The boys were so busy setting out the tin cups and plates that it was not till Zeb beat on a tin basin with a spoon to announce that the evening meal was ready that anyone noticed that the professor was missing. Night was closing in and the sky was overcast.

The boys began to worry. They set up a loud shout.

"Pro-fess-or! Oh, pro-fess-or!"

The little gulch rang with it. But no answer came.

"Now what in the world has happened to him?" frowned Jack. "We must go and find him at once. He must have——"



The sentence was never completed. At that instant Zeb set up a shout, and a ton of earth and rocks, more or less, came hurtling down the steep bank into the camp. The stones and dirt were mingled with mesquite bushes and in the midst of the landslide was a figure that they made out to be the professor.

Luckily, the avalanche had missed the camp-fire and the supper table, and when they had extricated the professor, and brushed him off, the boys learned that he had almost missed his way, and being shortsighted, in the dark had walked right over the edge of the steepest part of the arroyo instead of by a sloping path up above.

However, nothing was injured about him but his feelings, and since his bag of specimens was intact, the man of science, after a few minutes, was able to sit down and eat with as good an appetite as any of them.

Zeb proved himself a good weather profit. About midnight it started raining, and such rain as the boys had never seen. It was not rain. It was sheets of water. Even the waterproof tents began to leak, and the fact that the trenches had been dug did not serve to keep the floors dry, for the hard, sun-baked earth did not absorb the moisture, and the downpour speedily spread half an inch or more of water over the ground.

"Turn out! turn out!" shouted Dick, who shared one of the three tents with the boys.

"What's the matter?" began Tom sleepily, and then splash! went his hand into the water.

"Gracious, has the river overflowed?" demanded Jack.

"No, but it's raining handsaws and marlin spikes," cried Dick. "Wow! my bed's wet through."

"Same here," cried Jack ruefully. "I guess we'd better get out of this."

Outside they found the professor hopping about barefooted in the water. He had on his pajamas with a blanket thrown round his shoulders for protection against the rain. The boys, despite their discomfort, could not help laughing at the odd figure. Zeb joined them, grumbling: "We made a big mistake in camping in this arroyo.

I ought to have had better sense. It's nothing more nor less than a river. All the desert up above is draining into it."

It was true. The water was almost ankle deep. Luckily, the old shanty in which their supplies were stored was raised above the ground, and the goods were all covered with a big waterproof canvas.

"Let's camp out in the shanty till daylight," suggested Jack.

"That would be a good idea if it had a roof," commented Zeb dryly.

"Why can't we spread some of the canvas over us?" asked Tom.

This was finally done, and thus passed most of their first night on the desert. Yet none of them complained, but made the best of it. The boys knew that it is the wisest plan to meet all camping mishaps with a smiling face.

By morning the rain had ceased. The sky was clear and the sun shone brightly. Their wet bedding and garments were soon dried and then the work of unpacking the sections of the Wondership was begun, for they were anxious to have the job completed and be on their way as soon as possible.

Old McGee had told the truth when he said they would not be molested.

An old Indian jogging by on a spavined horse and wrapped in a dirty blanket was the only person they saw all day. He was looking along the arroyo for a strayed burro. He stared at them in stolid silence for a while and then rode off, shaking his head. No doubt he was at a loss to account for such strange goings on.

That evening when Dick took his line down to the river, he met with unusually good luck. He had just added a fine carp to his pile of fish when, chancing to look up, he saw a boat coming round the bend.

In the craft were three figures, one of whom he recognized instantly as Masterson. The recognition was mutual and Masterson, who had the oars, started hastily to pull away from the place. But Dick shouted to him.

"Don't let me drive you away," he cried.

Masterson shouted back something about "fresh kid" but kept pulling up the stream, and soon he was round the bend and out of sight.

"Now, I wonder what he is doing out here?" mused Dick, "and those two cronies of his. They look sort of shady to me."

He cudgeled his brains to find a reason for the presence of Masterson so far from home, but was unable to arrive at any solution till an idea suddenly struck him.

"They're out here trailing us," he muttered. "Yes, I'm sure of it. But how in the world did they ever learn our plans? I guess I'll get back to camp and put the rest on their guard, for we don't want any spies hanging about, and those fellows were out on a spying expedition or I miss my guess."



CHAPTER XXVI.

THE START FOR THE UNKNOWN.

But the days went by, and the Wondership stood once more assembled and ready to take the greatest flight of her career, and no further sign of the three worthies, whom Dick suspected of designs against them, appeared. Zeb went to town once or twice, using a small burro for a saddle animal. Jack heard from his father, who said that he was progressing well, but was very much worried over money matters.

"If only you can find the Z.2.X.," he wrote, "we can all be happy again."

"I will find it," Jack murmured to himself, as he concluded reading the letter, and passed it over to Tom for his perusal.

Dick helped with the Wondership and spent the rest of the time fishing and hunting. He managed to get a few rabbits, but there was no other game in the vicinity. It was too barren for deer, although it was said there were plenty of them further down the river. The young reporter, who had quite a mechanical genius of his own, constructed a rough sort of boat out of boards from the walls of the old shack, and used it on his fishing expeditions, "punting" it along with a long pole made from a willow sapling from a grove on the river bank some distance below where they were camped.

One afternoon the fancy took him to pole up the current and round the bend below which Masterson's boat had appeared the evening Dick saw and recognized the son of the Moon proprietor.

He had not gone that way before and was surprised to find that, instead of the low banks that edged the river where the boys were camped, round the bend were steep, almost clifflike acclivities on both sides of the stream. In places these were honeycombed with caves, running back, apparently, some distance into the bank. Although Dick did not know it, these caves had once been the dwelling places of an extinct tribe of Indians.

The boy was surprised to see smoke coming from one of them, for he had supposed that they were uninhabited.

"Maybe there are Indians up there," thought the boy. "I guess I'll give them a look, and maybe get a good picture," for Dick invariably carried his camera with him on the chance of getting a good snapshot at something or other.

A rough path led up to the cave and it was well worn by feet which had, apparently, traversed it recently. Dick reached the entrance of the cave and peered in.

It was deserted; but to his astonishment he saw, from the way it was fitted up, that whoever lived in it were not Indians. Blankets lay on the floor, and the smoke was coming from a fire which had been used for cooking and was dying out. The utensils were not such as Indians use, being made of agate ware. Then, too, he noticed some old coats and other garments hanging on nails that had been driven into the wall.

As his eyes grew more accustomed to the light, he saw a suitcase in one corner. There were initials on it. Dick made them out to be W. M.

'"W. M.'? Who can that be?" he mused. "Whoever lives here is a white man, that is plain. But why is he a hermit? Anyhow, I'd better be getting out of this before he comes back. I've really got no business in here at all."

At this juncture he heard voices coming from the river. They were punctuated by the dip of oars. As he heard the speakers outside, Dick's mind suddenly realized who "W. M." was.

"What a chump I was not to think of it before!" he exclaimed. "It's William Masterson, of course, and that's his voice outside. Gee whillakers, they must have camped here on purpose to spy on us."

Just then it occurred to Dick that he was, as a matter of fact, spying on Masterson. He went to the cave door. Below was a boat containing Masterson and his two friends. They had apparently been to town for supplies, for the boat was full of canned goods and provisions.

Just as Dick got to the door Masterson spied the home-made boat lying on the bank at the foot of the cliff.

"Say, fellows," he exclaimed, "somebody's been paying us a call."

"Some thieving Indian, judging from the looks of that boat," said Sam Higgins.

"Well, we're not receiving callers of any kind right now," sputtered Eph angrily.

Dick crouched back into the doorway of the cave. He was trying to think what to do. It was an awkward situation. He didn't want to be caught in what looked, on the face of it, like an act of spying, and yet he didn't wish Masterson and his cronies to think him a coward.

"Say, fellows," spoke up Higgins suddenly, "you don't think it could be one of those kids from the camp below, do you? They may have seen us snooping around there at night and got wise to where we are hiding."

"It had better not be one of them," said Masterson in a loud, threatening voice. "If I catch him, I'll break every bone in his body."

"I guess I'll have a fight on my hands," muttered Dick. "Well, serves me right for butting in," he added philosophically.

"Let's go up and see who it is?" said Eph. "He must be in the cave."

"You go first," said Sam Higgins, who was not over-brave, "it might be a bad man or an Indian."

"Pshaw, I'm not afraid!" said Masterson. "Give me your pistol, Sam, if you're scared."

"I'm not scared, but there's no use running into trouble," said Sam. "Besides I'm kind of lame. I think I—er—wrenched my ankle getting out of the boat."

"I guess you wrenched your nerve," sneered Eph.

Then, headed by Masterson, with the pistol in his grasp, they began to ascend the pathway. Dick was in a quandary. But he decided that the only way to tackle the problem was to take the bull by the horns. As Masterson reached the mouth of the cave the boy dashed out like a redheaded thunderbolt.

Taken utterly by surprise, Masterson stepped back.

Bang!

The pistol went off in the air and the next instant Masterson, despite his efforts to save himself, toppled off the narrow path and went rolling down the bank into the river. Luckily for him, he was a good swimmer, and struck out lustily as he came to the surface.

"Wow!" yelled Dick, and charged like a young buffalo at Eph.

Young Compton tried to strike him but Dick, with lowered head, charged him in the stomach. With a grunt Eph fell back, and in his fall knocked over Sam Higgins, just behind him.

"Whoop-ee!" shouted Dick, rejoicing in his triumph. He leaped over the recumbent forms of Eph and Sam and dashed down the path to the place where he had beached his boat.

He jumped on board and poled off just as young Masterson reached the shore and pulled himself out of the water.

"You infernal young spy!" shrieked Masterson, beside himself with rage, "I'll get even with you for this, see if I don't!"

Sam and Eph, who had picked themselves up, shouted other threats at Dick. But he turned round and, with a pleasant smile, waved a hand as the current carried his boat round the bend. He felt in high good humor at the way he had gotten out of a difficult situation. It was fortunate for him, though, that he had taken Masterson and his cronies so utterly by surprise, otherwise the adventure might have had a different conclusion.

He had established one fact, however, and that was that Masterson and the others were spying on them every night and watching every step in their preparations for the departure for Rattlesnake Island.

That night a strict watch was kept in the camp, all the adventurers taking turns at sentry duty. But nobody came near the place.



CHAPTER XXVII.

THE PROFESSOR'S SECOND DILEMMA.

Early the next day old man McGee paid them a call. He came to take back the burro they had hired from him for convenience in getting back and forth from Yuma. He also wanted to get a ladder which had been left at the deserted shanty. The old man rode into camp on a razor-backed horse and professed great astonishment when he saw how nearly completed the work on the Wondership was.

"But you kain't fool me," he said knowingly. "I may be old but I'm wise. That thing fly? Why, you might as well tell me the Nat'nul Hotel in Yuma could go kerflopping about in the air. By the way," he went on, "frum ther talk in ther town you ain't ther only ones as is goin' down ther river. There's three young chaps has bought two boats and allows that they're fixin' to take a trip."

"Is that so?" exclaimed Jack with a significant look at his chums. "I think we can guess who they are."

But old man McGee was busy fussing with the donkey and didn't hear him. He was going to carry the ladder back to town on the little creature's back. He lashed the ladder across the saddle so that it stuck out on both sides of the burro, who viewed the proceedings with a kind of mild surprise. It brayed loudly and flapped its long ears in a way that made the boys laugh heartily.

"There," said old man McGee at last, "that's done. Now I reckon I'll bid you so-long and good-luck, and be on my way. When are you goin' ter start?"

"To-morrow morning," replied Jack, "if everything is all right."

"Hold on a minute," said Tom suddenly, as old man McGee was riding off. "I've got a notion for some rabbit pie. Give me the rifle, Dick, and I'll go a little way with Mr. McGee, as far as that little willow wood where you got the cotton-tails."

"All right," said Dick, "and tell you what I'll do. I'll come, too. I can borrow Jack's rifle."

"It's in the tent," said Jack. "Take good care of it."

"I'll do that," promised Dick.

Jack and Zeb went back to their task of putting the finishing touches on the Wondership, stocking her lockers with provisions for the Rattlesnake Island trip, while old man McGee, accompanied by the two boys, rode out of the camp.

The professor was away collecting specimens somewhere and had not been seen since breakfast time.

The donkey, carrying its odd burden, walked behind old McGee's horse and the boys kept pace alongside, listening to the old prospector's everlasting stories of how some day he would strike it rich. His faith never wavered. He believed implicitly that eventually he would make the "big strike" and live in affluence for the remainder of his life.

The willow grove, where Dick went rabbit-hunting, was up the river and on its banks far away from the water nothing grew but cactus, greasewood and mesquite. As they neared it the monotony of the walk began to pall on Dick. He wanted to have some fun.

He fell behind and took a magnifying glass from his pocket. It was one he used in his photographic work. Holding it up he focused the sun's rays through it so that they fell in a tiny burning spot on the donkey's back. After a few seconds the heat burned through. The donkey gave a loud bray and kicked up its heels wildly.

Before old man McGee knew what was happening, the creature had jerked the rope by which he was leading it out of the old man's hand and dashed off toward the willow wood.

"Hey, come back, consarn ye!" shouted old McGee. "What's the matter with ther critter, anyhow? He's gone plum daffy."

Dick, doubled up with laughter, watched the circus. There was the donkey with the ladder across its back racing at full speed toward the wood, and after it came old McGee on his bony old horse, shouting at the top of his voice.

Straight for the wood the donkey raced, kicking up its heels and braying loudly. It dashed in among the trees of the willow wood and at the same instant there came an appalling yell from among the trees.

"Gracious, what's happened now!" gasped Tom, and then catching Dick's laughing eye, he exclaimed:

"Dick, this is some of your work!"

"Maybe," said Dick, still choking with laughter, "but what on earth is happening in the wood?"

"Help! Lions! Help! They're after me! Help!"

The cries came thick and fast.

"It's the professor," choked out Dick.

"He says there are lions in there," cried Tom, looking rather alarmed, but at this juncture something happened to the donkey that momentarily distracted their attention. In trying to pass between two saplings the animal had bumped the ladder against them and brought itself up with a round turn. But it still struggled forward and kept up its braying:

"Cotched, by ginger!" shouted old man McGee. He galloped toward the runaway donkey, but the next moment a curious thing happened.

In pressing forward, the donkey had bent the saplings over with the ladder until it became entangled in their branches. Suddenly the animal ceased struggling and the saplings sprang up, no longer having any pressure on them, and the donkey was fairly lifted from its feet and carried up into the air. And there he hung, threshing about with his hoofs and suspended from the ladder. At the same instant the figure of the professor emerged from the wood. He looked rather sheepish.

The boys ran up to him.

"What's the matter, professor?" asked Dick.

"Yes, you called for help," added Tom.

"Um—er—ah did I call?" inquired the man of science.

"You certainly did. You scared us almost to death," said Dick.

"Something about lions," added Tom.

"Lions—er—did I say lions, boys?"

"You did," Dick assured him.

The professor gave a rather shamefaced smile. He looked at the donkey suspended from the ladder between the two straightened saplings.

"Um—er—perhaps it would be better to say no more about it," he said. "I do not suppose that I am the first man to have been scared by a sheep in wolf's clothing."

"Or a donkey in a lion's skin," chuckled Dick.

In the meantime old man McGee had arrived at the donkey's side and was scratching his head to think of some way to relieve it from its predicament. The boys solved the problem for him by cutting the branches that held the ladder and Mr. Donkey came down to earth. The professor, with rather a red face, had gone back to his work of collecting specimens, which the arrival of the long-eared beast had interrupted in such a startling manner.

"Thar, I hope that's taught you some sense," said old man McGee, as the donkey was once more on terra firma. As he rode off, Dick burst into shouts of laughter. His little joke had certainly turned out to be better than he expected and for many days after that he had only to slyly introduce some talk about a lion to cause the professor to look at him in a very quizzical way.



CHAPTER XXVIII.

THE UPPER REGIONS.

The boys were up with the sun the next day. It was the morning which was to witness the start of the flight for Rattlesnake Island. Everything about the Wondership was in readiness for the enterprise, and there only remained the tin breakfast utensils and the tents to be packed when they had concluded the morning meal.

Naturally excitement ran high. The hunt for the island, too, might be a long one. But they felt that ultimately they would find it, that it would not be like the three buttes of Peg-leg Smith.

When everything was declared ready, Jack opened the charging-tube of the gas reservoir and poured in some of the volatile powder that made the lifting vapor. In fifteen minutes the gauge showed a good pressure in the tank and the valve was turned.

In the hot sun the balloon bag expanded quickly. At length the bag was almost full.

"Everything ready?" cried Jack, at length, when all were on board.

"Ready," said Tom at the engines.

"Then off we go!"

Tom pulled the clutch lever and the propellers whirled. Jack gave the steering and controlling wheel an impulse and like a huge bird the Wondership shot up. But she rose slowly, for besides the unusual number of passengers, she was also carrying a great weight in supplies.

As the craft rose three figures watched it from under the concealment of a clump of mesquite.

"There they go, boys," said Masterson, for it was he and his two cronies.

"Yes, they're off for Rattlesnake Island," sneered Eph. "I hope they get bitten."

"I'll bet they don't dream that we know everything about their plans," chuckled Sam. "I'd like to get even with that red-headed kid."

"Well, you'll get a chance before long," declared Bill Masterson. "I don't see that there's any use in hanging around here any longer," he went on. "The thing to do now is to get our boats and go down the river."

"Won't they be astonished when they see us," said Eph.

"Maybe they'll try to chase us away. They outnumber us," said the timid Sam.

"They'd better not," vaunted Bill Masterson. "I guess we've got as good a right to that old island as they have."

"That's right," echoed Eph, following his leader's sentiments. "I guess they haven't got any mortgage on it."

Viewed from the Wondership, the desert spread out below was a wonderful panorama. Through it, like a deep wound, the Colorado cut its way and far beyond were the pale, misty outlines of mountains. As they flew onward, the character of the scenery began to change.

The river appeared to sink, while mighty walls, of most gorgeous colors, cliffed it in. The rocks glowed with red and yellow and blue like a painter's palate. But this was only in the deep canyon. On either side the desert, vast and unlimited, stretched away grayly to the horizon.

"It must have taken centuries for the river to have cut such a deep valley," said Tom, looking down as they flew far above it.

"Some say that the river didn't cut it," said Zeb. "They claim that there was a big earthquake or some sort of a shake-up, and that made that big hole in the ground."

Below them they could see birds circling above the swiftly racing waters flecked with white foam. So far no sign of land answering the description of Rattlesnake Island had come in view. But several small, isolated spots of land were encountered, and on one, which looked something like Rattlesnake Island described on the map, they descended.

The boys were delighted at the way the great Wondership settled down into the canyon and then came to rest on the back of the island round which the water rushed and roared. They scattered and ran about on it, enjoying the opportunity to stretch their legs.

Jack, Tom and Dick took a rifle along with them and they were glad they had done so, for as they made their way through a patch of brush a beautiful deer sprang out and dashed off. Jack had the rifle at his shoulder in a minute and the creature bounded into the air, as the crack of the report sounded, and then fell dead.

The boy felt some remorse at having killed it, but he knew they would be in need of fresh meat and some venison would be a welcome addition to the ordinary camp fare. The boys carried the deer back and Zeb skillfully skinned and quartered it. While he was doing this, the boys speculated as to how the animal could have come to the island.

Zeb set their discussion at rest by explaining that it had probably swum the rapids to escape a mountain lion or a lynx. He said that he had often shot deer under similar conditions. As it was almost noon, they decided to wait on the island till they had eaten lunch. Zeb sliced off some venison cutlets and cooked them to a turn over hot wood coals. The boys thought they had never tasted anything better than the fresh meat.

While the plates and knives and forks were being washed and put away, the professor wandered off on his perennial quest of rocks and specimens. He said that he would be back in a short time but was anxious not to miss the opportunity of finding some possibly rare stones.

But everything was ready and the boys were waiting impatiently half an hour later, and there was no sign of the professor.

Suddenly they heard his voice shouting to them from the distance.

"What's he saying?" asked Jack.

"Hark!" admonished Tom.

The professor's shouts came plainly to their ears the next minute, borne on a puff of wind that swept through the canyon.

"Help! Help!" was the burden of his cries. "Get me out!"

"Now, what's happened to him?" demanded Zeb, with a trace of impatience.

"I don't know, but he must be in trouble of some sort," cried Jack.

"Maybe it's another donkey," mischievously suggested Dick.

The cries were redoubled. They waited no longer but started off across the island on the run. Zeb carried his big forty-four revolver.



CHAPTER XXIX.

A MUD BATH.

The ground was rough and rocky but they made good time. Bursting through a screen of trees from beyond which came the professor's piteous cries, they received a shock.

The man of science was in the center of a large, round hole full of black mud that bubbled and boiled and steamed as if it were alive. All that was visible of the professor was the upper part of his body.

Seriously alarmed, the boys shouted to him to keep up his courage, and that they would get him out.

"How did you get in?" asked Zeb, cupping his hands.

"I fell in," rejoined the poor professor. "The ground gave way under my feet. Hurry and get me out, it's terribly hot."

They looked about them desperately for some means of extricating him from his predicament. But just at the moment none was offered, and with every struggle the professor was sinking deeper in the black, evil-smelling pool of mud.

"Gracious, what are we to do?" cried Jack in despair.

"He's too far out to reach him," said Zeb, equally at a loss.

"But we must do something," chimed in Tom.

Suddenly Zeb had an inspiration. A tree grew on the banks of the mud volcano, the sudden caving in of which, under the professor's weight, had precipitated him into it.

"If I could get out on that branch," said Zeb, "I might be able to bend it enough to bring my feet over him and then work back toward the edge of the mudhole."

"It's worth trying—anything is worthy trying," agreed Jack.

Zeb took off his coat and then shinned up the tree. Then, hanging by his hands he began working out along the branch. As he went it bent till it hung right over the mudhole. Before long his feet dangled above the professor's head.

"Now then, professor," panted Zeb, "take hold on my feet and work along toward the edge of the hole with me."

The professor seized Zeb's boots with the grasp of a drowning man. The branch cracked ominously.

"Easy thar, professor," warned Zeb earnestly. "Don't pull more'n you can help or we'll both be in the soup."

The professor lightened his grip and slowly, hand over hand, Zeb began the slow journey back along the branch. It was a feat only possible to a man whose muscles were of iron. And before it was over even Zeb was almost overcome. Perspiration streamed from his forehead and soaked his shirt as he dropped from the branch, having accomplished the journey and pulled the professor to the bank.



"That's what I call toeing a man out of trouble," punned Dick, in the general relief that followed.

"Good thing it warn't no further," puffed Zeb, mopping his forehead. "My arms feels as if they'd been stretched on one of them racks you read about in the history books."

"How did it happen, professor?" asked Jack, as they scraped the mud off the scientist.

"It's hard to say," was the response. "I was walking along, intent on my collecting, when I came to a barren patch of ground that was crusted over with stuff that looked like salt. I stepped out on it to investigate and suddenly in I went. Faugh! how it smells."

"Yes, it isn't exactly perfumed," said Jack. "But how did such a place come there?"

"It's one of those mud-springs of hot water that are found in several places throughout the West," said the scientist. "It must have been quiescent for some time and then the thin skin of alkaline earth formed over it. In Europe, or if we had that spring near a large city, it would be possible to make a fortune with it."

"In what way?" asked Dick.

"As a curative bath," replied the professor. "Every year people spend fortunes to go to Europe and take just such baths."

"Reckon I'd go without washin' then," commented Zeb.

"I'd just as soon bathe in rotten eggs," said Dick.

"Well," said Jack, "I guess we've got off about all the mud we can for the present. We'd better be getting back. It's mighty fortunate that we came in time."

"Yes, I was slipping into the stuff all the time," said the professor. "If I'd been alone on the island I might have never been seen again," he added in quite a matter-of-fact tone. "It's too bad I lost that bag of fossils, though. I had some fine specimens."

"Goodness, no wonder you sank down!" exclaimed Jack. "Why didn't you let go of them?"

The scientist was mildly surprised.

"Why, how could I," he asked, "until it became a question of life or death? It's too bad I had to lose them," and he shook his head mournfully at the thought.

The journey was soon resumed, the Wondership rising buoyantly out of the dismal canyon. They were not sorry to get back to the upper air for the gloom of the deep gulch had affected their spirits. But so much time had been consumed in getting the professor out of his predicament that it was not long before twilight set in and they still had caught no glimpse of anything resembling the island they were in search of.

They decided to come to earth and make camp for the night and resume the search in the morning. They made a hearty supper off the venison which remained, and turned in, without setting any watch, as there was no necessity for it out there with not a soul about for scores of miles.

It was about midnight when Jack was awakened by a wild yell from Tom.

"Ow! Ouch! Leggo my toe!" the younger of the Boy Inventors was shouting.



CHAPTER XXX.

NIGHT ON THE COLORADO.

"What's the matter? What has happened?" cried Jack.

"Is it Indians?" cried Dick, who had a lively imagination.

"Something grabbed my foot," declared Tom.

"Grabbed your foot?" repeated Jack.

"Well, maybe, nibbled at it, would be better," replied Tom. "It isn't hurt, but I was awakened by it. I guess the thing, whatever it was, must have been scared away."

"What could it have been?" came from Dick.

"Perhaps it was a bear," suggested Tom.

"A bear, nonsense. I guess it was all imagination," scoffed Jack. "You ate too much at supper, Tom."

"It was not imagination, I tell you," retorted Tom indignantly. "I felt it just as plainly as anything."

"Well, I don't see what——" began Jack and then he broke off.

From outside the tent had come an appalling crash of tin dishes, followed by unearthly grunts and squeals. The uproar was terrific. It sounded as if every piece of tinware in the camp was being hurled and battered around.

"What under the sun——?" gasped Jack.

"It's Indians; they've attacked the camp," cried Dick.

A weird screech split the night. Jack seized up a rifle.

"Come on, boys," he cried, but it might have been noticed that Dick was not particularly alert in following.

Zeb and the professor rushed out of their tents and their shouts added to the confusion. There was a bright moon and by its light Jack saw a small, peculiarly-shaped animal charging about blindly here and there. The next minute he saw, too, that the creature's head was caught fast in an enameled cooking pot.

It rushed about and uttered the muffled squeals that had attracted their attention. Jack raised his rifle and fired. The creature fell dead at the first shot. Zeb and Jack rushed up to it.

"A badger!" exclaimed Zeb, "and he's got his greedy head stuck fast in that mush cooker."

"And in charging about trying to get it off he'd made a wreck of our pantry!" exclaimed Jack, looking at the tin utensils scattered in every direction about the wooden box in which they were kept.

"It must have been that badger that came sniffing at my toes," said Tom.

"Or maybe it was Indians," laughed Jack, looking slyly at Dick, who was glad that they couldn't see how red he turned.

"Indians?" exclaimed the professor guilelessly. "Were there any Indians about?"

"Dick thought he saw some," explained Jack with a chuckle.

The dead badger was pulled out of the pot into which it stuck its head to lick out the remains of some oatmeal that had adhered to its side, and the boys went back to bed. But they did not sleep much after the uproar into which the camp had been thrown, and were glad when it began to grow light.

Zeb cooked a fine breakfast to which he urged everybody to do justice, as they had a long and possibly a trying day ahead of them. The badger was given decent burial by Dick.

"Let its fate be a lesson to you," said Jack, at which they all laughed, for Dick was always on the spot at meal times.

When the morning meal was finished and the things all packed away, the Wondership was inflated and soared into the clear air. Nights and early mornings on the desert are cool, and it was crisp and invigorating in the hours before the sun had risen high. But by noon the heat grew blistering, and they were still soaring above the river without a trace of Rattlesnake Island being visible.

However, that afternoon they sighted a group of islands of which the largest at once attracted their attention. A prominent feature of Rattlesnake Island, as outlined on the map, was a big dead pine, situated like a beacon, at the summit of the peak into which the island rose.

The river at this point broadened out. Great cliffs overhung it. They were made up of strata of brilliant colors. It looked from above as if they had been painted by some titanic sign painter—nature, the artist.

Jack was the first to call attention to the island which had caught his eye while he scanned the river below them with the binoculars. He at once noticed its formation, long and narrow, with a high, rocky peak rising out from amongst trees and bushes which clothed it almost to the summit.

Then his eye caught a great white pine trunk, standing like a flagpole almost at the apex of the peak.

"Hurrah, boys!" he cried. "I guess that's the place. Welcome to Rattlesnake Island!"

Tom was steering, "spelling" Jack at the wheel.

"You can see the island?" he demanded.

"Yes, or if it isn't it, it's like enough to be its twin brother."

Everybody began to get excited. Zeb took the glasses and after a careful scrutiny and a reference to the map, declared that the island below them tallied in every way with its description.

"Then down we go," said Jack.

"All right," nodded Tom, who was almost as good an air pilot as his cousin.

The Wondership dropped rapidly. Soon they were immediately above the island, which was now seen to be rocky and precipitous, except at one end where there was a great open place, bare and desolate looking.

On the edges of this cleared spot, which looked swampy and unwholesome, were serried rows of trees, every one of which was dead as if from a blight, and offering with their gaunt, leafless branches a sharp contrast to the green leafiness of the rest of the island.

Jack scanned the place sharply as they dropped down and Tom prepared to land on the edge of the swamp. As they got closer to the ground, he suddenly became aware of something that caused him a sharp shock of surprise.

"Why there's somebody on the island!" he exclaimed.

"Somebody on the island?" echoed Zeb incredulously.

"Yes, or at least there's a dwelling place."

The boy pointed to a rude sort of shack built of logs and roofed with boughs, which stood on the edge of the cleared space.

"Great Methuselah!" ejaculated Zeb. "Can someone have stolen a march on us?"

"I don't know, but it looks queer, and see, there's a shovel. Somebody has been digging here."

"But who could it be?" demanded Tom, mystified.

"Gosh! Looks as if we've bin euchered after all," grumbled Zeb.

The Wondership came to earth at the edge of the lifeless-looking, bare space. They clambered out of the machine and stood on what was, undoubtedly, Rattlesnake Island, for every landmark on the map had been verified as they dropped.

They looked about them for a minute and then Zeb drew his revolver out of the holster and began idly twiddling the cylinder.

"I want ter make sure she's in workin' order," he said with a grim comprehension of the lips, "before we do any investigating."



CHAPTER XXXI.

THE ISLAND OF MYSTERY.

There was an air of oppression, hard to explain, about the island. But they all felt it. The boys were inclined to talk in whispers and even Dick Donovan's usual lively spirits seemed daunted. There was something about the blistered, barren look of the cleared space on the edge of which they had landed that gave them all an odd feeling of melancholy.

Zeb was the first to shake this off.

"Our first job," he said, "is to find out who is on the island and what they've been doing."

Here and there in the black, swampy-looking bare space, they could see where holes had been dug, but when they examined the spade, which Jack had seen from the Wondership as they descended, they found that it was rusty and had evidently not been used for a long time.

It was the same in the rude hut which they examined. Some rusty utensils and a few ragged old garments were all that was inside. The dust lay thick on the floor and a large squirrel leaped out of the roof as they entered.

"Well, whoever was on the island has moved on again," declared Zeb.

"Or died," said Jack in a low tone.

"Wa'al, what I say is," observed Zeb, "ther sooner we git at that what-yer-may-call-um stuff and get away agin, the better it'll be for all of us. There's suthin' about this island I don't like."

The others agreed, all except the professor, who, on hands and knees, was examining some rocks with his magnifying glass.

"Where shall we make camp?" asked Dick.

"I don't much fancy this side of the island, somehow," said Jack, "but we could pitch the tents on that little plateau up there and be comfortable and have a good view up and down the river at the same time."

And so it was arranged. Leaving the Wondership on the edge of the clearing, they made camp on the flat ledge of sandy soil interspersed with rocks that Jack had selected. From it they had a good view in both directions. Above them was a small island, and below them the river leaped and roared in a series of big rapids.

Their preparations for camping occupied all the afternoon. It was supper time when they had finished and everything was shipshape and comfortable. In the meantime Dick had wandered off with the rifle and returned with four good-sized rabbits and three squirrels which Zeb cooked into a savory stew.

They turned in early as they had all worked hard and were tired. Just what time it was that he awakened, Jack did not know. But he thought it was after midnight. Taking his watch he went to the door of the tent to look at it in the moonlight, as he did not wish to arouse the others by striking a light.

The moon flooded the island. Jack looked about him, enjoying the beauty of the scene. The cliffs were great masses of black and white and the rushing river gleamed like silver. He glanced toward the black waste, on the edge of which they left the Wondership. The next instant he uttered a startled exclamation. Above the bare patch of dark-colored earth tall white figures were dancing, gleaming in the moonlight.

Jack's heart gave a bound and he caught his breath for an instant. Then he felt inclined to laugh at his own fears. What he had taken for ghostly figures were columns of vapor writhing and twisting as they steamed upward from the bare end of the island. What caused them, Jack did not know. He noticed, too, that the whole patch of barren land glowed with a strange phosphorescence like rotted wood.

Fascinated by the spectacle, he stood gazing at it. There was something eerie about the dancing, pirouetting columns of vapor. They looked like a party of ghosts dancing a quadrille. They twisted and contorted and bowed and soared upward and sank again in a kind of rhythm.

"Gracious, this is a spooky sort of place," thought Jack. "I wonder what causes those wavering columns? Maybe some sort of hidden hot springs like the one the professor fell into. I know one thing, I don't like this island overmuch. As Zeb said, there is something queer about it—something in the air. I don't know what, but I for one won't be sorry when we leave it."

He fell to musing about his father waiting so many miles away for news of the discovery that was to rehabilitate his fortunes and place the radio telephone in the list of practical inventions that have created an epoch in the world's history.

"Poor old dad," he thought "After all, he's really having the most trying part of this thing. Waiting back there for he doesn't know what, and with nothing to do but wait. I wonder if we are going to succeed? We will, we must! But, supposing that the map was wrong and that——"

His musing broke off suddenly and he crouched forward watching intently. His eyes were staring wide-open and startled at the Wondership. Its bulk lay blackly against the faint, phosphorescent glow of the black barren.

Then he felt his scalp tighten and his mouth go dry while his heart seemed to stop for an instant and then pound furiously, shaking his frame.

For a second he had seen something that had almost startled him into a cry. A dark figure was creeping round the Wondership, crouched like an ape as it examined the craft.

The boy had hardly caught a glimpse of it before it vanished, gliding swiftly like an animal into the brush. Jack rubbed his eyes.

"Am I seeing things?" he asked himself, "but no, I'm positive, as sure as I stand here, that that was a human figure sneaking about down there. Who could it have been?"

Jack did not sleep much more that night. The thought that they were not alone on the island was a disquieting one.



CHAPTER XXXII.

THROUGH THE WOODS.

The next morning Jack watched his opportunity, and under the pretext of hunting, left camp after breakfast and made his way to the side of the Wondership. He wanted to examine the vicinity for footmarks. But he found none, which was not surprising, for the ground on which the craft had been brought to rest was hard and firm, and not likely to take on any impressions.

In the bright, sunny glow it was hard for the boy to believe that he had actually seen the mysterious figure in the moonlight. But although he tried to assure himself that he had been the victim of an illusion, and that he had mistaken the shadow of a waving tree branch for a man, Jack knew that he was not laboring under a mistake. He was certain he had seen rightly; but he decided, for the present, to say nothing to his companions about the events of the night.

Having failed to find any tracks round the Wondership, he started off through the trees on his hunt. He was traversing a small glade when, in a clump of flowering bushes, he heard a sudden scuffling noise.

Startled, he stopped. The sound came again and this time it was accompanied by a shrill scream as of some creature in pain. Jack parted the bushes and made his way through them. On the other side he came across a rabbit. The little creature was struggling violently and squealing with the peculiarly human screech that rabbits have when in pain.

The boy saw that it had been caught in some way and could not get away. Greatly mystified, he dropped to his knees beside it and the next instant solved the puzzle.

The rabbit was caught in a trap ingeniously made from pliable willow twigs and set in a "rabbit run." For a minute the full significance of his discovery did not dawn upon Jack. Then it came like a bolt from the blue.

Somebody on the island, other than themselves, had set that trap! Perhaps it was the strange, half-ape-like man he had seen by the Wondership the night before. The boy looked round him in the silent wood as if he half expected to see somebody watching him.

He was not afraid, but he felt that creepy feeling that accompanies the mysterious. Suddenly he recollected that he had left his rifle behind when he plunged into the bushes.

He remembered this when the desire came to him to put the rabbit out of its misery. It had been caught by the hind leg and had wrenched it out of joint in its frantic struggles to get free. Jack made his way back to where he had left his rifle. But when he got back to the trap ready to end the poor creature's life, the rabbit was not there!

The trap was empty!

Then he looked about him. The ground was covered with blood and fur as if the rabbit had been torn to pieces.

"Some animal," was his first thought. Then, on examining the trap, he found that the thong which had ensnared the rabbit had not been broken or torn loose as would have been the case had some wild creature pounced on the rabbit and dragged it off.

It had been untied!

Jack had just made this discovery when he noticed something fluttering from a thornbush. He was sure it had not been there before, for he had noted the surroundings of the trap carefully. He examined the object that had caught his attention. It was a bit of canvas, seemingly torn from a garment made of that material.

"There is somebody else on the island!" gasped Jack, looking round with white cheeks.

He clutched his rifle firmly. Looking about him he half expected to see some wild face peering at him out of parted bushes. But nothing of the sort happened. Feeling very uncomfortable, Jack came away from the place and made his way back to camp.

This time he made up his mind to confide in Zeb. The prospector was as mystified as Jack over the events of the night and the incident of the rabbit trap. But he was unable to throw any light on the affair.

"It might be an Indian," he said, "or——"

"It might be the man that built that hut and left the shovel sticking in that barren place down yonder," said Jack.

"In that case, wouldn't he be livin' in ther hut instead of snoopin' round the island?" asked Zeb.

This view seemed to be incontrovertible. At noon the professor, who had been scouting over the island looking for specimens which might give him some clue as to the mineral deposits they had come in search of, arrived in camp breathless and indignant.

"A joke's a joke," he said to the boys, "but this is going too far."

"What's the matter, professor?" asked Dick.

"Yes, what's happened?" asked Tom, who saw that the man of science was really angry, and for some reason blamed them for whatever had irritated him.

"As if you didn't know," declared the professor. "I set my bag of specimens down on a rock while I went to investigate a peculiar-looking formation."

"Well?" said Jack.

"Well, I heard a soft footstep and the crackling of some twigs. I looked round and my bag of specimens had gone. Now which of you boys played that foolish joke on me?"

"I'll give you my word we know nothing about it, professor," declared Tom. "Dick and I have been working all the morning unpacking stuff from the Wondership."

The professor looked at them incredulously.

"That's right," struck in Zeb, "they haven't been out of my sight."

"But—but," stammered the professor, "my dear sir, that bag of specimens didn't walk off, you know. Besides," he added, "I heard a human footfall distinctly."

"It may not have been the boys, though," spoke up Jack seriously.

"Indeed, who else then?" inquired the professor stiffly.

"An unwelcome neighbor," replied Jack. "We are not alone on this island."

"Not alone? What do you mean?" demanded the professor in thunderstruck tones.

"Just this, that there is someone else on it. Who or what it is I don't know."

And Jack went on to explain all that he had seen.



CHAPTER XXXIII.

THE SECRET AT LAST.

Mysteries are always uncomfortable. As Jack proceeded with his narrative, Dick and Tom looked nervously about them. Even the boys' two elders looked grave. The presence of a man on the island was almost inexplicable. But Jack's story was so circumstantial that there was no room to suppose that he might be mistaken. Besides, he had the bit of canvas to show, the scrap that he had taken from the thornbush.

After dinner Tom and Dick resumed their work of unloading necessaries from the Wondership. Jack and the two elder members of the party discussed plans.

"You haven't found any trace of mineral-bearing rock yet, have you, professor?" asked Jack.

The professor shook his head.

"Not a speck of anything that even remotely corresponds with the black sand that Zeb brought East with him," said the man of science, dejectedly.

"It isn't possible that we have been fooled," said Zeb.

"Or landed on the wrong island," struck in Jack.

"It must be the right island," declared Zeb.

"How do you make that out?" asked Jack.

"Well, it's got every mark on it that the map gives, for one thing," said Zeb.

"That's so," agreed the professor, and then he added hopefully: "However, I haven't covered half the ground yet."

Tom and Dick came tramping back at that juncture. They carried some canned goods and Dick bore the rusty shovel that they had seen the day before sticking up in the black barren.

"It was sticky and moist out there," he said, "but I figured we could always use this shovel, so I went out and brought it along."

He flung himself down full length in the shade for it was hot and there was not a breath of wind to fan the canyon. The professor, who sat facing Dick, concentrated his attention for an instant on the soles of the youngster's boots. Then he leaped up with a yell that startled them.

"What is it? The wild man?" gasped Dick, looking round him in alarm.

"No, your boots, your boots; look at them!" cried the professor.

"Is there a snake on them?" cried Dick, preparing to jump up.

"Don't move! Don't move for your life!" fairly screamed the dumpy little geologist, springing forward. He fell on his knees at Dick's boots as if they had been sacred, and with trembling fingers flaked off, into his left palm, some black mud which stuck to them.

Then he stood erect, his face aglow with triumph and enthusiasm such as the man of science rarely permitted himself.

"Gentlemen," he said, with a flourish, "there is no reason to look further for the mineral-bearing ground."

"You have found it?" choked out Jack.

"Yes."

"Where?"

"On Dick Donovan's boots."

They looked at him as if they thought he had suddenly gone demented. Dick examined his boots carefully as if he expected to see money plastered all over them.

The professor extended his palm. In it lay the black earth he had scraped from Dick's boots. In it tiny particles glittered and gleamed like myriads of infinitesimal eyes.

"Z. 2. X.," said the professor in solemn tones, and he waved his hand down toward the black barren where the moist, unhealthy-looking bare patch lay quivering and sweltering in the sun. A kind of haze hung above it, like a very thin fog.

"There it is," he went on, "down there. Waiting to be extracted from that black earth. Look."

He shook the black earth from his palm. Where it had lain there was a red, irritated-looking patch. The professor showed it. It looked like a slight burn.

"Did that stuff do it?" asked Jack.

"Yes; and that's almost as definite a proof as an analysis, of its intense radio activity. You noticed that the sample that Zeb had was enclosed in a leaden tube. That was the reason. Such powerful stuff would inflict bad burns if not handled properly."

"So that was why you made us include asbestos gloves and foot coverings and black goggles in the outfit?" cried Tom, who had been much puzzled over the reason for that part of the equipment.

"That was why," said the professor, "and that also is the reason we brought along those lead containers. Z. 2. X. or its ally, radium, or in fact vanadium or any of the allied radio-active metals, would destroy any other sort of container."

"Let's go down now and start digging," suggested impulsive Dick.

"Don't venture out there till you are fully equipped for the job," said the professor. "Serious results might ensue. In the meantime, I am going to analyze this sample in order to be doubly sure."

Jack gave a deep sigh of relief. After all, it was not a dream. They had found the valuable earth. It was now only a question of transportation. His father's fortunes were saved. The radio-'phone would be rushed to perfection and placed on the market within a short time of their return home.

While Jack lay back and indulged in daydreams, the others watched the professor as he tested the black sand over a portable assaying furnace and made all sorts of experiments to determine its value and the proportion of the different precious metals contained in it.

There was a slight rustling in the bushes behind him. Jack, whose nerves had been rather on edge since the occurrences of the preceding night and that morning, faced round quickly.

The next instant he uttered a loud shout.

Peering out of the bushes was a hideous, hairy face, more like an ape's than a human being's. From it glowed two wild, piercing eyes, like those of a beast of prey.

As Jack shouted and the others started toward him, the face vanished like a flash.



CHAPTER XXXIV.

THE INTERLOPERS.

"Well, we'll git ter ther bottom uv this afore we leave ther island," declared Zeb vehemently, "but right now, pussonally, I'm more interested in gitting those lead carboys filled up with Z. 2. X. and gitting away from here."

"So are we," said Jack, thinking of his father.

They all donned their asbestos gloves and foot coverings under the professor's directions and put on the huge black goggles that had been brought along at the scientist's directions.

"I guess we'd scare that wild man into conniption fits if he could see us now," chuckled Tom, surveying his mates as they started out for the black barren.

"Yes, we look like a lot of men from Mars," agreed Dick.

Armed with shovels they attacked the dark, soft earth at a place the professor indicated. For an hour or more they worked and filled three of the lead carboys. Then Jack spoke.

"It's queer," he said, "but I begin to feel terribly tired, and I haven't worked long, either."

"So do I," said Tom. "I don't feel as if I could lift another shovelful."

"I'm all in," added Dick, throwing down his spade.

"Same here. Jes' 'bout tuckered out," chimed in Zeb.

"It's the effect of the stuff we are working in," said the professor. "Anyhow, we've done enough for to-day. We'll load the lead carboys on the Wondership and then knock off. I don't want you boys to get sick."

They took the loaded carboys to the grounded craft and the professor sealed and soldered a cover on each of them. Then they went back to the camp. Curiously, as soon as they reached it, the lassitude they had felt while working on the black barren left them. Jack proposed a hunting trip to Tom. Dick said he wanted to write up his notes from which, on their return, he was going to construct a big "story" for his paper.

The two chums struck out across the island. They met with fairly good luck. Jack brought down some rabbits and a partridge. Tom got three partridges and some squirrels. Game appeared to be plentiful on the island and Jack had a theory that at one time it must have been connected with the mainland.

At last their walking brought them out on the upper end of the island facing the smaller spot of land above. As they emerged from the trees, both boys got a big surprise.

Two boats had just been beached there!

"What in the world!" stammered out Jack.

"Who can——" began Tom, when the question was answered. The boys saw three figures coming down to the beach. They, seemingly, had been looking for a camp site.

"It's that fellow, Bill Masterson," explained Jack.

"So it is, and those other two are his cronies. The sneaks, they've followed us here!" cried Tom indignantly.

"Let's watch from behind these bushes and see what they do," said Jack.

They watched from a place of concealment while the three youths on the island above unloaded the second boat which they had towed down the river, carrying their camping equipment and provisions in it. They set up their tents quite boldly in full view of the other island and then proceeded to build a fire.

"How on earth did they get down the river without having a spill?" cried Jack.

"How did they know where Rattlesnake Island was?" wondered Tom, neither of the boys, of course, knowing of the opened letters.

"They seem prepared to make a long stay," commented Tom, after a minute, "but it's a wonder they weren't wrecked."

"I don't know," said Jack. "Zeb says the river is much higher now than he has ever seen it. That means that the rapids are not so dangerous as at low water. But they were taking quite a chance, at that."

The boys watched for a while longer and then returned to camp with their game and their news.

"If they try to land on this island, we'll soon chase 'em off," declared Dick vehemently.

"Then they'd have a case at law agin us," said Zeb.

"How do you mean?" asked Jack.

"Wa'al, we ain't filed no claim yet and in the eyes of the law them deposits down there in the black barren is as much theirs as ours."

That evening Zeb occupied himself with making several signs of intention to file claim which he intended to post all round the black barren, thus marking it off as if it had been a mine. Before they went to bed, Jack and Tom made another excursion to the upper end of the island where they watched the campfires of the interlopers for some time.

Suddenly, while they watched, they saw one of the boats with three figures in it shoved off. The craft began to drop down the river. Masterson, who was at the oars, steered straight for Rattlesnake Island.

"They're going to land here," declared Jack.

"What do you think of that for nerve," gasped Tom.

"The worst of it is, we can't stop them."

"No, that's so. Let's hide behind this rock and see what they do."

The boys slipped behind a big boulder and a moment later the boat was beached.

"Well, here we are," came in Eph's voice, "and if the stuff is worth all you say it is, we ought to get enough out in a couple of nights to make us rich."

"Gee! I can hardly wait till it's time to start digging," said Sam Higgins. "Here we are, on Tom Tiddler's ground, picking up gold and silver."

"Wait till we get it before you start hollering," said Masterson gruffly.

"What time will we start over?" asked Sam.

"About midnight. It will be plenty of time."

"But how are we going to locate it?" objected Eph.

"We can see where they've been digging, can't we?" said Bill Masterson, "or if they haven't started yet, we can hang around and watch till they do."

The three worthies sat under a rock not far from where the boys were and talked. It appeared that Bill Masterson had read up on mining and claim law and knew that the boys could not order them off the island. They had a right to take all of the mineral-bearing earth that they could.

Suddenly, however, their talk stopped.

"What are you doing, Eph?" demanded Sam indignantly.

"Nothing. What do you mean?" asked Eph in an astonished voice.

"You threw a rock at me."

"I didn't."

"You did. Ouch! There's another."

"One hit me, too," cried Eph, springing up, and at the same moment a yell came from Masterson.

Jack and Tom, as much surprised as the three marauders, heard the rocks pelting around them. Suddenly they looked up. Standing on a high rock above the place where Masterson and his cronies were talking, was a strange-looking figure in tattered clothes outlined in the moonlight.

He was busily hurling rocks down at the intruders. Suddenly a demoniacal laugh split the air and the creature vanished, running swiftly, crouched, with long arms hanging.

"It's the wild man!" gasped Tom, while the three worthies on the beach uttered a startled cry.

"It's ghosts, that's what it is," declared Sam Higgins shuddering.

"Nonsense. It's those kids. That's who it is," said Bill, but his voice was rather shaky.

"I never heard anything human laugh like that," declared Eph. "Ugh! it makes my blood run cold."

"Maybe we'd better go back," said Sam. "If we've got a right here I'd just as soon land in the daylight."

"You're a fine pair of babies," growled Bill. "I'm sorry I brought you along. Ghosts indeed—Wow! what was that?"

Another long ringing peal of laughter sounded through the night. It reverberated against the steep walls of the canyon and was flung mockingly from crag to crag. The boys felt their blood chill as they heard it. There was something diabolical in the merriment of the wild man who, they knew, was making the hideous sounds.

"I'm going back to the other island," declared Sam.

"If you move I'll knock your head off," said Masterson. "It's just a trick of those kids to scare us, that's all it is."



CHAPTER XXXV.

TRIUMPH.

It was midnight. The moon rode high in a cloudless sky, and the camp of the Boy Inventors, to all appearances, was wrapped in slumber. Through the woods came three creeping, cautious figures. Each carried a spade and a sack. They paused by the camp and looked about them.

Then, by the bright moonlight, they saw the bare plateau below. The black barren where the adventurers had been working that afternoon. Masterson was the first to see traces of digging. He seized Eph's arm and pointed.

"That's the place," he said in a hoarse whisper. "See, they've been at work there already."

"Tom Tiddler's ground," whispered Eph.

"I guess we'll get some of it, too," chuckled Sam, who had gotten over his fright in a sudden greed at the thought of riches.

Silently, for they had sacks tied round their feet, the three interlopers crept down the rocky slope toward the black barren. The dark ground, thickly sown with mineral wealth, glittered in the moonlight as if a frost had fallen on it and made it gleam iridescently with millions of sparkling points of light.

As the trio stole down the slope, dark figures from the Boy Inventors' camp followed them. Led by Zeb, they found hiding places and watched operations as Masterson and his cronies began to dig. They wielded their shovels frantically.

"And we can't stop them," groaned Dick.

"Wait a minute," said the professor.

They continued to watch, and before many minutes had passed they saw Sam Higgins lay down his shovel with a grunt.

"Go on and dig," ordered Masterson.

"Yes, hurry up, we haven't got all night," urged Eph.

Sam made a few more feeble movements and then quit.

'"I can't do any more," he said languidly.

"Ouch! my hands are burning," cried Eph suddenly, "and I feel as if all my bones had turned to water. What's the matter with the place?"

After a few minutes more both Eph and Sam gave up, but Masterson stuck doggedly to his task, although his hands were burning terribly, and the radio-active stuff was eating through the sacking on his feet. At last he, too, had to give in. They were too weak to carry the sacks they had partially filled across the island, owing to the effects of the black barren, and staggeringly they hid them to call for them at a later time.

"I thought so," said the professor, as the hidden watchers saw Masterson and the other two wearily clamber up the slope. "They'll have bad sores to-morrow and may be crippled for some time."

"But they'll recover?" said Jack, whose conscience began to smite him.

"Oh, yes, but they will have quite a lesson first," rejoined the professor.

"Let's see what they do next," suggested Jack, and he and Tom carefully made their way to where the trio had left the boat. Masterson ordered Sam to get on board; but just as the timorous youth was about to obey another hideous laugh from near at hand startled him so that he almost jumped out of his skin.

He leaped forward, but in his alarm missed the boat and gave it a shove that sent it into the stream. Sam fell flat on his face, while Masterson, with an exclamation of dismay, leaped for the boat. But the swift current had it in its grasp and bore it rapidly away. Masterson sprang on Sam and began beating him violently as the cause of all the trouble. It was serious enough for them. The loss of the boat had marooned them on the island.

The boat drifted past a rocky point further down the island shore. Had they been there, they would have been able to seize it. They watched it with alarmed eyes as it sailed down the current. All at once a dark figure dashed from the trees and made a spring from a high rock, hoping, seemingly, to land in the boat. Instead, there was the sound of a heavy fall and then a piteous groan.

Whoever it was had jumped for the boat, had missed it and fallen on the rocks. Not caring whether Masterson and his cronies saw them or not, the boys raced along the beach. From the groans of the injured person they knew that he was badly, possibly mortally, hurt.

In a few minutes they reached his side.

"It's the wild man!" cried Jack, as they gazed at a hairy, wild-looking man who lay stretched out, breathing heavily, on the rocks where he had fallen. His only clothing was a pair of tattered canvas trousers and a ragged shirt.

"Poor old Foxy. He's done for at last, is Foxy, for his sins," groaned the man in an insane voice. "He suffered terrible for his crimes, has Foxy, but it's all over now."

"Foxy!" exclaimed Jack. "That's the man that came down the river with Blue Nose Sanchez. The man who stayed in the boat."

"He must have landed here and then gone crazy from privation," said Jack. "I can't find that any bones are broken," he said after a brief examination. "Suppose we carry him back to camp?"

"I wonder where that Masterson outfit has got to?" said Tom, as they picked up the wasted form of Foxy, who was raving and moaning by turns.

"I don't know. They are in a fine predicament now. They've got no food and no boat They're marooned on this island."

"I suppose we'll have to help them out," said Tom.

"I guess so, though they don't deserve it."

"I lost that boat," moaned Foxy. "I could have got away in it. Poor old Foxy. It's tough on Foxy," and he began to weep.

The professor found that the man had not suffered any broken bones but the fall had bruised and sprained him and he was helpless. From scattered bits of his ravings they learned what he had endured on the island and how, when the black sand began to burn him, he had had to give up working on it. Then his boat had drifted away and since then he had lived the life of a wild man, setting snares for rabbits and partridges, and eating them raw, tearing them with his clawlike fingers.

Early the next day the expected happened. Chastened, and with burned and swollen hands and feet, Masterson and his cronies came into the boys' camp at breakfast time. They looked crestfallen and sheepish, but the boys did not want to make them feel any worse than they did, so they spared them questions at first.

But when Masterson begged them to get them out of their predicament and take them back to Yuma, Jack felt that it was time to put them through a cross examination.

"You followed us here to try to cut out some ground from under our feet, Masterson," he said, "and you know you told me in Nestorville you wanted to get even with me."

"Don't rub it in, Chadwick," said the humbled Masterson. "I'll do anything you say if you'll only get us out of this terrible place. I can hardly walk, and my hands feel as if they'd been burned in a fire."

"How did you know our destination?" asked Tom. Masterson made a full confession and at the end begged forgiveness.

"This ought to be a good lesson to you to mind your own affairs," said Jack as he concluded.

"I know a man who made a big fortune just minding his business," said Dick. "For my part," he went on, "I'll forgive you, but I want you to sign a paper promising not to publish anything about this expedition."

"I will—oh, I will," said Masterson. And then he wrote as Dick dictated. The boys witnessed and signed the paper.

"And now you'd better eat breakfast," said Jack.

Three days later, the Wondership made two trips to Yuma. On the first she took the original party with the addition of the insane Foxy, who was placed in an asylum. He never recovered his reason but died in the institution. Also, there was carried a part of the leaden carboys which they had filled.

Masterson and his cronies had been left behind on the island to pack up the camping equipment and thus make themselves useful. Zeb went to the U.S. Assay Office and formally filed their claim to the island and its riches. In the meantime, the professor took charge of Foxy and turned him over to the authorities.

As for the boys, they sailed back to Rattlesnake Island, after sending a telegram to Mr. Chadwick. It was brief.

"We win," was all it said.



CHAPTER XXXVI.

THE HOMECOMING.

The next day Masterson and his companions, very much subdued, boarded the Wondership as passengers. All of them were still suffering painfully from the effects of the burns, their only reward from their ill-advised raid on the black barren.

"Boys," asked Masterson, "can't you take our camping equipment along? It's a shame to have it rot here."

"All right," said Jack. "I think we may be able to sell it for you. Come on, we'll get to work now!"

"You're not such a bad chap," said Eph when he heard Jack agree to Masterson's suggestion.

"He's the finest chap on earth!" exclaimed Tom.

"That he is," added Dick Donovan.

"He is a model young man," declared Professor Jenks, overhearing Tom's last remark.

Jack flushed with pleasure and embarrassment. It was very gratifying to know that his friends thought highly of him, but at the same time he wished they would not give him that uneasy feeling with their sincere compliments. So he hurried away, asking the others to follow him toward getting together Masterson's outfit.

While the dumpy little geologist went once more to search for strange specimens, the boys readily set to work and in a very short time the camping equipment was placed on board the Wondership.

When the boys arrived at Yuma, Masterson found no difficulty in selling the camping outfit to old man McGee, who decided to make one more try to find the Three Buttes.

"Don't you think you're too old, and that the gold, after all, may not be there?" Tom asked the eccentric miner.

"Nonsense!" exclaimed McGee indignantly. "As I tole you afore, it stands ter reason thar's gold out thar, and 'at it war'ent up to Peg-leg Smith nor'n to Guv'nor Downey, nor'n to McGuire, nor'n to Dr. De Courcy, nor'n to any of 'em to find the Buttes, but as I says afore, I says ag'in—'at ther good Lord never made nuthin' thet wasn't of some use. Very well, then, the desert is good fer nuthin' else but mineral wealth, and Providence made it so plagued hard ter git at so 'at all of us couldn't git rich at once. I've been arter the Buttes all me life, and this wack I'm goin' to land it rich!"

The fanatical old prospector, chuckling gleefully and sucking his pipe, ambled away while Tom looked after him, shaking his head sympathetically.

"Look out! Look out!" someone shouted in Tom's ear. "There's a beauty, a wonder!"

Tom, startled, whirled about to see the professor, gazing intently at a small rock upon which one of Tom's heels was resting. The professor violently pushed him aside, out came his little hammer, and in a moment the new specimen was in his bag. Then, the man of science, without looking up to see whom he had spoken to, pounced on another stone.

Tom could not help laughing outright at the professor's queer ways and deep concentration on his pet hobby.

"What a funny world this is!" remarked Tom, still amused. "Here is a man forever after rocks, rocks, and there goes a miner set upon becoming rich and discovering some imaginary mine."

He saw Jack waving to him from the veranda of the hotel.

"Listen, Tom," said his chum when they stood side by side, "I was thinking that it would be a splendid idea to send the Wondership to New York, and that from there we travel to Nestorville, via the air route."

"Great!" cried Tom, delighted. "But say, are we to take Masterson along?"

"Of course not," replied Jack. "He can go back to Boston on the train."

"Good for you!" declared Tom, slapping his chum on the back.

"But I haven't told you my main idea yet," said Jack, smiling,

"What is that?" asked the other wonderingly.

"Can't you guess?"

"No," Tom began to say, and then the roguish twinkle in Jack's eyes gave him a sudden inspiration. "You don't mean to use the Z.2.X. to send messages with while we fly nearer and nearer to our old home town?"

"That is exactly what I wish to do," said Jack quietly.

"Whoop! It's great!" cried Tom, throwing his hat in the air; and as he saw Dick coming toward them, he fairly pounced on the astonished reporter with the news.

"Flamjam flapcakes of Florida!" gasped Dick.

And so it was arranged. A few days later our party boarded a train for the East. Jack, Tom, Dick and Professor Jenks arrived at New York.

(They had left Zeb behind to attend to the work in the barren fields.)

The Wondership, as on the previous occasion, was quietly but quickly assembled, and made ready to take its homeward flight. They had chosen a spot on Manhattan island still very meagerly developed, and so were not at all troubled by curious onlookers. Jack, to whom his father had explained in detail the use of Z.2.X.—or Coloradite, as they had decided to call it—busied himself almost exclusively with the radio telephone apparatus. When all was ready, he sent his father the following telegram:

"Expect message, using Coloradite from New York."

The next morning they ascended. Round and round the Wondership circled, a golden speck against the blue sky. In a quarter of an hour the great metropolis seemed nothing but a giant beehive, with millions of busy workers ever hurrying in hundreds of different directions. The cars and automobiles were only like giant bees, moving somewhat swifter than those on what looked like fine threads of cotton or wool.

"What a small place New York is after all," observed the professor.

"It is larger than Boston," said Tom slyly,

"Perhaps," admitted the man of science haughtily, "but not as learned or stately—no city can take its culture away from Boston."

Jack smiled, and in order to change the conversation, asked Tom, "How high now?"

"About fifteen hundred feet," guessed Tom.

"Wrong," said Jack, glancing at the barograph on the dashboard in front of him. "We have reached two thousand eight hundred feet."

"I must be asleep," said Tom, frowning. "Shall I connect the alternator?"

Jack nodded and prepared to send greetings to his father, hundreds of miles away. They were out in the country now. As the Wondership glided through the air, the professor, in viewing the villages, farms, green pastures, and stretches of woodland, regretfully shook his head as the thought occurred to him that he was missing many a precious stone. He looked over to Jack with the idea of suggesting a descent, but he saw the boy inventor patiently adjusting the tuning knob, and waited, realizing how anxious Jack was to test the Coloradite.

The little professor, extremely interested, saw Jack place his lips to the receiver, and for the second time in his life, send out the distinct call:

"Hullo, High Towers!"

Many minutes passed without an answer. Jack's face became grave. Was part of the machinery not properly adjusted? He went over the instrument very carefully. In so far as he could see, everything was just as it should be. Then a thought came that made him dizzy—was it possible that the Coloradite was not suited for the work, that Mr. Chadwick had been misinformed?

"What's up?" inquired Tom, glancing up from his engines.

"By the ghost of Guzzlewits!" gasped Dick. "Don't say it won't work, Jack!"

The professor, ordinarily cool and very calculating, was strangely stirred. He watched the young inventor's face. Did it mean failure?

"I don't know," said Jack at last with forced calmness. "I will try again."

Once more Jack, oppressed by a vague fear, sent out the words:

"Hullo, High Towers!"

The reply came with startling swiftness, relieving the party from the mental strain. In one voice—the professor included—they yelled,

"Hurrah!"

"Congratulations!" came Mr. Chadwick's voice in return.

"Why the delay?" asked Jack, smiling with

"A small lever snapped. It required a few minutes to repair it. How far from New York are you now?"

"About forty miles."

"Good! Try to land here before sunset."

"Why?" asked Jack.

"Nestorville has a little surprise for you!" replied Mr. Chadwick, and Jack heard him chuckle.

"Good for Mr. Chadwick!" cried Dick in glee, for Jack had so arranged the instrument that all of them in the Wondership could hear Mr. Chadwick's voice.

Then followed a long conversation between father and son. Mr. Chadwick had almost completely recovered his health, and was again working over new experiments. Dick insisted that he be permitted to tell the story of their adventures on the island of the Coloradite Treasure.

"You won't tell it right," he declared to Jack, and insisted so strenuously that the boy inventor had to let him speak to Mr. Chadwick.

Dick set his choicest language agoing, and his vivid description of Jack's part in every incident was embellished by the most flowery adjectives in his vocabulary. Jack had to listen, and grin.

By the time his long story was done, Nestorville was sighted. As soon as the people saw the Wondership, pandemonium broke loose. Not only Nestorville, but officials and crowds from the neighboring towns had poured in, and the reception the boys and the professor received lingered with them for many, many years.

Later, as time went on, Mr. Chadwick's fortune was completely rehabilitated. Professor Jenks no longer was so eager to search for rocks, and while doing so get into all sorts of difficulties. He lived more at home, becoming at last, as his spinster sister declared, "a man with the proper spirit to make an ideal husband." Of course, the professor had received a very substantial sum of money from the boys.

Jack and Tom soon found themselves wealthy, and often in fancy trace the days back to that afternoon when they found the sturdy miner lying on the roadside, having been knocked unconscious by Masterson's careless driving of his automobile.

Zeb, continued to take charge of the work on Rattlesnake Island, to which the boys never returned. For a long time the supply from the black barren appeared to be inexhaustible. Suddenly, however, it ceased, and no more was dug. But what had been mined had been more than sufficient to make all prosperous.

Dick, with his share of the proceeds, which the boys insisted that he accept, bought the Nestorville Bugle. From the very start, he made it a live, progressive paper. Sometimes, when the now busy editor had a spare hour, he invariably visited his two friends, and the three—sometimes, too, the little professor joined them unexpectedly—recounted old-time stories.

But the boys were not made lazy by wealth and fame. To this very day, Jack and Tom, with Mr. Chadwick's aid, are devising many inventions calculated to benefit mankind. Possibly, at some future time, we shall hear something more about these, but for the present let us take our leave and say good-by.

THE END