CHAPTER XIII.

THE STRANGEST VESSEL ON THE LAKES.

The newcomers found themselves in a cylindrical-shaped chamber, possibly twenty feet long by twelve feet or so at its widest part. The rivet-studded walls showed that the structure was of metal, but comfortable leather-covered divans were placed along each side, inviting to rest and meditation. Obadiah Ironsides invited his guests to sit on these while he explained his craft.

After he had explained how it was driven by gasoline engines on the surface, and by electrical motors when under water, he conducted them into the engine room. Except for the electrical driving machinery it did not differ radically from that of the luckless Sea Ranger. A striking feature of the machinery, though, was the huge pumps for exhausting the "sinking tanks" of water when the operator of the craft wished to rise, and the appliances for supplying fresh air in quantities when submerged, by the expedient of sucking out the exhausted atmosphere.

"How long could you keep submerged?" inquired Tom.

"For two days, if necessary. I have accomplished that already. Possibly, at a pinch, that time might be lengthened considerably," was the response.

A visit to the forward compartment then followed. This was the space devoted to the torpedo discharging machinery, for, as Obadiah had explained, the primary purpose of the Huron was for warfare. And a formidable craft for that purpose she appeared to be. The interior of the conning tower was next inspected. It was a place of mysterious levers, and wheels of glittering brass and steel. Like the rest of the craft it was lighted by electricity.

On the walls were gauges to show submergence, speed, air-pressure and several others, which were far too technical in their purposes to explain here. A comfortable seat was provided for the steersman, who could control the unique steering apparatus by one hand by means of a lever, or, in case of necessity, by pedals—like those of an automobile. This left his hands free to attend to torpedo discharging and so on.

"In designing this craft," said Obadiah Ironsides, "it has been my aim to provide a craft that was of positively 'one-man control.' It was to try out how far this was feasible that I took my lone trip under the lake to-night."

"And did you find your craft handled all right?" inquired Tom.

"I did till I bumped your vessel on rising," said Obadiah Ironsides, with a whimsical grimace.

"Is it not possible to provide some sort of apparatus which will give you warning of the vicinity of other craft?" asked the professor, who had listened and observed with the deepest attention while this singular hermit of the underwater talked.

"It is," rejoined Mr. Ironsides; "in fact, I have been experimenting with one which is in readiness to be affixed to the Huron. It is similar in its workings to those used by Atlantic liners in feeling their way through a fog."

"Then your submarine is complete?" asked Tom.

"Yes. In two weeks' time I am going on a trip through the great lakes with her, and then I shall have her shipped to attend the government tests at Newport News."

"One question more," put in the professor, "you have chosen a very out-of-the-way place to conduct your experiments."

"For a very obvious reason," said Obadiah Ironsides, with one of his pleasant laughs, "you must know that every navy in the world is experimenting with submarines. They are, in conjunction with torpedo destroyers, the war vessel of the future. The Russo-Japanese war proved that. Now, then, the competition is naturally keen among inventors to produce the best type of submarine. Inventors, as a class, are a splendid, upright set of men; but, I regret to say, that all are not so. Some of them are unscrupulous to a degree. It was to escape the surveillance of spies of a rival submarine concern that I buried myself up here. And there you have it," he concluded with a laugh, "unless, indeed, you wish to know whence I get my funds?"

Tom and the professor held up their hands in protest.

"My dear sir," said the professor.

"Not at all," laughed Obadiah. "My father was the well-known maker of iridium steel. He amassed a fortune in its manufacture. I learned my business in his foundry. When he died he left me his large fortune, which I devoted to experimental work. My dear mother soon followed him to the grave, and then, having only my work left to live for, I plunged into it with a vengeance. Possibly my ample funds have helped me to go further than some inventors with more ability but less capital," he concluded modestly. "So," he broke off with a laugh, "there you have the autobiography of Obadiah Ironsides, at your service. And now, as it is late, and I'm sure you are tired, we will retire."

"Have you a boat to get ashore?" asked Tom, wondering when the resources of this wonderful craft would be exhausted.

"I have one. A water-tight craft bolted to the deck. She is reached by a trap in the ceiling of this cabin. But unless you insist upon going ashore I'll show you that feature of the Huron some other time. But to my mind, the order of the day—or, rather, night—is bed."

"Beds?" inquired Tom, looking about him as if he rather expected to see some spring from the floor of this wonderful craft.

The professor merely tried to look unamazed, as became his dignity, while Jeff and Rosewater were both frankly overcome and speechless by the wonders they had beheld.

"I haven't advanced quite as far as that yet," laughed Obadiah, noting Tom's glance at the floor, and reading it aright; "but those divans can be converted into very comfortable Pullman couches, and opposite the galley, which you recollect is between the engine room and this apartment, is a bathroom and shower, and all the fittings just as you would find it in a hotel."

"Say, is there anything left out on this wonderful craft?" gasped Tom in amazement.

"Yes, one thing," laughed Obadiah, "a contract with Uncle Sam!"

Levers and springs controlled the couches, which were reversible. On the underside, as they turned over, were discovered comfortable mattresses, snowy sheets and neat counterpanes. They lost no time in turning in, Tom having an indistinct recollection of hearing Rosewater murmur, as he sank off to sleep:

"Ef dis yar tea kittle sinks in de night ah don' cahr. Ah'se gwine ter sleep till dat Gabriel blows his horn."

It was broad daylight when Tom awoke. This fact was evidenced by the sunlight streaming cheerily through the open hatchway leading to the deck. An appetizing aroma of frizzling ham and eggs, and the added savor of hot coffee, filled the air. It proceeded from the galley where Obadiah had already set Rosewater to work.

Tom leaped up and made for the bathroom. He reveled in the shower, and, having aroused the professor and Jeff, he fell to his dressing with a feeling of renewed vigor. In daylight, even inside this steel shell, things looked much brighter than they had during the gloom and uncertainty of the night. He had hardly completed his dressing when Obadiah himself appeared, accompanied by an elderly man of benign appearance.

"This is Sam Wrenchly, my foreman," he explained. "He has looked over the damage to the Sea Ranger and informs me that it will take two days to repair her."

"Two days!"

Tom could not repress a groan. He sank down on the edge of the bunk and buried his head in his hands. What might not happen to his brother and his chum in two days? It was a crushing blow, and Tom could not be blamed for feeling "knocked out" for an instant.

Obadiah placed a hand kindly on the lad's shoulders.

"Come, cheer up, Tom," he said softly, "I have news for you. Sam here knows something of this Captain Rangler and his haunts."

Tom looked up, alert in an instant. The old man nodded his head sagely, and smiled under his gray beard.

"Yes, Rangler and I met many years ago," he said; "but I have occasionally heard of him since."

"And you think you know where he has taken my brother Jack and my chum Sandy?" asked Tom.

"I think so," said the old man calmly. "Did you ever hear tell of Castle Rock Island?"

CHAPTER XIV.

OFF ON A LONG CHASE.

"Castle Rock Island!" echoed Tom, in an amazed voice, "why—why—that's Mr. MacTavish's island where we were going camping."

"Aye, it used to belong to a man named MacTavish, a lumber capitalist from Mackinac. It may belong to him yet for all I know, but no one's lived on it for many years, and it's become a sort of roost for a gang of rascals," replied old Sam Wrenchly.

"You are certain of this, Sam?" inquired Obadiah Ironsides.

"As certain as I'm standing here," rejoined the old man indignantly, as if he didn't much like having his word questioned, "wasn't I keeper of the old lighthouse that used to stand there, and didn't I have trouble with this fellow Rangler at that time?"

"So there used to be a lighthouse on it?" asked Tom.

"Yes. I guess the ruins of it are there yet. But that channel isn't used any more, and the lighthouse, if it's still there, must have fallen into ruins. Yes, it was a queer sort of place was that island."

"Queer? In what particular way?"

It was Obadiah Ironsides who put the question.

"Why, there were all sorts of tunnels and places in it. They say they were made by Indians who formerly mined there for copper. Some says as they're haunted by ghosts and such. But I place no stock in such stuff. All I know is that the tunnels is there. I've seen them with my own eyes. One of them was right close to the lighthouse. Its mouth wasn't a hundred yards from it. The way I discovered it was, my cow fell into it one day. Aye, and a fine job I had getting her out, too," quoth the garrulous old man, "she was a strawberry-colored cow, and as good a milker as ever——"

"Never mind that now, Sam," said Obadiah, in his gentle but decisive way, "I think if you will put the finishing touches on that submarine device for detecting the location of nearby craft, that it will be a good thing. We may need it as soon as possible."

The old man looked surprised, but made no comment.

"I'll get to work on it right off, sir," he said, shuffling up the steel ladder, "all it needs is the threads put on two bolts. Wonder what's in the wind now," he added to himself, as he clambered laboriously up to the deck and then sculled ashore by the boat with which he had come off to the Huron.

At this juncture, the professor and Jeff emerged from their ablutions and presently the whole party was ready for breakfast. Tom, despite his worry, did ample justice to the meal. The novel surroundings gave it an additional zest.

When breakfast was concluded, Tom was for going on deck at once, but Obadiah checked him.

The inventor and promoter of the Huron-type of submarine had been in deep thought throughout the repast. Tom, and the rest with him, concluded that his mind was busied with some problem connected with his work. But it now proved that it had been otherwise.

With the suddenness, and yet thoroughness characteristic of him, Obadiah Ironsides had arrived at a decision which was to prove of great moment to the Bungalow Boy and his friends.

"You wish to reach Castle Rock Island without delay, of course, and discover if Rangler and his rascally crew have really made it their destination?" he said without preliminaries.

"Why of course," rejoined Tom, rather puzzled as to what could be coming next, "anything like a clew is worth investigating and—and this seems to be a red hot one."

Obadiah Ironsides smiled slightly at the lad's impetuous way of putting it.

"But how are you to get there till the Sea Ranger is repaired?" he asked.

"That's just it," muttered Tom disconsolately, "Two days of delay, and who knows what may happen in that time? It's really mortifying. But I suppose there's no help for it. That is, unless there is some fast craft we could charter right here at Brownhaven."

"I think there is one," said Obadiah quietly.

"There is one?"

"Yes."

"Where is it? I'd like to——"

The inventor held up a hand. Tom had started to his feet.

"No need to look very far for that craft," said Obadiah smiling.

"I don't quite understand——"

"You are on board it."

"On board it?"

"Yes. Right now. The Huron is at your disposal. I feel that I was responsible for delaying you at a critical moment. All I can do to repay you for the annoyance and anxiety is to place myself and the Huron at your command. No, don't thank me. I have a selfish reason, too. Most of us have, I fancy, for our so-called good actions. I like to see rascals punished. That's one reason for my aiding you in your pursuit. I wish to thoroughly try out the Huron on a long cruise, that's another reason——"

"And number three?" demanded Tom, whose eyes were dancing with excitement and gratitude.

"Number three," quoth Obadiah heartily, "is that I like you. You're the right type of boy. You know the old saying that 'Providence helps those who help themselves.' Well, in this case, I'm going to play Providence."

"You and your fine craft," broke in the professor. "Mr. Ironsides, you are a man in a thousand. We can never be sufficiently grateful to you."

"No sah! No sah! No sah! Dat we can't, sah!" struck in Rosewater.

Crash!

In his enthusiasm the negro dropped an armful of plates he had been removing.

The accident, and the negro's comical expression of dismay, broke the tension of the moment, which was becoming quite emotional. They all broke into a hearty laugh.

"I guess you can show your gratitude best by not smashing the inventor's plates, you black rascal," admonished Jeff, as Rosewater, quite abashed, sought the seclusion of his galley.

"And now, come on deck," invited Mr. Ironsides, "and take a look at the good craft Huron in broad daylight."

They gladly obeyed the invitation. On gaining the deck, via the steel stairway, an animated scene met their gaze. All about spread the sparkling waters of the harbor—a tiny place—with the tree-enclosed town nestling on a hillside at some little distance. Close at hand lay the poor Sea Ranger, a big, jagged hole showing in her bow. Ashore, almost opposite to them, was the smokestack and high palings marking the site of Mr. Ironsides' experimental ship yard, where he fondly hoped the future submarines of Uncle Sam's navy would be constructed.

On the foredeck of the Huron several men had just completed straightening out the damage done to the diving torpedo boat when she had her accidental encounter with the Sea Ranger.

The deck was of whaleback shape, formed of plates of the inventor's secret metal. All round were iron uprights, supporting a rail made of steel chain. Everything about the exterior of the craft was painted a dull gray color—like that of the sea on a cloudy day. Mr. Ironsides explained that this color made the craft almost invisible, even when lying on the waves not more than a mile from another vessel. Not a bit of bright work or brass was visible. Nothing, in fact, to catch a betraying ray of light.

Aft of the helmet-shaped conning tower, with its two goggling eyes, and its smaller "optic" for the projection of the rays of a powerful searchlight, was a humpy-looking object, not unlike the half of a giant gray watermelon. This, the inventor explained, was the Huron's "long boat." It provided an emergency means of leaving the craft in case of accident.

It was bolted to the deck and hermetically fastened by means of gaskets. It was designed to be entered from below by a trap door of metal which could be instantly closed and sealed. A similar door was in the boat. In case it was desired to arise to the surface it was a simple matter to crawl up into the boat, close the door in the Huron's "skin," and then close a similar contrivance in the deck of the singular long boat. This rendered it practically a water-tight bottle of steel. To rise to the surface four bolts were loosened when the "boat" would, of course, detach itself from the Huron and shoot to the surface. This accomplished, those within could unbolt the round plate by which they had entered, and obtain air and a view of the surroundings. To make this miniature submarine more complete, a tiny gasolene motor of four horse power was fitted inside it, enabling it to make about six miles an hour on the surface.

There were many other features of the Huron, to explain which, in detail, would be wearisome. They may all be summed up by saying that not a contrivance for safety or comfort appeared to have been overlooked. It would have been hard to imagine a more completely outfitted craft for the purposes for which she was designed. Possibly we should mention that she also carried a "field wireless" apparatus, with an adjustable telescopic steel pole to carry "the aerials." This was stored below, but when needed could be brought on deck and communication established within a radius of four hundred miles. The generators were, of course, operated by the machinery in the hull below.

By the time all this, and much more, had been explained by Mr. Ironsides, a boat appeared from the shore, conveying old Sam Wrenchly, who was to form one of the Huron's crew, and his belongings. The boys then took a trip to the Sea Ranger, and selected what they wished to carry along. Necessarily, the outfits were limited, so far as bulkiness was concerned.

Before the boat returned to the shore, Tom composed, and entrusted to the workman who rowed the boat back, a long telegram to Mr. Dacre. This informed him minutely but concisely of all that had occurred, and told him the Huron's destination. Tom took the liberty of advising his uncle, should he decide to come north, to take train to Brownhaven and proceed to Castle Rock Island with the Sea Ranger, which by that time would be repaired. If all went well they would await his coming there, the message concluded. Tom felt much relieved when this had been done, and, with a lighter heart than he had felt for some days, watched with interest while the electrical winch hoisted the Huron's anchor.

A few moments later, with Mr. Ironsides at the wheel, the submarine nosed out of Brownhaven Harbor. She moved through the water rapidly and with little vibration.

"Hurray! We're off!" exclaimed Tom, who, with the professor and Jeff, was seated on the whaleback deck.

"Yes, off into the unknown," quoth the professor, who was at times given to what he himself would have called "hyperbole," and Tom, "high faluting" language.

CHAPTER XV.

"WE'VE STRUCK A SUBMERGED WRECK!"

It was one of the most fascinating experiences that had ever befallen Tom Dacre—this of sitting at his ease on the metal back of a submarine monster, rushing through the water at a speed which Mr. Ironsides declared was almost twenty-five miles an hour. The spray flew back in the faces of the party on deck, whipping the keen blood into their cheeks. The roar of the water, as the submarine parted it in two mighty foam-crested waves, was like that of a waterfall.

"Better come inside now," said Mr. Ironsides, after a while, "I'm going to try a burst of speed, and you might get drenched."

When they were all assembled in the conning tower, and pretty closely packed, too, they were, in that narrow metal structure, Mr. Ironsides pressed a button. Far off somewhere within the submarine, a faint tinkle responded. It was a bell calling on old Sam in the engine room to "let her out." Like a race horse when the barrier flies up, the Huron gave a sudden leap forward as her three propellers bit into the water. A wave, like a tidal inundation, rose high on each side of her bow. From the conning tower she appeared to be plowing her way through a canyon whose walls were of water.

So suddenly had the burst of speed followed the signal to increase her rate of progression, that the party were thrown one against the other. Tom almost lost his feet, fetching up against the professor with a bump that caused the man of science to ejaculate a most undignified "Ouch!"

"Well, what do you think of it?" inquired Mr. Ironsides, who had stood calmly at his steering lever with his lips compressed into a line, and his hawk-like eyes peering keenly ahead during all the confusion.

"Think!" exclaimed Tom, "I don't know what to think. It's—well—marvelous doesn't describe it."

"So you are impressed, eh?" asked the inventor, in whose tones an under current of satisfaction was plainly perceptible.

"Impressed! My dear sir, we are dumfounded!" gasped the professor.

"Wait," went on the inventor with a queer sort of smile, "you haven't seen half yet."

"What's coming now?" wondered Tom. He was about to speak, but instead a sudden cry forced itself to his lips. Looking down the water-walled canyon through which they were rushing he became all at once aware that the huge black hull of a lake steamer was looming right ahead of them.

At the terrific pace they were making (the speed indicator recorded thirty knots), it seemed impossible to avert disaster, swift, awful and in evitable.

Tom glanced at the others. The professor's lips were parted with a look of horror. Jeff was white and was gripping a hand rail so tightly that the blood had left his knuckles. Rosewater had turned a sickly gray under his black skin.

"Fo' de lan's sake!" he kept murmuring over and over.

Then Tom's gaze was turned toward the inventor. He stood at his lever as immovable and unmoved as a figure carved from stone. A half smile appeared frozen on his face.

They were very close to the black, wet sides of the steamer now. Tom, looking upward, could see figures scurrying about her lofty decks. They were gesticulating and pointing, and doubtless shouting as they saw this little fury of the lakes bearing down on them. Even in that thrilling moment Tom found himself wondering how it would feel if the Huron was engaged in war and the vessel they were rushing upon was one of a fleet of Uncle Sam's enemies.

Try as he could to repress it, a shout would force itself to his lips. So close were they to the steamer now, that one could plainly see the rivets in her tall, black sides. Tom even noted her name, North Star.

"Mr. Ironsides!" he cried, springing to the inventor's side.

Had the man gone suddenly mad? Did he wish to hurtle them all into destruction?

The professor, too, sprang forward.

"Great heavens!" he cried, "we will be dashed into eternity. I implore! I order! I insist——"

Swish-h-h-h-h-h-h-h-h-h-h!

A strange sound suddenly filled Tom's ears. The daylight was blotted out. The lights flashed up all through the diving boat. The floor tilted at a sharp angle, throwing the occupants of the conning tower once more into a confused mass.

While they were still in a swirl of confusion, the inventor's lean, claw-like hand shoved over a lever. The roaring noise ceased. The Huron resumed an even keel.

"We—we took a dive under that vessel?" gasped Tom, in a voice of incredulity.

"We did," smiled Obadiah. "You must forgive me for scaring you, but sometimes I feel like a schoolboy. I love to play tricks. I guess you thought we were going to smash into that ship's side."

"Well, I didn't see how it could be avoided," said Tom, rather shamefacedly, for the inventor's eyes were fixed on him with a whimsical smile.

"My dear sir!" expostulated the professor, "I—we—of course, you must understand I was in no sense alarmed——"

"Not any more than that time on the Omoo, when poor Jack and Sandy played ghosts with green faces," grinned Tom, sotto voce.

"Ah done heard dem golden harps playin' jes' as plain!" confessed Rosewater frankly.

"Well, as you see, the Huron is under perfect control at all times," said Mr. Ironsides. "We have dived under the keel of that craft, and I imagine, caused those on board her to indulge in a considerable amount of speculation as to whether they really saw us or not."

He laughed in a care-free, boyish fashion that he had, and which made it difficult for his companions to realize that their shipmate was one of the brainiest men in the United States. They had merely had a specimen of Mr. Ironsides' way of amusing himself.

"Shall we come to the surface?" he asked presently.

"I don't think it would be a bad idea," said the professor, in a rather relieved tone, "this darkness is—is——"

"It kind of gets on one's nerves," said Tom, finishing the sentence for him.

"Oh, you'd soon get over that," said Mr. Ironsides easily. "Of course, it's natural, though. I'll never forget the first time I went down in this craft. I was alone. I didn't want any one else to risk his life. For a time I was in a state of delightful uncertainty as to whether she'd rise again or not."

"It must have been mighty unpleasant," volunteered Tom.

"It was, I can assure you. But then I had the pleasure of feeling that my boat had really dived, whether or not she would come up again," said Mr. Ironsides, in as matter-of-fact a tone as could be imagined.

"Queer sort of pleasure," thought Tom, glancing at the young inventor curiously.

"I think it's the—the loneliness under the water that impresses one," he said aloud, looking out of the conning tower window. Ahead lay a black void. It was the same all about them. The Huron was encompassed by solid walls of water. It was a weird, uncanny sensation, and all of the party seemed to fall under its spell.

"Ready!" cried the inventor sharply, pulling another lever.

It was as well he had uttered the warning, for at that instant the prow of the Huron inclined upward sharply. The same swishing sound that had filled the submarine when they sank made itself noticed.

"It is the compressed air forcing the water out of the submergence tanks," explained Mr. Ironsides. "What you heard when we sank was the noise of their being filled by an emergency device, especially designed for a quick dive."

"Which, in that case, was necessary," remarked Tom somewhat grimly.

All at once, while the submarine was still tilted sharply on her upward course to the surface of the lake, a bell above Mr. Ironsides' head tinkled sharply.

Coming, as it did, in the midst of their acute mental tension, it jangled Tom's nerves sharply.

"It's the sensograph!" exclaimed Mr. Ironsides, with what Tom fancied was one sharp flash of alarm.

"What does it mean?" began Tom. "Are we——"

"It means that we are in dangerous proximity to a submerged wreck!" was the disquieting reply.

The words had hardly left Mr. Ironsides' lips before there was a jarring crash.

The submarine quivered throughout her structure. Her swift motion ceased as if she had been dealt a mortal blow.

As if he had been the victim of some ugly nightmare, Tom felt the diving boat begin to sink. She seemed to be lying over on her side—helpless beneath the waters of the lake.

CHAPTER XVI.

IN THE GRASP OF CALAMITY.

Once before Tom had faced death in the depths. This was when he had battled with the octopus in the wreck of a sunken treasure ship in the tropic seas. But then he had been fighting for his uncle's life, and his success had been dependent on his own efforts.

Imprisoned in the stricken submarine, however, the experience was far different, and vastly more alarming. In the first place, none of them could do anything but await the result of Mr. Ironsides' hasty efforts to right his craft, and the inaction was as hard to endure as the actual peril.

From a speaking tube close to the helmsman's ear a voice trickled up from the depths of the diving vessel's interior. It was old Sam calling up from the engine room.

"What's happened, sir?"

Tom could hear the words as plainly as one can sometimes hear a voice coming over the phone even when one is at some distance from the receiver.

"We've struck something, Sam. I don't know what yet," shouted back the inventor, in a steady, even tone. "Better stand right by your engines. Are they working all right?"

"Splendidly, sir," came back the response. "Any other orders, sir?"

"No, that's all for the present, Sam."

Tom felt ashamed of himself. With this feeling came a new one of self-possession, taking the place of the deadly, almost nauseating fear he had experienced an instant before. If the inventor and his assistant could be calm, so could he, Tom Dacre, master his terror.

He stepped up to Mr. Ironsides, making his way with some difficulty, for the submarine was still wallowing over on her side. But, in obedience to Mr. Ironsides' previously telegraphed orders, she was backing slowly away from the hidden obstruction she had collided with.

"Any orders, Mr. Ironsides?"

The inventor glanced round. His face was lined and rigid, but he showed no trace of his deep anxiety other than this. For all the excitement he betrayed, he might have had ice water instead of blood in his veins.

"Ah! It's you, Tom Dacre? Yes, I have some orders. I wish you would go forward into the torpedo chamber and see if we are taking in any water. I'm rather afraid that a plate may have been sprung."

"And if there is a leak?" asked the professor, who, like Tom, had succeeded in mastering his first alarm.

"If there is," was the placid response, "we must stop it; or," he paused for an instant, "or remain down here."

Even Tom blanched anew at these words. Death in a watery tomb was staring them in the face. But he hastened off on his errand. Anything was better than helpless inaction at such a moment.

Fortunately, the lights had not been extinguished in the crash, and the metal-walled torpedo room was illuminated brilliantly with a flood of electric light. To his great relief, Tom, after a careful examination, was able to report that there were no apparent injuries to the Huron, forward. She seemed to be as tight as a bottle, thanks, doubtless, to her double "skin."

"I hardly thought that she would be seriously damaged," said the inventor calmly. "See, she is coming up on an even keel, too, now. I guess we'll start a little investigation right here."

"Ain't we a-gwine up to de top?" whined Rosewater, who was cowering in a corner.

"Not yet," was the calm response, "I want to find out just what it was we struck."

"Good heavens! The man must be made of his own metal," Tom heard the professor gasp under his breath. But, excepting Rosewater, none of them remonstrated.

While they watched him curiously, Mr. Ironsides shoved the engine room signal lever over to "Ahead, slow."

The backward motion of the diving craft ceased. She began to creep forward.

All at once, Mr. Ironsides pressed a button at his elbow. A sharp click responded, and the water in front of the Huron became illuminated with a flood of brilliant, blinding white light. Tom could see fish dart off out of the lane of light like coveys of partridges. Some, fascinated seemingly by the rays, flocked about the conning tower, dashing themselves against its thick lenses like moths round a lamp chimney.

"That searchlight is the most powerful I could devise," said Mr. Ironsides, in a tone of quiet satisfaction. "I guess it's doing its work all right."

"I guess so," agreed Tom enthusiastically. The boy had quite forgotten his alarm in the sensation of watching the wonderful illumination of the waters.

"Keep a sharp lookout," urged the inventor. "I am anxious to see what it was that we struck."

Tom found himself wondering over the necessity for this, but he held his peace, and busied himself in gazing out of the conning tower windows. For some time nothing appeared in the field of light but masses of water. The liquid looked greenish and almost solid—like thick glass—in the powerful rays of the searchlight.

"It must be somewhere hereabout," commented Mr. Ironsides, after several minutes had gone by without revealing anything.

He began to move the searchlight about, controlling its shiftings by a worm-gear and wheel.

All at once Tom spied something, a dark, indefinite-looking mass, off to the right.

"Look! Look there, Mr. Ironsides!" he cried.

"Jove, boy, you have sharp eyes!" commented the inventor, turning his gaze in the direction Tom had indicated.

"Is that what we struck, sir, do you think?" asked the boy.

"We'll go closer and see what it is. Oh, don't be afraid, professor; there's no danger this time," he added, for the man of science had begun to protest against what he termed "sheer recklessness."

Slowly, very slowly, the Huron crawled through the lower waters.

It speedily became evident that the indefinite object that Tom had seen, looming up vast and shadow-like in the searchlight's path, was the sunken wreck of some sort of a vessel. As they drew closer, they could make out the masts and see the big black hull.

"Humph!" commented Mr. Ironsides. "It's lucky the sensograph gave warning when it did, or we might not be in as good shape as we are now."

Under the inventor's handling, the Huron was moved slowly round the sunken craft. She had been lumber laden, evidently, for part of her cargo could be seen still lashed to her decks.

As they rounded her stern, Tom saw a name in white paint inscribed on it.

"Mary J. Jennings—Rockport."

"Why, I recall reading about the loss of the Jennings!" he cried. "It was last winter, in a bitter storm, that she was lost with all hands. At least, they supposed she was lost, for she never reappeared. I suppose her load of lumber had kept her from sinking altogether, though she was water-logged enough to be submerged."

"I guess that's it," agreed the inventor. "That craft," he went on solemnly, "is the grave of a crew of brave men."

"And might have proved the cause of our being doomed to a tomb on the bottom of the lake," struck in Tom. He shook his fist at the sodden wreck as the searchlight illumined her outlines.

The inventor turned to him with a smile.

"Makes you feel mad, doesn't it, Tom?" he asked.

"Well, not mad, exactly. I hardly know how to describe it," faltered Tom.

"How would you like to have revenge on her, to put her out of the way for good?" asked the inventor.

"How do you mean?" asked the lad, rather incredulously.

"I mean that if she should ever come to the surface she is a real menace to navigation. As it is, she almost caused the loss of the Huron. I should like to remove her forever."

An inkling of his meaning dawned on Tom.

"You mean that you want to torpedo her?" he demanded.

"Yes. It would give me a whole lot of satisfaction. What do you say?"

"That would certainly be a revenge of a twentieth century character," spoke the professor.

"By George!" exclaimed the inventor, with more animation than he had shown since our party had encountered him, "we'll do it. Here, Jeff, you take the wheel. Keep her circling round the wreck. Tom Dacre, I've a job for you in the torpedo room."

"A job for me?" echoed Tom wonderingly.

"Yes. You are appointed assistant annihilator of the submarine Huron."

CHAPTER XVII.

CAPTAIN RANGLER RE-APPEARS.

Leaving Jeff at the wheel, with strict orders not to meddle with anything, the inventor preceded Tom into the torpedo room. He produced a bunch of keys and unlocked a metal closet, high up on one wall of the place. From this he produced a globe, about ten inches in diameter and a dull black in color.

From the top of it a small key projected. While Tom watched with fascinated interest, the inventor went into the extreme forward part of the torpedo room, which, of course, was right up in the bow of the Huron.

A cylindrical tube—not unlike the breech of a rapid fire gun—projected into the place, and the inventor rapidly adjusted several small wheels and valves. Then he opened the rear of the tube and motioned to Tom.

"We're about ready now," he said. "You might bring that torpedo from the rack."

He indicated a cage-like basket, in which he had placed the metal globe after taking it from the closet.

"The torpedo?" said Tom, looking about him.

Not unnaturally the boy was looking for one of the cylindrical, cigar-shaped implements of war, which he had always associated with the word "torpedo."

Mr. Ironsides smiled slightly.

"I mean that metal globe," he said.

"What! Is that a torpedo?" demanded Tom incredulously.

"Yes, and one twenty times more powerful than the Whitehead type in use in our navy to-day."

"But it looks more like a bomb than a torpedo. Where is its driving machinery? How does it go through the water?"

"You'll see all that in a minute. For many reasons, the ordinary type of torpedo is not much used for submarine work. So I had to go to work and think out a torpedo of novel design as well as a boat. That globe is the result. Thank you," as Tom handed it to him, using every precaution against dropping it, as you may be sure.

"Now, then," said Mr. Ironsides, drawing a brass tube out of the breech of the firing cylinder, "you see, I put this globe in this tube—this way."

As he spoke, he thrust the metal globe into the brass tube, which it fitted snugly. The key-like projection remained sticking out of the end of the tube, however.

"If the Huron was used for surface work," went on Mr. Ironsides, "she could, if her officers wished, handle and fire ordinary torpedoes. But to overcome the pressure at this depth, terrific driving force is necessary. To furnish this, I use compressed air superheated, coupled with an explosive gas, generated in the muzzle of the torpedo tube as the bomb passes through. Do you follow me?"

It is doubtful if Tom did. But, at all events, he grasped the main idea of the inventor's discourse.

"Now, then," went on Mr. Ironsides, "I am going to start the mechanism which combines the two elements contained in this globe into a death-dealing combination."

He twisted the key, and a clicking sound resulted like that which emanates from a mechanical toy when it is being wound up.

"We're all ready now," he declared finally. "The only thing left to do is to 'ram home,' as they say in the navy."

So saying, the inventor thrust the brass tube, containing the projectile, into the breech of the firing tube, in much the same manner as the brass cartridge is thrust into the breech of a naval gun.

Then he closed the breech and locked its mechanism with a sharp snap.

"Now, Tom Dacre, boy," he exclaimed, an exulting note in his voice, "we are ready for our up-to-date act of justice on yonder sunken wreck."

Tom caught the infection of his enthusiasm.

"In a few moments she will be blown to bits?" he questioned, marveling even while he spoke.

"Yes. If all goes well, that schooner will have ceased to exist at precisely," the inventor drew out his watch, "in precisely four minutes. I'm going to the conning tower. The firing lever and appliances are there. Do you wish to accompany me, or will you remain here?"

"I guess I'll go with you," rejoined Tom.

"Then hurry. It would be awkward if those gases in the bomb became uncontrollable before we had fired it from the Huron's side."

They found Jeff at the wheel, slowly circling the water-logged wreck, according to instructions. Tom glanced at the bulk of the half-sunken schooner with a kind of pity. In his mind she was dissolved into fragments already.

Mr. Ironsides, without a trace of haste in his manner, took the wheel from the Trulliber lad. He so manipulated the submarine that, within a few moments, she was at some distance from the sunken wreck, hovering like a hawk that is about to strike. Tom hastily described to the others his experiences in the torpedo room.

They listened with keen interest. Their discussion of what was to come was broken in upon by the inventor's voice.

"I guess we are about ready now," he said.

Tom fixed his gaze on the man. He stood at the wheel motionless. Without a very keen imagination it was easy to picture him as a kind of fate about to hurtle a deadly thunderbolt.

"Now!"

The word came suddenly, and was followed by an almost imperceptible movement of the inventor's hand to a polished quadrant. A lever moved swiftly across the shining sector.

Almost instantly a shock made the submarine quiver. Tom knew that the tremendous forces that were to drive the bomb through the water had been released.

"Watch the wreck, please. If all goes well, you'll see something worth watching."

It was Mr. Ironsides speaking again. The faces of the visitors to the submarine were speedily glued against the observation lenses.

Tom saw a white streak cut through the water, leaving a train of bubbles in its wake. Then came a jar, and he felt a queer sensation on his ear drums, but that was all. All except that right ahead of them the black bulk of the wreck seemed suddenly to dissolve into nothingness. It had been and—was not!

Obadiah Ironsides' twentieth century revenge on the object that had so nearly caused disaster to his wonderful diving craft was complete.

"It's like magic!" gasped Tom, hardly able to believe that the solid timbers had been entirely obliterated before his very eyes.

"It is magic," breathed the professor.

"Now, I think we may as well arise and note the effects of our shot," said Mr. Ironsides, in his usual matter-of-fact voice. Now that the shot had been fired, and had been successful, the slight flush of anxiety on his pale face had vanished, leaving it as icicle-like as ever.

Up they shot, at what seemed lightning speed.

They were on the surface almost before they realized it. The welcome light shone in through the conning tower lenses, and the sunlight sparkled on the dripping back of Mr. Ironsides' strange sea monster.

"Let us open the conning tower hatch and go out on deck," suggested the inventor, after notifying old Sam in the engine room to switch his power from the electrical motors to gasolene.

They were nothing loath to do so. Although the time had seemed short, they had been below the surface for some hours, and the air was beginning to feel stuffy.

Tom inhaled with delight the fresh atmosphere, and the cool breeze that swept over the lake. He took it in by great lungfulls. The others did the same.

A glance about at the surface of the water showed the terrible havoc the bomb had wrought on the submerged wreck. The surface of the lake in their vicinity was strewn with beams and bits of timber. The wreck had literally been blown into a thousand pieces.

All at once, Tom's attention was caught by something close at hand. At first he thought it was an ordinary bit of wreckage. He leaned over the chain-rail the better to view it. Suddenly, however, he recoiled with a cry of horror. The object, lazily bobbing on the surface, had suddenly turned upward.

Then Tom saw that what had attracted his attention was the body of a man, undoubtedly one of the unfortunates who had been caught below decks when the schooner sank. And now the bomb had set him free from his tomb.

Even as Tom's horrified gaze rested for an instant on the grisly object, it vanished, leaving a widening circle of wavelets about it. Instinctively, Tom bared his head.

"I am saying farewell to a brave man," he said, as the others hastened to his side to inquire the reason of his sudden cry.

As there was no reason for lingering in the vicinity, the Huron, soon after, was put under full speed, and under her powerful engines she passed through the straits before sundown.

Supper was eaten, and Tom once more emerged on deck before the after-glow had faded. He gazed about him abstractedly. The lad was sorely troubled. Now that the excitement of the novel trip on the submarine had worn off, thoughts of his brother's plight and of Sandy's misfortune came back to him with redoubled force.

All at once—to the westward—a dark cloud appeared against the glowing sky.

"Smoke!" decided Tom. "Some craft coming this way."

For half an hour or more he watched till the outlines of a tug appeared from the direction in which he had first noticed the column of vapor.

Tom watched her without especial interest for a time, and then the blood began rushing through his pulses in leaps and bounds. He bounded to his feet and rushed to the conning tower. Thrusting his head over the hatchway, he gave a shout that electrified those below.

"Captain Rangler's tug is dead ahead and coming toward us!" he announced.

CHAPTER XVIII.

A MAN OF QUEER MANNERS.

At just about the same moment that the submarine encountered the sunken wreck, Jack Dacre, as well as Sandy MacTavish, was sucked into the black and treacherous slime of the slough. As our readers will recall, we left both lads in about as bad a situation as could be imagined.

Jack's cries were beginning to grow feeble, when aid appeared from an unsuspected quarter. From the margin of woods surrounding the swamp, there suddenly emerged the figure of a rough-looking man. He carried a gun and was accompanied by two savage looking dogs.

"Hullo! What's the trouble here?" he demanded in an amazed voice, as his gaze lighted on the two struggling lads. By this time the marsh had engulfed Sandy to the arm-pits. Jack was in almost as bad a fix.

"For goodness' sake, help us out of this," implored Jack. "We can't hold out much longer."

The man grunted, but seemed in no hurry to aid them.

"You must be a fine pair of young fools," was his comment. "Any one could see that there was quicksands in thar'."

"Who are you, and how did you come here?" he demanded roughly the next minute.

"We'll tell you all that when you get us out of this," ejaculated Sandy. "Mon! mon, will ye stand glowerin' there, while we are sinking deeper all the time?"

"Serves you right for blundering in there," was the astonishingly heartless response.

The man turned away, whistling to his two dogs, and vanished in the woods. But, after all, the action was not as cold-blooded as it appeared. Instead of leaving the two lads to their fate, as it first had appeared, the man presently returned with some sticks of young timber.

He thrust these toward the two immersed lads, grumbling, the while, savagely to himself. Neither Jack nor Sandy was, fortunately, too weak to take advantage of this grudging aid. It was well that this was so, for the man didn't appear anxious to help them further. But when both lads had caught on to the sticks, with a firm hold he did bestir himself to pull and tug, and soon, what with their own struggles and the man's efforts, the two lads were out of the marsh. They were pitiful objects, indeed, as they stood on its marge. Black mud clung to them, like a sort of sticky paste. Their faces were strained and white. Perspiration poured in rivulets down them. Besides, they were shaky and unnerved from their ordeal.

But their appearance in no wise seemed to move the pity of the man. He laughed grimly as his two dogs flew furiously at the two newly rescued lads.

"Lucky for you that them dogs didn't come on you when I wasn't by," he said, filling and lighting a short pipe, and seating himself on a log. "They'd have torn you limb from limb. Now, then," he demanded, with a sudden accession of fierceness, "who are you, anyhow? What are you doing on Castle Rock Island?"

"We've escaped——" began Sandy, when something warned him that it would be as well to disguise the true state of affairs from this gruff, unsympathetic sort of individual.

"Oh, ho! You've escaped, have you?" said the man, with an ugly leer. "And from what, pray?"

"From our boat. It was wrecked," volunteered Jack, with a sufficient statement of facts to cover the case. "But is this Castle Rock Island, really?"

"Of course, it is. Didn't I say so?"

Jack and Sandy exchanged astonished glances. So they had reached their destination, after all. But in what an astonishing way!

"Well," glowered the man, "is that all?"

"I guess so," responded Jack, "except that we fell into the marsh while looking for a place where we could get some food and rest. We've got money to pay for it," he added, thinking that the man might live nearby.

The fellow's eyes lit up at the mention of money.

"How much you got?" he questioned.

Jack displayed a roll of bills of comfortable proportions, for, as we know, the rascals on the tug had not thought it worth while to search their young prisoners.

The man's eyes dwelt on the money as if in speculation. He remained silent for a few seconds. Then he spoke in his gruff way.

"Come with me," he said, rising to his feet.

"Do you think he is all right?" whispered Sandy, as they prepared to follow.

"Frankly, I don't. But we must trust to luck. We've got to get something to eat, and I imagine he is some sort of a woodsman. He may have a good heart, even if his manners are gruff."

"A-weel," sighed Sandy, "I don't trust him a bit more than you do. But we maun find some place to rest, I'm thinking."

So they plunged into the woods after the man, who was looking back at them interrogatively. He strode along at some distance ahead. Ever and anon he would glance back to see if they were following. But he didn't speak.

They must have progressed thus for half an hour or more, when they suddenly emerged upon the shore from the trail they had hitherto been following. Before them spread the waters of the lake in all their vast solitude. Behind them lay the forest, and to their right towered a great mass of rocks and craggy cliffs, that were wild and primeval looking. But it was none of these things that transfixed the gaze of the two lads, and, tired as they were, filled their eyes with eager interest.

What captured their attention, to the exclusion of every other feature of the landscape, was a tower of rough outline, about forty feet or more in height, which stood directly in front of them on a little rocky promontory.

It was built of stone, which had, apparently, been taken from the cliffs adjoining. A rough flight of steps, also of stone, encircled it outside, reaching to the summit. The ruins of what had once been a light-house lantern on the top proclaimed the uses to which the tower had been put before it fell into ruin. About its base creepers grew luxuriantly; but they had been cleared away at one point, where a door, heavily studded with iron rivets, was observable.

"Do you live here?" inquired Jack, as the man walked up to the door with the confident air of possession.

"I do—yes. If you want anything to eat, you had better come inside."

Such was the gruff rejoinder of the man, as he inserted a key in the door and swung it open. Evidently, the outside stairs were not used by him. A closer view, in fact, showed that they were tottering, like the rest of the structure, and probably were not safe.

Sandy and Jack exchanged swift glances, as the man undid the door. Was this some trap that they were being enticed into? But, hungry and faint as they were, the lads were not in a critical mood. While they still hesitated, the man turned round.

"Well," he said grumpily, "are you comin' in, or ain't you? I can't wait here all night."

"We'll be right with you," said Jack with alacrity, stepping forward and resolutely putting his fears behind him, "I hope dinner's ready," he added by way of a small pleasantry.

But in return for his smiling remark, the man only mumbled something, and whistled to his dogs. Then, followed by the two lads, he entered the ancient door, which groaned on its hinges, with what Jack's excited mind interpreted as a note of warning. But it was too late to turn back now.

As the man swung the door to behind them and locked it, Jack felt that they were committed to the adventure, come what might.

CHAPTER XIX.

WITHIN THE TOWER.

Inside they found themselves in a circular room. The floor was bare, but fairly clean. Facing the door was a rusty stove, with an iron pot and a kettle smoking and steaming on it, in a way that gave promise of a speedy meal. For the rest, there was a rough table and several chairs set about in disorder. In one corner was a tall cupboard.

Their host approached this receptacle after he had set down his gun, and produced three tin cups, three tin plates and the accompanying knives and forks. Likewise, he set out bread, and salt and pepper casters. This done, he took off the pot from the stove, and with a ladle, dished out upon each dish a fairly generous portion of a kind of stew.

"There's water in that bucket in the corner," he volunteered, sitting down and beginning to shovel in his food with scant courtesy.

The lads filled their tin cups at the receptacle mentioned, and then fell to on the food, with what appetites may be imagined. Whatever their hardships had been, they had not interfered with their abilities as trenchermen.

While they ate, the man eyed them curiously, but he said nothing. In fact, once or twice, when Jack looked up and caught the fellow furtively eying them, the other looked hastily away, as if he had been caught in some mean act. In this manner the meal was eaten, and when it had been despatched the man spoke.

"You said something about paying," he grunted in his mumbling tones.

"Certainly," rejoined Jack; "how much do we owe you?"

"Well, now, considering that I have to use powder and shot for everything I get, and that you two lads have made a terrible hole in my larder, I don't think a dollar apiece is too much."

The man looked up, as if he half-expected the lads to refuse to pay this exorbitant sum. But Jack readily paid him, only remarking that they felt so much better that he would willingly have paid even more.

"And noo," began Sandy, "the question arises, what comes next?"

"Yes, how are we to reach some point where we can communicate with our friends?" asked Jack.

The man hesitated. Then, as if an idea had suddenly occurred to him, he spoke:

"There's a small steamer that rounds the islands regularly. She'll touch in here this evening. Tell you what you do—give me another dollar each, and I'll let you sleep upstairs in a room I have till it's time for you to catch the boat."

This answer seemed straightforward enough. At all events, Jack and Sandy felt so sleepy after their meal that they were ready to accept it without much hesitancy. Two more dollars were passed over, and then the man conducted them to a stairway at one side of the room. He mounted it, mumbling to himself all the while; but by this time the lads had come to the conclusion that the fellow was a sort of harmless eccentric, and did not pay much attention to his manner.

Up and up they climbed, circling the tower several times, it seemed, till they arrived at a small door opening off the staircase. The man opened this, and showed them into a room. It contained a rough bed and some scanty furniture. It had one window high up in the wall—too high for the lads to see out; but it was well-lighted and ventilated—the latter for the excellent reason that the window was always open. It was not glazed.

"There, I reckon you can make out there, all right," said the man.

As he prepared to leave the room, Jack reminded him of his promise to awaken them in time for the inter-island boat, in case they overslept.

"Don't worry," said the man, with more of a friendly air than he had yet assumed, "I'll take good care of you."

There was a sinister intonation in the way that he said this last which did not escape Jack's quick ear. But it was too late to worry now. If the man meant them harm, they were fairly in his power; and the only thing to do was not to let him see that they suspected him.

Removing their shoes, coats and waistcoats, the lads flung themselves down on the bed. Sandy, after mumbling a few sleepy comments on the strange place in which they found themselves, dropped off into profound slumber. Jack, in a pleasant sort of half-waking, half-sleeping doze, remained alert some minutes longer.

It was just as he was dropping off to sleep in good earnest that he thought he heard a queer noise at the door.

"It sounds as if some one had locked it on the outside," he muttered drowsily.

He started to arouse himself to investigate; but in the very act of summoning his drowsy faculties the boy's weariness overcame him. His tired limbs mutinied, his eyes closed, and he was off to dreamland as soundly as Sandy.