"Is the projectile damaged?" asked Mark anxiously.

"Doesn't seem to be—at least, on the outside," answered Jack, as he looked at the huge shape of the Annihilator looming up before him. "But I'm afraid it's all up with Mr. Roumann."

He bent over the German scientist. The man seemed lifeless. There was quite a cut on his head and his clothes were torn.

"He's breathing a little!" cried jack. "We must get Professor Henderson here. He'll know what to do—if anything can be done for him."

"They must have exploded a bomb in here," said Mark, as he looked around at the ruin about, them.

"Something like that," admitted jack. "Here, help me carry Mr. Roumann out of the fumes," for there was a choking smell in the shop.

The two boys found it hard work to carry that limp form out, but they managed it. Just as they got outside the shop they saw Professor Henderson running toward them, followed by Washington and Andy.

"What has happened?" asked the inventor, for he had not been able to learn much from Washington's excited account.

"I don't know," answered Jack. "We heard a explosion, just after we saw two men running away from the shop, and we found Mr. Roumann senseless."

Professor Henderson bent over, and placed his hand on the heart of his friend.

"I'm afraid he's dying," he said.

"Dying?" cried jack in dismay.

"Yes; and if he expires, the secret of the wonderful power will die with him. We will never be able to get to Mars!"

The professor placed his ear against the breast of the unconscious man.

"There is still a spark of life," he remarked. "Perhaps I can save him. I will try my electric remedy."

He got up and hurried to the house. Mr. Henderson had invented a number of medical appliances, not the least of which was an affair, different from an electric battery in that it allowed a current to be administered internally. It was this that he now decided to try on the unfortunate German.

He came back in less than a minute with a curious machine. It was shaped like a box, but on the outside had a number of shiny knobs, and several wires ending in brass handles.

Professor Henderson placed a brass handle in each of the palms of the German, directing Mark and jack to hold them there. Then he placed several of the shining knobs at the back of his head, and ran a long wire around his waist.

"Now, Andy," ordered the inventor, "if you will take hold of this rod and place the end of it on his tongue when I open his mouth, I think we may be able to revive him."

This was done, and Mr. Henderson turned on the current. There was a buzzing sound from the box, and a slight tremor was visible throughout the whole body of the unconscious man.

"It is beginning to work!" exclaimed the professor. "He is coming to!"

Mr. Roumann opened his eyes.

"Take the rod from his tongue, Andy," directed Mr. Henderson.

The hunter did so, and the German, looking curiously about him, asked:

"Is the projectile damaged?"

"It doesn't seem to be," replied Jack quickly.

"Are you much hurt?" asked the professor.

Mr. Roumann passed his hand slowly across his head.

"I feel rather strange here," he said. "There seems to be some injury."

Mark silently pointed to the cut. Mr. Henderson quickly examined it.

"The skull is not injured," he announced. "It is merely a scalp wound. Wait a moment now and I will give you something to make you feel better."

From a small pocket case he took a spoon and a bottle. He poured out a strong-smelling liquid, and administered a few drops to the German. The latter's pale face at once became flushed.

"I think you will be all right now," said Mr. Henderson. "But it was a narrow escape. Do you feel well enough to let us take you to the house?"

"I think so. But guard the shop well. That crazy machinist came back, and some one was with him. Then came an explosion—and I don't remember any more."

"I'll guard the place!" exclaimed Andy. "And if any of those chaps come around—well, they'll wish they hadn't," and he looked significantly at his gun.

Mr. Roumann was getting better every moment, and was soon able to stand. He was assisted to the house, where Mr. Henderson attended to the injury on his head.

Then, after some more medicine had been administered, and the electric remedy had been applied again, the German announced that he felt almost as good as ever, except for an aching head.

"How did it all happen?" asked Mr. Henderson, and Jack and Mark told what they knew of the explosion.

"I was working over an extra air-pump that I wish to take along with us," stated Mr. Roumann, "when I was startled by seeing two strangers standing near my work bench. One I recognized as the insane machinist who was here before. The other—"

"The other was the same one who looked in the window one night, and who, I believe, stole the power plates," interrupted Jack.

"I wish I had known that," went on Mr. Roumann. "I would have made him give them back. But I did not have time to do anything. Before I could stop him the crazy machinist had thrown something at me, which I now know must have been a bomb. Then came the explosion, and knew nothing more until you revived me. Is the place much wrecked?"

"I think not," answered Jack.

"We will go look in a little while; just as soon as we see that you are all right," announced the professor.

"Oh, I am all right. Go now. I am anxious to know."

Having assured himself that the German was able to walk to the shop, Mr. Henderson an assent, and the two boys, Washington and two scientists started for the place where Annihilator was kept.

"How did you happen to see it, Washington?" asked Mark.

"I was out fixin' a loose board on mah chicken coop," explained the colored man, "when I seen dem two rapscallions come runnin' out ob de place. I knowed dey hadn't no right dere, an' I hollered at 'em. But dey didn't stop, an' de nextest t'ing I knowed dere was a big bang. I run in, an' I seed Mistah Roumann all blowed to pieces."

"Hardly as bad as that," said the German with a smile.

"Well, almost," insisted Washington.

They reached the machine shop. The smoke had all cleared away, but the fumes from the bomb were still noticeable.

"I wonder what their object could have been?" said Jack.

"I believe they are urged on by some of my enemies," was the German's reply. "But let us see what damage has been done. I hope it is not much."

Pieces of broken machinery, twisted wheels, bent levers, shattered cogs and smashed plates were all about one corner of the shop. But the great projectile was still in place. It had not even been jarred.

Mr. Roumann went to an opening in the side that led to the engine-room. No sooner had he entered than he uttered a cry.

"The Etherium motor is damaged!" he exclaimed, and with fear in their hearts the others followed him inside the Annihilator.



CHAPTER XIII

AN ALARMING THREAT

The main machines in the engine-room were the two motors, one designed to send the projectile through the atmosphere, the other intended to propel it through the space filled with what is called ether.

It was to these two massive machines that the eyes of all were now directed. The smaller one, the atmospheric motor, did not appear to have been damaged, but several wheels and pipes of the other were broken and twisted.

"Is it ruined?" asked Professor Henderson.

Mr. Roumann was anxiously looking at the apparatus to see what damage had been done by the bomb.

"Can't we go to Mars?" inquired Jack.

"I think so," was the reassuring reply of the scientist. "It is not damaged so much as I feared. The wheels and pipes are easily replaced, and as long as the generator and the distributing plates are not disturbed, I can easily repair the rest. But it was a fortunate chance that the bomb did not explode nearer the projectile. Otherwise we would have had to give up our journey."

"And we would have had to if you had been killed," remarked the professor. "I thought the secret of the power was going to die with you!"

"It will," replied Mr. Roumann, "but not just yet. I shall never disclose the source of the power until I reach Mars, get what I am after, and come back. Then I may bequeath it to you, Professor Henderson, in return for the kindness of yourself and your young assistants."

"I will appreciate that. But you had better go to the house now and let me doctor you up."

"No, I feel well. I want to get right to work repairing the damage. It will delay us several days, but we cannot avoid it. I wish I could catch the men responsible for this outrage."

"Have you any idea who they were?"

"No; but I suspect they were in the enemy of mine. A man who used to work for me, but whom I discharged because of dishonetesty. His name was Zeb Forker."

"One of the men who threw the bomb was same one who was at the window one night," said Mark. "Do you suppose he could be Forker, Mr. Roumann?"

"No, I do not believe so. But we will not discuss that now. I fancy the men will not bother us again."

"I'll tell Andy to keep a better watch," said Mr. Henderson.

"And we'll help him," added Mark. "There is little for us to do on the projectile now, and we can do guard duty, Jack and I together."

It took Mr. Roumann several days to repair the damage done to the Etherium motor by the bomb. During that time Andy and the boys were constantly on guard about the shop, but the crazy machinist and his companion did not return.

Washington White agreed to stand guard part of one night, and, as the others were tired, they agreed to it. But a fox or some animal got in among the colored man's chickens, and at the first sound of alarm from his favorite fowls, Washington deserted his post and rushed for the coop. Jack, who was awakened by the noise, looked out of the window.

"It is some one trying to get in, Wash?" he asked.

"Dat's what, Massa Jack."

Jack awakened Mark, and the two hurried down with their guns. They found the colored maw making a circuit of his coop.

"I thought you said some one was trying to get in," observed Jack.

"So dey was, Massa Jack. I done heard de most, tremendousness conglomeration of disturbances in de direction ob my domesticoryian orinthological specimens, an' I runned ober to see what it were."

"You mean that something was after your chickens?" asked Mark.

"Dat's de impression I done endeavored to prognostigate to yo', but seems laik I ain't understood," replied Washington with an injured air.

"Oh, I understand you, all right," said Jack, "but I thought you meant some one was gettin in the machine shop."

"No, dere ain't been no one dere, but I was skeered dat somebody was after mah chickens, but I guess it were only a rat. I'll go back an stay on guard now."

"No, you'd better go to bed," decided Jack. "Mark and I will finish out the night."

"All right," agreed Washington, who, to tell the truth, was getting sleepy.

There were no further disturbances, and Mark and Jack found their tour of duty rather lonesome.

"Well, I suppose we'll start in a day or so," marked Jack, as they paced about the big shed which housed the great projectile.

"Yes. The motor seems to be in good working order again. But say, I've just thought of something."

"What?"

"Suppose something should happen to Mr. Roumann or to the motor while we were half way to Mars? I mean, suppose he should die, why, we wouldn't know how to stop the motor, and we might keep on going forever."

"Oh, I guess he'll tell the professor enough about it so that in case anything happened we could start it or stop it. It's only the secret of the power that he wants to keep."

"I wonder what he wants to go to Mars for, anyhow?"

"Well, you know what he said. That he wants to get possession of some wonderful substance. I guess it is the same stuff that makes the planet seem red to us."

"What's he going to do with it?"

"I don't know."

"Wonder what it is?"

"I don't know that, either. Maybe it's some sort of a mineral, like radium."

"Radium would be valuable, if he could get that. Maybe that's what he's going after."

"No, I think not. If it was, he wouldn't be particular about not telling us. We'll just have to wait and see."

The following two days were busy ones, as many little adjustments had to be made to the machine. But at last Mr. Roumann announced that all was completed.

"We will start day after to-morrow," he said. "All the stores are in the projectile, I have every thing arranged, and we will begin our trip Mars."

"Are we going to go up like a balloon, through the roof of the shed?" asked Jack. "If we we'll have to take the roof off."

"No, we'll start out through the great doors," said the German. "My plan is to elevate the nose or bow, of the projectile, point it toward the sky, at a slight angle, by means of propping it up on blocks. Then we will get in, seal all the openings, and I will turn on the power, and off we go. We can shoot right through the big doors at the end of the shed, and no one will know anything about it, for we will leave the earth so fast that before any one is aware of our plans we will be out of sight."

"That is a good idea," commented Mr. Henderson. "Have you boys put everything in the projectile that you'll need?"

"I guess so," replied Jack, "though it's hard to tell what you really will need on another planet."

"All I want is my gun and some ammunition," declared Andy Sudds. "I can get along with that."

"How about you, Washington?" asked Jack.

"'Well, I suah would laik t' take mah fowls along."

"I don't see how you can do that very well, Wash," objected Mr. Henderson. "We would have to carry food for them, and our space is very limited at best. I'm afraid you'll have to get rid of your chickens."

"Couldn't I take mah Shanghai rooster?" begged the colored man. "He's a fine bird, an' maybe dem folks on Mars nebber seed a real rooster. I suah does hate to leab him behind."

"Oh, I guess you could take him," agreed Mr. Roumann.

"I'll gib him some ob my rations," promised Washington. "He eats jest laik white folks, dat Shanghai do. Golly! I'se glad I kin take him. I'll go out an' make a cage."

"What will you I do with the rest of your fowls, Wash?" asked Mark.

"Oh, a feller named Jim Johnson'll keep 'em fer me till we gits back. Jim's a cousin ob mine."

The next day was spent in jacking up the prow of the projectile so that it pointed in a slanting direction toward the sky.

"Am yo' aimin' it right at Mars?" asked the colored man, pausing in the work of making cage for his rooster.

"No; that isn't necessary," said Mr. Roumann. "Once it starts upward, I can steer it in any direction I choose. I can send it directly toward Mars."

"Hit's jest like a boat," observed Washington.

"That's it."

"Well, to-morrow we start," spoke Jack that night, as they were gathered in the dining-room of the professor's house after supper, discussing the great trip.

"And to think that in ten days we'll be on thirty-five millions of miles away from the earth!" added Mark.

"It's a mighty long way," said Andy. "Mebby we'll never git back."

"Oh, I guess we will," declared Jack "We got back all right from—"

His words were interrupted by a breaking of glass. One of the windows crashed in, and something came through it into the room. It fell upon the floor—a square, black object.

"Dat's one ob dem bombs!" cried Washington. "Look out, everybody! It'll go off!"

There was a scramble to get out of the room, Washington falling down on the threshold. Jack, who was in a corner, behind some chairs, found his way blocked. This gave him a chance to take a little longer look at the object that had been thrown through the window.

"That's not a bomb!" he cried. "It's something wrapped in black paper."

The professor, Mark and Mr. Roumann stopped their hurried egress. They came back and looked at the object. As Jack had said, it was something tied up in black paper with pink string.

"It doesn't look like a bomb," observed Mark.

"More like a brick," said Jack, and started toward it.

"Maybe it's an infernal machine," suggested Mark.

Jack hesitated a moment, listened to detect any possible ticking of some hidden clock mechanism, and then, as no sound came from the object, he picked it up. Rapidly tearing off the paper, he disclosed a harmless, red brick.

"Some one wanted to scare us," remarked Andy.

"There's a paper wrapped around the brick—a white paper," said Professor Henderson.

"So there is," spoke Jack as he removed it. "There's writing on it, too."

He held it up to the light.

"It's a message," he went on, "and not a very pleasant one, either."

"Who's it from?" asked Mr. Roumann.

"It's signed 'The Crazy Machinist', Jack, and this is what it says:"

"Beware, I am still after you! I will yet blow you sky-high!"

"He threw that in through the window!" cried Mark. "He must be outside here. Let's see if we can't catch him."

"That's right," added Jack. "Andy! Washington! Come on!"

The boys, followed by the hunter and the man, hurried from the house.



CHAPTER XIV

OFF FOR MARS

It was dark outside, and coming from the lighted room, the searchers at first could discern nothing. Then, as their eyes became accustomed to the gloom, they could make out objects with greater distinctness.

A movement in a tree, just outside the broken window, attracted the attention of Andy.

"Here's something!" he cried.

He raised his gun, which he had caught up as he rushed from the house, and fired high enough in the air, so as not to hurt whoever was in hiding. The flash of the weapon showed a man in the act of sliding down the trunk.

"Catch him!" cried Jack.

They all made a rush for the tree, but the flash of Andy's gun, while it revealed the man to them, also had the effect of momentarily blinding the men and boys. For an instant they could see nothing, and when the effect of the flash passed away the man was not in sight in the semi-gloom. They could hear him running through the underbrush outside of the garden, however, and took after him.

But the crazy machinist, if indeed it was he, got away, and after a vain search through the garden and about the machine shed, they all returned to the house, Mr. Roumann and the professor having joined in the hunt.

"What do you suppose he did it for?" asked Mark, when they were again gathered in the dining-room, examining the strange message.

"He wanted to scare us," suggested Jack.

"No, I really think he means to do us an injury," said Mr. Roumann. "He has some fancied grievance against us, or he is being used as a tool by Zeb Forker. Perhaps the man who stole the plates was with him, and he hoped to get some more during the confusion. I think we had better take a look at the machine shop."

They acted on this suggestion, but an examination there showed that nothing had been disturbed. No one had been in the place.

"I'm going to sleep here to-night," said German scientist. "I'm not going to take chances at the last moment. I'll stay here."

"So will I," decided Andy, and with his gun he mounted guard outside, while Mr. Roumann made up a bed in the projectile. They were not disturbed, however, any more that night.

"Now for Mars!" cried Jack, as the sun rose the next morning, and he jumped out of bed. "Hurry up, Mark! One would think you didn't care about going!"

"Well, I guess I do, but I don't see what good it does to get up so early. We aren't going to start until ten o'clock."

"No; but I couldn't sleep any longer," declared Jack. "I'm going out to take a look at the Annihilator."

He quickly dressed, and was on his way down stairs when there arose quite a commotion out of the garden. Washington's voice was heard crying:

"Come back heah, yo' unregenerated specimen ob a ungrateful bipedical ornithology! What fo' yo' want t' distress mah longanimity fo'? Come back heah!"

"What's the matter, Wash?" asked Jack.

"Oh, dat Shanghai rooster got away jest as I were shuttin' him up in de cage, an' I'se been runnin' all ober de garden after him. 'Pears laik he doan't want t' go t' Mars."

"Wait a minute and I'll help you," volunteered Jack. "Come on, Mark," he added. "Washington's pet has got away."

The two boys went below, and, with their aid, the colored man succeeded in catching the rooster, which, crowing a loud protest, was shut up in a wooden cage and taken to the shop, ready to be placed in the projectile.

There was little to do at the last moment. Professor Henderson had arranged for a relative to come and live in the house during the time of the journey to Mars, and this gentleman arrived about nine o'clock.

Meanwhile, the last of the stores and supplies had been put in the Annihilator, a final inspection had been given the machinery, and all the scientific instruments were in place.

Washington carried the cage containing his rooster into the storeroom, where there was a large quantity of provisions, sufficient to last for a year, in case, after reaching Mars, the travelers should find on the planet no food which they could cat.

There was a plentiful supply of water, and machinery for distilling more out of the atmosphere. The gas that occupied the space between what might be termed the two skins of the projectile had already been pumped in, and nothing remained to, do but for the adventurers to enter the great airship, as it might be designated, seal up the ports, turn on the power and start.

Mr. Roumann looked critically to the bracing up of the Annihilator, to see that it was slanted just right. Then he went carefully over every inch of the great machine, to make sure that there were no openings which were not closed. As he reached the port that communicated with the storeroom, he found it only partly shut.

"Did any one of you open this?" he asked suddenly.

"I didn't," replied Jack. "Why do you ask?"

"Because I was sure I closed and locked it from the inside early this morning," was the answer. "Washington, did you open it when you put your rooster in there?"

"No, sah. I went in de inside way. I didn't tetch it."

"That's very strange," murmured Mr. Roumann, as he locked the port, and each one, in turn, had denied meddling with it. "I was sure I locked it."

The matter appeared to give him a little uneasiness, but, as he had much to do to get the projectile ready for the flight, he had to leave the solution of the matter until another time.

The great doors of the machine shed were thrown open. They were designed to allow such large bodies as airships to pass out, as Professor Henderson had, in years previous, constructed a number of aeroplanes and dirigible balloons. So there would be no trouble in speeding the projectile directly out of the shop.

The great question, now that all was finished, was whether or not the projectile would move, and in the manner and with the speed necessary to get to Mars. There had been no chance for a trial flight, and it all depended on whether or not Mr. Roumann had correctly estimated the powers of his motors.

He was sure he was right, and, from calculations made, Professor Henderson was also positive. But it yet remained to prove this.

"Well, we may as well get in," said Mr. Roumann at length. "Everything is done that can be done. The next thing is to start the motors, and—then we'll see what happens."

It was a nervous moment. Once they were in, side the great projectile, sealed up, would they ever be able to emerge again? It was a momentous question.

"Well, here goes!" exclaimed Jack with a jerky laugh as he stepped into the Annihilator.

"I'm with You," added Mark as he followed his chum.

"Come on, Washington!" cried Jack from within.

"Wait till I take one mo' look at terra cotta!" said the colored man.

"You mean terra firma, I guess," spoke the professor.

"Yes, sah. Dat's hit. Terra flirma—de earth. I wants t' bid it good-by."

Andy Sudds, still carrying his gun, went in next. Then followed Amos Henderson, and finally the German scientist. The latter clamped fast the cover of the opening by which they had entered. The interior of the Annihilator was brilliant with electric lights.

Mr. Roumann made his way to the pilot house, to see that all the levers and wheels that controlled the engines were in working order. Then he went to the engine-room, where he adjusted the two motors.

"Well," he said a bit nervously, "we are all ready to start."

"Let her go!" cried Jack gaily.

There was no crowd on hand to see them off. Professor Henderson's relative was the only spectator.

Mr. Roumann and Mr. Henderson went to pilot house again. They held a brief consultation.

"Come here, boys, if you want to see us start the motors going," called the professor.

Jack and Mark stood in the doorway. Mr. Roumann grasped a lever. He threw it over. There was a spark as the electrical contact was made.

"The atmospheric motor is now ready to start!" he remarked. "Push that knob, Professor Henderson."

The professor pushed in a small, shiny knob. Mr. Roumann turned a small wheel, and closed another electrical switch.

Instantly there was a trembling through t whole length of the projectile. Would it move? Would it leave the earth and go to Mars?

There was a moment of hesitancy, as if the great machine had not quite decided.

Then came a more violent vibration. There was a humming, throbbing, hissing sound. Suddenly the boys, and all within the projectile, felt it swaying. A moment later it began to shoot through space like a great rocket.

"Hurrah!" cried Jack. "We're off!"

"Yes," added Mr. Roumann joyfully, "we are on our way to Mars!" and he grasped the steering wheel and peered through the thick plate-glass windows of the pilot house into the vast space before them.



CHAPTER XV

SOMETHING ABOUT MARS

"Are we really in motion?" asked Jack, after a moment's silence. "It doesn't seem so."

"We are certainly in motion," declared Mr. Roumann. "See this dial?"

He pointed to one near the steering wheel. The hand on it was gently vibrating between some of the figures.

"We are traveling that many miles a second," went on the scientist. "The atmospheric motor is not working as fast as I hoped it would, but we are going fast enough. When we start the Etherium machine we shall go much more speedily."

"And when will that be?" asked Mark.

"I can't tell exactly. It will not be until we have passed through the atmosphere of the earth, and there is no way of ascertaining in advance just how thick that stratum is."

"Then how will you know?" asked Jack.

"By means of my instruments. When the hand on this dial points to zero I will know that we are beyond the atmosphere, and that it is time to start the Etherium motor."

"How do you know in which direction to steer?" asked Mark. "Can you see anything out of that window?"

"Not a thing," replied the German. "Look for yourself."

Jack and Mark peered through the plate glass. All they could see was a sort of white, fleecy mass of clouds that surrounded the great projectile.

"It's just like when we were above the clouds in the Electric Monarch," said Jack.

"Exactly," agreed Mr. Henderson.

"But if you can't see anything, how can you tell where to steer?" asked Mark.

"By means of this instrument," replied Mr. Roumann, indicating another among the many on the wall of the projectile. "This is automatically kept pointed at Mars, and by means of a hand and dial I can tell how to keep the Annihilator aimed directly at the red planet."

"Even when it is on the opposite side of the earth from us?" asked Jack.

"We are now far above the earth," was the answer, "and the planet on which we lived offers no obstruction to my telescope being pointed at Mars, even though it is daytime, when Mars is on the opposite side of the earth."

"Have we traveled as far as that?" asked Jack in awestruck tones.

"We have come just thirty thousand miles since leaving the earth," replied Mr. Roumann.

"But we don't seem to be moving at all," objected Mark.

"That is because we are shooting through space so fast, and because you can see no stationary objects with which to make a comparison, as when you are traveling on a railroad train," continued the German. "And, as we are not dependent on tracks, or roads, with their unevenness, there is no motion to our projectile, save that of moving through space. That is why it seems as if we were standing still."

"But thirty thousand miles!" cried Jack. "I thought the earth's atmosphere was variously estimated at from only forty to two hundred miles in thickness."

"The oxygen atmosphere may be," agreed Mr. Roumann. "As a matter of fact, the atmosphere we are now in would not support life for you and me a single instant. But it is atmosphere, nevertheless, or my instruments would indicate something different, and my atmospheric motor would not work. No, I expect to be traveling through the atmosphere for several days yet. Then we shall reach the true ether, and the Etherium motor will be put into operation."

"Well," said Jack, "this trip isn't going to be very strong on scenery, anyhow."

"No," agreed Mr. Roumann. "We shan't be able to observe anything but this fleeciness until we get to Mars."

"We can see the stars and moon at night, can't we?" asked Mark.

"There isn't going to be any night," replied the German with a smile. "We are now in the region of perpetual day."

"No night!" repeated Jack blankly.

"No. Just stop to think for a moment. We have left the earth, and are many thousands of miles away from it. You know that which causes night and day on the earth is the rotation of it on its axis. Half the time the part we are living on is turned away from the sun, and the other half of the time turned toward the sun. Now, the sun is fixed in space. We are also in space, and we are so comparatively small that there will never be any shadows to cause night. We are like a small point in space, and the sun is constantly shining on us. We do not revolve, so there will no night, only day."

"Are we headed for the sun?" asked Mark

"No, for Mars. But as we will take good care not to head for any other planet, so as to get it between us and the sun, we shall never have any darkness,"

"But it doesn't look like sunshine out there," objected Jack, pointing out of the window.

"No, because we are surrounded by a mass of vapor. I think it will presently pass and we shall see the sun. The difference in temperature between the projectile and the surrounding atmosphere causes us to be enveloped in a sort of cloud. When the outer shell of the Annihilator is the same temperature as the atmosphere through which we are flying, we shall emerge into sunlight."

This happened a little later, and soon they could observe the great ball of fire hanging in space.

"It seems to be smaller than when we were on the earth, doesn't it?" asked Mark.

"It is seemingly smaller," replied Professor Henderson. "We are going away from the sun you know. Mars is not as close to it as we are on our planet—I mean the one we have just left—is ninety-two millions of miles from the sun, while Mars is one hundred and forty-one millions of miles away, though its orbit is so eccentric that distance varies about thirteen millions of miles. That is, it may be thirteen millions of miles more than its mean, or average, distance, so that at times it is as far away from the sun as one hundred and fifty-four millions of miles."

"My! That's a good ways," observed Mark.

"Yes," went on Mr. Henderson, "and, in consequence, the light and heat received by Mars from the sun is a little less than half of that which our earth receives."

"Whew! We'll be mighty cold in winter—if we arrive in winter," said Jack with a shiver.

"Unless the Martians have a means of making up for this loss of light and heat," said Mr. Roumann. "I believe they have."

"I shall be much interested in seeing how the great canals on the planet are dug," said Professor Henderson. "I have seen a map of Mars, made by a scientist named Schiaparelli, and he has drawn a number of large bodies of water, among which are intermeshed continents and islands. The surface of Mars must be a curious one."

"I believe we shall find it so," spoke Mr. Roumann. "Astronomers tell us that the water on it is never frozen, except near the poles. There great ice caps are to be found."

"But what makes the planet so red?" asked Jack.

"That," said Mr. Roumann quickly, "is what hope to discover and use for our benefit, but I not wish to discuss it now."

They talked of Mars for some time further, discussing the many queer features, and during this time the Annihilator was shooting through space at terrific speed. Inside the projectile the adventurers moved about, living and breathing, comfortably as if they were on earth, for the great tanks of stored air provided all the oxygen they needed. Nor did they feel either heat or cold thanks to the marvelous construction of the projectile.

"Isn't the year on Mars longer than the year on earth?" asked Jack as he and Mark stood near the entrance to the pilot house, interested in watching the various indicators record the speed they acquired, the distance traveled, and the density the atmosphere.

"Yes; it is about twice as long," answered Roumann. "But I shall tell you more about Planet—"

"If you'll kindly promulgate yo'se'ves in dis disrection yo' will find sufficient condiments an' disproportionate elements to induciate a feelin' ob intense satisfactoriousness," exclaimed Washington White, poking his head in from the sleeping room compartment.

"That means dinner is ready," cried Jack. "That's the stuff! Our first meal on the trip to Mars!"



CHAPTER XVI

THROUGH THE ETHER

"What's that, Washington?" asked Mark, as the colored cook put something on the lad's plate. "It looks like chicken."

"It tastes like chicken," added Jack, after making a test.

"It am chicken," declared Washington. "I roasted some ob mah fowls, an' put 'em in de cold storage room. I was purty suah dere warn't any chickens on dat red planet where we're goin'."

"Probably not," answered Professor Henderson. "It was a good idea, Washington. Pass me some, please."

"Ain't Mr. Roumann comin' to dinnah?"

"Not now," answered the scientist. "He will stay in the pilot house until I relieve him."

"It seems mighty queer to be sitting down to a meal, and all the while we're shooting along at fifty miles a second," remarked Jack.

"Yes; it doesn't seem as if we were moving at all," agreed Mark.

Indeed, the dining-room of the Annihilator was a very comfortable place, though the space was rather contracted, due to the shape of the projectile and the necessity for carrying a great quantity of stores. The living-room served as the place for serving the meals, which were prepared in a sort of galley or kitchen off the engine-room.

"It's like eating in a dining-car on a railroad train," observed Andy Sudds, "only it is more steady. No curves, and nothing like that."

"Do you like it?" inquired Mr. Henderson.

"Well, it's nice, of course, and there isn't any better cook than Washington, but, to tell the honest truth, I've eaten with more satisfaction when I made a fire in the woods and boiled coffee and fried bacon. I'm sort of hampered for elbow room."

"Still, it isn't as crowded as when we all got in the cylinder and were shot up from the center of the earth on the geyser," commented Jack.

"That's right," came from Mark.

Professor Henderson, having finished his meal, went to the pilot house to relieve Mr. Roumann.

The latter paid a visit to the engine-room before sitting down.

"Is everything all right?" asked Jack.

"The motor is working like a charm," was the reply. "I shall soon expect you boys to take your turn at guiding the projectile through space."

"I want to wait until we get into the ether," said Jack. "We'll go faster then. It's something wonderful to steer a machine going a hundred miles a second."

"I should say so; six thousand miles a minute," observed Mark. "The fastest automobile would seem like a snail compared to it."

"Yes, and we are going faster than some stars," added Mr. Roumann.

"But there isn't anything to see," objected Andy. "Now, I like scenery when I travel."

"Well, it's something to always be in sight of the sun," put in Mark.

"Yes, and when we get to Mars there'll be plenty to look at," suggested Jack. "We can see the rings around it."

"Mars hasn't any rings around it," retorted Mark, who had a good memory for scientific facts. "That's Saturn you're thinking of."

"Oh, yes, so it is. But hasn't Mars got a lot of moons, or something like that? Seems to me I've heard about 'em."

"Mars has two moons, or satellites," stated Mr. Roumann, who had studied much about the red planet, "but they do not amount to much, compared to our moon. One is about ten thousand miles from Mars, and is called Deimos, and the other, which is but sixteen hundred miles from the planet, is called Phobos by astronomers."

"And how far away is our moon from the earth?" asked Mark.

"It varies from about two hundred and fifty-two thousand miles to two hundred and twenty-one thousand miles."

"Then I should think the people on Mars would get more light from their two moons, so much closer to them, than we do from our moon, so far off," remarked Jack.

"No, they don't, at least as far as we know. The one closest to them gives about one-sixtieth of our moonlight, and the outer one about one twelve-hundredth, so you see that's not much. A peculiar feature of the inner moon is that it makes a revolution about Mars in seven hours, or more than three times in a day, and it rises in the west and sets in the east, while the moon farthest away from the planet rises just as our moon does, in the east, but it comes up only once in about five days."

"Golly!" exclaimed Washington, who had been listening. "Dat suah am a funny place. Two little moons, one shootin' around you three times a day, an' de odder one circlin' around once in five days! Land a' massy! I'll git all turned around up dere!"

"Yes, you'll have to be careful, Wash," cautioned Jack. "If you go out for a moonlight walk you may have to come home in the dark."

"Den I ain't goin'; an' when I do I'll take a lantern."

Mr. Roumann told the boys much more of interest about Mars, and then, taking them to the engine-room, he showed them something about adjusting the motors and other machinery, though he did not disclose the secret of the power.

"Now we'll go to the pilot house, and I'll show you some things there," he concluded.

They found Professor Henderson at the wheel.

"Is everything all right?" asked the German.

"I think so," answered the scientist. "This airship doesn't behave exactly as the ones I constructed before, but it seems to be moving along at good speed."

"Yes, we have increased our rate of progress," stated Mr. Roumann. "We are now going nearly fifty-five miles a second. At that rate we shall be beyond the atmosphere sooner than I expected."

The remainder of that day they kept on shooting forward toward Mars, nothing occurring to mark the passage of time, save the monotonous ticking of various clocks. There was nothing to be seen, save the glare of sunlight outside.

"Aren't we ever going to meet with world, or a wandering star, or something?" asked Jack rather discontentedly.

"There's no telling when we may pass near one," said Mr. Roumann.

"S'posin' we hit one?" asked Washington, his eyes becoming large with fear.

"There's not much danger. My instruments will warn me when we approach any of the heavenly bodies, and we can steer clear of them. The only things we have to fear will be comets, and their orbits are so irregular that there is no telling when we may get in the path of one."

"What will happen when we do?" asked Mark.

Mr. Roumann shrugged his shoulders.

"We'll do our best to get out of the way," he said.

"And if we can't?"

"Well—I guess that will be the end of us."

This was a new danger, and one the boys had not thought of before. But the German scientist did not seem to attach much importance to the matter.

They traveled on for two days, nothing of moment occurring. The Annihilator, true to its name, fairly ate up space, though they were still far from Mars.

It was on the morning of the third day. The two boys and Professor Henderson were in the pilot house, and Mr. Roumann was in the engine-room, adjusting the Etherium motor, for he expected to shortly put it in operation. Suddenly Jack, who was looking at one of the instruments on the front wall, uttered a cry.

"What's the matter?" asked Mark.

"We're approaching something!" was the answer. "Some sort of heavenly body. Look at that indicator!"

The hand or pointer on a peculiar dial was moving violently to and fro.

"Call Mr. Roumann," suggested the professor. "I don't know just what to do."

Mr. Roumann hurried into the pilot house, gave a quick glance at the indicator, and exclaimed:

"We are nearing a planetoid, or, as some call them, an asteroid!"

"Is there any danger?" asked Mark.

"No. Fortunately the instrument gave us timely warning. I shall simply steer to avoid it. It is a small, unnamed planet flying around in space. There are many of them."

"Can we go close enough to it to see it?" asked Jack, who was a curious lad.

"I think so. I'll try it, anyhow."

Mr. Roumann made some adjustments to the levers and wheels controlling the motor, and, by turning on a little more power on one side of the projectile, caused it to swerve to one side. A few minutes later he called out:

"Look from the window!"

The boys gazed out. They saw that they were rushing past a dark mass, that looked as if it was composed of heaped up, black rocks, piled in fantastic masses, with great chasms here, and towering peaks there. It seemed to be several miles in diameter, and looked like a great ball.

"A small, dead world," remarked Mr. Henderson. "I suppose our planet will be like that some time."

"I hope not by the time we get back to it," commented Jack. "I wonder if we will ever get back to earth again?"

It was the first time he had expressed any doubt on this score.

"There's the last of the dead planet!" Mark cried.

They looked to see the black mass vanish into space.

"Yes, and we have reached the end of the atmosphere!" suddenly cried Mr. Roumann as he glanced at a dial. "Now we will begin to travel through ether."

He adjusted some levers, turned two wheels, threw over electric switches, and there came a perceptible jar to the projectile.

"What was that?" asked Jack.

"I have disconnected the atmospheric motor," explained the German, "and the Etherium one is now working. We are shooting along through ether at the rate of one hundred miles a second."



CHAPTER XVII

A BREAKDOWN

After the first trembling, due to the increase of speed, the sensation of traveling at one hundred miles a second was no different from that when they had been speeding through the atmosphere at fifty miles a second.

"We'll soon be on Mars now," observed Jack.

"Oh, we'll have to keep going for several days yet," declared Mr. Roumann. "But I believe we shall eventually reach there. The Etherium motor is working better than I dared to hope. It is perfect!"

As they were constantly in the glare of the sun, there was no night for those aboard the Annihilator, and they had to select an arbitrary time for going to bed. When any one wanted to retire, he went to the bunk-room, which was kept dark, and there slumbered.

For two days the Etherium motor kept sending the projectile through space. The adventurers divided their time in looking after the machinery, taking scientific observations or reading the books with which the small library was stocked. Occasionally Jack or Mark would play the electric piano, getting much enjoyment from the music.

"If folks on earth heard these tunes up in the air, I wonder what they'd think?" asked Jack.

"Humph! I guess we're too far off for them to hear anything that goes on inside this projectile," said Mark. "Why, we're nearly seventeen millions of miles above the earth now."

"Good land a' massy! Don't say dat!" cried Washington, who was setting the table for dinner.

"Why not? It's a fact," declared Mark.

"I knows it is, but don't keep dwellin' on it. Jest s'posin' we should fall. Mah gracious! Sebenteen million miles! Why, dat's a terrible ways to drop—it suah am!"

"You're right," assented Jack. "But hurry up dinner, Washington. I'm hungry."

The two boys were in the midst of the meal when they felt a curious sensation. Jack jumped up from the table.

"Do you notice anything queer?" he asked Mark.

"Yes. It seems as if we were falling down!"

"Exactly what I thought. I wonder if anything could have happened?"

The Annihilator was certainly falling through space, and no longer shooting forward. This was evident, as the motion was slower than when the projectile was urged on by the mysterious force.

"Let's go tell Mr. Roumann and Professor Henderson," suggested Mark.

They started toward the pilot house, but met the two scientists rushing back toward the engine-room.

"Has anything happened?" asked Jack.

"Yes," answered the German. "The Etherium motor has stopped working!"

"And are we falling?" asked Mark.

"Yes, in a sense," answered Mr. Henderson, as the other inventor hurried on. "The gravitation of the earth no longer attracts us, but we are not heading in a straight line for Mars. We may be falling into some other planet, or the sun."

Then he, too, went to the engine-room, and the boys followed. They found the place strangely quiet, since the throbbing and humming of the main motor had ceased. The dynamos that kept the light aglow and the air and other pumps were in motion, however.

"What's the matter?" asked Mr. Henderson.

"There's been a breakdown," was the reply of the German. "And it looks to me as if some one had been tampering with the motor."

"Tampering with the motor?"

"Yes. Some of the plates have been smashed. I believe there is some one concealed on board—some enemy of mine—who hopes to destroy us."

"What can we do?" asked Jack.

"Nothing, until the motor is repaired," replied the German scientist.

"But we are falling—"

"Yes, I know. But we can't fall with anything like the speed with which we were traveling, and though we may go downward, comparatively speaking, for a day or so, we can quickly regain our former place as soon as the motor is running again."

"But can you fix it?"

"Yes, I have some spare plates. But I wish you boys would make a search through the projectile."

"What for?" asked Mark.

"For the person who smashed the plates. I believe some one is concealed here who seeks to kill, us. We must find him."

"And I think I know who it is!" exclaimed Jack.

"Who?" asked Mr. Henderson.

"The crazy machinist. I believe he sneaked here through that open port leading into the storeroom."

"That's it!" cried Mr. Roumann. "He must have done this. See if you can't find him."

"Come on, Mark," said Jack. "We'll look for the rascal."

"And I'll help," added old Andy. "I'm pretty good on the trail. Maybe I can locate him."

"Do so, then," advised the German. "The professor and I will repair the motor."



CHAPTER XVIII

A VAIN SEARCH

The boys, with the old hunter, immediately began a search. Washington was needed to aid the two scientific men, who quickly prepared to substitute new plates for the smashed ones. The broken plates looked as if they had been struck with a sledge hammer.

Once the adventurers got used to the different motion of the projectile, which was now falling in some unknown direction of its own weight and not forced onward by the power of the motor, they did not notice anything strange.

"Let's begin at the pilot house and work back," proposed Andy. "If that crazy machinist did the damage, it would be natural for him to want to get as far away as he could from the engine-room. That place would be the pilot house."

So they searched there, but there was no sign of any one. Indeed, it would have been a pretty small person who could have concealed himself in the prow of the projectile, occupied as it was with all sorts of mechanism.

"Well, he isn't here, that's certain," declared Andy, who had brought his gun along. "Now for the bunk-room."

There they had no better luck. They peered under the berths, above them, and even turned back the sheets and blankets to look for the intruder. He was not to be found.

Nor was he in the living-room, which was looked over from top to bottom, and every corner examined.

"If he's any place, it must be in the storeroom," declared Jack.

"Unless he's outside the projectile," suggested Mark.

"He couldn't live for a minute in a place without atmosphere," was Jack's opinion. "No, he's in here somewhere, and we must find him."

But it was more easily said than done. The storeroom contained many things, piled together, and it would have been easy for a person to conceal himself among them. The boys and the old hunter looked in every possible place, as they supposed, even taking down many boxes and barrels to peer behind them, but they did not find the man they sought.

"I don't believe he's here," said Jack as he paused in the hunt.

"Say, do you know, I have an idea," said Mark. "Maybe that motor broke itself."

"How could it do that?"

"Well, it might have got to going too fast, and the power may have broken the plates. Anyhow, we didn't hear any person in the engine-room, and there doesn't seem to be any one here."

"That's so."

"I'll make an affidavit that there ain't a person on this airship but ourselves," declared Andy.

"Let's ask Mr. Roumann if it's possible that the motor smashed itself," proposed Jack, and, having no further place to search, they went back to where the two scientists and Washington were busily engaged.

"Yes," replied Mr. Roumann, after Jack had stated his question. "It's possible for that to have happened, but not very probable. I think some person is hiding on board here, and that he did it."

"But we can't find any one."

"That may be. He is well concealed. Well you can't do anything more. Suppose you two boys turn in and help us?"

Jack and Mark were glad to get busy, and for several hours they labored in the engine-room, where the two scientists were toiling. As this rendered it unnecessary for Washington to be there, the colored man went to his kitchen, while Andy again made a vain search of the projectile, looking for the crazy man.

Though Mr. Roumann had provided duplicates of the power plates for the Etherium motor, it was quite a task to take out the broken pieces and insert the new ones.

"Can't you run the atmospheric motor while we're fixing this one?" asked Jack. "That would prevent us falling, I should think."

"No, for the reason that there is no atmosphere for it to work on," declared Mr. Roumann. "But don't worry. We shall soon be under way again. We will be somewhat delayed in reaching Mars, that is all."

They labored hard all the rest of that day and part of what corresponded to the night, though of course the daylight outside never ceased. Little of it could penetrate the projectile, however, for the big car was all sealed up, save for the observation window in the pilot house and one on the side.

"There," announced Mr. Roumann, after inserting the last new plate. "I think we are all right."

It had been nearly eighteen hours since the motor had so suddenly stopped.

"Will you start it now?" asked Jack.

"Yes. I wish you and Mark would go to the pilot house and turn on the power. Do it very slowly. Mr. Henderson and I will stay here and see how the motor behaves."

It was an anxious moment when the power was turned on the repaired machinery, but, to the delight of all, the motor again began to give out the mysterious force. The projectile ceased to fall, and once more was hurled onward.

"That's the stuff!" cried Jack, as he noted the needle of the indicator moving around, showing that they were again headed for Mars.

Once more they were shooting through the ether. The wonderful motor worked even better with the new plates, and Mr. Roumann said they had increased their speed about twenty-five percent.

"So we will soon make up for what we lost," he added.

They were all tired that night, for the work of making the repairs had not been easy, and Andy had gone over the whole projectile many times, looking for the hidden insane man.

"I don't believe he can be here," was Mr. Henderson's opinion.

"He certainly is," declared Mr. Roumann, "and we shall have more trouble from him."

"I hope not," ventured Professor Henderson.

It was on the second day after the accident, when the Annihilator was speeding along, that Jack and Mark, who were in the pilot house with Mr. Roumann, noticed a peculiar trembling of one of the needles on a dial designed to indicate the nearness of heavenly bodies.

"We're coming close to something," said Jack.

"We certainly are," admitted the scientist, with an anxious look at the instrument.

"Maybe it's Mars," suggested Mark.

"No, it can't be that planet."

"What is it?" inquired Jack. "Look, the needle went all the way around that time."

Mr. Roumann bent over the gauge. Then he consulted some charts of the sky, and made a few calculations.

"Boys, I am afraid we're approaching a large comet," he said gravely. "And, what is worse, it is attracting us toward itself. We are in great danger!"



CHAPTER XIX

ESCAPING A COMET

The two boys looked at the German scientist. He was gazing, as if fascinated, at the swiftly moving needle of the gage that had told of the nearness of the comet.

"How far from it are we?" asked Jack.

"Many thousands of miles," replied Mr. Roumann. "But that distance is nothing compared to the rate at which we are traveling. We are almost certain to crash into it, or the comet will collide with us."

"And when it does, what will happen?" inquired Mark quietly.

"That is hard to say," was the answer of the German. "We know very little about the composition of comets. They may be composed merely of flaming gasses, or they may be a train of burning meteors, held together by attraction. The head may be some vast, blazing world, as large as our planet. In fact, comets are very baffling to astronomers."

"Well, if a comet is nothing but gas, it won't hurt if we run into it, will it?" inquired Jack.

"That's just the trouble. We don't know that it is gas," said Mr. Roumann. "It may be solid, and then to rush into it at terrific speed would mean that we would be demolished. Also, if the gas is flaming, you can easily imagine what would happen to the Annihilator. There would be nothing left of it—or us—in less than an instant."

"But isn't there some way of escaping it?" asked Mark.

"I'm going to try," responded Mr. Roumann. "Jack, ask Professor Henderson to step here. I wish to consult him."

Jack delivered the message, and it was overheard by Washington White. Something in Jack's manner told the colored man that there was trouble aboard.

"What's de mattah?" he asked.

Jack saw no reason for concealing the danger from the cook.

"We're heading into a comet," he, said.

"What? One ob dem tings wid long, fiery tails, Massa Jack?"

The youth nodded.

"Am we gwine t' hit it?"

"I'm afraid so."

"Well, I hopes we does!" exclaimed Washington with great earnestness. "I hopes we knocks it clean outen de universe, dat's what I hopes."

"We're a great deal more likely to be knocked out ourselves, Wash."

"No, sah! Don't yo' believe anyt'ing like dat!" exclaimed the colored man. "I know dis airship. I helped build it, an' it's de strongest one de perfesser eber made. A comet won't be one, two, six wid it. We'll jest knock a piece of his tail off, at's what we'll do. I don't laik comets. Dey allers brings bad luck. Onct, when I was a young feller, I had a ten-dollar gold piece. Dat same year a comet was observed, an' de fust t'ing I knowed somebody done up an' stole mah ten-dollar gold piece. Comets brings bad luck, an' I knows it; Golly! I want t' see one ob 'em busted all t' pieces."

"I guess you don't appreciate the danger," said Jack gravely, as he followed Professor Henderson back to the pilot room, where the two scientists began to consult.

"We have decided on a plan, Mr. Henderson and myself," said Mr. Roumann. "The fact that so little is certainly known concerning comets makes it difficult to know what to do. We might keep on our course and come to no harm, merely pawing through a gaseous mass which makes up the comet's tail. But there is a danger that we might strike the solid head of it, for that the head is solid, and of a glowing, fiery mass, which gives off a train of sparks, is my belief. To collide with a fiery ball, larger than the sun, would indeed be terrible. So we have decided to try to pass through the less dense part the tail of the comet."

"Can't we steer to one side, or above or below the comet?" asked Jack.

"Impossible," replied Mr. Roumann. "We have made some calculations, and have ascertained that this is Donati's comet—the one of 1858—and the head of it is two hundred and fifty thousand miles in diameter. The tail is many millions of miles long, and as many thick. To pass entirely beyond it would consume much time. In fact, we could not move quickly enough to escape it, as we are now being attracted out of our course toward the comet."

"How far off is it now?" asked Mark.

"About seven hundred and twenty thousand miles."

"Then we'll be up to it in about two hours," went on Mark, making a rapid calculation.

"I only hope we don't get into it, as well as up to it," commented Jack.

"We all do," observed Mr. Henderson. "But now, boys, we are going to do our best to escape. Mr. Roumann will remain in the pilot house to steer the projectile, while you and I will attend to the Etherium, motor."

"Try and see if you can get any more speed out of it," advised the German. "Use the accelerator plates, as I instructed you. Perhaps we can pass so quickly through the gaseous tail, or a portion of it, that we shall not be harmed."

"Even if it blazes?" asked Jack.

"Even if it blazes. The gas between the two shells of our projectile will absorb an enormous quantity of heat. It is our only hope."

Their hearts filled with apprehension, the two boys accompanied Professor Henderson back to the engine-room. There the scientist changed the plates on the motor, and made some adjustments, as suggested by Mr. Roumann, so that more speed would develop. Anxiously they watched the gages, to see if the motor did work any faster.

"It's increasing!" cried Jack, as he watched the needle swing, until it indicated a rate of one hundred and thirty miles a second. "We are going faster than we ever went before."

"And we need to," observed Mr. Henderson. "A comet is a terrible mass to escape from."

In spite of the increased speed of the projectile, it could not be noticed by those within it. For all they could tell they were stationary, but they were really flying through the ether at enormous velocity. For over an hour the motor was worked at the increased rate. Then, leaving the boys in charge for a few minutes, Mr. Henderson went to the pilot house to ask Mr. Roumann if there was any chance of escape. He met the German coming toward the engine-room.

"Well?" inquired the professor.

"No, not well—bad," was the gloomy answer.

"Why so?"

"I can't force the Annihilator to one side or the other. I have tried, time and again, to steer it away from the comet's head and into the less dense part of the tail, but, so far, without success. The rudder arrangement appears to be affected by the comet and will not work."

"What can we do?"

"Nothing, unless, perhaps, we can get a little more speed out of the motor. The rudder might work then."

They tried, but without success. Not a bit more speed could the Etherium machine be induced to give out. Indeed, Mr. Roumann admitted that it was working faster than he had ever expected it would.

"I'll go back and make one more attempt to steer out of the way," he said.

He was gone for perhaps ten minutes. In that time Mr. Henderson, aided by Jack and Mark, tried to adjust the motor differently, but unavailingly. Mr. Roumann came hurrying back from the pilot house.

"It's of no use!" he exclaimed. "We are heading right toward the point of the comet. We must prepare for the worst!"

There was silence for a moment. It was an awful fate to meet, and they realized it. Then Washington White, looking into the engine-room from his kitchen, exclaimed:

"Now, don't yo' all go t' worryin' 'bout dat ole comet. It can't hurt us, an' we'll knock it into smithereens!"

"You talk that way because you know nothing of comets," said Mr. Roumann solemnly.

"I don't know nuffin' 'bout 'em?" demanded the colored man. "I knows too much ob 'em, dat's what I does. Didn't I lose mah ten dollars?"

He stopped suddenly. From without there came a terrible roaring sound, that grew louder and louder.

"The comet!" cried Mr. Roumann. "We are almost upon it. That roaring is caused by the flaming gases!"

There was nothing that could be done. There was no place to go—no place to run to—no place in which to hide. They could only stand there and wait for total annihilation, which they expected every moment.

The roaring grew louder. It was like the howling of a mighty mind. The projectile seemed to tremble.

Then there came a brilliant light, rivaling even that of the sun, in the rays of which they constantly were. The light streamed in through the plate-glass ports in the engine-room. It showed violet rays, purple, orange, green, yellow—all the colors of the rainbow.

"We'll be consumed in a moment!" murmured Mr. Roumann. "We are in the midst of the comet!"

Several seconds passed. There was no increase in temperature. After all, would the wonderful gas in the space between the two shells of the projectile absorb the terrific heat?

The light faded away. Only the glow of the sun remained. The Annihilator shot onward.

Mr. Roumann rushed to the pilot house. He uttered a cry.

"We have escaped the comet!" he called to the boys and Professor Henderson, who followed him. "We went right through a small section of the tail. And I was mistaken in thinking it was composed of flaming gases. It is only nebulous light. There is no harm in a comet, after all!"

"Dat's what I said all along," remarked Washington White, as he went back to his kitchen. "All a comet is good fer is t' bring bad luck. Look at mah ten dollars. I wish we'd batted dis one inter pieces!"



CHAPTER XX

THE MOTOR STOPS

They were hardly able to realize their escape. That is, all but Washington. He took it as a matter of course.

"How did it come about?" asked Jack.

"It's hard to say," replied Mr. Roumann. "I couldn't steer away from the comet, but it's probably just as well that I could not. It seems that the mass of queer light attracted us to it, but to a certain section where we came to no harm. And we must have gone through it at an angle, or we would have been much longer within its influence."

"Can we see the comet?" asked Mark.

"There it is," replied the German. "Only it doesn't look as a comet does when you view it from the earth. We are too close to it."

They looked from the side window of the projectile. Far off appeared to be a great mass of clouds, except that instead of being white, the mass was colored with many hues, It was so vast in extent that they could see neither the beginning nor the ending of it.

"Our first comet," remarked Jack.

"And I hope our last," added Mark.

"Yes, indeed," interjected Mr. Roumann. "Now I think we will slow down the motor somewhat. We must save some of the energy for our return trip, though I have a large surplus. Still, we cannot be too careful."

"Are we once more headed for Mars?" asked Mark.

"Yes, we are pointing directly toward it. Perhaps you boys will go and slow down the motor, while Professor Henderson and I make some scientific notes concerning the comet. It will be great information to the astronomers on earth. Many of their theories will be changed, I fancy."

Jack and Mark started for the engine-room.

They passed through the living or dining-room, where Washington was setting the table for dinner.

"What I done tole yo'?" he demanded triumphantly. "I wasn't skeered ob no ole comet."

"That's right, Wash," admitted Mark. "You had one on us that time."

Andy Sudds was in one corner of the room, oiling his gun.

"Getting ready to go hunting?" asked Jack.

"Well, I heard Mr. Roumann say we'd be on Mars in a few days," replied the old man, "and if there's any game there I want to get a shot at it."

"That's right," said Jack. "I guess I'll take—"

He got no further. From the engine-room there sounded a tremendous racket, as if some one was pounding on the machinery with a big hammer.

"What's that?" cried Mark.

"Something's happened to the motor!" exclaimed Jack. "Maybe it's going too fast! Come on!"

They ran to the engine-room. The sight that met their eyes was a startling one.

Standing with his back to them was a strange man. Over his head he was swinging a sledge hammer, which he brought down with great force upon the Etherium motor.

"I'll smash it! I'll stop this machine! I'll send us all to the bottom of the universe!" the man was muttering.

"Quit that!" cried Jack, springing forward.

The man paused and turned.

"The crazy machinist!" shouted Jack. "Hell break the engine all to pieces!"

"That's what I will!" replied the infuriated man. "I'll end this voyage now!"

Once more he brought his hammer down on the machine, and the motor, with a hissing of gas and a shower of sparks, stopped working.

Jack and Mark were brave lads. They sprang upon the man, though he was large and strong, and his strength was added to by his insane fury.

In an instant they were in the midst of a fierce fight. The maniac tossed them aside as if they were mere infants, but they returned to the attack. They sought to hold his arms to prevent him from doing any further damage with the hammer. Fortunately for the lads, the man was forced to drop the weapon, to enable him to grapple with his two assailants.

"Can you hold him?" cried Mark.

"Not very well," panted Jack, as his grip of the man's arms was broken and he was flung across the room.

"Help! Help!" suddenly cried Mark. "The crazy machinist is here!"

Washington and Andy, in the living-room, heard the yells of the boys. They rushed to the scene, and, taking in the situation at a glance, flung themselves upon the unfortunate man, aiding the boys in holding him.

Even their strength was not sufficient, and it was not until Mr. Roumann, leaving Professor Henderson in charge of the pilot house, had come up, that they were able to secure the maniac.

He was quickly bound with ropes, and placed in the storeroom as a prisoner, while the German turned his whole attention to the motor, a part of which had been broken. Once more the Annihilator had ceased to advance, and was falling through space.

"Can you fix it?" anxiously asked Jack, who was panting from the terrible struggle.

"Yes," replied Mr. Roumann. "Fortunately he did not smash a vital part. I will soon have it running again."

In less than half an hour the motor was repaired, and was speeding the projectile on its way. It was not set at the greatest power, however, as Mr. Roumann did not want to put too much strain upon it.

"Now I have time to inquire how it happened," he said to the boys. "Tell me about it."

They related how they had come upon the crazy machinist.

"Then he has been hidden on board all the while," commented the German. "I was not mistaken in thinking some one opened that port after I closed it. He sneaked in here the night before we started, and has been waiting his chance to do us some damage. It was he who smashed the plates."

"But where could he have concealed himself?" asked Jack.

"I don't know. We'll see if he will tell us."

They went to the storeroom, where the maniac was bound.

"Why did you try to damage my machinery?" asked Mr. Roumann.

"Because it is an infringement on my patent," was the surprising answer. "I invented a perpetual motion machine, for making dog biscuits, and you have used it to make your airship go. Therefore I smashed it. I have the sole right to make dog biscuits for the king of the cannibal islands. I'm his private secretary."

"He is hopelessly insane," murmured Jack.

"I fear so," agreed Mr. Roumann. Then he asked: "Where have you been hiding?"

"Ah, I fooled you, all right," said the man with a cunning laugh. "It was just like a game of hide and seek to watch you hunting for me, and me looking at you all the while. Ha, ha! Oh, I had a good place."

"Where was it?" asked Mr. Roumann soothingly.

"Right up there," answered the machinist, pointing to the roof of the storeroom. The German made an investigation, and discovered a small compartment where it had been intended to make a port, but the idea for which had not been carried out. This left a space in the wall of the projectile, large enough for a man to conceal himself in. No one would suspect he was there.

"I sneaked on board one night," went on the man. "I managed to open a port into the storeroom. And I lived high, I can tell you."

"Golly! He's been at mah kitchen stuff!" exclaimed Washington.

"Did that other man come aboard with you?" asked Jack. He referred to the tramp who had peered in the window of the professor's house.

"No. He's been elected King of France," was the answer. "He had to go over there to get his crown fitted on. I'm all alone here. A few minutes more and I would have smashed that engine."

"I guess you would," responded Mr. Roumann. "Well, we'll take good care that you do not get loose again."

The bonds of the maniac were made more secure, and Washington White was told to keep, close watch over him.

It was the day after this occurrence, though Jack and Mark had not gotten over talking about it, that they were in the pilot house with Professor Henderson. The projectile was speeding along rapidly, and from calculations that had been made it was believed they would arrive at Mars in about two days.

"I'll be glad of it," said Jack. "I want a chance to stretch my legs."

"And grow lighter," added Mark. "You're fatter than ever since you began this trip."

"That's because I don't have any exercise. But I'll make up for it. I understand that on Mars one can jump twice as far as he can on the earth, due to the less dense atmosphere."

"Well, we'll soon see," said Mark.

Mr. Henderson suddenly bent over one of the indicators. He pressed a lever, turned a wheel, and then exclaimed:

"The Etherium motor has stopped working 'again! I wonder if the maniac is loose!"

"We'll see!" cried Jack, as he and Mark hurried toward the engine-room. They found Mr. Roumann there.

"The motor has stopped!" exclaimed Jack.

"I know it."

"Has there been an accident?"

"No."

"What's the matter, then?"

"We have completed our journey through the ether. The motor will only work in that."

"And that means—" began Mark.

"That we have reached the atmosphere of Mars!" exclaimed Mr. Roumann in triumph.



CHAPTER XXI

MARS AT LAST

Anticipating, as they had for some time past, such an announcement, it was none the less startling to the boys.

"Then we are really nearing Mars?" exclaimed Jack.

"Not only nearing it, but we will be there within twenty-four hours," answered the German scientist. "I was looking for this. I expected the Etherium motor to stop as soon as it reached the atmosphere of the planet, and it has done so. We will not have to start it again until we make the return trip. I will now again put into operation the atmospheric motor, and we will see how it behaves. Kindly inform Mr. Henderson, so he will understand what is taking place."

Mark hastened to the pilot house with this message, and then returned to watch Mr. Roumann, the professor agreeing to remain at the steering wheel until relieved by his friend.

Mr. Roumann began adjusting the second motor. It had been kept in readiness for instant service, and did not require much attention.

"I don't see why we have to use it at all," said Jack.

"Why shouldn't we?" Mark wanted to know.

"Because if we are near Mars it ought to attract us, just as if we were near the earth. We ought to fall right into it."

"That is just the danger," commented Mr. Roumann. "We don't want to fall. We want our projectile under perfect control, and I can only attain that end by using the motor. Besides, we are not near enough to Mars to be attracted by its force of gravitation, even supposing it is the same as that of our earth. We might not be attracted at all, and if we did not use the motor we might float around the planet as if we were a moon. No, if we wish to reach Mars we must use the atmospheric motor."

A few minutes later it was started, and the Annihilator was once more speeding along, this time under new power, and not quite so fast. All on board the projectile found themselves anticipating what they would see on the new and wonderful planet they were soon to visit.

"It hardly seems possible," murmured Jack, "that we have made such a journey—the longest on record."

"It will be more wonderful if we get back to earth," spoke Mark.

"Oh, I don't know," went on his chum. "We may like it so on Mars, that we'll want to stay. And there isn't any reason why we shouldn't, provided we find nice people there. We haven't many friends, Mark. Our best ones are right here with us. We could just as well stay as not."

"Yes, provided, as you say, that the Martians are nice people. But you must remember that we're going to be strangers in a strange land."

"Well, one always treats strangers politely," declared Jack. "I guess we'll get along all right. Anyhow, I'm glad we're near there."

"So am I," declared Mr. Henderson. "I will be able to make some scientific observations, and, perhaps, write a book about them when I get back to earth. I might make some money out of it."

"You won't need to make money, if what I suspect is true," said Mr. Roumann.

"What is that?"

"Well, I can't go into details now, but I hope to secure something that will make our fortunes. There is only one thing I fear."

"What is that?"

"The Martians may prevent me taking any of it away. But I am not going to borrow trouble. Let us see how the motor is working."

They had all gone, with the exception of Andy and Washington, to the pilot house, and they now returned to the engine-room.

"Ha! That is rather strange!" exclaimed Mr. Roumann as he looked at the buzzing machinery.

"What's the matter?" asked Mark.

"The atmospheric motor is running much faster than I ever saw it go before. I wonder if that crazy machinist could have gotten loose and meddled with it?"

"I'll look," volunteered Jack, but he soon ascertained that the man was still securely bound.

The motor was humming and snapping away, and a gage connected with it showed that it was forcing the Annihilator along at the rate of two hundred miles a second.

"That is faster even than we moved when the Etherium machine was working at its best," said Mr. Roumann with a puzzled look. "Can I have made a mistake in my calculations? I hardly think so."

"Jack, run to the pilot house, and see if the automatic steering apparatus is all right. Also see what the speed gage there indicates." Jack hurried off, and soon returned.

"We're heading right for Mars, as indicated on the chart," he said, for there was an arrangement whereby the projectile could be automatically steered.

"What speed does the gage there show?" asked the German scientist.

"Two hundred miles a second."

"The same as here," murmured Mr. Roumann. "I wonder what can cause it?"

He leaned over the motor, and made some calculations. Then he exclaimed:

"I have it!"

"What is the reason?" inquired the professor.

"It is because we are speeding through an atmosphere much less dense than that of our earth. There the motor would only work at a certain speed. Here, in the atmosphere of Mars, it goes more than twice as fast, because there is less resistance."

"Is that good or bad?" asked Jack.

"Good. We shall reach the planet all the sooner now. Boys, get ready to land on Mars in a few hours!"

The news was startling in itself, but so many strange things had happened on the trip that this only produced a momentary impression.

"Yo' say dat we am shortly goin' t' promulgate eurseves inter conjunctionary juxtaposition wid de exterior circumference an' surface ob de planetary sphere commonly called Mars?" asked Washington White.

"If you mean whether or not we are near Mars, why, we are," answered Jack with a laugh. "But, Wash, if you use such language as that I don't know what the Martians will think of you."

"I knows," answered the colored man with great dignity. "Dey'll take me fo' jest what I am—a mostest profundity educationalized specimen ob de human fambly. But I'se glad we's so neah Mars."

"Why? Are you tired of being cooped up here?" asked Mark.

"Not prexactly, but mah Shanghai rooster am. He's dat lonesome dat's he's homesick for t' git out an' do a bit ob scratchin' on de ground."

"Look out that he doesn't fly away when he gets on Mars," cautioned Jack. "Things there are twice as light as they are on the earth, and he'll only weigh a pound or so, instead of two or three."

Washington grunted, but said nothing. He served a meal, probably the last one that would be eaten before their arrival.

"We have been just twelve days, so far, on our journey," declared Mr. Roumann. "That is a little longer than I calculated, but it was due to unexpected troubles."

"Well, we've been very comfortable here," commented Mr. Henderson.

And indeed they had. Except for the rather cramped quarters, and the absence of scenery, they had lived as well as they could have done at home. They had plenty to eat and drink during their marvelous trip through space, they had enjoyed the reading of books, had listened to fine music, and had been traveling in perpetual sunlight.

What was before them? Every one asked himself that question.

On and on the projectile sped. Mr. Roumann, who had taken charge of the steering wheel called the attention of the boys to a small, dark object off to the right.

"What is it?" asked Jack. "It looks like a bright ball of fire."

"One of the moons of Mars," was the answer. "That is Deimos, and we are now but ten thousand miles from the planet, for that is the moon distance from Mars."

"How small it is!" commented Mark.

"Yes, it isn't much like our moon, but I suppose it answers for the Martians."

"But if we're only ten thousand miles away from Mars, and are traveling at two hundred miles a second, we'll be there in less than a minute!" cried Jack.

"We would, only I have shut down the motor. We are now approaching only from the force of the attraction of gravitation, and that, I find, is much less than on our earth. At the proper time I will reverse the motor, to make our landing easy."

The indicators showed that the Annihilator was now traveling along at about the rate of a fast automobile.

"We're almost there!" cried Mark.

Mr. Roumann adjusted the machinery. Sometimes he speeded it up, and again he slowed it down. He found he had the projectile under perfect control. Once again he set the motor in motion, approaching Mars at a fast rate.

They shot past another shining body.

"The second moon!" he called to the boys. "We are but sixteen hundred miles away now."

"Get ready to land!" cried Jack. "All ashore that's going ashore!"

"Maybe we'll land in the water," spoke Mark.

"No, I can so regulate the projectile that such a thing won't happen," declared Mr. Roumann.

"I will send it ahead for a few seconds, and then see what happens."

They sped forward. Suddenly there loomed up before them a great mass. It seemed to be rushing to meet them. It looked something like the earth, as seen from a balloon at a great height.

"Mars!" cried Mr. Roumann. "There is the planet we aimed for! Mars at last!"

He reversed the motor. The motion of the projectile became less. Nearer and nearer it approached the wonderful planet on which all their thoughts were centered.

"But it isn't red!" objected Jack.

"Wait until night," said the German. "We are approaching it from the daylight side."

"Am we goin' t' ram it hard?" asked Washington.

"I trust not," was Mr. Roumann's reply.

He reversed the atmospheric motor still more. They were so near the planet now that they could distinguish land and water, great buildings, patches of woodland and open spaces.

"There are people there! I see people!" cried Jack.

Indeed, there did seem to be a mass of beings looking up at the approaching projectile.

Very gently the Annihilator came nearer and nearer. There was no doubt now but that Mars was inhabited—but by what a strange race! Before those in the projectile had time to wonder at the inhabitants, they felt a sudden jar. The Annihilator came to rest. It had landed in a soft bed of sand.

"Welcome to Mars!" cried Mr. Roumann, opening a door in the side of the craft and stepping out, followed by his companions. They were at once surrounded by a throng of the queerest people that they had ever imagined.

A great shout arose, and as the adventurers stood in a group near their craft, they suddenly found themselves being moved forward toward the crowd by some strange, mysterious force.



CHAPTER XXII

QUEER PEOPLE

"Hear! Hold on! Quit shovin' me!" cried Washington White. "Stop, Massa Jack!"

"I'm not pushing you," replied the boy, who, with the others, was being moved forward against his will. "I can't seem to stop!"

Nor could the rest of them. It was just as if some one had commanded them to walk forward toward the crowd that stood waiting for them, and they could no more avoid obeying than they could had they been pulled by wire cables.

"What can it be?" murmured Mr. Roumann. "Hold back, all of you. They must have attached invisible wires to us, and are going to make prisoners of us!"

"There are no wires on me," observed Mark, carefully feeling about him.

"Nor me, either," added Jack.

"I'll soon make 'em stop!" exclaimed Andy Sudds, and raising his gun to his shoulder, he fired over the heads of the Martians, intending to frighten them.

To the surprise of the adventurers the gun only made a faint sound, about half as loud as it usually did, and they saw something small and black pop out of the muzzle, and sail lazily through the air for a short distance, then fall.

"Would you look at that!" exclaimed the hunter in great disgust. "Look how my bullet flew! First time I ever saw a bullet come from a gun! We're in a strange land, friends!"

"I have it!" cried Professor Henderson. "The attraction of gravitation on Mars is a third of that on the earth. The atmosphere is also less dense. Your gun only makes half the noise, Andy, and the bullet doesn't go nearly as fast, nor with nearly so much force. That's why you could see the bullet. It went very slowly. Your gun is of no use here."

"And is that what makes us move?" asked Jack. "Because we're so light?"

For they continued to advance toward the crowd, which seemed to be anxiously awaiting them.

"That's partly the reason, I guess," replied the professor. "The other part is that they are exerting some strange force upon us. We'll find out later what it is."

"I wish dey'd let me be!" exclaimed Washington, vainly struggling to hold himself back.

"What queer people!" exclaimed Jack. "Look at what large heads they have!"

"And what small bodies!" added Mark.

It was indeed so. They found Mars, at least the portion where they had landed, to be inhabited with a strange race of beings.

There were men and boys and a few women in the crowd, but they were unlike any men, boys or women they had ever seen. Their heads were about three times as large as those of the ordinary person, and the eyes, ears and nose were of extraordinary size. Indeed, the eyes bulged out in quite an unpleasant fashion, and the ears of the Martians were not unlike those of an elephant in proportion, though they were shaped more like those of a human being. As for a Martian nose, it was elongated, and capable of being moved in any direction, as were also the ears.

As the adventurers felt themselves being urged forward, by what means they knew not, they noted that the Martians were staring at them with their great, protruding eyes, that they were listening to their talk with their great ears thrust forward, and were lifting their flexible noses toward the travelers as if to get wind of them, as wild beasts do.

"They're certainly sizing us up in great shape," observed Jack. "But whatever kind of clothes have they got on?"

Well might he ask, for the Martians seemed to be covered with a combination of fur and feathers. They wore no garments that could be put on or taken off, but seemed to be provided by either Nature or skill with suits that were a part of themselves. Men, women and children were all attired alike.

Suddenly the travelers felt themselves come to a stop. A murmur arose from the crowd, and from the midst of the assemblage there stepped forth a man, who seemed to be a sort of leader. On his head was a golden band, and attached to it was a small, glittering triangle. He approached quite close to the little party, and the boys noticed that he seemed to float along, rather than to walk, and that his progress was very swift. He looked searchingly at the strangers with his big eyes, and then addressed them in a queer language. By the tones of his voice it was easily guessed that he was asking them questions, and it did not take much of an imagination to guess that he was inquiring whence they came, how they had arrived, and what they wanted.

"I can't understand his language," remarked Mr. Henderson, turning to his friends. "Can any of you?"

They all shook their heads.

"Let me try him in German," suggested Mr. Roumann, and he gave a brief explanation, in that language, of their trip from the earth. The man with the glittering triangle on his head did not comprehend.

"I can speak several languages," remarked Amos Henderson. "Let me tackle him."

Accordingly, the professor spoke in several languages, including the Esquimau, which he had picked up on his journey north, and in the language used by the inhabitants in the center of the earth. But to all these the leader only shook his head.

"Suppose we try Latin?" suggested Mark, who was a proficient pupil in that language. "Latin is a very old language. Maybe he understands that."

"Go ahead," said Jack.

Mark accordingly began to recite part of the first book of Caesar, beginning: "All Gaul is divided into three parts," which every, schoolboy knows. But this was no better.

"Let me try a bit of Greek on him," said Mr. Roumann. "I used to be a pretty good Greek scholar."'

But Greek appeared to be an unknown tongue to Mars. The leader, however, seeing that the strangers had arrived at the end of their resources, called to some persons in the crowd, and these, coming forward, addressed the world-dwellers in different dialects. But they were no more understandable than had been the first speech of the man with the glittering triangle.

"Guess we'll have to resort to first principles, and draw pictures for them," said Mark.

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 altitude 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," assented 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 illustrate 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."