Just then Jack uttered an exclamation, and pointed to the head of the leader.

"What's he doing? Making faces at you?" asked Mark.

"No; but look at that triangle!" exclaimed Jack. "It's a right-angled one."

"Well, what of it?"

"This: If they understand triangles, they must know something about mathematics and geometry. Suppose we draw for them that problem in geometry which states that the sums of the squares constructed on the base and alt.i.tude of a right-angled triangle is equal to the square constructed on the hypotenuse? If he knows that, maybe we can get to some understanding with him."

"Go ahead and try," a.s.sented Mr. Henderson.

Jack accordingly took up a stick, and drew in the sand the geometrical problem of which he had spoken. It is one of the simplest. No sooner had he done so than the Martians set up a cry.

"What's the matter?" asked Jack. "I hope I haven't made them mad."

"No; they appear to be delighted," said Mr. Roumann. And sure enough, the Martians showed evidences of pleasure. They pointed to the triangle on the head of their leader, and then to the one Jack had drawn.

Then, from somewhere in the rear of the crowd, there came another man. He was slightly larger than his companions, but that was not saying much, for, aside from their great heads, the Martians were all little people, not much more than up to Andy's shoulder, and Andy was not much over five feet in height.

But it was not the size of the newcomer that attracted the attention of the travelers so much as it was the device he had in the golden circle on his head. For this device was exactly the same as the one Jack had drawn in the sand to ill.u.s.trate the problem. It was a triangle, with squares drawn out from the three sides. He looked at the drawing in the sand, and made a low bow to the newcomers.

"Well, that appears to have taken their fancy," said Mark. "I can't understand it."

"I can," spoke the professor quickly. "The Martians are a very learned people. That's why their heads are so large and their bodies so small. They make a special study of the sciences, and geometry and mathematics probably are their favorites. That is why they understand Jack's problem. Science is the same throughout the universe, though conditions may differ on different planets. I think we have arrived at a means of communicating with the Martians, at least until we have learned their language."

The Martian with the triangle and squares on his circlet of gold appeared to be a grade higher in authority than the one with the simple triangle. He now addressed the travelers, but they could not understand him.

Seeing this, he stooped and drew in the sand another geometrical problem, leaving it half completed.

"You finish it, Mark," said Jack, and the boy did so, much to the delight of the crowd.

"They all are well up in geometry," declared Mr. Roumann.

"But I'd like to understand what force it was that made us move?"

spoke Jack.

"I'll see if I can find out," said Mr. Henderson, and he made motions to indicate that they would like to know what power it was that moved them away from the projectile.

A smile came to the face of the leading Martian. He pointed to his big head, and then to the travelers. Then he fixed his great eyes on them.

Instantly they felt themselves being moved backward to the projectile. They went a few feet, then were moved forward toward the crowd again. Then they found themselves stationary.

"It's thought force!" cried Jack. "That's what it is. They simply will for a thing to be done, and it is done--at least with persons from another planet. They have the power to make us move by merely wishing it."

"Then they ought to be able to read our thoughts," spoke Mark.

"Maybe their power extends only to motion," suggested Mr.

Henderson.

The chief leader spoke again, and it was evident that he was asking if the explanation and demonstration he had given was satisfactory. The professor nodded his head to indicate that it was.

The leader addressed the throng of people, and they turned and started away. The leader remained, and turning to the adventurers he pointed off toward a distant city, and indicated that they were to go there.

"And leave our projectile behind!" exclaimed Jack. "We don't want to do that."

This did not meet with the approval of the others. They were in a strange land, and the Annihilator might be the means of saving their lives. If they left it there was no telling whether or not they would ever see it again.

As well as he could Mr. Henderson made motions that they did not like to leave their craft behind. But the Martian, with a frank smile, seemed to say that it would be safe.

"Guess we can't help ourselves," remarked Mr. Roumann. "If we don't go they'll make us. Better go willingly. Besides, I want to see their city."

"But what about our prisoner--the crazy machinist?" asked Jack.

"Oh, I guess he will be all right. He had a good meal just before we landed, and he was asleep. We'll go with these queer people, and come back to-night to the projectile," said Mr.

Roumann. "Come on."

They started to follow the leader, who beckoned them forward. He went off at a rapid pace, and the travelers found themselves being urged on just as speedily by that mysterious thought force.

"This is a great way of traveling," observed Jack.

"It suah does beat walkin'," commented Washington White, who, after his first fright, appeared to take it all as a matter of course. "But I hopes dat dey's got suffin' t' placate mah inner conscientiousness wid, 'case I'se gittin' mighty hungry."

"Oh, I guess these people have to eat, even if they are mostly brains," suggested Jack. "Anyhow, we've got plenty in the projectile."

"If dat air crazy man don't git loose an' cat it all up," added Washington. "I sh.o.r.ely hopes dat he doesn't hurt mah Shanghai rooster."

"Never mind about him. Look what a wonderful country we're in,"

said Mark.

And indeed they were in a strange land.

CHAPTER XXIII

THE RED LIGHT

At first glance Mars had not seemed to be much different from the earth they had left, but when the travelers had gotten over their first astonishment at seeing the strange people, they saw that there were many points of dissimilarity.

In the first place, there appeared to be a great deal of water about them. There were ca.n.a.ls or broad rivers on every side, with only narrow strips of land dividing them. The Annihilator had landed on a broad, sandy plain, one of the largest on the planet, as it afterward developed, and so gentle had been the descent, that the projectile was not injured in the least. But leaving that vicinity, and following their guide, the travelers found themselves in the midst of a network of waterways.

"These must be some of the ca.n.a.ls the astronomers see," observed Jack.

"Yes," a.s.sented Mark. "There isn't much land to spare. I should think the Martians would be a sort of water race. But they don't appear to have any boats."

"Yes, they do," put in Mr. Roumann. "Here comes one now."