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

For many years before space flight was accomplished, there had beendiscussions and theories about how to communicate with Martians, if anyexisted. 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 theywere about twenty miles away from their G-boat—the planetary landingcraft—they probably would have fled. Except that they had theirorders, they probably would have shot first and asked questions later.

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

"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 roundand not much bigger than a child's. They've got real long legs andarms, 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 littletoo fast, sir. They've just come up to us. I don't know whether that'sfur 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, andinterested. Von Frisch tried to communicate in the only method he hadheard about.

While his companions watched curiously, he shut his ears to the runningfire of questions from Powers, squatted and drew a right angledtriangle in the red desert sand. By one of the sides he drew threemarks, 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, andwith 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 asmall circle with rays from it, for the sun. He drew four largerconcentric circles around it, with small circles for planets on therim of each one.

He pointed to the third planet, then at himself, then at hiscompanions, one by one. Then he pointed at the fourth planet and at theMartians, 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 theMartians had were weapons until they used them. They didn't realize itthen, as a matter of fact, because the Earthmen were dead, all three ofthem.

The Martian hunting party came back from the desert with word of