, as was Sandy, that with everyone whom they suspected, except the maid Miss Serena had accused, present in that room, the loss of the carefully hidden object must be impossible.

“When did you last see it, wherever you had it?” asked the man from London, cool and practical.

“We left it where Dick had discovered it—in the fuselage of Jeff’s airplane. One of us watched, taking turns, all afternoon. Just before we came in here we made sure it was all right, and Larry, who has the longest reach, pushed it in as far as he could get it and still be able to take it out again.”

“Whether she did or not,” the pilot, Tommy Larsen, jumped up, “if the life preserver was safe an hour ago, and gone now, it was taken during that hour. Maybe within the last few——”

“Yes—I think it was in the last few minutes!” Sandy declared. “We didn’t talk about the emeralds being hidden in it until almost the last thing before we went to fetch it here.”

“Come on, everybody—spread out—” cried Jeff. “We’ll get that-there girl——”

“Wait!” begged Sandy. “Everybody will get mixed up and hunt in the same places. We ought to organize——”

Sandy guessed that she would have given her opinion, if asked, that the search was useless.

She was given no time for the comment. Leaving her with the white-faced stewardess and the pilot, whose injuries prevented him from being of much use due to his evident weakness, the others, under Mr. Everdail, were grouped into parties. Given a definite territory, each set out, one group to search the grove under Jeff’s leadership, another to cover the shore section, boathouse and boats, with Captain Parks and his men in the party. Others, under the mate and engineer, divided the rest of the searchers to beat the further and less cultivated woods on the estate and to walk the roads, while Miss Serena gladly agreed to telephone to outlying estates, and to the nearby town to have a watch kept for any unknown person, woman or man.

“But it was locked and all doors down,” Jeff grunted. “Why waste time there?”

“I guess we thought, just at first, somebody might have hidden the preserver somewhere—we thought we saw somebody in the hangar the day the mystery started, but we found no one, so Dick thought——”

“Well, go tell them to come and help me in the grove. Don’t waste time there!”

Sandy separated from the superstitious one, as the latter rushed among the trees, muttering that some omen had warned him of trouble.

As the beaters separated, and widened the circle of their search, the sounds of calls, shouts, voices identifying one another grew fainter.

“They’ve organized and started,” Sandy reported. “What have you two found?”

“Nothing,” Dick said dejectedly. “We ought not to have left that thing unguarded.”

“Whoever got it can’t be far off,” interrupted Dick. “No one but Miss Serena and Captain Parks—and we three—knew about the hiding place until the last part of the meeting.”

“All right,” Larry moved to the small door. “The spring lock’s set. The place is surrounded. Nobody’s in here—” They were outside as he made the last statement. “Slam the door and try it, Dick. All right. Come on, let’s find Jeff.”

When they reached him, in the dying glow of the flashlight Dick trained on a body lying in a heap, they identified the man who had been warned by his gypsy fortune teller to “look out for a hidden enemy.” He was lying at full length in the mould and leaves.

Slowly, while they held their breath, understanding came into the dazed eyes, the breath was drawn in, and Jeff struggled to a half-reclining posture.

“The rest—oh, I’m sick!—I got a bang in the solar plexus—I sent the rest of the men out to the edge of—the woods—oh!—my stomach—to beat in towards me—when I come around this-here tree, somebody was waiting and poked me—oh!”—

“Hey—everybody—yoo-hoo!” Larry cupped his hands and began to shout in various directions.

Unexpectedly, from the water of the inlet, and yet in a muffled, unnatural tone, there came the sputtering roar of a motor.

“But there’s no boat out—the only boat with an engine is the hydroplane——”

The men came running. They had scanned the place by the wharf, and, satisfied that no one lurked there and that the tender was secure, they had gone further along the inlet coast.

“It’s the hydroplane, then!” Dick decided. “It’s coming from the water-dock inside the boathouse, now—there it is. Hey! You! Stop!”

“What’s happened? What’s the excitement? The hydroplane—there it goes!”

“That isn’t fast enough!” objected Pilot Larsen. “I’d fly that amphibian crate only—I’m too weak and dizzy——”

“Jeff’s hurt, too,” said Dick, desperately. “I guess they’ll get away with the emeralds!”

“But Jeff could go along.” Dick took up the idea eagerly. “Couldn’t you, Jeff? And tell him what to do in an emergency!”

“Yes—sure I could! Not in the ‘phib’ because we don’t know how much gas—the gauge is out of whack—but we got the airplane ready this morning—if it wasn’t the night of the thirteenth I’d have said something about it long ago!”

“Forget about the thirteenth—remember the thirty emeralds!” cried Sandy. “Come on, all—help us get that crate out and started. It’s a flight for a fortune!” They took up the cry. Dick and Larry ran off.

Those of the servants and seamen who were not too excited by the escape of the hydroplane to hear, followed the Sky Patrol as they raced through the grove. Jeff, supported by Sandy and friends among the men, came more slowly, still unwell from the blow in a tender spot.

“Mr. Everdail could fly the crate if he was here—he’s an old war pilot,” said Larsen, but they did not wait to locate him. As soon as the engine was warmed, the instruments checked, in spite of the delay at cost of precious moments, Larry donned the Gossport helmet, Jeff got in behind him, Sandy and Dick, without waiting for invitations, snapped their belts—the engine roared—and they were off!

Larry was keyed up to a high tension; but he had no lack of confidence in himself. Night flying, of course, differed from daytime piloting. But Jeff was in the second seat, with the Gossport tube to his lips.

Sandy and Dick were in their places, ready to observe and to transmit signals by using the flashlamp—one flash, directed onto the dash before Jeff so it would not distract Larry, meant turn to the right, two meant a left turn, three quick flicks would tell of the discovery of the hydroplane.

Jeff was too upset to pilot; and since the morning adventure he had no second control stick; but he could give instructions.

“I see a light,” Sandy said as the airplane swung far out over the dark water. “A green light, but the hydroplane wouldn’t carry lights.”

As they swung in a banked turn to circle over the Sound, the green disappeared and its place was taken, as it seemed, by red.

“The hydroplane must have its electric running light switched on,” Sandy mused, unable to convey his idea, because Larry had the engine going full on.

“That must be the hydroplane,” Dick decided. “He—whoever is in it—is afraid to run without his lights.”

“Larry, they’ve spotted that-there boat,” Jeff spoke through the tube to the young pilot. “Yep. More to the left. That’s it—both at the same time! Stick to the left, rudder, too. Good boy. Now the stick comes back to neutral. Hold her as she is—better cut down the throttle a little as we bank and turn to the left.”

CHAPTER XVIII
OUTWITTED!

From their cockpits Sandy and Dick watched the hydroplane. At cruising speed their airplane made nearly three miles to the hydroplane’s one. Its mysterious occupant must know that they were trailing him, but he held to a straight course so that his lights were never in a different place as their craft above swung to show its observers the red and then the green.

“He’s making straight for Greenwich, on the Connecticut side,” Dick decided, knowing a good deal about the Sound ports.

“We’ll be getting tired of turning to the left all the time,” Jeff suggested. “Think you could follow a sort of zig-zag, flying slantwise across the course of that-there boat, then coming around an angle and flying slantways back to the other side?”

“Good! Here we go—to the right. Get your eye on that Fall River Liner, coming up the Sound—that’s about the point of our first leg.

“Now, touch of right rudder and right aileron—and stick back to neutral. There! She’s level. Keep moving stick and rudder a bit, steadily. Now she’s banked and turning. Neutralize! That’s the ticket.

“There! The nose is on that steamer. That’s it—don’t let her swing off that point for awhile—and watch that you don’t nose down—that’s right, back a bit on that-there stick, up she comes, stick back to neutral.”

Thus directed, and admonished, Larry managed to give the airplane a swinging, zig-zag course, so that its greater speed was used up in the longer legs of its slanted progress, and since the hydroplane did not try any tricks or change its path, the Sound was being crossed in the wake of the steamer by the boat and in a corkscrew path by its aerial bloodhound.

“I think I know what is going to happen,” Sandy decided, as they crossed the course of the hydroplane so that its two tiny colored beams showed at the same instant. “He’ll wait till we get closer in to the Connecticut shore line and then he’ll ‘douse the glim’ and leave us with nothing to watch.”

Bending forward Dick began to rummage in a compartment built in his section of the seating space.

He believed that he could outwit any effort to escape by taking advantage of the landing flares, attached to small parachutes, which Jeff carried as a precaution during his former night hops to the old estate.

“Better cut the gun and glide down a couple of hundred feet,” Larry heard Jeff’s voice in his earphones. “If he tries any tricks——”

“That’s queer!” Sandy exclaimed to himself, as he stared down and saw the small, swift boat open a vivid, glowing eye at the bow.

Larry, holding the airplane in a moderate glide, saw the beam glowing out beyond the airplane’s nose, felt that he was as low as he dared be with land ahead, and drew back on the stick to bring up the craft to a level keel, opening the throttle as the glide became a flat course about three hundred feet higher than the water.

“There it goes around!” shouted Dick, unheard, excited, as the beam of the hydroplane swung in a wide arc from shore, heading once more back toward Long Island.

“Good boy,” Jeff spoke to Larry. “You made that turn without a hitch. With that searchlight to guide you, I don’t need to talk through this-here thing any more.”

It puzzled Sandy, and he swung around to look questioningly back at Dick. The latter, unable to see his expression, but guessing his idea, shook his head.

As Larry banked and came around on a new slant across the hydroplane’s path, which seemed not so true to the straight line as it had been, Dick secured a parachute-equipped landing flare, sent it over safely past the wings, and watched the white glare light up the surface of the water.

To Larry’s disappointment, they were so far to one side and behind the hydroplane that the flare failed to disclose its occupant.

He held up a hand, and pointed ahead, then opened the throttle, came onto a straightaway course over the hydroplane, rapidly overhauled it and got well ahead. Then, cutting the gun and gliding, as it came up under them, he signaled, and Dick, waiting, ignited a second flare.

CHAPTER XIX
A BAFFLING DISCOVERY

“Somebody had to be in that hydroplane,” Sandy mused. “They were there to switch on the light, to turn the boat, and to set it on the new course!”

Quickly he peered to the side and back, downward at the water in the place where the first landing flare had settled into the water.

Just a little closer to their position, should have been the spot where the clever miscreant might have abandoned the boat.

Sooner than that, Sandy guessed, the unknown person could not have quit the hydroplane: otherwise the turning from shore would have continued and the hydroplane, instead of proceeding in a straight course away from land, would have swept in a wide circle, round and round.

“There’s no life preserver in the boat either—so that’s what the mystery man used to swim away with—Mr. Everdail’s jewels!” he added.

Straining his eyes, he peered, looking for a bobbing head, a round white object supporting a body, as the flare died. Dick, arguing in much the same fashion, stared from the other side of the fuselage and gave a shout of elation.

Sandy prodded Jeff, and quickly the pilot, much recovered, gave Larry his instructions.

“Nose up—we’re getting too low. Right! Now a right bank—not too steep. Don’t get excited. That-there lad in the hydroplane headed her outbound and then took to the water. Now we’re heading in—steady with that-there rudder—don’t try to jam her around—now she’s all right. Level off and hold her as she is.”

Larry obeyed all instructions, doing the work as Jeff gave the order. Larry was rapidly growing sure of his ability.

He fought down the excitement that wanted to express itself in hasty manipulation of his controls and kept a steady hand and a cool brain.

Dick, scribbling hurriedly, passed a note to Sandy, who read it in the light of the flash, and then passed both paper and light to Jeff.

Dick, recalling a wide, spacious cement-floored parking space at a nearby bathing resort, had suggested “setting down” there. As he read the note Jeff shook his head.

“Dangerous trying to land there!” was the note Jeff passed back as Larry flew the airplane at just above stalling speed toward the shore. Dick agreed. After all, there might be automobiles in the parking lines, and the light might be bad for Larry. Even using a power-stall by which, with the engine going and a flat gliding angle, the airplane could settle gradually closer until it took the ground with hardly a jar, the maneuver would not be safe, Dick admitted.

“Here comes another ’plane!” Sandy called out, taking the flashlamp from Jeff again as the older pilot handed it back. “He’s flying right after us.”

“Steady, Larry!” Jeff cautioned. “Hold as you are. That-there is our amphibian—and I reckon the boss is doing the control job.”

The amphibian, as they made out its pontoon understructure, came fairly close alongside. Its speed was almost identical with their own and at first all four occupants of the land crate wondered who was in it, and why.

“All right, buddy,” admonished Jeff. “Stick to your job. Sandy or Dick will read the dots and dashes—if he’s using Morse code——”

“He is spelling out something with his flashlight,” Sandy decided, as he saw short flickers and longer dashes of light while the amphibian kept a course within close range but at safe wing distance.

“‘G-i-v-e r-e-p-o-r-t,’” Sandy read, and as he handed Jeff the note, Sandy, using his own light, sent back the Morse code answer:

Then, with the beam directed in the path the mysterious unknown must have taken, he tried to show the occupant of the amphibian what he meant.

Evidently the endeavor succeeded, for the amphibian dived, and took to the water, while Larry, directed by Jeff, swept around in a circle out of range if the amphibian rose unexpectedly, but within visual range of its maneuvers.

Watching intently, his comrades saw that the amphibian kept on toward shore in a taxiing course on the water surface.

A shout greeted the advent of an automobile on a shore drive. As it swung around a curve, close to the water, its bright headlights fell in a sweeping line across the water—and picked out a round, white dot bobbing, vividly lit, in the rays.

With the glare from the dropped light picking out things in sharp silhouette, they saw a man clamber out onto a pontoon and rescue the floating prize.

“Now, I wonder if that is Mr. Everdail—or if it’s somebody else?” thought Larry, correcting for a tendency of the nose to fall away.

“Whoever it is,” he concluded, “he can’t get away. He has the life preserver. But we have superior speed. And a good tankful of fuel.”

He glanced at the gauge to reassure himself, made an almost automatic correction of a wing tip, pushing up in a gust of air as he saw that his surmise about fuel was correct.

As soon as it got under way again and took up its climb, the amphibian, coming to their level, showed its pilot holding up the life preserver, as the flare still settled toward the water. In the glow they recognized the triumphant, smiling millionaire.

The flight back to the landing field was without event. Larry made the landing first, and his companions tumbled out to join the waiting cluster of people while they all “took hold” to run the airplane out of the way so that the spiraling amphibian, its wheels down, could shoot the flare-lit field, and land.

“Here!” Mr. Everdail was triumphant as he threw the life preserver out of his cockpit to Larry. “As I live and breathe, that life preserver ought to be in a museum!” He grinned as he came to the ground. “That’s the flyingest life preserver I ever saw—first it goes joy-riding in a seaplane, then in the ‘phib’ and now it runs off on the Sound and comes riding back with me.”

“Let’s see what’s in that-there!” Jeff urged. “That’s most important, right now!”

The crowd trooped into the hangar, where Larry, at Jeff’s direction, switched on the overhead electric lamps.

Close around Mr. Everdail, Jeff, Captain Parks and Miss Serena, with the youthful Sky Patrol in their midst, the rest of the sailors, and most of the house servants gathered.

“Somebody give me a good knife,” ordered Mr. Everdail. “We’ll cut this thing to ribbons and get rid of all the suspense!”

Larry held out the round, heavy inflated “doughnut” as half a dozen pocket knives were unclasped and held out to the millionaire.

“You know as well as I do, sir,” the yacht captain turned to his employer to answer his amazed cry, “you know that all the life preservers have the yacht’s name and port painted on them.”

“And that’s so, too,” said the mate, advancing and backing up his captain’s declaration.

“No, sirree!” Captain Parks stated. “That’s not the yacht property. It hasn’t any marks on it at all.”

“Maybe it’s the one off the hydroplane,” Larry was dejected, but not convinced that the life preserver was a strange one to all.

“Not that!” the mate declared. “It’ud be marked Scorpion. No, Mr. Everdail, this is no life preserver we’ve ever seen before.”

“Please, sir, do that!” urged Sandy. “I can be sure it’s the one we found in the airplane fuselage, anyhow—I remember that little rusty stain in the cover.”

CHAPTER XX
SANDY TURNS OVER A NEW LEAF

“The flares died just too soon,” Dick informed him. “Maybe Mr. Everdail saw more than we did.”

“There’s one way to check up,” Jeff suggested. “Who’s not here who was in the house before the life preserver was missed?”

“You can learn nothing from that,” Miss Serena spoke up. “Too many are away.”

“We can get somewhere, anyhow,” Larry insisted. “Captain Parks, can you account for your men?”

“The fellow who flew with you in the seaplane isn’t here,” remarked Larry, quietly, and, after a glance around, he said: “Neither is the yacht stewardess.”

“I sent her to her cabin,” Miss Serena stated. “She was greatly disturbed about this affair.”

“Yes, but she is a high-strung girl,” argued the lady; and during the silence that followed, she turned to her relative.

“Atley,” she told the millionaire, “we are getting nowhere. For my part I believe that the emeralds have already been destroyed!”

“Certainly. That seemed to be the purpose, in the London hotel. A person as clever as that must have planned this entire affair and has undoubtedly accomplished his wish and vanished long ago—or else he can never be caught because we have no way to discover him.”

“He ought to be caught and punished,” Jeff argued. “That-there set of emeralds was too precious for us to let somebody do a thing like this-here.”

“We know who was on the yacht,” Larry agreed with Jeff. “At least we can try to find out who threw the emeralds off.”

“We know,” Dick broke in. “Don’t you remember that Miss Serena recognized the maid—Mimi—by her uniform?”

“Then why don’t we go and question her?” Larry suggested. “Make her tell what she knows!” A murmur of assent broke out among the seamen who were naturally anxious to be cleared of any possible suspicion.

“Did you get an answer from Mrs. Everdail when you telegraphed her about Mimi?” asked Dick.

“Not yet,” he admitted. “I don’t believe Mimi is the one. She was with my wife during the last seven years and you get to know a person’s character in that time.”

“Just the same,” Larry insisted, “many respected bank tellers have been discovered for what they were after bank money disappeared.”

“As I live and breathe!” Mr. Everdail spoke gruffly, “I begin to wonder if you shouldn’t be the one to have ‘suspicious’ for a nickname. You have suspected Jeff, and me, and my friend who was with me, and Larsen, here, and his passenger—Captain Parks and now Mimi! It will be Miss Serena next!”

“I guess I caught the disease from Sandy,” Larry was red-faced, “I admit I deserve the nickname now.”

“If Sandy doesn’t object to losing the nickname, then—” Mr. Everdail smiled a little teasingly.

“Oh, he’s welcome to it,” Sandy cried. “I’ve turned over a new leaf!”

“I used to take one little thing for a start, and make up my mind that whoever did it was the one I must suspect,” Sandy explained. “But that’s like trying to prove a man guilty because I think he may be.”

“That’s so,” Dick began to chuckle. “Pinning clues onto folks is like the clothing salesman who tried to sell a white linen suit to a man who wanted a dark grey one. ‘I’ll give you what you want,’ the salesman said—and he went over and pulled down all the shades!”

“Now I mean to listen, and watch, and not suspect anybody, as if I had a dark suit and a light one to sell and I’d wait to see who the different suits fitted!”

“By the way,” Captain Parks turned to his employer. “How about that cruise around New York to see the buildings lighted up that you told me to get the yacht ready for?”

“As I live and breathe!” Mr. Everdail slapped his thigh. “I forgot all about our birthday dinner and cruise for Sandy.”

“Well, the dinner was being got ready when you sent for us,” remarked the captain.

“Then let’s go on board the Tramp and see what the chef trots out.” Mr. Everdail led the way, inviting the others who had not originally been planned for.

“That’s right,” laughed Dick. “After a crack-up, always take a rest-up.”

“Now we’ll shelve this mystery.” Mr. Everdail led the way to the tender which would transfer them to the yacht for the evening run around illuminated Manhattan. “Eat, and have a good time, Sky Patrol.”

With the zest of healthy youth the chums “shelved” the mystery and hid their chagrin at being wrong again. The repast provided by the yacht chef was worth their attention. Especially palatable was the iced lemonade which the hot, humid night made very delightful.

“How do they get these ice-cubes the same tint as the lemonade?” Larry wondered, admiring the yellowish tone of the cubes, as he stirred the clinking mixture in his tall glass.

“Dye!” he chuckled. “If you want special food or drink you have to dye-it!”

“It leaves me ‘cold’,” Larry came back at him. “But I’m interested about this ice.”

“It’s simple enough,” the youngest member of the Sky Patrol broke in. “They pour some of the lemonade into the compartments in the ice-trays and freeze that. It is better than plain ice because it doesn’t weaken the lemonade at all.”

“That’s right,” Larry agreed. “Why, Mr. Everdail, I was only curious. I don’t know much about refrigerating plants and I didn’t think they could turn the ice any color they liked—but I see they can.”

He dropped the subject, finished his drink and, with the others, partook of a frozen sherbet also prepared in the yacht’s icing plant.

Finished, they were invited on deck to see the sights of Manhattan’s night sky, with its millions of electric bulbs, on signs and in high windows, and on skyscraper domes, painting a fairy picture against a dark heaven.

“Only what I explained,” Larry retorted. “I hadn’t thought about colored ice cubes, ever——”

“Well—think! If they can freeze lemonade, and get yellow ice cubes, they can freeze lime juice—even something darker—and get——”

“Green cubes!” Larry broke in. “Yes—or freeze indigo and get blue ones. What of it?”

“What better place could Captain Parks—or anyone else—find if he thought the life preserver idea might be too open?”

“Certainly they could.” Sandy was earnest. “If the Captain ordered that they be kept for his special use—and if he drank lime juice. Come on, let’s ask him.” They followed Sandy to the bridge.

“Captain,” Sandy asked, “what’s your favorite drink? Lemonade or——”

CHAPTER XXI
THE SKY PATROL GIVES UP

At Sandy’s sensational announcement there was a stampede from the bridge. Soon after Dick and Larry raced through the cluttered and deserted dining saloon, it was invaded by the captain, the millionaire, Miss Serena and others, with Sandy in the lead.

He made a disgusted gesture toward the open front of the refrigerating box, to the four ice cube trays lying empty on the galley floor.

“Sure they were!” the chef, who had observed their invasion of his cookery compartment with amazement, spoke up. “I had to use all of ’em to freeze the cubes for your dinner. No use to fill ’em again till I wash ’em up, so I left ’em out while I ‘defrost’ the box—cut off the current and let the box get warm enough to melt the frost that collects when you freeze a lot of cubes.”

He indicated the refrigerating unit which had heavy ice clinging wherever the chill had congealed the moisture from the evaporation of the water.

Food, ice-drip trays and vegetables in their dry-air receptacles, were all they discovered by a painstaking search. A glance into the “hydrator” packed with vegetables, crisp lettuce, long endive, and other varieties, a foray behind and under everything satisfied them that another clue had “gone West”—and left them very much out of favor.

No matter how closely they examined the built-in box, with its glossy enamel and bright, aluminum trays, nothing except food and drinkables in bottles revealed themselves.

“I thought that was how it would turn out,” Jeff, coming from the after deck, declared.

“I’m disgusted with the whole thing,” the yacht owner grumbled. “I ought to have known better than to trust three young men under seventeen to solve such a mystery.”

“The date has nothing to do with it,” Mr. Everdail snapped. “It’s their lack of self-control and experience.” He turned and stalked out of the galley and after him, sorry for the three members of the disbanded Sky Patrol, Jeff moved.

“Sorry, buddies,” he said, shaking hands at the pier to which the yacht tied up briefly. “Don’t let it stand between your coming out to that-there new airport once in awhile to see me. I guess if Atley is through with you he’ll be done with my crate too, so maybe we’ll meet up one of these days soon. If we do, and I have the money for gas and oil, Larry, you get some more flying instruction. You may not be a crackerjack detective, but when it comes to handling that-there crate, you rate mighty good.”

He said a pleasant word to each of the other two, added a friendly clap on the arm and, with Mr. Everdail saying a brief, if not very angry farewell, the Sky Patrol quit its service, finished its air work and took to its feet.

Explanations at home accounted for the termination of their stay, which had been arranged by telephone at the beginning; and it seemed to them that the Everdail Emerald mystery was, as Dick dolefully said, “a closed book without any last pages.”

So despondent was Larry at his failure as a sleuth that he did not like to discuss their adventures with his chums.

His depression was more because his air training was over than from a real sense of failure. To Larry, one only failed when one failed to do his best—and that he had not failed in.

As a week went by Dick saw something to laugh about in their wild theories, their almost fantastic deductions. He found an old stenographers’ note book and jotted down, in ludicrous terms, the many clues and suspicious incidents they had encountered.

“If I hadn’t gone off ‘half-cocked’,” he told his comrades, “maybe we would have seen something or somebody really worth following up.”

That very afternoon he passed a news stand and was chained in his tracks by a small headline in black type at one corner of a paper, in a “box,” or enclosure of ruled lines that set it off from the other news.

“Take a look at this!” he hailed Larry as the latter sat on Dick’s porch, whittling on the tiny struts of a model airplane.

Under that heading the story reminded readers that the Everdail estate had been haunted several weeks before according to report.

The millionaire, it went on, coming East to meet his wife, returning on their yacht from Europe, had investigated the uncanny events reported to him by his caretaker and others.

He had learned nothing, the reporter had gleaned from the caretaker of the deserted estate.

However, it ended, as soon as Mr. Everdail had sailed on the yacht to join his wife at their lakeside camp in Maine, uncanny light, odd noises and other strange things had become evident again, as an excited local correspondent had notified the paper. Reporters, searching, and watching, had found nothing so far but the public would be informed as soon as they discovered the secret.

“I don’t know what to think,” Dick admitted. “No ghost does those things. A real person has some reason for doing them. Who? And why?”

“The only way we’ll find out is by going there, at night, and watching,” Larry declared.

“Not for me,” Sandy said, surprising his chums. “We were ‘kicked out’ once. If we were to be caught on the place we’d be trespassers—and if the clever news reporters are watching and don’t find anything, how can we?”

“I’m going to be too busy earning money to finish my flying lessons to bother, anyway,” Larry decided.

“Larry! Sandy! Look who’s coming. That’s the man who flew in the ‘phib’ with Mr. Everdail—the day the yacht came in!”

CHAPTER XXII
THE “GROUND CREW” TAKES HOLD

Dick rose to meet the man, tall, quiet, and with a smile of greeting on his face that belied the creases of worry around his eyes.

“I ought to,” Larry also advanced, rather sheepishly. “I tackled you the day you floated the dory out to the cracked-up seaplane.”

“Oh, no hard feelings, my friend,” the man shook hands. “You wrenched a shoulder that was already pretty painful—but you thought you had a jewel robber to deal with, so let’s let bygones sleep.”

“I don’t believe I’ve introduced myself,” the man began. “I’m Mr. Whiteside. Of course you wonder what I am here for.”

“I’ve kept pretty well in the background of this case,” he told them. “I am, by profession, an official of Mr. Everdail’s eastern enterprises. But I consider myself something of an amateur detective ‘on the side’ and I want you three to help me.”

“But Mr. Everdail ‘discharged’ us.” There was no resentment, only remonstrance, in Larry’s quiet remark.

“Oh, I know it. I have seen him, been up in Maine. But he has given me a free hand, and I think you three can be useful. You see, I want that hangar watched, now that the reporters have gone away. I can’t be there day and night—I know,” he broke off to explain, “that you three have suspected me of having something to do with the wrong side of the affair, and naturally enough. I came upon Larry unawares, at the seaplane. I accepted his offer about surrendering jewels and actually had a gun in my hand at the time. No wonder I fall in line as—well, as a suspected person. I don’t hold that against you. As it happens, I am trying to recover the missing jewels, just because I made such a failure of rescuing them before.”

That might, or might not be true, Sandy reflected; but he maintained a careful guard over expression and speech.

“We aren’t doing anything about the mystery,” stated Sandy, wondering if that might be the plan—that this man had come to try to pump news out of them. If so, Sandy was determined that as long as they had given up, been given up, it did not matter if the man knew it or not.

“I need you for something else,” he said. “Atley Everdail isn’t here to help, if any situation developed where I would need a pilot. I have a theory that makes me think I shall need one——”

The man who had piloted the cracked-up seaplane was again able to fly, he responded, but was not safe for a long flight. Besides, the detective argued, he wanted someone who had proved himself trustworthy in more things than flying.

“I’ve had only about nine hours instruction,” Larry said honestly. “I wouldn’t like to risk soloing on that. I can taxi, handle the ’plane to get into the wind, take off and fly level, bank, turn, circle, spiral, climb, shoot the field and set down. But——”

“That is all settled in advance,” Mr. Whiteside stated. “Tommy Larsen is ‘kicking around’ without a job. I’ve got his consent to finish your instruction, and put you in trim for a license by the end of Summer.”

Sandy, watching his friend’s face take on an eager light, a look of longing, decided that Mr. Whiteside could not have found a more certain way to fascinate Larry and enlist his cooperation.

“That would be great!” Larry declared. Then he became more serious, adding. “Finishing up my course would be fine, but if it means that I’d have to do anything against Mr. Everdail’s wishes, after he told us——”

“But he has agreed with Miss Serena that they are destroyed,” Dick objected.

“When Everdail gave me all the facts he had about the London attempt to ruin the emeralds, the first idea I had was that some independent robber had failed to find the real gems and, in spite, had damaged the imitations.”

That supported his decision that neither a single robber nor a band of miscreants had planned the affair. They would have taken all the real stones, and he believed that these were numerous.

“I weighed the situation,” went on the detective. “A robber would be enough of a gem expert to know the stones were imitations and would have taken the others. But—some Hindu fanatic, in India, where the emeralds came from originally, might have a fixed idea that they must be destroyed. He might not know imitations from real ones.”

“That would explain why acid was put on them,” agreed Dick. “It wouldn’t explain any other attempts, though.”

“No! I argued that as soon as a Hindu accomplished the entry to the hotel and believed he had destroyed the stones, he would stop.”

“We wanted to take every precaution, Larry. There was a chance that no Hindu was involved. It might be someone with what the French call an idee fixee—a fixed notion—a demented purpose of destroying emeralds—no other stones were treated with acid except those lying in the little pool around the emeralds.”

“Anybody who remained in England would have to—he’d be left there. But—” Mr. Whiteside leaned forward and spoke meaningly, “—a man sailed from England—and although I did not know it at the time, I have checked up, since, and the man from London is an English circus acrobat—who went in for ‘stunting’ on airplanes.”

“The man who claimed to be a secret agent of a London insurance firm?” asked Dick, amazed.

“Then we have found the man who is guilty!” exclaimed Dick. “He was with Tommy Larsen, hired him to go out to meet the yacht!”

“That seems to be the fact,” Mr. Whiteside admitted. “Before the arrival of the yacht I had no inkling that this fellow had come over; but Mrs. Everdail was so nervous and worried, we decided to fly out to meet the yacht, just as Jeff, who had been retained before Everdail found me, decided to do.”

“I said, early in the adventure, that nothing was what it seemed to be,” Sandy remarked. “This backs me up. But——”

“Look at this, Mr. Whiteside—we are sure he made a try for the emeralds in the seaplane he hired. He thought they were destroyed—at least he had done all he could to destroy them. Then—why did he make another try?”

“Perhaps! He must have learned that the real gems were not ruined at all,” Mr. Whiteside explained.

“Do you think his confederate threw the real ones overboard, in the life preserver, with the ruined imitations tied to it?”

“That doesn’t check up,” he said. “The confederate—Mimi—knew the imitations! She wouldn’t throw them at all. If she knew the real ones were hidden in that life belt she’d have flung that. But we know that the imitations went overside and were in the gum—as Sandy cleverly discovered. So—that makes it all muddled up again!”

“That’s what I want to discover. It does come in—I’m sure of that! You, and Dick and Sandy, can help, I believe. Two to watch the hangar, taking turns, and with my aid whenever I can manage it. You, Larry, to perfect your flying technique and be ready if I need you.”

“Well, I say, let’s reorganize,” Dick had a twinkle in his eye. “You, Larry, will be the sole member of the Sky Patrol—and Sandy and I will be—er—the ‘ground crew’!”

“All right,” agreed Sandy. “Dick, you and I are the ground crew. As soon as you’re ready, Mr. Whiteside, we’ll take hold!”

CHAPTER XXIII
LARRY “SOLOS”

Taking hold, for the “ground crew,” required some argument with parents. Mr. Whiteside seemed to have some magical way of overcoming objections to possible night activity, however; and the next morning found the two reinstated assistants riding with Mr. Whiteside on a ’bus bound for the town nearest to the old Everdail estate.

The caretaker raised no objections. He seemed entirely satisfied that Mr. Whiteside was exactly what he claimed to be, and so Dick, who had held some misgivings, accepted the man as a detective and worked with a will to discover some clue to the means used by the “ghost” for getting in and out of the hangar.

In that the trio failed, and had to give up until night would let them return and establish a keen guard over the haunted structure.

“I don’t feel uneasy about short hops,” the pilot informed him. “I don’t think I’d want to take a long control job just yet, though. Now let’s see what Jeff put into you. Before I go up with you, tell me what you’d do if you were really starting off alone.”

“First of all,” Larry said, “I’d go over to the weather display board, to see what the flying conditions would be.”

“You did learn!” Tommy was pleased. “Yep! That’s important. Then——”

“I’d notice the windsock, while I’d go to my crate. If it wasn’t already running, I’d start the engine—being sure to repeat every syllable of the ‘mech’s’ words when he turned the prop.”

“You wouldn’t want any mistake on your part to have the juice on when he swung that prop to suck in the charge—good!”

“Of course, if the airplane was on a cement apron in front of the hangar, it would be all right to start the engine there. But in sandy ground, or on a dusty apron, I’d be sure the tail wasn’t pointed so the propeller blast would throw dust on ’planes or on people.”

“No, sir. Then I’d warm up the engine—by granny-golly-gracious! I forgot something——”

“Well, unless I’d seen him do it, before even the engine was started, I’d want to be sure the ‘rigger’ of my crew would go over the crate and wipe it with a soft rag, so any frayed wires would be noticed—and I’d want to be sure he had inspected the ’plane either when it landed last or before I’d take off.”

Larry went through the explanation of his method of taxiing, with the elevators up enough to keep the tail on the ground as he used the throttle to regulate speed, and the ailerons to govern the wings and keep them from being tipped up or down by wind or uneven ground, as well as his idea of using the rudder to hold the ship on its straight travel to the point of take-off and how he would turn.

“All right! If you know all that about getting set, you might as well let me see you do it!” Thus Larry began his tenth hour of instruction.

That completed, and with a quiet compliment for the way he had made his final check of the engine and instruments while the chocks were still under the wheels, with a word of advice about not trying to lift the ship off the ground in a cross-wind until a safe margin of speed was assured, Larsen bade him return that afternoon. Larry, pleased, went to his lunch, turning over in his mind the many things he had done, to see if he had done any of them in the wrong way.

“I corrected the tendency of the wind to turn the crate as we taxied, and I lifted her off and leveled for a couple of seconds so that the prop could bring back flying speed before climbing.”

He had also chosen a moderate climbing angle, keeping a watch for any incoming craft as he went higher before banking and turning.

“I remembered to return the controls to neutral when I had the ship flying just the way I wanted it to,” he mused. “And I didn’t over-control. Maybe—maybe it won’t be long before Tommy will let me solo.” It wasn’t!

At three that afternoon Larsen informed him that he was to take up the dual-control craft they had hired from a flying friend of the pilot’s at Roosevelt Field the second, on Long Island.

He walked to the airplane, standing before its hangar, determined to use the after seat, as did most pilots flying alone in a dual machine, and turned to Tommy inquiringly.

“Yes, sir. If I am in the front and you are in the other place, and the airplane balances and flies easily, there must be something to make up the difference when you aren’t along!”

And when the sack had provided stability in the front place, Larry, feeling a little anxious, but more about making mistakes under the pilot’s watchful eye in starting than about his performance in the air, got the engine started, warmed up, checked, put the craft into the wind, signaled for chocks to be pulled away, gave a spurt of the “gun” to start it, accelerated speed till the ship began to want to take the air itself, having remembered to use the elevators to lift the tail skid free from dragging—and with a return of elevators to normal right away to keep the craft level on its run—he drew back on the stick, widened the throttle feed a trifle, returned the elevators to normal as he attained the safe climbing angle, and was up and away on his first solo flight.

The whole fifteen minutes that he stayed up were like moments of freedom—alone, master of his craft, able to control it as he would—there is not, in the whole world, another sensation to equal that of the first solo flight of a youthful pilot who combines confidence in himself with knowledge of his ’plane and how it responds.

And when he made his landing, perfectly setting down on wheels and tail-skid as Jeff had taught him, “I wish all my pupils were like him,” said a flying instructor who had been watching. Larry, doffing his tight “crash” helmet, overheard.

And that marked the beginning of ten days of flying, sometimes with Tommy to give him the evolutions of recovering from side-slips, skids, tail spins, and other possibilities of flying, none of them hazards at sensible altitude, and with a calm mind guiding the controls. At other times “stunts” were taught, not to make him a daredevil, but because, in flying, an airplane sometimes gets into positions where the pilot must know every possible means of extricating it. Solo, and with Tommy, Larry became a good pilot.

CHAPTER XXIV
A PUZZLING DEVELOPMENT

“Hooray!” Dick slapped Sandy’s shoulder. “The ‘man higher up’ has come down to earth! Here comes Larry!”

“You’re a sight for sore eyes!” Sandy exclaimed as the youthful amateur pilot joined his friends.

“I haven’t seen much of you, I know.” Larry sat down on the swing by Dick on the latter’s veranda. “Daytimes I’ve been studying rigging and checking up on an airplane, because Tommy thinks a pilot ought to know everything there is to know about his ship because he may have to do things himself if he gets hold of a careless rigger.”

“If the pilot didn’t know the right way he couldn’t say if his helper was doing things the wrong way,” agreed Sandy.

“Tommy has been very good to me, giving me his time, in his room, so he could tell me all the ‘fine points’ he has picked up about flying.”

“Watched, evenings, turn and turn about, till midnight,” Dick told him. “Mr. Whiteside took the day shift and came on to relieve us every midnight.”

“But you wouldn’t expect anything to happen if you’d seen all the reporters who have been ‘hanging around’ the old estate. Why, one has slept in that hangar a couple of nights.”

“No ghost with any self-respect would make a show of himself for newspaper publicity!” Dick chuckled.

“Almost all we needed to do was to watch the reporters,” Sandy said. “But they have given up, I guess. There was only one out last night, and he told me he thought the paper that ran that ‘box’ had played a trick on the others and on the readers.”

“That’s good,” Larry remarked. “Now the coast will be clear, the ghost can walk, and I will be with my trusty comrades to trip him up.”

“It seems queer to me,” Dick spoke. “I’ve thought a lot about it. The fellow who played ghost must be searching for something. What can it be?”

“Here’s something that just came to me.” Sandy bent forward in the lounging chair. “Nothing has happened at night, for ten days. But all that time, Mr. Whiteside has been on the ‘day watch,’ as he calls it.”

“When Jeff flew us there, the first time, there seemed to be somebody in that hangar when we started in,” Dick added to Sandy’s idea.

“You’re right,” Sandy admitted. “By the way, Jeff is back at Bennett Field, taking up passengers for hire again.”

“I’m not worrying about Jeff.” Larry was caught by the suspicious action of their “detective” in taking the day watch while nothing occurred at night.

It was close to noon when the ’bus deposited them at the town from which they had to walk to the estate.

Strolling down the quiet street toward the main highway, Sandy’s alert eyes, always roving, caught sight of the estate caretaker. They hailed him and ran to the corner where he had turned to wave to them.

“What makes you say that?” Sandy’s grin of salutation changed to a look of hurt surprise.

“Why wouldn’t I say it? Ain’t it enough I had reporters an’ all rampagin’ through the place without you three got to come, on top o’ that Whiteside feller and Jeff——”

“Yep! Nights it’s been bad enough—now it’s daytimes! Ghosts! Reporters! Snoopers! And now you fellers in the daytime!”

“What about Mr. Whiteside—and Jeff?” Dick wanted to get to the bottom of a startling situation.

“Well, if you must know—that Whiteside feller was there, as per usual, and along come Jeff, limpin’——”

“Had his foot tied up, Master Larry. Said he was flyin’ and his power quit and he had to come down in a bad spot and a lot more.”

Once started on his troubles and their cause, the caretaker needed no more prompting. Jeff, he went on, had met Mr. Whiteside and said that if he wanted to fly he’d have to go in that other thing that they put in the water——”

The man nodded as they walked down toward the highway. After he helped the others to get the water-and-land ’plane onto the field, he grumbled, and had turned the propeller blades till his arms ached, the superstitious pilot, saying he had stumbled and fallen that morning and knew something would go wrong, had decided that they had no time to repair or find the trouble in the amphibian.

They must get going, he reported that Mr. Whiteside had declared, and Jeff had argued that if he had a six-B slotted bolt, he could fix his motor.

“I never did hear of a six-B slotted bolt—or any slotted bolt,” declared Dick, while Sandy and Larry assented.

“Neither did the hardware man here in town after that Whiteside feller gave me five dollars to walk in the four miles and—back!”

“That sounds to me like sending a new machine shop hand to the foreman for a left-handed monkey wrench,” he chuckled. “They’ve played a joke——”

“That doesn’t fit in,” argued Larry. “A bandaged foot, a limping pilot, an engine that wouldn’t start—and sending this gentleman on an errand that would take him away for a good while——”

All three comrades wished heartily that Jeff had revealed the information. Since he had not, each cudgeled his brains for some likely place within walking distance of the estate.

“That ‘six-B slotted bolt’ makes me think his engine hasn’t anything wrong with it at all,” Larry stated, finally. “Furthermore, I think he put down his crate in some handy—good—spot!”

“A crackerjack pilot like Jeff could get in on a pretty small field,” Larry argued. “One place I can think of that isn’t a bad landing spot is the fairway of the ninth hole on that golf course yonder.” He indicated the grounds of a golf club. “It’s away from everything, and he might fly over the course, see that no foursome or twosome was likely to get there for some time—” Dick nodded, agreeing; but Sandy shook his head.

“What bothers me,” he stated, “is that if his engine is all right, Mr. Whiteside would have met him and gone in Jeff’s ship.”

“But, Larry—why wouldn’t they use the hydroplane boat?” Sandy was not convinced.

“I think the amphibian would be quicker—and maybe they don’t want to land but need the pontoons in case of——”

“I have guessed the answer,” he cried. “They wanted to get rid of this gentleman,” he nodded toward the caretaker. “Then they could search that hangar——”

But they, themselves, had done that thoroughly! Larry made the objection but Dick waved a hand to dismiss it.

“The ghost hadn’t found anything. We hadn’t!” he argued. “Maybe they’ve decided there is something—and if it isn’t there when they make a good search, they think they know where else to look—and it’s either in the water—or over the water—or——”

“In the swamp where the seaplane crashed!” shouted Sandy, complimenting Dick with a sound smack on his back.

“Then let’s look on that fairway and see if the airplane is there, and if the engine runs.”

While they discussed these proofs of Dick’s quick wit, the sound of an airplane engine turned all eyes skyward.

“Come on—get in!” Larry urged. “I can fly this crate—and we’ll see what they’re going to do!”

CHAPTER XXV
HIGH WINGS!

If he never did so again, Sandy lived up to his decision to turn over a new leaf for once.

Usually impulsive, generally quick to adopt any new suspicion, he surprised his chums by catching Larry by the coat and dragging him back to the ground as his foot rested on the wing-step bracing.

“No!” he cried. “No! Larry—Dick—you, Mister! Come on, quick—under these trees yonder!”

“Don’t you understand?” he urged. “Jeff will fly over his crate to see if it’s all right. He may see us. Come on!”

So sound was his argument that the others hurried with him to the concealment of the nearby grove, after Larry had thoughtfully cut out the ignition so that the propeller would not revolve if its observers flew low enough to distinguish its position.

Coming closer as it dropped lower, the amphibian circled in a tight swing over the fairway several times and finally straightened out, flying toward the wind that came from almost due North on this first cool day after a humid July week, and began to grow smaller to the watchers.

“We don’t need to hurry,” Sandy insisted. “I think I know—at last!—what this all means.”

Three voices, that of the caretaker no longer grumpy, urged him to explain. Too earnest to be proud of his deductions, Sandy spoke.

“When the hangar was first haunted, and we found chewing gum that the ghost had put there, as we thought,” he told an interested trio, “none of us could work out any answer to the puzzle.

“But stop and think of these things,” he continued, urging his two friends to use their own imaginations. “The amphibian was old-looking and didn’t seem to be much good, and the gas gauge was broken, and the chewing gum was quite fresh. That might look as though——”

“Some pilot was getting the ‘phib’ ready to fly and chewed gum as he worked and put the gauge out of order to keep anybody from knowing he had filled the gas tanks.”

“Well,” Sandy grinned, “the chewing gum disappeared! Supposing the fellow we thought we saw vanishing really was there and got out some way. He’d know, from Jeff landing us and our going in, that the amphibian might not be usable when he’d need it——”

“He was getting that ready, Dick, for the emeralds—remember how Sandy discovered the place the imitations were hidden?”

“Oh, no,” Sandy protested. “It just flashed over me—putting all the facts together, the way I made up my mind I’d do.”

“That was proved—the seaplane coming out to the yacht proved that the passenger who said he was a London agent, and wasn’t at all, had changed his plans. Well, say that he had arranged with Mimi, Mrs. Everdail’s maid, to have her throw over the jewels——”

“But she wouldn’t make the mistake of giving a confederate the wrong ones. She’d seen the real ones.”

They were working on the check-up and warming of the engine as they talked. Dick made the objection to Sandy’s theory.

That could be true, Sandy admitted. But he argued that the girl must have seen the captain take the stern life preserver to his cabin, and might have guessed, even observed through a cabin port, what he did. In that case she would have thrown over the life preserver knowing that her confederate would put it in the seaplane. And he had done exactly that!

“But the passenger jumped with a different life preserver!” Dick was more anxious to prove every step of Sandy’s argument than to find flaws in it.

“I think we found the life preserver that they might have had on board the seaplane all the time. And the other one—we never thought of the yacht’s name being painted on its own things. So we took it for granted that we had the real hiding place.”

“Thank you, sir. Well, if that was true—and if it wasn’t—why is the ghost walking again in the very hangar that the seaplane wreckage is in?”

“You’re right. And the passenger, who has been out of sight, has been haunting the hangar, trying to find the other life belt,” Larry took up the theory. “Mr. Whiteside must have guessed that, too, and he planned today to make a good search and if he didn’t find what he wanted——”

“He’d fly over that swamp and see if the other belt had fallen out of the seaplane—and he’d need a pilot—so he got Jeff!” Dick put the finishing touch to the revelation. “Larry kept Tommy busy, so Mr. Whiteside got Jeff.”

“Then we ought to be flying—the engine wasn’t very cold—it’s safe to hop.” Larry took a step toward the airplane.

“I still claim we needn’t hurry,” Sandy argued. “If we go too soon, they will be sure to see us and give up.”

“But they may find the life preserver if it’s still there and get away with the emeralds.”

“If it’s still there, Larry, it will take some hunting. Anyway, we almost know their plans. If they don’t find anything they will come back to the hangar with the crate. If they do——”

“Well, I don’t say not to follow them. But I do say let’s take our time. Isn’t there some way we can work out so they won’t be likely to discover us?”

The airplane, with a more powerful engine and better flying qualities, could go higher than the amphibian which was both slower and more clumsy. To that argument he added the information that if the binoculars they had first used were still where Dick had put them, in the airplane pocket, they could find the ship’s “ceiling”—the highest point to which power would take it and the air could still sustain it at flying speed—and from that height, in one look downward discover the truth or falsity of their theory.

“If the ‘phib’ is flying low over the marsh, we can go off as far as we can and still see it,” he finished. “Then if they fly back to the hangar, we can outfly them on a different side of the island and get here in time to leave Jeff’s crate while we go and see what they do. They won’t suspect that we’re near, and if the caretaker goes with us as a witness to check up our story and to help balance the fourth seat, we can either come back if they do or follow them if they go somewhere else.”

With a cry of delight, unheard in the engine drone, Dick took the powerful glasses from his eyes, passed them to Sandy and then rubbed his hands vigorously to rid them of the chill of the high altitude.

Sandy had only to take one look when he located the object of their flight, to know that his deductions had all been sound.

Close to the grassy, channel-divided marsh, flying in a sort of spiral to cover every bit of ground, the amphibian was moving.

Larry, informed by Sandy’s gesture of the discovery, nodded, took a second to jam his cap tighter, glad that it fitted so close that it could partly save his hair from the blasting, pulling wind—he had no helmet!—banked and leveled off into a course that would take them straight away from the locality.

After a short flight he came around in a wide swing, so that the airplane was over the Sound and then crossed the marsh again from that direction.

That caused Larry to determine to circle over the place. They had found something, perhaps, down below!

When Sandy waved in an excited gesture, twenty minutes later, and Larry’s keen eyes saw the amphibian, a tiny dot, moving over the Sound, he felt sure that the missing life preserver had been found.

Taking a quick glance at gas gauge, altimeter, tachometer and his other instruments, he nodded.

“All right,” he told himself. “We’ll follow them and see what they do and where they go.”

CHAPTER XXVI
THE RACE

Judged by the theory they had worked out, the action of the men in the amphibian indicated that they were flying away with something they had found.

“If they had given up, so soon,” Dick mused, holding his head low to avoid the icy blast of their high position, “if they’d given up Jeff would go straight to the hangar again. But they’re going across Long Island Sound toward Connecticut, just as the unknown person in the hydroplane boat did with the other life preserver.”

Larry, holding speed at a safe flying margin so that the sustentation, or lifting power of the air, was greater than the drag of the airplane as it resisted the airflow, let the nose drop a trifle, let the engine rev down as he glided to a lower level where the air would not bite so much. They would be able to follow quite as well, dropping behind just enough to keep the line of distance between them as great as if they were higher and closer over the amphibian.

With his glasses, Dick could observe and indicate any change of direction or any other maneuver.

They had devised a hastily planned code of signals, very much like those used by a flying school instructor giving orders to a pupil where the Gossport helmet was not worn.

Dick, watchful and alert, lowered his chilled glasses and Sandy, keeping watch, saw his right arm extend straight out from his shoulder, laterally to the airplane’s course.

Sandy repeated the gesture after attracting Larry’s attention by a slight shaking of the dual-control rudder which was still attached, but which, on any other occasion, he had been careful not to touch.

Gently he moved the stick to lower the left aileron, bringing up the right one, of course, by their mutual operation; rudder went left a trifle and in a safe, forty-five degree bank, he began to turn.

Almost instantly Dick again removed the chilly glasses, stuck his arm out ahead of him with his forearm and hand elevated, and motioned forward with the wrist and hand.

Larry, getting the message correctly, reversed control, brought the airplane back to straight, level position on the new angle, and held it steady, revving up his engine and lifting the nose in a climb as Sandy gave him Dick’s sign, hand pointed straight upward, to climb.

“I can’t guess this one,” Sandy muttered. “They started to turn one way, then went on only a little off the old course, and now they’re coming up toward where we are.”

The problem was not answered, either by the continued gain in elevation or by the later change of plan.

To Sandy’s signal Larry cut the gun, keeping the throttle open just enough to be sure the engine, in that chill air, would not stall, and with stick sent forward and then returned to neutral, imitated the gentle glide of the amphibian.

What it meant none of the three knew any better than did the half frozen caretaker who wished very sincerely that he had never come.

“Sandy! Sandy!” Dick cried as loudly as he could. “They’ve done a sharp turn—they’re going back home I think!”

Larry did not need to have the intricate signal relayed, nor did he wait to be told his passengers’ deduction. Their own maneuvers had given him a clue.

With the first change of direction and the following indecision that showed in the amphibian’s shifts of direction, Larry spelled a change of plan on the part of its occupants. The resulting glide, enabling his chums to speak above the idling noise of the engine, indicated a similar possibility in the other ship—Jeff and Mr. Whiteside were talking over plans.

He rightly decided that they had recalled sending the caretaker on a foolish errand. They must get back and make some explanation or he would suspect them, perhaps report to somebody else. They could not know that he was shivering, crouched down in the last place of Jeff’s own airplane.

Now for a race, Larry muttered, almost automatically moving the throttle wider as he prepared to alter their course.

Not only must they get the airplane back to the golf course and set it down and have its engine still, themselves being hidden before Jeff flew over it. Furthermore, they must get to the hangar and be somewhere near the field when Jeff brought home the amphibian—or they would never know whether he and his companion had found anything or not.

To avoid being sighted and identified when passing the amphibian, the airplane must cut inland instead of making a beeline for the golf course.

“That would make the return to their objective form a rough letter “L” in the air.

However, at the far end of its flight the amphibian must turn inland a similar distance to fly over the golf fairway. That made the flying problem one of speed and not of distance traveled.

The airplane, selected for its wing-camber and span that gave it a low landing speed and good sustentation, was not fast.

“Distance to cover, seventy miles,” Larry pondered. “Our best speed, Jeff said, once, was about seventy miles an hour. The ‘phib’ does sixty, top.”

“No leeway to get to the hangar—Sandy might, barely, because he was on the track team, last school term. That is our only chance. But, at that, it will be ‘nip-and-tuck’!”

No air race can give the thrill of other forms of speed competition as does the horse race, the motor boat or sailing race, the track meet or the automobile speedway contests.

The distance is too great to permit spectators to observe it, the ships scatter, seek different elevations, or in other ways fail to keep that close formation which makes of the hundred-yard dash such a blood-stimulating incident.

The automobile contest generally follows a course where watchers have vantage points for gathering.

It is their skill, their ability to take advantage of every bit of tailwind, their power to get the utmost of safe “go” out of engine, wings and tail assembly, that keeps them alert and decides the outcome.

It could not be watched or followed; but to the occupants of the ship it was a thrilling competition with the mystery element adding zest; and when, with a fair tailwind aiding him, Larry shot the improvised “field” of the ninth fairway, making sure at cost of one complete circuit that no one was there, playing, the thrill for them was not over.

Sandy caught Larry’s idea even before the airplane had taxied to its place, close to the original take-off.

“I’m off!” cried Sandy, coat flung aside, collar ripped away, as he leaped fleetly along the soft turf. Not waiting to observe his progress, Dick and Larry busied themselves getting the airplane tail around into the same position it had originally occupied.

From the air, to an observer who had no idea that his craft had been used, all should seem natural, Larry decided as he and Dick, with Sandy’s discarded garments, and with the caretaker ruefully grumbling, chose a place of concealment.

Already the drone of the amphibian came from the shore side of the field, and in a low, quick swing, followed by a zooming departure, Jeff and Mr. Whiteside passed overhead.

CHAPTER XXVII
SANDY’S DISCOVERY

Although he was the central figure in an unusual situation, Sandy was more puzzled than enlightened by its surprising development.

A footrace against a flying ship was novel enough; but the maneuver of the amphibian was still more strange. It was baffling to Sandy.

Hearing the approach of an aircraft he sought concealment under roadside trees, continuing his steady trot. His heart sank as he identified the amphibian making its swinging oval from water to land and around the fairway and back.

He knew that it was safe for him to leave his shelter. The “phib” was past him in its zooming return from the golf course.

“Now we’ll never know what they found, or if they found anything in the swamp,” he told himself dejectedly.

“That’s their crate, all righty,” he muttered. “But—they’re not landing on the estate. I suppose they’ve come to see that Jeff’s ’plane was safe. Now they’ll go on to Connecticut and we are defeated.”

He came out onto the road, walking with bent head as soon as he had caught his breath again.

“No,” he decided. “When I don’t join them they’ll come over to the estate. It might be a good idea to go on to the landing field and see if the amphibian dropped off anything with a small parachute.”

He pursued his way without haste. While he had been divesting himself of his coat Larry had urged the caretaker to go on to his duties.

“I’ll go on!” Sandy murmured more cheerfully. “I’ll have a clear half hour to myself. Maybe—without anybody talking and disturbing me—I might think out some answer to all the queer things that have happened.”

The failure of the amphibian to return to its home field he disposed of by deciding that its pilot meant to take something to some rendezvous in Connecticut, the one, no doubt, the hydroplane boat had made for.

The thing that came into his mind and stuck there, offering neither explanations nor a solution was the mystery of how that man had disappeared out of the hangar on their first visit.

“I’d like to find out how the ‘ghost’ gets in and out again,” he reflected.

To his surprise, astonishing him so much that he stopped in the middle of a stride, the lodgekeeper’s gate of an estate he was passing opened suddenly and Sandy found himself staring at the last person in the world he expected to meet.

“I—” Sandy made up his mind to see if he could startle Jeff into a change of expression and changed his stammering indecision into a cool retort:

“I—met the estate caretaker in the village. He asked me to run on ahead and tell you—and Mr. Whiteside—” Sandy watched, “—he could not find a Six-B slotted bolt anywhere!”

“Sorry he had all the trouble. We got the ‘phib’ engine going and I took Whiteside off on a little private matter in that.”

“No. Set down in the little inlet, yonder.” He waved toward the shoreline concealed beyond the estate shrubbery. “It was closer to my own crate—it’s stalled yonder in the golf course.”

Yes—stalled! Sandy repressed a taunt and pretended to accept the false statement.

“I hear Larry’s been getting instruction off that-there Tom Larsen,” Jeff turned suddenly on Sandy.

It would do no harm, Sandy thought, to let Jeff know that his fellow conspirator, if that was Mr. Whiteside’s real standing, was not playing fair. “When people who may be wicked turn against each other, we learn a lot,” Sandy decided.

“Tommy’s a good pilot,” Jeff admitted. “Well—I’ll be on my way. See you at the next air Derby!” Jeff grinned at his joke and walked on.

While he hurried on, pausing only to collect a “wienie” and roll for lunch, Larry and Dick saw Jeff approach across the green of the fairway and took cover.

“He’s inspecting that airplane—I hope we didn’t leave any clues!” whispered Dick.

“He’s feeling the engine cowling—he wonders how the motor stayed so warm,” Larry retorted under his breath. “Now he’s looking around—get down low, Dick—well, he’s shaking his head. Now he’s in the cockpit. There! He caught the spark on a compression stroke—used his ‘booster magneto.’ There goes the engine.”

And, from the descent of Jeff, to give the ground careful inspection to the moment when he gave up his own baffling puzzle and took off, the youthful amateur pilot reported to Dick, from a spy-hole in the greenery.

“I wonder if Sandy knows Jeff has come on to take his airplane off,” Dick mused.

“It’s safe to go and see. If Mr. Whiteside is on the estate it will look as though we came out extra early. Besides, I’m hungrier than Little Red Riding Hood’s wolf. Come on!” Larry led the way from the golf course as he spoke.

“Somebody was in this hangar the day Jeff made his pretended forced landing,” he told himself. “We saw him. It wasn’t a mistake. We all saw him and that proves he wasn’t just a trick of light in the hangar.”

More than that, he deduced, the man had vanished and yet, after he was gone, there had come that unexpected descent of the rolling door which had first made them think themselves trapped. Sandy argued, and with good common sense, that a ghost, in broad sunny daylight, was a silly way to account for the man. He also felt that it was equally unjust to credit the drop of the door to gravity. Friction drums are not designed to allow the ropes on them to slip, especially if there is no jolt or jar to shake them.

“But the switches that control the motor for the drum are right out on the wall in plain sight,” he told himself, moving over toward them, since the rolling door was left wide open when the amphibian was taken out. “Yes, here they all are—this one up for lifting the door, and down to drop it. And that switch was in the neutral—‘off’—position when we were first here—and it’s in neutral now.”

He tapped the metal with the rubber end of his fountain pan and then shook its vulcanite grip-handle, to see if jarring it caused any possible particles of wire or of metal to make a contact.

His eyes, in that position, were almost on a level with the pole-pieces to which wires were joined to enable the switch metal, when thrust between the flat pole contacts, to make contact and complete the electrical circuit.

“I never saw double wires—and twisted around each other, at that,” he remarked under his breath. “No—I’m not quite right. The two wires aren’t twisted around each other. One wire is twined around the other.”

He traced the wires down into the metal, asbestos-lined sheathing cable, and was still not enlightened about the discovery. It was not necessary to have two wires. One was heavy enough for the hundred-and-ten volt current that came in from the mains.

“That wire, being twined around the other, makes me think it was added—after the first one was put in,” he declared.

Sandy, when he turned around, ten minutes later, knew all that the inside of the haunted hangar could reveal.

Another five minutes, concentrated close to a certain spot on the outside of the building, gave him his final clue.

But instead of waiting to tell his chums his great discovery, instead of keeping vigil, Sandy went away from there as fast as he could walk.

CHAPTER XXVIII
NIGHT IN THE HANGAR

Never was a returning prodigal greeted with more delight than was Sandy when, close to dusk, with a parcel under his arm, he joined Dick and Larry inside a little Summer house in the Everdail estate grove.

“Where have you been?” demanded Larry. “We hunted high and low! We thought something had happened to you when we saw Jeff fly his airplane away, came here and didn’t locate you.”

“Following farmer boys down hot, sunny furrows while they picked vegetables for market, Dick.”

“To ask them if their fathers would buy a book on family crests and have their coat of arms thrown in free.”

“No, Larry. It was an excuse to get them talking. I got the book out of Mr. Everdail’s library and used it to make them think I was a subscription agent—so I could ask questions.”

“About what?” demanded Larry, and Dick nodded to show he wanted an answer also.

“Well—about who is related to who, and family scandals, and who works for this one and that one—just ‘gossip’.”

“Stop that! Tell us where you’ve been and what you did? We’ve worried ourselves sick, nearly.”

He had been all over that section of the farm-lands, he asserted, to see if he could pick up any information that would give him some connection between either Mr. Whiteside or Jeff, or the mysterious seaplane passenger—and Mimi or the yacht stewardess.

“If I knew that, I thought we could start patching clues together,” he finished. “Because Jeff has a lot to do with this mystery.”

“I think you’re right,” Dick agreed. “But what started you off on that track?”

Spying carefully to be sure that Mr. Whiteside was not in sight, and being certain that no one else was watching, Sandy led his chums into the hangar.

“Look at them before it gets too dark, Dick. Do you see anything strange? You know as much about wiring circuits as I do. We both built amateur short-wave sending and receiving sets. You, too, Larry. What isn’t right about the switches or—the wires?”

Then his comrades observed what had first attracted Sandy’s attention, puzzled him and led to further search.

One wire, somewhat lighter in its insulation than the other, was wound around the heavier one. They traced it, as Sandy had done. It seemed to wind on down, as did others he showed, from each switch-pole, into the protective sheathing of metal and insulation; but none really were wound any further. From there on down, they ran behind the other wires!

“Bend down, close to the floor,” urged Sandy. “See all the dust and lint piled up?” He scraped some aside.

“My!” exclaimed Larry. “Golly-gracious-gosh-gravy-granny! The wires come out from behind the sheath and turn along the floor, close to the wall—and there’s dust all covering them! No wonder we didn’t notice them.”

Back along the hangar wall they crept, until they came up to the small wooden cupboard with its dusty, frayed protecting burlap across the front. Under the cupboard boards the wires ran well concealed by more dusty lint which seemed to have been swept into the corners by the lazy act of some cleaner.

“Inside here—but don’t use a light—inside here, there are smaller duplicate switches for the electric light arc and the motors,” Sandy informed his breathless, admiring cronies.

Trooping around to the rear, at one corner, Sandy bade them bend down and examine the bolted metal sheaths, large plates of sheet iron, that composed the walls of the edifice.

“I don’t see anything,” objected Dick, dejected that he had not been as quick of wit as had his younger chum. “But, then, you saw it first by daylight.”

“I did, that’s so.” Sandy gave them all the information he had. “I saw a break in the paint, only up one-half of this big plate of iron.

“The bottom half pushed inward,” he explained. “It has hinges fixed to the inner part so it will lift up into the hangar and we can creep in.”

“Now,” he said, as Dick, last to crawl in, cleared the edge of the metal, “see how clever this is—the inside of the two plates it has to come down against are fixed with something soft—I think it’s felt—to keep the plate from clanging. It fits so well that the only way I found out about it was by the sun making the dent in the paint show up a few little bright worn spots of bare metal.”

“Well, Larry, he said he flew over here at night. He chews gum and we saw how fast he chewed the day he pretended to be forced to land here. He knew all about the emeralds. And the most telling thing against him is that his wife—Mimi—is Mrs. Everdail’s maid and was on the yacht——”

“Talking to farmer boys—what they didn’t know, they found out from their older sisters when any of them were picking up early potatoes or snipping asparagus or digging up onions.”

Sandy agreed with Larry’s exclamations but urged his chums to leave the hangar: they knew all it could tell them. He wanted to replace the book he had used and get away from the hangar for awhile.

In the old, disused house, to which Mr. Whiteside had secured a set of keys for them so they need not hang around the grounds until there was work to be done, they talked in low tones. Sandy believed that Jeff had coaxed his wife to put acid on the gems in the London hotel, as had been done.

“He might be as much of a fanatic as that,” admitted Larry, but not with any great delight—he had always liked Jeff. “He is as superstitious as a heathen.”

“That’s so. But somebody said she did, or thought she must know the real ones.”

“That doesn’t prove she did, Dick. The real ones were hardly ever removed from safe deposit,” Sandy argued.

“Then why did she throw over that life preserver?—” and as he began the inquiry Larry saw the answer.

“Jeff didn’t use the amphibian, though. And he brought us here and induced us to aid him, saying we were helping Mr. Everdail.”

“Yes,” Dick supplemented Larry’s new point. “Another thing, Sandy, that doesn’t explain why he’d take three boys and fly a ship he could never use on water—with an amphibian right here.”

“I am only saying what I believe. I don’t know very much. But what I do know points to Jeff.”

No, Sandy agreed, Jeff did not expect to do that. He argued that Jeff must have planned to superintend the affair, while the man in the seaplane with Tommy Larsen secured the gems, whereupon Jeff could chase him, probably turn on him and get the emeralds, and then pretend on his return that the man had gotten safely away.

“But we don’t need to guess,” Sandy said. “Before I began asking questions I met Jeff on the way here.” He explained what made him suspect the man who said he must repair his “stalled” engine with a bolt that he knew was not made—a slotted bolt. “I slipped down across that estate to the inlet and saw the amphibian. And Mr. Whiteside was in it, supervising the filling of its tank!”

They saw that Mr. Whiteside carried a life preserver. In black on its side was painted “Tramp, New York.”

“Well, Sky Patrol—and Ground Crew,” he hailed them. “We are going to see some excitement at last!”

“By watching in and around the hangar to-night—and this time our bait will be this life preserver that I discovered in the swamp. I guessed the ‘ghost’ was searching the amphibian and the seaplane for the right life preserver. I devised a plan to get rid of the caretaker while Jeff and I made a complete, exhaustive search, this noon. We found nothing; so Jeff flew me over the swamp and we got—this.”

“Let’s open it!” urged Sandy, all his former suspicions gone in his eagerness. “We can take out the emeralds and then put the empty doughnut in place.”

“No. We won’t tamper with it. I want to deliver it, intact, to Atley Everdail. His is the right to open it.”

“No. Dick will watch inside the hangar, Larry and I by the doors. Sandy will be in or near the amphibian. If Jeff is the culprit we’ll soon know—if he had a confederate we will discover that, perhaps, also.”

“If it isn’t Jeff at all—and I hope it won’t be,” Larry said, “if it turns out to be the seaplane passenger who discovered that in his terror he chute-jumped with the wrong belt, and he comes to hunt the right one——”

“Or if it is Captain Parks, or his mate, or a seaman—” Mr. Whiteside began to chuckle as he led them toward the dark loom of the hangar, “Or—even if it turns out to be—me!—”

“No. Why?” The man stared at him through the night. “What makes you ask?”

“Because Jeff did—he walked under a ladder where a man was pruning a tree as he came to the gate of the estate next door.”

“Hm! Then—if he’s as superstitious as he makes believe,” Larry laughed, “he’d better watch out.”

And Dick, as they entered the hangar, rolled down the doors, set the switch at neutral and he was alone with Sandy in the pitchy blackness, echoed the sentiment.

“Do you know,” he spoke through the darkness. “Dick, we’re not watching that amphibian at all! If Jeff did come here and managed to get away, he’d go straight there and fly off.”

Dick agreed, declared that with Larry and Mr. Whiteside within call he dared to wait in the hangar alone, and Sandy, going out through the secret way, encountered Larry and the detective, consulted them, had their sanction for his idea and hurried off toward the next estate.

CHAPTER XXIX
SANDY’S TRAIL

Wearisome though his vigil was, Sandy made the best he could of it by going over all the events that had happened.

With his chums he had become friendly with Jeff at the newly opened municipal airport. Jeff had flown them to the old estate, pretended that his motor died, simulated a forced landing, then explained it all in a way that looked sincere enough at the time—but now!——

Jeff had been the one to accompany Larry to the wreck of the seaplane, and to bring the life preserver back, when he took Tommy Larsen to the emergency hospital.

One little thing bothered Sandy at that point in his musing: why had Jeff not made away with the life preserver at once?

“Oh, but he hadn’t seen his wife then,” he thought. “Mimi told him her news, about seeing the captain of the yacht hide the real jewels—and being an airman, he hadn’t known that all yacht equipment has its name painted on it in case of a wreck at sea.”

Skipping many other things that seemed to point out Jeff as the ringleader, deceiving his employer and war buddy, Mr. Everdail, Sandy came down to the present suspicious circumstance.

“Jeff left the amphibian here on purpose. Of course he knows that Mr. Whiteside won’t leave the real jewel ‘preserver’ unguarded here, but he must know the plan to have it in the hangar. He thinks he is clever enough to outwit us all—but Jeff,” he addressed the imaginary image of the pilot, “you walked under a ladder, today. Don’t forget how superstitious you are. And—this time—it is an omen, and no mistake.”

Making no effort to be quiet, the oarsman sculled to one of the steps arranged for embarking on the amphibian in water, looped a line around a strut to hold his boat against the drift of slack tide and a slight wind, and came onto the amphibian.

Sandy, crouched low in the passenger’s cockpit, hoping Jeff would not notice him, was dazzled by the beam of a searchlight pocket lamp which Jeff flashed around.

“Don’t you know the plan?” Sandy wanted to take advantage of Jeff’s momentary indecision: perhaps he would “give away” something.

“Yeah! I know what Whiteside planned. But he didn’t plan for anybody to be here. What’s the need?”

“In case the—ghost—got away from the others and knew this airplane was here.”

“Why, that-there is so! And if the gas-boat come and filled up the tank—I sent it, this afternoon and that was what Whiteside stayed here for, to see that the ‘phib’ got gassed and oiled up—the—ghost—could use it, if that-there ghost was a pilot.”

“Yes,” he said. “And you suspect me. I know you have, ever since the start of this business——”

“Oh, yes—I did.” Sandy thought fast: he decided to clear Jeff’s mind. “But don’t you remember that I turned over a new leaf?”

“It’s funny,” Jeff remarked. “This-here psychology I’ve read about ain’t so far wrong when it says that folks who gets the wrong slant on a thing comes to believe it so strong that even the truth looks like a fib to them.”

“Oh, well,” Jeff turned and found his way back to the rowboat. “Time will tell. I seen a flock of birds circle over my head this afternoon and that-there is a sure sign of good fortune. I’ll come out cleared!”

“Don’t forget,” he called over his shoulder, “if you can suspect me, I can suspect you—and Whiteside—and Dick—and Larry!”

When the boat touched the wharf Sandy was a tiny figure moving with careful strokes through the water, screened by the amphibian as he swam for a sandy outcrop of the shore not far beyond the flying craft.

The dark figure of the pilot, moving across the estate shore paths had, at a good distance behind it, a shadow. Sandy had managed to hold his bundled clothes enough out of water to be fairly dry.

Sandy, waiting until he got to a shrubbery, moved so it was between him and his quarry. He, too, crossed the ascending turf.

It startled Sandy to see Jeff turn in at the old house, climb the veranda steps, cross the porch to the door—and go in.

Jeff could watch from the doorway. He might see a figure in the open space of the lawn around the house.

The pilot, he reasoned, would go through the house after seeing that no one seemed to be following; but to be doubly sure he would go on to the front, coming out there, or to the side opposite where he had entered. Sandy matched his plans to the chance. He went, Indian-still and crouched, to a point where an ornamental tree would be in line with his movement from the side door, then in that shelter moved back to the hedged path, bent low and ran down to a cross path that took him to another point of the grounds.

But, when a half hour had elapsed and no one had come out, he was puzzled. Had his maneuver been executed too late? No, Jeff could not have gotten out of sight because the lawn was too wide to cross in the brief time Sandy used up.

He did not dare to find out. That “what” might be answered by “watching!”

Once he thought he caught a glint of light in the library window; but it could have come from a high beam of some automobile headlight, on the distant highway that passed the estate.

Therefore he did not see the dark figure that emerged cautiously from the grove and, with intent, careful gaze, studied the hangar.

CHAPTER XXX
DICK ENCOUNTERS THE “GHOST”

When Dick had tried crouching, sitting on his heels, walking and every other device he could think of to end the interminable difficulties of trying to pass time with nothing to do and nothing under him but the hard cement hangar floor, he began to wish he had never met Jeff or gotten into the adventure at all.

Countless times his nerves had been pulled by sounds which turned out on second thought to be only the contracting of the hot metal, subjected to the sun all day, as the evening breeze robbed it of its warmth.

No wonder that he failed to react to a slight clinking, hardly more than would be made by the scratch of wire in a lock.

But the shrinking of metal had made intermittent noises, sharp and not repeated.

This sound, so insistent, so prolonged, began, at last, to make an impression. “Now what can that be?” he wondered, becoming strained in his effort to make his ears serve him to the fullest degree.

“It can’t be a rat’s claws,” he decided. “There aren’t any rats. There’s nothing to draw them, here.”

At the emission of a sharper click from some unlocated point he felt his spine chill, his nerves grew tense and a queer, uneasy feeling ran over his muscles, an involuntary tremble.

Then he drew his legs in under him as he sat with his back against the metal sheathing of a corner.

That was a complication for which nothing had been planned. Larry and Mr. Whiteside, Dick knew, were lying in the shadow of the hedge behind the hangar, watching the cleverly devised back entry way.

Because it had been supposed that the “ghost”—Jeff—or whoever it was, would use that means of getting in, Dick’s own position had been chosen. He had selected a place sharply diagonal in direction from it. In his corner he could not be seen in the beam of a flashlight from the small cupboard unless its user came all the way out: otherwise the sides would shape the path of the light so it would not come near him.

But a man or ghost entering from the side, and playing any light around, would show Dick fully exposed.

“Well,” Dick thought. “I can only wait and see what happens—and be ready to chase if I am discovered. Maybe I can catch and hold the ‘ghost’ till the others get to us.”

Careful not to scrape his soles in the cement, he gathered himself into a crouching, compact, alert figure.

Dim and hardly distinct to his straining eyes, there seemed to be in the slightly lighter gloom of the floor where the door opened, a shadow.

He could not see out through the opening because he was almost in a straight line with the wall on that side.

He waited, becoming shaky with the strain, for what seemed like a dragging eternity.

When it seemed that he could not stay as he was another instant, the door was slightly moved, and then softly closed. So quiet was the operation that he did not hear the latch click. He had detected no change in the color of the door itself as it hung, slantwise to his view, and he heard no sound of feet on the cement.

At any rate, he knew that he was not alone inside the edifice, and if Dick’s common sense was too great to let him think of uncanny spirits, the sense of danger supplied chills and thrills a-plenty.

It threw no beam, only a sort of dull phosphorescence; but Dick’s quick eyes ran instantly to its source—some small flashlamp covered with colored cloth, a handkerchief, perhaps.

Behind that silhouette, because the light was aimed in the direction away from Dick, he saw what caused him to emit a revealing gasp.

“A woman!” gasped Dick, and at the same instant the figure whirled, Dick leaped up, the light went out and Dick rushed blindly forward.

In his rush, Dick’s arms were carried around the shoulders he could not see. Like a serpent, sinuous, tense, powerful, the woman squirmed around in his arms.

He tried to hold her with one hand as he strove to open that door with the other, while he took the beating of her furious hands on his bent face.

CHAPTER XXXI
A TRIUMPH FOR THE ENEMY

Sandy was first to hear the call and locate it. The others, not expecting a cry for help from within the hangar until they had seen some one go in, when Dick would be only a sort of surprise attacker while they proposed to make the capture, Larry and the detective were confused for an instant.

Then, recovering, and supposing Dick had called from close inside the hangar, they took the quickest way in, and interfered with one another at the small opening in the plates.

Sandy, dashing toward the hangar, correctly supposing Dick had called from its smaller doorway, did not see Jeff emerge from the old house and start on a run in the same direction.

Dick, clinging with all his strength to a wiry, supple powerful body, strove to keep that hold while he captured the hands that were pounding at his neck and averted face.

Dick clung. He heard the aides coming in through the metal opening. He caught the pound of Sandy’s approaching shoes.

He realized that with a hand at her side the woman was striving to get at something in her skirt.

That lessened his ability to hold with the arm that was already aching from its prolonged strain. His hand gripped convulsively in the folds of the dress at the back; but his grip was not as tight as it had been because his mind was concentrated on stopping that other hand!

Like a cat the figure squirmed, a heel, small and sharp, came down on his foot. He grunted and winced and the figure broke his grip.

Pushing him, leaping backward, only to catch balance, the form wheeled on agile feet and ran for the grove.

Sandy, within sighting distance, cut into the wood to intersect the path of flight.

They all disappeared into the grove, and Jeff, coming rapidly closer, paused to listen to the sound of the pursuit.

A smile, inscrutable in the dark, crossed his face, twisted his lips. He turned into the hangar.

Down the wood’s path raced Dick, Larry slightly ahead of him, the detective, older and not so quick, bringing up the rear.

“Here she is—” Sandy shouted, but a crash indicated that he had stumbled or missed his footing on slippery sod or pebbles.

Their quarry was fleet, clever and terrorized: she led them always toward the water, down hill.

Sandy, having hurt his foot somewhat in his stumble, was quickly out of the race.

He decided to go back and see if the hangar, with its door wide, was still deserted. Sandy had a misgiving that the woman might be a decoy and that the hangar ought to be watched.

“That’s—so,” panted Dick. He decided that the other two must be both fleeter and more agile than he, with his fat; so he returned with Sandy, to a point where they saw that the door was in the same relative position they had left it—wide.

“I don’t think we need to stay here—both of us,” Sandy said. “And if Jeff went into the house, he may have come out. Suppose he plans to get hold of that life preserver, and the woman was sent ahead to get us all away—” He considered that, then went back to his original idea, “Then it would be a good thing for me to get back to where I can watch that amphibian.”

In a short time two others returned, to knock on the door and to inform Dick, when he opened it, that the woman, clever planner that she proved herself, had arranged the small motor-boat of the estate so that its engine was going; by a ruse she had gotten far enough ahead of them while they stopped to “capture” her discarded coat after she had cried out as if she had stumbled. That enabled her to get to the boat. They had no way to overtake her as she swept out of the inlet. Evidently she had started the boat motor in the afternoon while they were away, or they would have heard the roar of the start though no one had noticed the softer purr of it as it idled.

Then they went into the hangar and Mr. Whiteside, listening to Dick’s report, from Sandy, of Jeff’s movements, swung his flashlamp around.

CHAPTER XXXII
A DOUBLE PURSUIT

“Not alone is Sandy on watch, but I arranged to have Tommy Larsen bring his airplane to the golf green Jeff used this afternoon,” Mr. Whiteside told them, as he walked, recovering breath, toward the hangar door.

“Tommy is to keep his engine warm, idling, and to be ready, at the first sign of escape, to take the air and overtake Jeff,” he added.

“But maybe Sandy might get into trouble,” urged Larry. “He’d fight to stop Jeff, and that man is in a dangerous mood if he’d do what he has done.”

“It will do no harm to go over,” agreed Mr. Whiteside, slamming the door behind them. “It’s shorter down along the water.”

At a jog trot they went down the slope and at the wharf Dick gave a cry of surprise.

“Then that woman—Mimi—came back to rejoin Jeff!” argued Larry, and broke into a run. “Come on, fellows!”

Down the wharf path they ran, turning into the shell-powder path that skirted the inlet on the far side of which the amphibian lay moored.

“Sandy will stop them,” panted Dick, a little to the rear because of his weight. Larry called, over his shoulder, that with two to give battle to, Sandy might need them before they could arrive.

“There’s somebody—on the lawn!” cried Dick, swinging off in that direction. From behind a large tree emerged a figure. Larry and the detective followed at a run. But the man who came quickly forward to meet them gave all three a surprise.

“Something new has come up, sir. I was waiting there by my ship a good while back, and I heard another one cruising and spiraling, shooting the field, I guess, because he came in and set down. My crate, just the way you ordered, was down by the grove, not in plain sight in the middle of the course. But Jeff set his ship down, left the engine running, and went off. I stayed hid to see what would happen, but when he didn’t come back, I thought I’d better go and find you—and see if it meant anything to you.”

“Jeff’s working with his wife, we think,” volunteered Larry. “Anyhow a woman slipped in and led us out of the hangar and started away in a motor boat, and then she must have come back, because yonder’s the boat——”

“I have orders, at that,” Mr. Whiteside told the pilot. “You go back and get into the air and then cruise around—just in case Jeff does get started.”

“He could start his motor and taxi while it warmed up, and be half across the Sound before he took off if he wanted to, in that ‘phib,’” the pilot said. Turning, he called that he would get going, and returned beyond their view beyond the trees.

Dick, Larry and Mr. Whiteside, listening for a call from Sandy, went hurrying along. But no call from Sandy. He had decided that it would be a wiser thing to hide than to risk doing battle with the pilot if he was actually as bad as they suspected; with that in mind he had crawled in through the opening from the back, into the fuselage of the amphibian. There, fairly comfortable, he lay, full length, listening. The open top allowed air to come because a strong, puffy breeze had gotten up, driving great, black thunderclouds before it.

Sandy regretted his ruse presently, because he heard a boat and realized that he could not see who occupied it: furthermore, while his position would enable him to be hidden and to go along if Jeff took off, he would be helpless in case of an accident to the craft.

Jeff got his engine going by setting it on a compression point when he had primed the cylinders and using his booster magneto to furnish the hot sparks that gave it its first impulse.

Then, as soon as he heard Jeff drop the mooring rope and get in, Sandy backed to a point where he could crawl to hands and knees, poked his head up carefully, saw Jeff, adjusting his helmet as the engine roared, and was able to climb over the seat back into the place behind the tank before Jeff decided they were warmed up enough, got the craft on the step and lifted it into the darkness, lit by intermittent flashes of approaching lightning.

“Now, Mister Jeff,” he remarked, safe behind the roar of their climb. “Go anywhere you like—life preserver and all. I’ll make the tracks ‘sandy’ for you if you want to stop!” He employed a railway expression, whimsically applying it to the airplane instead.

Dick, Larry and the detective, hearing the roar of the engine, delayed not a moment in their dash around the rest of the inlet shore.

As they reached the vicinity of its starting point and called and searched for Sandy, they heard the drone of another engine and saw the red-and-green and the white flying lights of what must be Tommy’s craft, also going northerly in pursuit.

“There he goes!” Larry cried. “There must be some place in Connecticut that Jeff and the woman with him know about—remember, Tommy’s passenger had him flying in that direction when the seaplane crashed, and the hydroplane boat went that way—by gracious-golly-gravy! Do you suppose it could have been the woman who ran off with that other life preserver, while Jeff pretended he was too sick to take up a ship?”

“Let’s go back to the house and make sure he didn’t stop there to see what Jeff had been doing before,” Larry suggested. “He may have missed going with Jeff. If the woman had been along he’d have had no place and they would have left him here. But there isn’t a trace.”

“No signs of any struggle either,” said the detective who had investigated with his flash.

In the library, where Sandy had told Dick he had seen a glimmer of light, they saw nothing especially unusual, unless they could attach importance to an old photograph album, lying open on a corner settee with several small snapshots removed and only the gummed stickers left to show they had been there and what their size was.

“I wonder if he saw two people coming and crawled into the fuselage,” Larry said.

“I’m ready—and I think I’d be safe to fly, even if it does look like storms. We could outfly Jeff, anyhow, catch up with him——”

“It’s a Long Distance book, too—and its open at the E’s!” Dick glanced swiftly down the pages, “Evedall—Ever—Everdail!” he looked up with a surprised face.

“Long Distance?” He gave the number of the Everdail Maine estate, secured from the open book. “Has that number been called recently? Can you tell me?”

“Hello! It has! At ten o’clock. Thank you. Someone has been using our house telephone, then. Goodbye!”

“And by Jeff!” Larry consulted his watch. “The time checks with the report Sandy gave that Jeff was here. He called Mr. Everdail—why?”

“But it had to be a pilot who did all the things we have evidence of, Dick.”

“And he’s flying after Jeff!” gasped the detective—leaping up he started out. “Come, boys—Larry, will you try to fly us? I’ve been on the wrong angle all along. Will you take us in Jeff’s airplane, Larry?”

Jacketed from the supply Jeff kept for passengers, two of the Sky Patrol and a discomfited detective rose in the air and joined the pursuit.

CHAPTER XXXIII
A BATTLE ABOVE THE CLOUDS

Hour after hour, into a North wind that cut down their forward mileage somewhat, Larry held the airplane.

He flew low, in order to hold the coastline of the ocean, because he did not dare try to navigate, inexperienced as he was, with no practice at “blind flying” above the clouds.

Thunderstorms menaced, but always they were to the inland side, and Larry did not have to pass through them, or climb above them and lose his way.

Boston, easily recognized for its expanse and illumination, as well as by the name-markers on certain roofs, painted there by air-minded owners, finally came into view.

Noting its white boundary lights, its red warnings, its windsock to give him the direction of the air currents, he circled the field several times, to be sure he would not foul any other ship, and to see if any signal would be sent him.

Presently, after a commercial freight carrier had taken off, he got two red lights, a signal to land, and as the field was wonderfully well lighted, and he had learned to judge distance from the ground well, Larry was repaid for his self-control and confidence and care by making a perfect three-point landing.

While they were gassing up the airplane, he went to the administration building and chatted with the field manager.

“The others are still ahead of us,” he reported to Larry and Dick as they munched a hurried meal and drank hot coffee, also securing additional flying togs to supplement what they had.

“Well, the amphibian stayed only a few minutes, and it wasn’t gone five minutes before the other one came in——”

“Oh, dear,” he finished. “I gave Tommy orders to ride down Jeff if he had to, in order to stop him, and to get him arrested. I wish I could stop him!”

“Sandy was there—they saw a boy, and Jeff got him some gloves; and they seemed surprisingly friendly.”

“That means that Jeff is innocent and has made friends with Sandy; but where is the woman?”

“With Tommy!” exclaimed Larry. “Then he’s the one we want to catch, as well as to save Jeff and Sandy from being driven down.”

Friendly pilots, considering Larry such a boy aviator as Bobby Buck had proved to be, gave him some instructions that were most valuable, concerning night flying. The wind would be dead ahead, for most of his trip toward Maine, and he could check his direction by that until he had to veer to the West of North, when the wind, quartering, would drift him off the course—but they gave him rough corrections, and advised him to get above the clouds that were bearing down on Boston—local thunder storms.

Once more the low-wing craft took the air, climbed to a good height, Larry used his instructions, got the nose into the wind and drove ahead.

Slowly, as the distance behind them increased, their distance behind the other two ships grew less. Minute by minute they cut their handicap. Dick strained his eyes ahead, and to either side, watchful, eager.

Larry knew his business: Dick wore the instructor’s part of the outfit only because it was the only helmet they could get at the start.

Under them black clouds, torn by vivid streaks of blue-white light, reeled backward, their tops tumbling and tossing.

Above them the night sky shone serene, with the full moon, just nicked by the curve of old Mother earth, riding higher and higher.

That was a glorious picture, had any one of them had the wish to enjoy it. But they were intent on much more important sights than that of a lovely sky.

Closer and closer they approached. The two airplanes were vividly visible in the bright light reflected upward also from the fleecy tops of wind-tossed cloud.

“No—not stunting,” Larry forgot his voice would not reach Dick. “They’re maneuvering.”

It was clear to him. The amphibian, easily identified by its clumsy, bulky looking trucks, with the pontoons slung to braces, was trying to get away from a relentless biplane which sought to overtop it, to ride down onto its tail, force it down.

In the airplane with one sat a woman whose presence marked him for a dangerous character, after the Everdail emeralds.

Behind the other pilot sat one of the Sky Patrol, at the mercy of a devilishly minded adversary, and he was as helpless to save himself as Larry and Dick were to aid him!

Larry, thinking of that, but hoping against hope that for all his lack of experience he might see some opportunity to stop the other man, banked moderately and began to circle.

The amphibian, under Jeff’s adroit piloting, side-slipped from under its danger.

“Good!” panted Dick, unaware that his voice carried through the tube to Larry, who nodded.

Larry breathed a prayer of thanksgiving. Sandy was all right, saved for the time being from danger of being driven down.

“Listen, Larry,” he said into his tube. “If we could fly level with the amphibian, I could use my flashlight to flick a message to Sandy, and tell him to lower the life preserver while we fly directly under his craft, until we catch it and pull it into our ship.”

With his flashlight flicking the dots and dashes of the Morse code to Sandy, Dick spelt out a message explaining his idea. Twice he flashed the message, got an O. K. from Sandy, and told Larry.

There were some preparations on the other skycraft, then Larry dropped the nose of his plane and went down a few feet. The amphibian flew over them, high enough so its hanging pontoons would not scrape their craft, and as the cockpits were low, it could drop fairly close.

Sandy leaned out, a doughnut of white came shaking and swinging at the end of a rope. Dick braced himself, safety belt snapped tight, arms extended upward. Larry held his ship at flying speed and level. Once an air shift dipped the amphibian dangerously low, but Larry saw it coming and dived ten feet, then leveled again. Once more they tried to jockey into position.

Dick saw the doughnut swing toward him, threw his head back to avoid the blow, but it struck his chest. With a grunt, his arms closed and he clung. Sandy, feeling the tug of the rope, let go.

Dick dragged in the rope to prevent it from flying back into the empennage, fouling the tail assembly—and they had the preserver.

CHAPTER XXXIV
THE EMERALDS ARE FOUND

Larry sent his craft into a sharp dive. Tommy, trying to prevent the maneuver, came straight toward the spot they had occupied, but missed.

Now the clouds hid them. By use of his instruments he could keep on a level keel, Larry knew, and with the engine throttled off, they could not be traced by its roar.

Presently they sailed out into a clear area and Larry sighed thankfully. He watched for a landing field beside a lake shaped like a half-moon. That would tell him he could set down on the landing spot the millionaire had built before going West.

Then he saw it. They began to drop swiftly, coming ever closer to the field. And then they set down, safe and unmolested.

Before the chums were clear of the runway, Tommy set down his ship, tumbled out and let the woman with him—the yacht stewardess—get out as best she could. “What do you mean, double-crossing me?” screamed Tommy at detective Whiteside. “Why have you tried to get the emeralds after you promised me half of them?”

“They are all in it together, Mr. Everdail,” Tommy shouted, turning toward the millionaire.

“What are you doing with that stewardess?” demanded Larry. “She joined you on the lawn when you came from behind the trees.”

“Be still,” cried Everdail. “We can thresh it out later. Right now let’s get those emeralds.”

“Boss, I want you to take a look at this-here stuff I brought from your house,” said Jeff, drawing a parcel from his pocket.

“Good night!” Sandy was amazed. “Jeff, that’s the family history of the Everdails, that I saw when I visited the farm boys and found out you and Mimi were married.”

“That-there is it,” agreed Jeff, taking several tintypes from an envelope. “Boss, read that history of your family and see if it makes it plain why anybody wanted to destroy your gems.”

“Yeah,” grinned Jeff. “Thanks to Sandy for leaving the book there, and thanks to—a certain relative of yours for leaving a marker at the right place. Now, take a look at these pictures out of your family album. They are pictures of the man who originally got the emeralds in India, and his son. Whose face that you know is close to being the same?”

“Yes!” he babbled. “Yes! I am the son of the branch of your family that originally had the emeralds. My grandfather, for spite against my father, willed them to your family. Those emeralds ought to be mine—and my sister’s”—here he gestured toward the stewardess.

“Yes!” cried Whiteside Everdail—as they now learned his name was—“I grew up hating Atley Everdail’s family. I enlisted in the flying corps, got into his esquadrille, made a buddy of him, won his trust!

“I worked into his confidence, and watched every chance to get the emeralds. My time came when his wife went to London. I had my sister—stewardess, she was—already on the yacht.

“I beat the yacht to London. With her help—forced by threats—I got into the hotel and destroyed the gems—I thought. But on the way back to my room I saw Captain Parks, and began to suspect. I compelled my sister to admit the truth. The real gems were safe.

“I came to America, made the hinged door to the hangar, rewired the switches to get light by day to prepare the amphibian.

“I hired Tommy Larsen—he didn’t know the truth at first. Then I saw Jeff was getting suspicious, changed my plans and got a seaplane. I even went with Atley to see my own plan carried out,” he screeched.

“But everything went wrong. The life preserver hid the gems. I knew that, and made my sister run off with the wrong preserver, that I took from Jeff’s airplane. I thought the right preserver was in the seaplane, but Tommy was ‘wise,’ and refused to do any more than watch me, and when my sister came to get the emeralds, he tried to prevent me from getting away with it. You can piece out the rest. You’ll never punish me! You’ll never—take me alive!”

Eluding them, he dashed straight down to where Jeff’s amphibian, its prop still turning, stood fifty feet from the end of the runway. Tumbling into the cockpit, he threw the throttle wide. Down the few feet the amphibian roared, gathering speed.

The rend and crash, the tear of metal, wood and fabric as the craft dashed against a tree, was followed by a shrill scream from the stewardess.

In one thing the fanatic prophesied truly. They did not take him alive. But still they did not know where the emeralds were!

Next morning the Sky Patrol, the millionaire and others took the train from camp to the harbor.

But although Mimi showed which she thought was the right belt—although they ripped apart every life preserver on the yacht—no jewels appeared.

“I’ve thought of every possible hiding place,” Sandy told his chums, “and the only thing I can see to do is—if they were in a life preserver at all—what do you say to trying this—”

He outlined a plan. So promising did it seem that both Dick and Larry agreed to it.

That night an alarm of fire, red glow, yellow and red flames, and suffocating smoke, terrified everyone.

Tracing the smoke to the galley, Mr. Everdail was astounded to find Dick and Larry struggling with a man in pajamas—he had rushed in, had seen—too late—the red flares, colored fire powder and smoke pots that burned in buckets, and had been unable to disguise the fact that he had dragged two ice trays from the refrigerator. They contained—green ice!

Quickly overpowered, their captive confessed. The chef had taken the emeralds from the life preserver and frozen them in ice cubes of a deep emerald-green dye. These he easily preserved during the short times the trays were needed for other cubes, by putting them into one of the deep vegetable trays used in the refrigerating system.

That was how the chums were misled the night of Sandy’s birthday party. The trays had been emptied when they looked, and because the trays had just been used for tinted ice and were logically empty, they were fooled.

“But I was a coward—my conscience bothered me,” the chef admitted. “I wanted to return ’em, I wanted to take ’em. So, now—I’m glad I only kept them for you!”

“Well, Sky Patrol,” said Jeff as the boys pocketed their reward checks, “the sole of that-there right foot of mine itches. That means I’m to go into a new business and prosper—with the help of my Sky Patrol and Ground Crew. How about it?”

THE
HAUNTED HANGAR

CONTENTS

THE HAUNTED HANGAR

CHAPTER I
“SUSPICIOUS SANDY”

CHAPTER II
GHOSTS, GUM—AND GEMS

CHAPTER III
THE SKY PATROL ORGANIZES

CHAPTER IV
MYSTERY OVER THE OCEAN

CHAPTER V
MYSTERY IN THE FOG

CHAPTER VI
THE END OF THE CHASE

CHAPTER VII
THE SWAMP GIVES UP A CLUE

CHAPTER VIII
SANDY MEETS A “SUSPECT”

CHAPTER IX
JEFF ENCOUNTERS A “JINX”

CHAPTER X
LARRY’S CAPTURE

CHAPTER XI
“POP! GOES OUR MYSTERY!”

CHAPTER XII
THE HOODOOED AIRPLANE

CHAPTER XIII
THE “HOODOO” STRIKES

CHAPTER XIV
DICK HANDLES A CONTROL JOB

CHAPTER XV
A TRAP IS BAITED

CHAPTER XVI
THE “BAIT” VANISHES

CHAPTER XVII
A FIGHT FOR A FORTUNE

CHAPTER XVIII
OUTWITTED!

CHAPTER XIX
A BAFFLING DISCOVERY

CHAPTER XX
SANDY TURNS OVER A NEW LEAF

CHAPTER XXI
THE SKY PATROL GIVES UP

CHAPTER XXII
THE “GROUND CREW” TAKES HOLD

CHAPTER XXIII
LARRY “SOLOS”

CHAPTER XXIV
A PUZZLING DEVELOPMENT

CHAPTER XXV
HIGH WINGS!

CHAPTER XXVI
THE RACE

CHAPTER XXVII
SANDY’S DISCOVERY

CHAPTER XXVIII
NIGHT IN THE HANGAR

CHAPTER XXIX
SANDY’S TRAIL

CHAPTER XXX
DICK ENCOUNTERS THE “GHOST”

CHAPTER XXXI
A TRIUMPH FOR THE ENEMY

CHAPTER XXXII
A DOUBLE PURSUIT

CHAPTER XXXIII
A BATTLE ABOVE THE CLOUDS

CHAPTER XXXIV
THE EMERALDS ARE FOUND

Transcriber’s Notes

THE HAUNTED HANGAR

CONTENTS

THE HAUNTED HANGAR

CHAPTER I “SUSPICIOUS SANDY”

CHAPTER II GHOSTS, GUM—AND GEMS

CHAPTER III THE SKY PATROL ORGANIZES

CHAPTER IV MYSTERY OVER THE OCEAN

CHAPTER V MYSTERY IN THE FOG

CHAPTER VI THE END OF THE CHASE

CHAPTER VII THE SWAMP GIVES UP A CLUE

CHAPTER VIII SANDY MEETS A “SUSPECT”

CHAPTER IX JEFF ENCOUNTERS A “JINX”

CHAPTER X LARRY’S CAPTURE

CHAPTER XI “POP! GOES OUR MYSTERY!”

CHAPTER XII THE HOODOOED AIRPLANE

CHAPTER XIII THE “HOODOO” STRIKES

CHAPTER XIV DICK HANDLES A CONTROL JOB

CHAPTER XV A TRAP IS BAITED

CHAPTER XVI THE “BAIT” VANISHES

CHAPTER XVII A FIGHT FOR A FORTUNE

CHAPTER XVIII OUTWITTED!

CHAPTER XIX A BAFFLING DISCOVERY

CHAPTER XX SANDY TURNS OVER A NEW LEAF

CHAPTER XXI THE SKY PATROL GIVES UP

CHAPTER XXII THE “GROUND CREW” TAKES HOLD

CHAPTER XXIII LARRY “SOLOS”

CHAPTER XXIV A PUZZLING DEVELOPMENT

CHAPTER XXV HIGH WINGS!

CHAPTER XXVI THE RACE

CHAPTER XXVII SANDY’S DISCOVERY

CHAPTER XXVIII NIGHT IN THE HANGAR

CHAPTER XXIX SANDY’S TRAIL

CHAPTER XXX DICK ENCOUNTERS THE “GHOST”

CHAPTER XXXI A TRIUMPH FOR THE ENEMY

CHAPTER XXXII A DOUBLE PURSUIT

CHAPTER XXXIII A BATTLE ABOVE THE CLOUDS

CHAPTER XXXIV THE EMERALDS ARE FOUND

Transcriber’s Notes

THE
HAUNTED HANGAR

CHAPTER I
“SUSPICIOUS SANDY”

CHAPTER II
GHOSTS, GUM—AND GEMS

CHAPTER III
THE SKY PATROL ORGANIZES

CHAPTER IV
MYSTERY OVER THE OCEAN

CHAPTER V
MYSTERY IN THE FOG

CHAPTER VI
THE END OF THE CHASE

CHAPTER VII
THE SWAMP GIVES UP A CLUE

CHAPTER VIII
SANDY MEETS A “SUSPECT”

CHAPTER IX
JEFF ENCOUNTERS A “JINX”

CHAPTER X
LARRY’S CAPTURE

CHAPTER XI
“POP! GOES OUR MYSTERY!”

CHAPTER XII
THE HOODOOED AIRPLANE

CHAPTER XIII
THE “HOODOO” STRIKES

CHAPTER XIV
DICK HANDLES A CONTROL JOB

CHAPTER XV
A TRAP IS BAITED

CHAPTER XVI
THE “BAIT” VANISHES

CHAPTER XVII
A FIGHT FOR A FORTUNE

CHAPTER XVIII
OUTWITTED!

CHAPTER XIX
A BAFFLING DISCOVERY

CHAPTER XX
SANDY TURNS OVER A NEW LEAF

CHAPTER XXI
THE SKY PATROL GIVES UP

CHAPTER XXII
THE “GROUND CREW” TAKES HOLD

CHAPTER XXIII
LARRY “SOLOS”

CHAPTER XXIV
A PUZZLING DEVELOPMENT

CHAPTER XXV
HIGH WINGS!

CHAPTER XXVI
THE RACE

CHAPTER XXVII
SANDY’S DISCOVERY

CHAPTER XXVIII
NIGHT IN THE HANGAR

CHAPTER XXIX
SANDY’S TRAIL

CHAPTER XXX
DICK ENCOUNTERS THE “GHOST”

CHAPTER XXXI
A TRIUMPH FOR THE ENEMY

CHAPTER XXXII
A DOUBLE PURSUIT

CHAPTER XXXIII
A BATTLE ABOVE THE CLOUDS

CHAPTER XXXIV
THE EMERALDS ARE FOUND