The first terrestrial expedition to Mars didn't find any Martians. Neither did the second. Since there are so few Martians left, those facts are less surprising than that the third did.

For many years before space flight was accomplished, there had been discussions and theories about how to communicate with Martians, if any existed. But, of course, nobody was ready when the time came.

They fell back on that antiquated gimmick.

Von Frisch, Riley and Smith watched the half dozen Martians approach, and their watching was not without some trepidation. Except that they were about twenty miles away from their G-boat—the planetary landing craft—they probably would have fled. Except that they had their orders, they probably would have shot first and asked questions later.

"Sir, this is Von Frisch," said the engineer into the microphone of his helmet. He was a little breathless about it. "We're being approached by Martians!"

"How do they act?" asked Captains Powers back at the G-boat, immediately.

"They don't act hostile, sir."

"Stand by, then, but don't take any chances. What do they look like?"

"They're quite a bit taller than we are, but their bodies are round and not much bigger than a child's. They've got real long legs and arms, and big heads with big eyes and ears."

"Are they intelligent? Are they civilized? How do they breathe?"

"Wait a minute, Captain," protested Von Frisch. "You're going a little too fast, sir. They've just come up to us. I don't know whether that's fur on them or whether they're wearing clothes."

"Well, try to communicate with them, man!" exclaimed Powers excitedly.

Von Frisch did his best. The Martians appeared friendly enough, and interested. Von Frisch tried to communicate in the only method he had heard about.

While his companions watched curiously, he shut his ears to the running fire of questions from Powers, squatted and drew a right angled triangle in the red desert sand. By one of the sides he drew three marks, by another four.

Then he stepped back and looked questioningly at the Martians.

One of the Martians squatted in a tangle of pipestem arms and legs, and with a long finger drew five lines beside the triangle's hypotenuse.

"They understand the Pythagorean theorem, sir!" exclaimed Von Frisch.

"Good! They undoubtedly know some astronomy, then. Go on."

Von Frisch hesitated a moment, then erased the triangle. He drew a small circle with rays from it, for the sun. He drew four larger concentric circles around it, with small circles for planets on the rim of each one.

He pointed to the third planet, then at himself, then at his companions, one by one. Then he pointed at the fourth planet and at the Martians, one by one. To complete the matter, he pointed at the sky.

"We are Earthmen," he said. "You are Martians."

The trouble was that the Earthmen didn't realize the things the Martians had were weapons until they used them. They didn't realize it then, as a matter of fact, because the Earthmen were dead, all three of them.

The Martian hunting party came back from the desert with word of the strange creatures who came, apparently, from another world.

"Whether they have weapons, we do not know," said the leader of the hunting party. "But they wished to harm our people, so we killed them all."

"That is desperate action," said the patriarch of the village. "In what way were they dangerous to us?"

"Foolishly they disclosed their intention to us," replied the leader of the hunting party. "They informed us they planned to take over our world and to drive our people farther from the sun, to the great planet Jupiter."

"Then you did right," said the patriarch, blinking his big eyes.

Biggs and Golden were working near the G-boat. Their helmet radios were set to a different channel from that used by the exploring party, so they were unable to hear Captain Powers shouting frantically into his microphone and getting no answer. It was just after sunset, and Biggs was looking into the west.

"We ought to see it now, but it ain't there," commented Biggs.

"What ain't there?" demanded Golden.

"Mercury," said Biggs, who prided himself on being an amateur astronomer. "I reckon you can't see it from Mars without a telescope. Too close to the sun."

He chuckled.

"If there are any Martians," he added, "I reckon they think they live on the third planet. That's funny, ain't it?"