Produced by Anne Soulard, Tiffany Vergon, Joshua Hutchinson

and the Online Distributed Proofreading Team.

LOST ON THE MOON OR IN QUEST OF THE FIELD OF DIAMONDS

BY ROY ROCKWOOD

CHAPTER

I. A WONDERFUL STORY II. SOMETHING ABOUT OUR HEROES III. PREPARING FOR A VOYAGE IV. AN ACCIDENT V. THE WORK OF AN ENEMY VI. ON THE TRACK VII. MARK IS CAPTURED VIII. JACK IS PUZZLED IX. A DARING PLOT X. "HOW STRANGE MARK ACTS" XI. READY FOR THE MOON XII. MARK'S ESCAPE XIII. A DIREFUL THREAT XIV. OFF AT LAST XV. THE SHANGHAI MAKES TROUBLE XVI. "WILL IT HIT US?" XVII. TURNING TURTLE XVIII. AT THE MOON XIX. TORCHES OF LIFE XX. ON THE EDGE OF A CRATER XXI. WASHINGTON SEES A GHOST XXII. A BREAKDOWN XXIII. LOST ON THE MOON XXIV. DESOLATE WANDERINGS XXV. THE PETRIFIED CITY XXVI. SEEKING FOOD XXVII. THE BLACK POOL XXVIII. THE SIGNAL FAILS XXIX. THE FIELD OF DIAMONDS XXX. BACK TO EARTH—CONCLUSION

CHAPTER I

A WONDERFUL STORY

"Well, what do you think of it, Mark?" asked Jack Darrow, as he laid aside a portion of a newspaper, covered with strange printed characters. "Great; isn't it?"

"You don't mean to tell me that you believe that preposterous story, do you, Jack?" And Mark Sampson looked across the table at his companion in some astonishment.

"Oh, I don't know; it may be true," went on Jack, again picking up the paper and gazing thoughtfully at it. "I wish it was."

"But think of it!" exclaimed Mark. "Why, if such a thing exists, and if we, or some one else, should attempt to bring all those precious stones to this earth, it would revolutionize the diamond industry of the world. It can't be true!"

"Well, here It is, in plain print. You can read it for yourself, as you know the Martian language as well as I do. It states that a large field of 'Reonaris' was discovered on the moon near Mare Tranquilitatis (or Tranquil Ocean, I suppose that could be translated), and that the men of Mars brought back some of the Reonaris with them. Here, read it, if you don't believe me."

"Oh, I believe you, all right—that is, I think you have translated that article as well as you can. But suppose you have made some error? We didn't have much time to study the language of Mars while we were there, and we might make some mistake in the words. That article might be an account of a dog-fight on the red planet, instead of an account of a trip to the moon and the discovery of a field of Reonaris; eh, Jack?"

"Of course, I'm likely to have made an error, for it isn't easy to translate this stuff." And Jack gazed intently at the strangely printed page, which was covered with characters not unlike Greek. "I may be wrong," went on the lad, "but you must remember that I translated some other articles in this paper, and Professor Henderson also translated them substantially as I did, and Professor Roumann agreed with him. There is Reonaris on the moon, and I wish we could go there and get some."

"But maybe after you got the Reonaris it would turn out to be only common crystals," objected Mark.

"No!" exclaimed Jack. "Reonaris is what the Martians call it in their language, and that means diamonds. I'm sure of it!"

"Well, I don't agree with you," declared the other lad.

"Don't be cranky and contrary," begged Jack.

"I'm not; but what's the use of believing anything so wild and weird as that? It's a crazy yarn!"

"It's nothing of the sort! There are diamonds on the moon; and I can prove it!"

"Well, don't get excited," suggested Mark calmly. "I don't believe it; that's all. You're mistaken about what Reonaris is; that's what you are."

"I am not!" Jack had arisen from his chair, and seemed much elated. In his hand he held clinched the paper which had caused the lively discussion. It was as near to a disagreement as Jack Darrow and Mark Sampson had come in some time.

"Sit down," begged Mark.

"I'll not!" retorted Jack. "I'm going to prove to you that I'm right."

"How are you going to do it?"

"I'm going to get Professor Henderson and Professor Roumann to translate this article for you, and then you can ask them what Reonaris is. Guess that'll convince you; won't it?"

"Maybe; but why don't you ask Andy Sudds or Washington White to give their opinion?"

"Don't get funny," advised the other lad sharply, and then, seeing that his chum was smiling, Jack laughed, cooled down a bit, looked at the paper which he had crumpled in his hand, and said:

"I guess I was getting a little too excited. But I'm sure I'm right. Here's the paper I brought from Mars to prove it, and the only thing there's any doubt about is whether or not Reonaris means diamonds. I'll ask——"

At that moment the door of the library, in which Jack and Mark were seated, was cautiously opened, and a black, woolly head was thrust in. Then two widely-opened eyes gazed at the boys.

"What's the matter, Washington?" asked Jack, with a laugh.

"'Scuse me, Massa Jack," answered the colored man, "but did I done heah you' to promulgate some conversationess regarding de transmigatorability ob diamonds?"

"Do you mean, were we talking about diamonds?" inquired Mark.

"Dat's what I done said, Massa Mark."

"No, you didn't say it, but you meant it, I guess," went on Jack. "Yes, we were talking about diamonds, Washington. I know a place that's full of them."

"Where?" inquired the colored man, thrusting his head farther into the room, and opening his eyes to their fullest extent. "Ef it ain't violatin' no confidences, Massa Jack, would yo' jest kindly mention it to yo's truly," and Professor Henderson's faithful servant, who had followed him into many dangers, looked at the two boys, who, of late years, had shared the labors of the well-known scientist. "Where am dose diamonds, Massa Jack?"

"On the moon," was the answer.

"On de moon? Ha! Ha! Dat's a joke!" And Washington began to laugh. "On de moon! Ha! Ho!"

"Well, you can read it for yourself," went on the lad, tossing the paper over to the colored man. The latter picked it up, gazed at it, first from one side, and then from the other. Next he turned it upside down, but, as this did not make the article any clearer, he turned the paper back again. Then he remarked, with a puzzled air:

"Well, I neber could read without mah glasses, Massa Jack, so I guess
I'll hab t' let it go until annoder time. Diamonds on de moon, eh?
Dat's wonderful! I wonder what dey'll be doin' next? But I'se got t'
go. Diamonds on de moon, eh? Diamonds on de moon!"

As Washington turned to leave the room, for he had entered it when Jack and Mark were talking to aim, the latter lad asked:

"Did you want to see us about anything particular, Wash?"

"Why, I suah did," was the reply, "I did come t' tell yo' dat Perfesser
Henderson would be pleased to hold some conversations wid yo', but when
Massa Jack done mentioned about dem diamonds, I clean fo'got it.
Diamonds on de moon, eh?"

"Well, if the professor wants us we'd better go," suggested Mark. "Come on, Jack, and stop dreaming about Reonaris and the moonbeams. Get back to earth."

"All right; laugh if you want to," said Jack sturdily, "but the time will come, Mark, when you'll find out that I'm right."

"How?" asked Mark.

"I don't know, but I'm sure I can prove what I say."

The two boys were to have the wonderful diamond story demonstrated to them sooner than either expected. Following the colored man, the lads, Jack carrying the paper, made their way to the laboratory of Professor Henderson. His door was open, and the aged man, whose hair and beard were now white with age, was bending over a table covered with papers, chemical apparatus, test tubes, alembecs, Bunsen burners, globes, and various pieces of apparatus. Another man, not quite so old as was Mr. Henderson, was on the point of leaving the apartment.

"Ah, boys," remarked the older professor, as he caught sight of them,
"I hope I didn't disturb you by sending for you."

"No; Jack and I were only having a red-hot discussion about diamonds on the moon," said Mark, with a laugh.

"Diamonds on the moon!" exclaimed Professor Henderson.

"Diamonds on the moon?" repeated his friend, Prof. Santell Roumann. "Is this a joke, boys?"

"Mark thinks so, but I don't!" cried Jack, enthusiastically. "Look here, Professor Henderson, and also Mr. Roumann. Here is one of the newspapers that we brought back with us in our projectile, the Annihilator, after our trip to Mars. I have been translating some of the articles in it, and to-night I came across one that told of a trip made by some of the inhabitants of Mars to the moon, in a sort of projectile, like ours, only more on the design of an aeroplane.

"They landed on the moon, the article states, and found a big field, or deposit, of Reonaris, which I claim are diamonds. Mark says I'm wrong, but, Professor Henderson, isn't Reonaris to the Martians what diamonds are to us?"

"It certainly is," agreed the older scientist, and he looked for confirmation to his scholarly companion.

"Reonaris is substantially a diamond," said Professor Roumann. "It has the same chemical constitution, and also the diamond's hardness and brilliancy. But I don't understand how any diamonds can be on the moon."

"You can read this for yourself," suggested Jack, passing over the paper, which was one of some souvenirs brought back from what was the longest journey on record, ever taken by human beings.

Mr. Roumann adjusted his glasses, and carefully read the article that was printed in such strange characters. As he perused it, he nodded his head thoughtfully from time to time. Then he passed the paper to Professor Henderson.

The older scientist was somewhat longer in going over the article, but when he had finished, he looked at the two boys, and said: "Jack is right! This is an account of a trip made to the moon by some of the Martians, who have advanced much further in the art of air navigation than have we. Some of the words I am not altogether familiar with, but in the main, that is what the paper states."

"And doesn't it tell about them finding a field of Reonaris?" asked
Jack eagerly, for he was anxious to prove to his chum that he was right.

"Yes, it does," replied Mr. Henderson.

"And Reonaris is diamonds, isn't it?" asked Jack.

"It is," answered Professor Roumann gravely.

"Then," cried Jack, "what's to hinder us from going to the moon, and getting some of those diamonds? The Martians must have left some! Let's go to the moon and get them! We can do it in the projectile with which we made the journey to Mars. Let's start for the moon!"

For a moment there was silence in the laboratory of the scientist. It was broken by Washington White, who remarked:

"Good land a' massy! Annodder ob dem trips through de air! Well, I ain't goin' to no moon—no sah!! Ef I went dere, I'd suah get looney, an' I has troubles enough now wid'out dat, I suah has!" And, shaking his head dubiously, the colored man shuffled from the room.

CHAPTER II

SOMETHING ABOUT OUR HEROES

"Are you in earnest in proposing this trip?" asked Professor Henderson of Jack. The lad, with flushed face and bright eyes, stood in the centre of the apartment, holding the paper which the aged scientist had returned to him.

"I certainly am," was the reply. "It ought not to be a difficult undertaking, after our trip to the North Pole through the air, the one to the South Pole under water, our journey to the centre of the earth, and our flight to Mars. Why, a trip to the moon ought to be a little pleasure jaunt, like an automobile tour. Can't we go, Professor?"

"From the standpoint of possibility, I presume we could make a trip to the moon," the scientist admitted. "It would not take so long, nor would it be as dangerous, as was our trip to Mars. And yet, I don't know that I care to go. I am getting along in years, and I have money enough to live on. Even a field of diamonds hardly sounds attractive to me." Jack's face showed the disappointment he felt.

"And yet," went on the aged scientist with a smile, "there are certain attractions about another trip through space. I had hoped to settle down in life now, and devote my time to scientific study and the writing of books. But this is something new. We never have been to the moon, and——"

"There are lots of problems about it that are still unsolved!" cried Jack eagerly. "You will be able to discover if the moon has an atmosphere and moisture; and also what the other side—the one that is always turned away from us—looks like."

"It does sound tempting," went on the aged scientist slowly. "And we could do it in our projectile, the Annihilator. It is in good working order; isn't it, Professor Roumann?"

"Couldn't be better. If you ask me, I, for one, would like to make a trip to the moon. It would give me a better chance to test the powers of Cardite, that wonderful red substance we brought from Mars. I can use that in the Etherium motor. If you left it to me, I'd say, 'go to the moon.'"

"Well, perhaps we will," spoke Mr. Henderson thoughtfully.

"You'll go, too, won't you, Mark?" asked Jack.

"Oh, I'm not going to be left behind. I'll go if the rest do, but I don't believe you'll find any diamonds on the moon. If there ever were any, the Martians took them." For Mark had been partly convinced after the confirmation by the two professors of Jack's translation.

"I'll take a chance on the sparklers," said his chum. "But now, let's go into details, and figure out when we can start. It ought not to take very long to get ready."

As has been explained in detail in the other books of this series, Professor Amos Henderson and the two lads, Mark Sampson and Jack Darrow, had undertaken many strange voyages together. Sometimes they were accompanied by friends and assistants, while Washington White, a sort of servant, helper, and man-of-all-work, and Andy Sudds, an old hunter, always went with them.

Mark and Jack were orphans, who had been adopted by Professor Henderson, who spent all his time making wonderful machines for transportation, or conducting strange experiments.

The two boys had been rescued by Professor Henderson and Washington White from a train wreck. Although both boys were badly hurt, they were nursed back to health by the eminent scientist, who soon learned to care for the lads as though they had been his own sons.

They aided the professor, as soon as they were able, in constructing an airship, called the Electric Monarch, in which Professor Henderson hoped to be able to reach the North Pole. The boys thoroughly enjoyed the trip through the air, and had many thrills fighting the savage Eskimos. Finally, they succeeded in passing over the exact spot of the North Pole during a violent snowstorm.

Not satisfied with their experiences after conquering the North, the adventurers set out for the Antarctic regions in a submarine boat. This trip, even more remarkable than the first, took them to many strange places in the South Atlantic. They were trapped for a time in the Sargasso Sea, and they walked on the ocean floor in new diving suits, one of the professor's marvelous inventions.

It was on the voyage to the south that, coming to the surface one day, the adventurers saw a strange island in the Atlantic Ocean, far from the coast of South America. On it was a great whirlpool, into which the Porpoise, their submarine boat, was nearly drawn by the powerful suction.

The chasm might lead to the center of the earth, it was suggested, and, after thinking the matter over, on their return from the Antarctic, Professor Henderson decided to build a craft in which they might solve the mystery.

The details of the voyage they took in the Flying Mermaid, are told of in the third volume, entitled "Five Thousand Miles Underground." The Mermaid could sail on the water, or float in the air like a balloon. In this craft the travellers descended into the centre of the earth, and had many wonderful adventures. They nearly lost their lives, and had to escape, after running through danger of the spouting water, leaving their craft behind.

For some time they undertook no further voyages, and the two boys, who lived with Professor Henderson in a small town on the coast of Maine, were sent to attend the Universal Electrical and Chemical College. Washington remained at home to minister to the wants of the old professor, and Andy Sudds went off on occasional hunting trips.

But the spirit of adventure was still strong in the hearts of the boys and the professor. One day, in the midst of some risky experiments at college, Jack and Mark, as related in "Through Space to Mars," received a telegram from Professor Henderson, calling them home.

There they found their friend entertaining as a guest Professor Santell Roumann, who was almost as celebrated as was Mr. Henderson, in the matter of inventions.

Professor Roumann made a strange proposition. He said if the old scientist and his young friends would build the proper kind of a projectile, they could make a trip to the planet Mars, by means of a wonderful motor, operated by a power called Etherium, of which Mr. Roumann held the secret.

After some discussion, the projectile, called the Annihilator, from the fact that it annihilated space, was begun. It was two hundred feet long, ten feet in diameter in the middle, and shaped like a cigar. It consisted of a double shell of strong metal, with a non-conducting gas between the two sides.

Within it were various machines, besides the Etherium motor, which would send the projectile along at the rate of one hundred miles a second. This great speed was necessary in order to reach the planet Mars, which, at the time our friends started for it, was about thirty-five millions of miles away from this earth. It has since receded some distance farther than this.

Finally all was in readiness for the start to Mars. Professor Roumann wanted to prove that the planet was inhabited, and he also wanted to get some of a peculiar substance, which he believed gave the planet its rosy hue. He had an idea that it would prove of great value.

But, though every precaution was taken, the adventurers were not to get away from the earth safely. Almost at the last minute, a crazy machinist, named Fred Axtell, who was refused work on the projectile, tried to blow it up with a bomb. He partly succeeded, but the damage was repaired, and the start made.

Inside the projectile our friends shut themselves up, and the powerful motors were started. Off it shot, at the rate of one hundred miles a second, but the travellers were as comfortable as in a Pullman car. They had plenty to eat and drink, they manufactured their own air and water, and they slept when they so desired.

But Axtell, the crazy machinist, had hidden himself aboard, and, in mid-air, he tried to wreck the projectile. He was caught, and locked up in a spare room, but, when Mars was reached, he escaped.

The book tells how our friends were welcomed by the Martians, how they learned the language, saw many strange sights, and finally got on the track of the Cardite, or red substance, which the German professor, Mr. Roumann, had come so far to seek. This Cardite was capable of great force, and, properly controlled, could move great weights and operate powerful machinery.

Our friends wanted to take some back to earth with them, but when they attempted to store it in their projectile, they met with objections, for the Martians did not want them to take any. They had considerable trouble, and the crazy machinist led an attack of the soldiers of the red planet against our friends, the adventurers in the projectile.

Among the other curiosities brought away by our friends, was a newspaper printed in Mars, for the inhabitants of that place where much further advanced along certain lines than we are on this earth, but in the matter of newspapers they had little to boast of, save that the sheets were printed by wireless electricity, no presses being needed.

As told at the opening of this story, Jack had noticed on one of the sheets they brought back, an account of how some of the Martians made a trip to the moon, and discovered a field of Reonaris. This trip was made shortly before our friends made their hasty departure, and it was undertaken by some Martian adventurers on another part of the red planet than where the projectile landed, and so Professor Henderson and his friends did not hear of it at the time.

"Well, then, suppose we make the attempt to go to the moon," said Professor Roumann, after a long discussion in the laboratory. "It will not take long to get ready."

"I'd like to go," said Jack. "How about you, Professor Henderson? Oh, by the way, Washington said you wanted to see Mark and me, but I was so interested in this news item, that I forgot to ask what it as about."

"I merely wanted to inquire when you and Mark thought of resuming your studies at college," said the aged man, "but, since this matter has come up, it will be just as well if you do not arrange to resume your lessons right away."

"We can study while making the trip to the moon," suggested Mark.

"Not much," declared Jack, with a laugh. "There'll be too much to see."

"Well, we'll discuss that later," went on Mr. Henderson. "Practically speaking, I think the voyage can be made, and, the more I think of it, the better I like the idea. We will look over the projectile in the morning, and see what needs to be done to it to get it ready for another trip through space."

"Not much will have to be done, I fancy," remarked the German scientist. "But I want to make a few improvements in the Cardite motor, which I will use in place of the Etherium one, that took us to Mars."

A little later there came a knock on the rear door of the rambling old house where the professor lived and did much of his experimental work.

"I'll go," volunteered Jack, and when he opened the portal there stood on the threshold a small boy, Dick Johnson, one of the village lads.

"What is it you want, Dick?" asked Mark.

"Here's a note for you," went on the boy, passing over a slip of paper.
"I met a man down the road, and he gave me a quarter to bring it here.
He said it was very important, and he's waiting for you down by the
white bridge over the creek."

"Waiting for who?" asked Jack.

"For Mark, I guess; but I don't know. Anyhow, the note's for him."

"Hum! This is rather strange," mused Mark.

"What is it?" asked Jack.

"Why, this note. It says: 'It is important that I see you. I will wait for you at the white bridge.' That's all there is to it."

"No name signed?" asked Jack.

"Not a name. But I'll just take a run down and see what it is. I'll not be long. Much obliged, Dick."

The boy who had brought the note turned to leave the house, and Mark prepared to follow. Jack said:

"Let me see that note."

He scanned it closely, and, as Mark was getting on his hat and coat, for the night was chilly, his chum went on:

"Mark, if I didn't know, that we had left Axtell, the crazy machinist, up on Mars, I'd say that this was his writing. But, of course, it's impossible."

"Of course—impossible," agreed Mark.

"But, there's one thing, though," continued Jack.

"What's that?" asked Mark.

"I don't like the idea of you going off alone in the dark, to meet a man who doesn't sign his name to the note he wrote. So, if you have no objections, I'll go with you. No use taking any chances."

"I don't believe I run any risk," said Mark, "but I'll be glad of your company. Come along. Maybe it's only a joke." And the two lads started off together in the darkness toward the white bridge.

CHAPTER III

PREPARING FOR A VOYAGE

"Seems like rather an odd thing; doesn't it?" remarked Jack, as he and his chum walked along.

"What?"

"This note."

"Oh, yes. But what made you think the writing looked like that of the crazy machinist who tried to wreck the projectile?"

"Because I once saw some of the crazy letters he sent us, and he wrote just like the man who gave Dick this note. But come on, let's hustle, and see what's up."

In a few minutes they came in sight of the white bridge, which was about a quarter of a mile down the road from the professor's house. The two boys kept well together, and they were watching for a first sight of the man in waiting.

"See anything?" asked Jack.

"No; do you?"

"Not a thing. Wait until we get closer. He may be in the shadow. It's dark now."

Almost as Jack spoke, the moon, which had been hidden behind a bank of clouds, peeped out, making the scene comparatively bright. The boys peered once more toward the bridge, and, as they did so, they saw a figure step from the shadows, stand revealed for an instant in the middle of the structure, and then, seemingly after a swift glance toward the approaching chums, the person darted off in the darkness.

"Did you see that?" cried Jack.

"Sure," assented Mark. "Guess he didn't want to wait for us. Why, he's running to beat the band!"

"Let's take after him," suggested Jack, and, nothing loath, Mark assented. The two lads broke into a run, but, as they leaped forward, the man also increased his pace, and they could hear his feet pounding out a tattoo on the hard road.

The two youths reached the bridge, and sped across it. They glanced hastily on either side, thinking possibly the man might have had some companions, but no one was in sight, and the stranger himself was now out of view around a bend in the highway.

"No use going any farther," suggested Jack, pulling up at the far side of the bridge. "There are two roads around the bend, and we couldn't tell which one he'd take. Besides, it might not be altogether safe to risk it."

Mark and Jack, on their return, told Professor Henderson and the German scientist something of their little excursion.

"But who could he have been?" asked Mr. Roumann. "Perhaps if you ask the boy who brought the note he can tell you."

"We'll do it in the morning," decided Mark.

"It's peculiar that he wanted Mark to meet him," spoke Amos Henderson.
"Have you any enemies that you know of, Mark?"

"Not a one. But what makes you think this man was an enemy, Professor?"

"From the fact that he ran when he saw you and Jack together. Evidently he expected to get Mark out alone."

They discussed the matter for some time, and then the boys and the scientists retired to bed, ready to begin active preparations on the morrow, for their trip to the moon.

There was much to be done, but their experience in making other wonderful trips, particularly the one to Mars, stood the travellers in good stead. They knew just how to go to work.

To Washington was entrusted the task of preparing the food supply, since he was to act as cook. Andy Sudds was instructed to look after the clothing and other supplies, except those of a scientific nature, while the two young men were to act as general helpers to the two professors.

As the Annihilator has been fully described in the volume entitled, "Through Space to Mars," there is no need to dwell at any length on the construction of the projectile in which our friends hoped to travel to the moon. Sufficient to say that it was a sort of enclosed airship, capable of travelling through space—that is, air or ether—at enormous speed, that there were contained within it many complicated machines, some for operating the projectile, some for offence or defence against enemies, such as electric guns, apparatus for making air or water, and scores of scientific instruments.

The Annihilator was controlled either from the engine room, or from a pilot house forward. As for the motive power it was, for the trip to the moon, to be of that wonderful Martian substance, Cardite, which would operate the motors.

The projectile moved through space by the throwing off of waves of energy, similar to wireless vibrations, from large plates of metal, and these plates were the invention of Professor Roumann.

Perhaps to some of my readers it may seem strange to speak so casually of a trip to the moon, but it must be remembered that our friends had already accomplished a much more difficult journey, namely, that to Mars. So the moon voyage was not to daunt them.

Mars, as I have said, was thirty-five millions of miles away from the earth when the Annihilator was headed toward it. To reach the moon, however, but 252,972 miles, at the most, must be traversed—a little more than a quarter of a million miles. As the distance from the earth to the moon varies, being between the figures I have named, and 221,614 miles, with the average distance computed as being 238,840 miles, it can readily be seen that at no time was the voyage to be considered as comparing in distance with the one to Mars.

But there were other matters to be taken into consideration, and our friends began to ponder on them in the days during which they made their preparations.

CHAPTER IV

AN ACCIDENT

Washington White was kept busy getting together the food for the voyage, and he had about completed his task, while Andy Sudds announced one morning that his department was ready for inspection, and that he thought he would go hunting until the projectile was ready to start.

"Well, if you see anything of that queer man who sent me the note, just ask him what he meant by it," suggested Mark, for inquiry from the boy who had brought the message, developed the fact that Dick did not know the man, nor had he ever seen him before. He was a stranger in the neighborhood. But, as nothing more resulted from it, the two lads gave the matter no further thought.

"How soon before we will be ready to start?" asked Jack one day, while he and his chum, with the two professors, were working over the projectile, which was soon to be shot through space.

"In about two weeks," replied Mr. Roumann. "I want to make a few changes in the Cardite plates, which will replace the ones used on the Etherium motor. Then I want to test them, and, if I find that they work all right, as I hope, we will seal ourselves up in the Annihilator, and start for the moon."

"Are you going to try to go around it, and land on the side turned away from us?" asked Mark, who had been studying astronomy lately.

"What do you mean by that?" asked Jack. "Doesn't the moon turn around?"

"Not as the earth does," replied his chum; "or, rather, to be more exact, it rotates exactly as the earth does, on its axis; but, in doing this it occupies precisely the same time that it takes to make a revolution about our planet. So that, in the long run, to quote from my astronomy, it keeps the same side always toward the earth; and today, or, to be more correct, each night that the moon is visible, we see the same face and aspect that Galileo did when he first looked at it through his telescope, and, unless something happens, the same thing will continue for thousands of years."

"Then we've never seen the other side of the moon?" asked Jack.

"Never; and that's why I wondered if the professor was going to attempt to reach it. Perhaps there are people there, and air and water, for it is practically certain that there is neither moisture nor atmosphere on this side of Luna."

"Wow! Then maybe we'd better not go," said Jack, with a shiver. "What will we do, if we get thirsty?"

"Oh, I guess we can manage, with all the apparatus we have, to distill enough water," said Professor Henderson, with a smile. "Then, too, we will take plenty with us, and, of course, tanks of oxygen to breathe. But it will be interesting to see if there are people on the moon."

"If there are any, they must have a queer time," went on Mark.

"Why?" asked Jack, who wasn't very fond of study.

"Why? Because the moon is only about one forty-ninth the size of the earth. Its diameter is 2,163 miles—only a quarter of the earth's—and, comparing the force of gravity, ours is much greater. A body that weighs six pounds on the earth, would weigh only one pound on the moon, and a man on the moon could jump six times as high as he can on this earth, and throw a stone six times as far."

"What's dat?" inquired Washington White quickly, nearly dropping some packages he was carrying into the projectile. "What was yo' pleased t' saggasiate, in remarkin' concernin' de untranquility ob the densityness ob stones jumpin' ober a man what is six times high?" he asked.

"Do you mean what did I say?" asked Mark solemnly.

"Dat's what I done asked yo'," spoke the colored man gravely.

"Well, you didn't, but perhaps you meant to," went on the youth, and he repeated his remarks.

"'Scuse me, I guess I'd better not go on dish yeah trip after all," came from Washington.

"Why not?" demanded Professor Henderson.

"'Cause I ain't goin' t' no place whar ef yo' wants t' take a little jump yo' has t' go six times as far as yo' does when yo' is on dis yeah earth. An' s'posin' some ob dem moon men takes a notion t' throw a stone at me? Whar'll I be, when a stone goes six times as far as it does on heah? No, sah, I ain't goin'!"

"But perhaps there are no men on the moon," said Mark quickly. "It is only a theory of astronomers that I'm talking about."

"Oh, only a theory; eh?" asked Washington quickly.

"That's all."

"Oh, if it's only a theory, den I reckons it's all right," came from the colored man. "I didn't know it were a theory. Dat makes it all right. It's jest in theory, am it, Massa Mark, dat a stone goes six times as far?"

"That's all."

"Oh, well, den, why didn't yo' say so fust, dat it was only a theory? I don't mind theories. I—I used t' eat 'em boiled an' roasted befo' de wah." And, with a contented smile on his face, Washington went into the projectile, to finish stowing things away in his kitchen lockers.

The big projectile was housed in the shed where it had been constructed, and the professor and the boys were working over it there, carefully guarded from curious eyes, for the German inventor did not want the secret of his Cardite motor to become known.

The work went on from day to day, good progress being made. The boys were of great assistance, for they were practical mechanics, and had had considerable experience.

"Well, I shall try the Cardite motor to-morrow," announced Professor
Roumann one night, after a hard day's work on the projectile.

"Do you think it will work?" asked Mr. Henderson.

"I think so, yes. My experiments have made me hopeful."

"And if it does work, when can we start?" asked Jack.

"Two days later; that is, if everything else is in readiness, the food and other, supplies on board."

"They are all ready to be stowed away," said Andy Sudds, who had been hunting all day.

It was an anxious assemblage that gathered inside the big shed the next day, to watch Professor Roumann try the Cardite motor. Would it work as well as had the Etherium one? Would it send them along through space at enormous speed? True, they would not have to travel so far, nor so fast, but more power would be needed, since, as it was feared no food, water, nor air could be had on the moon, many more supplies were to be taken along than on the trip to Mars, and this made the projectile heavier.

"We will test the Cardite in this small motor first," said Mr. Roumann, as he pointed to a machine in the projectile used for winding a cable around a windlass when there was necessity for hauling the Annihilator about, without sending it into the air.

Into the receptacle of the motor, the German professor placed some of the wonderful red substance he had secured from Mars. Then he closed the heavy metal box that held it, and, looking about to see if all was in readiness, he motioned to those watching him that he was about to shift the lever that would start the motor.

"If it works as well as I hope it will," he said, "it ought to pull the projectile slowly across the shop—a task that would be impossible in a motor of this size, if operated by electricity, gasoline, or any other force at present in use. And, if this small motor will do that, I know the large ones will send us through space to the moon. All ready, now."

Slowly the professor shoved over the lever, while Jack, Mark and the others watched him carefully. They were standing back of him, in the engine room of the projectile.

There was a clicking sound as the lever snapped into place. This was succeeded by a buzzing hum, as the motor began to absorb the great power from the red substance, which was not unlike radium in its action. There was a trembling to the great projectile.

"She's moving!" cried Jack.

Hardly had he spoken when there was a flash of red fire, a sound as of a bursting bomb, and everyone was knocked from his feet, over backward, while Professor Roumann was hurled the entire length of the engine room.

"The Cardite motor has exploded!" cried Mark. "Professor Roumann is killed!"

CHAPTER V

THE WORK OF AN ENEMY

Jack's first act, on arising from amid a mass of tools, into which he had been tossed by the explosion, was to run to where Professor Roumann lay in a semi-conscious condition. An instant later Mark slowly arose, and made his way to where Professor Henderson was rubbing his forehead in a dazed fashion.

"Are you hurt?" asked Mark, of his aged friend.

"I think not," answered Mr. Henderson slowly, "but I fear Mr. Roumann is. See to him; I'm all right."

"He's breathing," cried Jack, who had bent over the German. "He isn't dead, at any rate."

"But he may be, unless he gets attention," said Professor Henderson.
"Get my medicine chest, Mark, and we'll see what we can do for him."

Jack had raised the head of the injured man on his arm, and was giving him some water from a glass. This partially revived the German, and he opened his eyes. He looked around, into the faces of his friends, as if scarcely comprehending what had happened, and then, as his gaze wandered toward the disabled Cardite motor, he exclaimed:

"Some enemy has done this! The motor was tampered with. The resistance block was loosened, and that caused the force of the Cardite to shoot out at the rear. We must watch out for the work of this enemy!"

"Don't distress yourself about that now," urged Mr. Henderson. "Are you badly hurt? Do you need a doctor?"

The German slowly drank the rest of the water which Jack gave him, and then gradually arose to a standing position.

"I am all right," he said faintly, "except that I feel a trifle dizzy. Something hit me on the head, and the fumes from the Cardite took away my breath for a moment. I think I shall be all right soon."

"Here is the medicine chest!" exclaimed Mark, coming back into the engine room. Mr. Henderson poured out some aromatic spirits of ammonia into a graduated glass, added a little water, and gave it to his fellow, inventor, who, after drinking it, declared that he felt much better. There was a cut on his forehead, where a piece of the broken motor had struck him, but, otherwise, he did not seem injured externally.

As for the boys, they were only stunned, nor was Mr. Henderson more than momentarily shocked. In a few minutes the German professor was almost himself again.

"We must try to discover who our enemy is," he said earnestly, as he looked over the disabled motor. "He might have blown up the whole projectile by tampering as he did with the machinery. Had I been testing the large, instead of the small motor, there would have been nothing left of the Annihilator, or us, either. Who could have done this? If that crazy machinist is around again——"

"I don't believe he could get here from Mars," interrupted Jack, with a smile.

"Hardly," added Mark.

"No, I guess he is still on the Red Planet, so it couldn't have been him," went on Mr. Roumann. "But it was some one."

Jack and Mark at once thought of the odd man who had sent Mark the note, and then had run away.

"Could it have been him?" suggested Jack.

"It's possible," remarked Professor Henderson. "We must be on our guard. I wonder if Washington——"

At that moment there sounded a violent pounding on the exterior of the projectile, and the voice of the colored man could be heard calling:

"Am anything de mattah? Andy Sudds an' I is out heah, an' we heard suffin goin' on in dere. Am anybody hurted?"

"It's all over now, Wash," replied Jack, for the two boys, and the two professors, had shut themselves up in the projectile while they conducted the experiment. Jack opened the door of the Annihilator and stepped out, being met by the colored man and the old hunter.

"You haven't seen any suspicious characters around, have you, Wash?" asked Mark. "Some one has been tampering with a motor, and it exploded."

"Nobody's been around since I've been here," announced Andy Sudds, with a significant glance at his gun.

"Maybe it's some ob dem moon-men, what don't laik de idea ob us goin' dere arter dere diamonds," volunteered the colored man.

"Perhaps," admitted Jack, with a smile. "But certainly some one has been around here who had no business to be, and we must find out who it was. Better take a look around, Wash."

"I'll help him," said Andy, and, with his rifle in readiness for any intruders, the old hunter followed the colored man outside the big shed.

Meanwhile Professor Roumann and Mr. Henderson were carefully examining the exploded motor.

"I should have looked at the breech plug before turning on the power," said the German, "but I had no reason to suspect that anything was wrong." He went on to explain that the explosion was something like that which occurs when the breech-block of a big navy gun is not properly in place. The force of the Cardite, instead of being directed against the piston-heads of the motor, shot out backward, and almost into the face of the professor, who was operating the machine.

"But what could be their object?" asked Mark. "Who would want to injure us, or damage the projectile?"

"Some enemy, of course," declared Jack. "But who? The crazy machinist is out of it, and as for that man who sent the note to you, he seemed too big a coward to attempt anything like this."

"Some one evidently sneaked in here and loosened the breech-plug," went on Mark, "and it was evidently done with the idea of delaying us. The enemy could not have desired to utterly disable the projectile, or else he would have tampered with the large motor, instead of the small one."

"Yes, the object seems to have been to delay us," admitted Professor Henderson; "yet, I can't understand why. Whoever did it evidently knows something about machinery."

"I hope they did not discover the secret of my Cardite motor," said
Professor Roumann quickly.

"They hardly had time," declared Mark. "We have been in or around the projectile nearly every minute of the day, and whoever it was, must have watched his chance, slipped in, stayed a few seconds, and then slipped out again."

They went carefully over the entire projectile, but could find no further damage done. Nor were there any traces of the person who had so nearly caused a tragedy. Washington and Andy, after a careful search outside the shed, had to admit that they had no clews.

"Well, the only thing to do is to go to work and build a new small motor," announced Professor Roumann, after once more looking over the debris of the one that had exploded.

"Will it take long?" asked Jack.

"About two weeks. Fortunately, I can use some of the parts of this one, or we would be delayed longer."

"Still two weeks is quite a while," suggested Mark. "Perhaps there'll be no diamonds left on the moon when we get there, Jack," and he smiled jokingly.

"Oh, I fancy there will. The article in the paper from Mars says there was a whole field of them."

"This brings up another matter," said Professor Henderson. "What will happen if we bring back bushels and bushels of diamonds?—which, in view of what the paper says, may be possible. We will swamp the market, and the value of diamonds will drop."

"Then we must not throw them upon the market," decided Professor Roumann. "The scarcity of an article determines its value. If we do find plenty of diamonds, it will give me a chance to conduct some experiments I have long postponed because of a lack of the precious stones. We can use them for laboratory purposes, and need not sell them. In fact, with the Cardite we brought back from Mars, we have no lack of money, so we really do not need the diamonds."

It was decided, in view of the shock and upset caused by the explosion, that no further work would be done that day, and so, after carefully locking the shed, and posting Andy on guard with his gun, the boys and the professor went into the house to discuss matters, and plan for work the next day.

"Mark," said Jack in a low voice, as they followed the two scientists, "I think it's up to us to try to find that mysterious man who sent the note. I think he did this mean trick!"

"So do I, and we'll have a hunt for him. Let's go now."

CHAPTER VI

ON THE TRACK

The two boys gazed after Professors Henderson and Roumann. The scientists were deep in a discussion of various technical matters, which discussion, it was evident, made them oblivious to everything else.

"Shall we ask them?" inquired Jack in a whisper.

"No; what's the use?" queried Mark. "Let's go off by ourselves, and perhaps we can discover something. If we could once get on the trail of the man who wrote the note, I think we could put our hands on the person responsible for the blowing up of the motor."

"I agree with you. We won't bother them about our plans," and he waved his hand toward the scientists, who had, by this time, entered the house.

"In the first place," said Mark, as he and his chum turned from the yard, and walked along a quiet country road, "I think our best plan will be to find Dick Johnson, and ask him just where it was he met the man who gave him a quarter to bring the note to me."

"What for?" asked Jack.

"Why, then, we can tell where to start from. Perhaps Dick can give us a description of the man, or tell from what direction he came. Then we'll know how to begin on the trail."

"That's a good idea, I guess. We know where he disappeared to, or, rather, in nearly what direction, so that will help some."

"Sure. Well, then, let's find Dick."

To the inquiries of the two lads from the projectile, Dick Johnson replied that, as he had asserted once before, that the man was a stranger to him.

"He was tall, and had a big black mustache," Dick described, "but he kept his hat pulled down over his eyes, so I couldn't see his face very well. Anyhow, it was dark when I met him."

"Where did you meet him?" asked Mark.

"Not far from your house. He was standing on the corner, where you turn down to go to the woollen mill, and, as I passed him, he asked me if I wanted to earn a quarter."

"Of course you said you did," suggested Jack.

"Sure," replied Dick. "Then he gave me the note, and told me where to take it, and I did. That wasn't wrong, was it?"

"No; only there seems to be something queer about the man, and we want to find out what it is," replied Mark.

"What was the man doing when you saw him?" asked Jack.

"Standing, and sort of looking toward your house."

"Looking toward our house?" repeated Jack. "Was he anywhere near the big shed where we build the machines?"

"Well, I couldn't say. Maybe he might have been."

"I guess that's all you can tell us," put in Mark, with a glance at his chum, to warn him not to go too much into details with Dick, for they did not want it known that some enemy had tried to wreck the projectile.

"Yes, I can't tell you any more," admitted the small lad.

"Well, here's a quarter for what you did tell us," said Jack, "and if you see that man again, and he gives you a note for us, just keep your eye on him, watch where he goes, and tell us. Then you will get a half-dollar."

"Gee! I'll be on the watch," promised Dick, his eyes shining at the prospect of so much money.

"Come on," suggested Jack to his chum, after the small chap had departed. "Let's go down by the white bridge and make some inquiries of people living in that vicinity. They may have seen a stranger hanging around, and, perhaps we can get on his trail that way."

"All right," agreed Mark, and they walked on together.

They had gone quite a distance away from the bridge, and had made several inquiries, but had met with no success, and they were about to give up and go back home.

"I know one person we haven't inquired of yet," said Mark, as they tramped along.

"Who's that?"

"Old Bascomb, who lives alone in a shack on the edge of the creek. You know the old codger who traps muskrats."

"Oh, sure; but I don't believe he'd know anything. If he did, he's so cranky he wouldn't tell you."

"Maybe he would, if we gave him a little money for some smoking tobacco. It's worth trying, anyhow. Bascomb goes around a great deal, and he may have met a strange man in his travels."

"Well, go ahead; we'll ask him."

The muskrat trapper did not prove to be in a very pleasant frame of mind, but, after Mark had given him a quarter, Bascomb consented to answer a few questions. The boys told him about looking for a strange man, describing him as best they could, though they did not tell why they wanted to find him.

"Wa'al, now, I shouldn't be surprised but what I know the very fellow you want," said the trapper. "I met him a couple of days back, an' I think he's still hanging around. Fust I thought he was after some of my traps, but when I found he wa'ant, I didn't pay no more attention to him. He looked jest like you say."

"Where was he?" asked Jack eagerly.

"Walkin' along the creek, sort of absent-minded like."

"You don't know where he lives, or whether he is staying in this vicinity, do you?" inquired Mark.

"Ya'as, I think I do," replied the trapper.

"Where?" cried Jack eagerly.

"Wa'al, you know the old Preakness homestead, down by the bend of the creek, about four mile below here?"

"Sure we know it," answered Mark. "We used to go in swimming not far from there."

"Wa'al, the old house has been deserted now for quite a spell," went on the trapper, "and there ain't nobody lived in it but tramps. But the other night, when I was comin' past, with a lot of rats I'd jest taken out of my traps, I see a light in the old house. Thinks I, to myself, that there's more tramps snoozin' in there, and I didn't reckon it was none of my business, so I kept on. But jest as I was walking past the main gate, some one come out of the house and hurried away. I had a good look at him, an'——"