CHAPTER I. WHICH INTRODUCES OUR CHARACTERS AND THE SUBMARINE BOAT. Readestown, U. S. A., is a smart, flourishing little city upon a certain river which runs down to the sea, and it owes its founding and success to a family of wonderful inventors by the name of Reade. Frank Reade, Jr., the latest representative of the wonderful family, is a young man whose name is a household word the world over. He is the inventor of so many wonderful machines, for traveling in the air, under water, or anywhere else that the people of this great country were by no means greatly surprised at the announcement which one day went forth that the young inventor had perfected a new submarine boat, and in conjunction with a famous scientist was about to make a trip of exploration through the great Atlantic valley, which is under the sea. But they were interested if not surprised, and everybody was agog to know just when the expedition was to start. And all the people would await with great interest the outcome of the new and wonderful enterprise. Some predicted a calamity. It did not seem an easy matter to remain under water in a submarine boat for days and weeks, living upon artificial air and deprived of heaven’s light. But those who knew Frank Reade, Jr., had no doubt of his success. Particularly Prof. Von Bulow, the distinguished German scientist, who was to accompany Frank. This gentleman was very enthusiastic over the enterprise. He had dined with the young inventor in the cabin of the Dart, and had spent some hours in its trial under the surface of the river at Readestown. Therefore he was able to vouch for its efficiency and practicability. “I will take my chances,” he said, with a broad smile; “it will be no danger, I am very well assured.” The professor was especially anxious to study phenomena of the deep sea, and also the topography of the Atlantic Valley. All that was known of this mighty depression had been gained by deep sea soundings. Certain specimens of its bottom had been brought up by the lead. Various forms of animal life unknown to science had thus been discovered. But it was only guess work after all. Here, however, was a mighty opportunity to explore the ocean depths literally. In his great machine shops at Readestown, Frank had constructed the Dart. Every detail of its draughting and plans had been made by him in his secret model room. The machinists had done the work under his directions. In this manner the famous Dart was built. In shape it was not unlike the model of a pleasure yacht. There was a hull of thinly rolled but strongest steel. It was provided with dead eye windows of convenient number, water-tight and provided with slides. Above the hull was an outer deck provided with a guard rail which extended from stem to stern. Then above this deck was a cylindrical body with windows, of toughest plate glass, and doors in its ends. This was the cabin of the Dart, and it was divided into various compartments, which we will describe separately. In the middle of the cabin cylinder was a section of straight plate glass, so that the travelers sitting in the cabin were in constant view of the sea and its depths. Two masts rose fore and aft, and forward was a pilot-house where were the nautical apparatus and the steering gear, as well as the electric keyboard. For the propelling and lighting power of the Dart was furnished by electricity. Over the pilot-house was a most powerful electric searchlight. With this the bottom of the sea was made as plain as broad daylight, and was a mighty advantage. This is a meager description of the exterior of the Dart. The interior was magnificent beyond description. Frank had spared no expense in the fittings of the Dart, so that it was a veritable floating palace. The first cabin was richly furnished; the second cabin contained half a dozen fine staterooms. Beyond was the dining cabin, and then one came to the cook’s galley. Below decks, however, was the region of wonder and mystery. Here was all the wonderful and secret electrical machinery. Also the mighty automatic reservoirs by which the Dart was made to sink or rise at the will of the inventor. Forward was the chemical room, where in tanks was stored the compressed air, and also manufactured the same, with which the travelers were enabled to live beneath the surface of the ocean. Tubes went to every part of the cabin with this chemical product, and there was also an apparatus for consuming the vitiated air or gases. So that the air supply was always of the purest and best. Truly, the submarine Dart was a wonderful product of the inventor’s skill and ingenuity. Few, however, could appreciate it more fully than Prof. Von Bulow, who was fairly captivated with it. “It is a most wonderful thing,” he declared earnestly. “There is nothing in the kaiser’s land like it. You Americans are a wonderful people.” Frank was besieged with hundreds of applications for various purposes. Hosts of cranks applied for permission to accompany him. Some letters were beseeching, some threatening. One mildly insane woman wanted him to recover her son from the clutches of an octopus. Another asked that her husband might be brought back from the realm of old Neptune. But one applicant, at least, received consideration at Frank’s hands. He was a bearded sea captain, who told of the sinking of a pirate ship in a certain latitude with a vast treasure aboard. Here was a reasonable request, and Frank agreed to look for it. He took the bearings as given him by Captain Bell and said: “If possible I will find your sunken treasure. It may be, though, that time and the action of the tides have buried it so deep that I will not be able to reclaim it.” “I think not, sir,” said Captain Bell, eagerly. “It occurred, to be sure, forty years ago, but I think it is upon a reef not so very far beneath the surface.” Then Captain Bell went on to tell the story of the lost treasure. “I was quite a young man, then,” he said, “and was in the navy, as captain of a small sloop-of-war, called the Utopia. “Reports were coming in thick and fast of Captain Longboots, the pirate, who was so venturesome as to penetrate within one hundred miles of New York City in quest of a prize. “His ship, the Vestal Virgin, odd name for a pirate, was a fast sailer, and most of our war vessels could not keep in sight of her. “The pirate captain’s real name nobody could learn, but he was called Captain Longboots from the immensely long boots which he wore at all times. “But there was a suspicion in the navy department that he was really Isaac Van Dorn, once a captain in the service, and who had become disgruntled on account of a reprimand from a superior officer, and sought revenge upon the Government by starting out upon a tour of piracy. “Well, the Secretary of the Navy selected me and the Utopia to go in chase of the pirate. “Just at this time there came a report that an English steamer had been overhauled, and a million dollars in American gold had been seized by Longboots. “This settled the question. I was at once in receipt of sailing orders. “We left Annapolis one bright day, and sailing down the river, soon reached the open sea. “I had nothing to guide me but my nose. I followed it, however, for five hundred miles out to sea, and in the direction of Bermuda. “My plan was not to attempt to overhaul the Vestal Virgin. “I caused the Utopia to be rigged up like a merchant vessel. The gunports were closed and painted, and everything warlike about her was concealed. “Then I lay in the track of foreign-going vessels for weeks. My game worked. “It was some while before the pirate showed up; but she did eventually, and bore down upon us. “We made a show of running away, but she overhauled us like the wind. We did not have any trouble in letting her overtake us. “She sent some hot shot across our bows and we hove to. We were all ready for a fight. “Behind our high bulwarks crouched our men all ready for boarding. The false ports could be knocked out in ten seconds, and an instant broadside given from ten guns. “Nearer drew the Vestal Virgin. When she was a hundred yards distant, Longboots himself appeared in the shrouds. I spoke to one of my men: “‘Pick that villain off; let it be a signal for the broadside.’ “The order went along. Every man was ready. The gunner I had spoken to was a dead shot. “He fired, and Longboots dropped to the deck. Then open flew our ports and we sent solid shot into her hull. “She went down instantly. We had just time to get away from the vortex. Only one of her men was saved. “He made a clean breast of all, and declared that there was fully a million and a half in treasure aboard the Vestal Virgin. We had some thoughts then of recovering it. “But the soundings were too deep. No diver could live at that depth. We turned our course homeward. “And this is how it comes that the Vestal Virgin and her mighty treasure lies at the bottom of the sea.” Frank had been deeply interested at this recital. As Captain Bell finished he said: “I will make every endeavor, be sure, to recover that treasure. If I do, a fair share of it is yours.” Captain Bell gripped Frank’s hand. “I hope you will succeed,” he said; “and I feel quite sure you will.” Then Frank showed the captain over the submarine boat. He was delighted. “Upon my word, skipper,” he cried. “I’m an old sea dog and reckoned never to leave the surface of the ocean while in life. But I’d give a good deal to take this v’yage with you.” Frank was thoughtful a moment. He had taken a great liking to Captain Bell. “Do you mean that?” he asked. “With all my heart,” replied the old skipper, eagerly. “And if I don’t work and earn my passage you can put me off at the first port. Shall I go with you?” “Yes,” replied Frank; “you may.” CHAPTER II. THE EXPEDITION STARTS. This made the captain a happy man. “I’ll go and tell my wife at once,” he cried. “When do we sail?” “In one week from to-day.” “Good! I’ll report for duty then. Good luck till I see you again.” And the bluff captain was gone. Frank had two valuable men in his employ who traveled with him the world over. One was a negro, black as coal and jolly as could be. He rejoiced in the name of Pomp. The other was an Irishman, as full of native wit as a nut is of meat. His name was Barney O’Shea. Barney and Pomp were almost as famous as their young master and his inventions. They were the warmest of friends, and yet to hear them talk one would have felt assured they were enemies, for they were fond of railing at each other in a mock serious way. If Barney could play a practical joke upon his colored colleague he was happy, and Pomp seldom failed to retaliate in kind. Really they were the life of any exploring expedition, and for faithful service and devotion Frank could hardly have replaced them. They were anticipating the submarine voyage with a great deal of relish. “Golly,” cried Pomp; “I’se jes’ gwine to be tickled to deff to git to trabeling once mo’. I’se been home jes’ long enough, dis chile hab.” “Begorra, I’m wid yez, naygur!” cried Barney, bluntly. “It ain’t often we two uns agree, but be me sowl it’s united we sthand on that, sor.” “It am yo’ fault, I’ish, dat we don’ agree on everyfing!” declared Pomp, solemnly. “How do yez make that out?” “Yo’ don’ take mah wo’d fo’ a cent.” “Begorra, I’d hate to take yoursilf for that!” cried Barney, jocularly. “Shure I’d kape the cint.” Pomp scratched his woolly head. “Yo’ fink dat am bery funny.” “It’s not so funny as yez are.” “Yah, yah! am dat so?” “Didn’t I tell yez?” “Don’ yo’ git too gay wif me, chile. Dar am jes’ sand enough in mah wool fo’ to take de conceit out ob yo’.” “Bejabers, I’d go soak me head if I had sand in me hair,” said Barney, contemptuously; “take a shampoo, naygur!” “Yo’ am gettin’ sassy!” “On me worrud, I’m the only gintleman on yer list av acquaintances, an’ bekase I tell ye yer faults it proves me your frind.” Pomp scratched his head again. Then he looked at Barney and Barney looked at him. Barney began to edge away and Pomp lowered his head. “Look out fo’ yo’sef!” “Kape away from me, yez black ape!” But Pomp made a dive for the Celt. Barney let out with both his fists. They struck the darky’s head like battering rams. But they might as well have been directed toward a stone post. They glanced off that hard surface with the greatest of ease. Then Pomp’s head took Barney in the ribs. The next moment the Celt was counting stars in a bewildering firmament. He recovered just in time to grapple with his assailant. Then followed a genuine old-fashioned wrestling match. The two jokers rolled over and over upon the ground, pounding and thumping each other until one or the other had enough. Frank Reade, Jr., at once began to put the Dart in readiness for her great trip. Stores enough to last for a period of many months were placed aboard. Every part of her mechanism was carefully examined and tested to make sure that it was all right. Three days before the appointed time for sailing Captain Bell and Prof. Von Bulow appeared in town. They had arranged their affairs and were all in readiness for the expedition. They were certainly the envied ones of a large coterie. To take a trip across the Atlantic Valley in a submarine boat was certainly no light privilege. The captain particularly was in excellent spirits. “We are sure to reclaim that million and a half of treasure,” he declared, confidently. “It will be a big haul.” Von Bulow was promising a hundred different scientific societies specimens from the bed of the sea. “It will be a big benefit to the world of science,” he declared. “Ah, my soul! I will make great fame!” Barney and Pomp were anticipating exciting adventures in the deep sea, and Frank was reflecting upon the success of his new invention. Thus all had some cherished plan or motive in view. While the people of the country waited expectantly for the day of departure, it came at last. The Dart rested in a large tank in the yard of the machine works. From this tank a wide and deep canal was locked twice into the river. The party went aboard exactly at noon. Frank had the moorings cast off, and the Dart entered the canal. She glided through the locks gracefully and appeared in the river. And now for the first time she was exposed to the view of the people. The banks were thronged, and a great cheer went up as the new invention appeared. Bands played and cannon fired salutes. The party of explorers remained on deck long enough to return the salutes. Then a cry went up from the crowd. “Sink her! Sink her!” Frank knew that the people wanted a demonstration of the Dart’s capabilities. And he was willing to gratify them. He went into the pilot-house and the others went into the cabin. Then Frank pulled the steel lever which opened the reservoir. Water displaced the compressed air. Gracefully the Dart settled beneath the surface. Frank pressed a key and the electric lights blazed forth. The bed of the river was as plainly revealed as in daylight. For some while the Dart remained under the surface. Then it reappeared once more. The people were satisfied. The air was rent with cheers, and it was a triumphal parting which the submarine travelers received. Then the Dart glided away upon her course. Down the river with great speed she went. In due course of time she reached the open sea. The great trip through the Atlantic Valley was begun. For some days the Dart stood straight out to sea. Frank had made his course by the best of the submarine charts. He had now reached what he believed to be the entrance to the great valley under the sea. This was at the beginning of the southeast branch of the Gulf Stream. The submarine course would extend to within a few hundred miles of the Azores and then southerly, finally terminating at Bermuda. All this vast space was a mighty depression, known as the Great Valley. It has ever been a mystery to sailors and geographers from early times. Ancient chroniclers speak of an old-time continent and nation of people due west from the coast of Spain. As this continent does not exist to-day, it has been believed that it has sunk by some mighty process of nature many centuries ago. There are plenty of mythical tales of the sunken world and its wonders now lying under the sea. That the keels of our modern ocean greyhounds may daily pass over a sunken world is by no means improbable. Perhaps some day our own American continent may be relegated to a like fate. Let us hope that it will not come in our day. But it can be seen that Prof. Von Bulow looked forward with immense interest to the possible revelations in store. He had already pictured out cities and palaces, valleys and towns, forests and mountains under the sea. Not until he was assured that he was at the entrance to the great Atlantic Valley did Frank make preparations to descend. Then he made deep soundings, and becoming satisfied that he had reached the right point, the descent was made. The travelers took a final walk on deck, and then the doors were hermetically closed. Frank stepped into the pilot-house and pulled the reservoir valve. Instantly the Dart began to settle. Down she went with a graceful plunge. There was a peculiar jolting, jarring motion as she displaced the water. Then the electric lights flashed forth. Those on board beheld a wonderful sight. About them were the wonders of the sea. The bed of the ocean lay below, replete with aquatic life and growth. The electric glare extended many hundred feet in all directions. The Dart rested upon a small coral reef. The whitest of sand lay spread between the clumps of sea plants. There were grottoes and cavernous depths, miniature forests and castles of coral. In all were specimens of curious submarine life. Shell and other fish were everywhere. Huge species of ray, sunfish, shark and octopus roved about. The lights of the submarine boat seemed to draw them from all quarters. They came with fish curiosity up to the very windows of the boat, and seemed anxious to effect an entrance. This gave Prof. Von Bulow a much desired opportunity. He studied them to his heart’s content while the Dart remained on the reef. Captain Bell was also interested, and he and the professor became quite warm friends. Frank was busy regulating the machinery of the boat preparatory to diving into the great valley. In the submarine outfit was a number of diving suits of a pattern invented by Frank Reade, Jr. They consisted of a helmet, with a reservoir of ample dimensions fastened upon the back, and which was supplied with air by a chemical generator, while the bad air escaped by a valve in the top of the helmet. Upon the helmet was also placed a small electric lamp, but of great power of penetration. With heavy weights upon their feet, the wearers of this ingenious diving suit, having not to depend upon cord or life line, could remain at great depths and for a long period under the sea. It was proposed with Frank’s permission to use the diving suits that Captain Bell and the professor should don these suits and take a walk upon the sandy bed of the sea. “Certainly you can take the suits,” said Frank. “Only be careful of sharks.” “We will do that,” replied the captain. “I hardly think we need fear them with a good ax and knife.” Barney brought up the suits from the lower cabin and he and Pomp helped the two explorers to don them. Soon they were equipped and ready for the departure from the interior of the submarine boat. Both were eager and excited. CHAPTER III. ADVENTURES OF THE CAPTAIN AND THE PROFESSOR. Frank had some misgivings as to the policy of allowing these two inexperienced men to leave the Dart. So he caused Barney to place one of the suits within easy reach, so that in case of need he could easily don it and go to their aid. The two divers were all equipped, and all that was now necessary was for them to leave the Dart. This did not seem such a very easy thing to do. It would seem that to open a door or window for exit would be to instantly flood the interior of the boat. And so it would have. Frank had provided for this contingency, however, in the construction of the boat. A door opened from the cabin into a vestibule. Entering this the divers closed a door behind them and opened a valve which flooded the vestibule. Then they opened the outer doors with impunity and walked out on the deck. The return to the cabin was effected by entering the vestibule, closing the outer door and turning another valve which expelled the water by pneumatic pressure. Then they could safely enter the cabin. This was only one of the simplest of the many wonderful devices with which the Dart was provided. Once out on deck the divers experienced queer sensations for a moment. The pressure of the water for a time made them blind and dizzy. But they soon recovered and went over the Dart’s rail. They stood upon the bed of the ocean. It was a wonderful reflection. About were all the wonders heretofore denied the sight of man. Truly this was no ordinary experience. Forgetting himself, Bell attempted to speak to the professor. But the latter, of course, could not hear him. It was only by putting their helmets together that they were able to converse, and then with difficulty. They walked in the pathway of light from the boat. Looking back through the plate glass windows they could easily see the interior of the Dart. Both divers now began to enjoy themselves looking for specimens and exploring the submarine recesses. While Captain Bell was not a scientist, he was nevertheless pleased to render aid to the professor. Thus they kept on, gradually working further and further away from the submarine boat, until finally they reached the shadows which indicated the limit of the searchlight. Beyond all was pitchy blackness, for it was into the unknown depths of the great Atlantic Valley. Captain Bell put his helmet close to the professor’s and shouted: “Is it safe to go further?” “I think not,” replied Von Bulow. “We had better turn back.” But even as he said this he saw a queer specimen of fish slowly make its way into a coral cave near. “I must have that fellow,” he exclaimed, excitedly. “He is a new variety.” Without a thought of possible peril the professor darted in pursuit. Into the cavern he went. Bell stood and looked after him somewhat doubtfully. The old sea captain did not reckon but that Von Bulow was amply capable of taking care of himself, though really he regarded it as a trifle risky. The professor turned an angle of the cavern and was out of sight. The captain was a trifle weary with the exertion of climbing over the slippery piles of seaweed, and did not follow. He waited what seemed to him an interminable time. The professor did not come out of the cave. “Whew!” exclaimed the old sea captain, finally. “Dash my timbers, but I’m afraid he’s come to harm.” The more the captain pondered over the matter the deeper became his alarm. At length he decided to go in quest of his companion. He entered the cave and turned its angle just as the professor had done. Only a strange sense of intuition and a swift downward glance saved the captain’s life at that moment. He saw a deep and yawning abyss at his feet. For a moment he was overcome with grisly horror. He saw how easy it was for any one to unwittingly walk into that death hole. The light on his helmet partly displaced the gloom. But unless one looked down he would be sure to walk over the edge. That poor Von Bulow had done this there was no manner of reason to doubt. For a moment the captain stood transfixed. It was a terrible reality. What was to be done? It was some time before his nerves were steady enough to enable him to advance to the verge and peer over. But all down below was as black as Erebus. Forgetting himself, the captain tried to shout down into the abyss, but no answer came back, of course. Was Von Bulow forever lost? Was he buried beneath that coral reef, never to be seen again by human eyes? It was terrible! The captain’s brain began to work in devising some scheme for rescue, but it was in vain. He leaned far over the verge. Ha! was he dreaming, or was his eyesight true? Was not that a star of light far down there in the darkness? He believed it was. Doubtless it was the electric light upon Von Bulow’s helmet. But it was visible only a brief moment. Then it disappeared. The captain leaned yet further over the verge. Unfortunate move! Suddenly and without warning he lost his balance! Over the edge like a flash he went. Down into the abyss he sank; but it was not like falling through air. He alighted without any serious jar upon a bed of sand fully fifty feet below. He was at the bottom of the pit. The helmet light made visible objects near at hand. The captain recovered himself and looked about him. He saw white walls of coral and long cavernous passages leading in all directions. He was really in the heart of the coral reef. But he looked in vain for the professor. Von Bulow was not in sight. Was the professor dead? Had he become the victim of some submarine monster? The captain did not believe this. He proceeded to examine critically the bed of sand upon which he rested. There were the marks of footprints and the part impress of a man’s form. Von Bulow had fallen here. But he had also arisen, for the footprints here led into one of the passages. Filled with excitement, Bell proceeded to follow them. He was soon deep in the passage. And as he pressed on he saw a flickering light in the far distance. Suddenly the light ceased to move and remained stationary. Bell knew what it meant full well. The professor had turned and saw the captain following him. He was waiting for him. Quickly Bell overtook his colleague. The two divers fairly embraced in their joy. “I thought you were lost,” cried Bell. “I gave you up for dead.” “Then you fell into the same trap!” “Yes.” “My soul! How terrible our position is!” “Yes; it is bad.” “We must get out of here or die. Do you believe it possible to do so?” Captain Bell shrugged his shoulders. “We have only to try,” he said. “You are right.” “Shall we not follow this passage to the end? It may yet have an upward trend.” “You are right.” So they set forth down the passage under the coral reef. It seemed ages that they wandered on. There seemed no end to the passage. They were rapidly growing exhausted. At length Bell sank panting down upon a shelf of coral. “My soul!” he gasped. “I fear we are forever lost!” “Perhaps we had better return,” shouted Von Bulow. “We seem to be going deeper into the center of the earth.” But Captain Bell shook his head. “No,” he replied. “We cannot go back now. Our only hope is in going on.” So they staggered on again. But unobserved by them all the while the passage had been trending upward. As good fortune had it they had chosen the only safe and sure way out of the reef. Suddenly a dazzling light shone forth far ahead. “The Dart!” gasped Bell, joyfully. “We are saved!” It was truly the submarine boat. A few moments later they came out of the cavern, and were in plain view of the boat. They saw that the cave from which they emerged was only one of many which they had passed in their way from the boat some hours before. For they had been a long time absent from the Dart. Indeed, so long that Frank had become greatly worried, and had even donned his diving suit preparatory to going out to search for them. But just as the young inventor was about to go forth Barney cried: “Dere they are, Misther Frank!” Sure enough, the two divers were seen rapidly approaching the Dart. “Mercy!” exclaimed Frank, with a deep breath. “I am thankful for that. I had given them up for lost.” But even as he spoke he gave a great shout of alarm. Behind the two men there suddenly appeared a giant form. Frank saw that it was an octopus. Its long tentacles were ready to grasp them. It was a moment of fearful peril. Barney rushed to the observation window, screaming and waving his arms wildly. “Look out wid yez!” he shouted. “Shure, don’t yez see phwat’s behind yez?” Of course the two men did not hear these words, but they saw Barney’s actions and at once understood. They turned quickly, but it was too late. Von Bulow was instantly encircled by a tentacle. Captain Bell was just quick enough to avoid one. Frank Reade, Jr., saw that only the most desperate of action would save the scientist then. He sprang down into the vestibule with an ax in his hand. He had already closed down his helmet. He closed the door and flooded the vestibule. CHAPTER IV. IN THE ATLANTIC VALLEY. It was but a moment’s work for Frank to spring out on deck. Then he reached the sands below. Swinging the ax aloft, he rushed to Von Bulow’s assistance. He was not a moment too soon. Captain Bell had already attacked the monster. But Frank’s arrival saved the day. The young inventor swung the ax over his head and made a slashing blow at the monster’s head. It struck the enormous hawk-like beak and slashed off part of it. Quick as thought Frank repeated the blow. The monster writhed and made an effort to encircle Frank with another of its long arms. But the young inventor this time buried the ax to the head in the creature’s cat-like eye. This was the telling stroke. It penetrated the brain, and the octopus straightened in death throes. The battle was over. Barney and Pomp were watching the contest from one of the windows of the submarine boat. “Golly!” cried Pomp, cutting a pigeon wing. “Marse, Frank am done fixed dat critter for suah!” “Bejabers! when Misther Frank goes for to do a thing, he does it up in illegant shape!” declared Barney. “Yo’ am right, I’ish.” Prof. Von Bulow was extricated from the embrace of the octopus, and all returned to the boat. The adventures detailed by the captain and the professor were thrilling, indeed, and the others listened to them with interest. “It will be hardly safe to repeat that sort of thing!” said Frank; “the next time you gentlemen go out on an exploring expedition, I think that one of us who is more experienced in that sort of thing had better go with you.” “We shall not demur,” said Captain Bell, with a laugh. “I am afraid we are hardly qualified to face such risks.” After Frank had concluded his inspection of the machinery it was decided to at once continue the journey into the Atlantic Valley. So the machinery was put in motion, and the boat dove into the dark depths to be lost from the world for many months. The searchlight showed all about for a great distance as plain as day. But the boat passed over immense depths where all was darkness far below, and into which the boat could not descend on account of the enormous pressure. There was an automatic gauge on the pilot-house which registered this pressure and determined the depth to which it was safe to go. Below this the boat would be crushed like an egg shell. But as a general thing the Dart was enabled to keep in view of the bed of the ocean. This was now much diversified by hills and even mountains. There were innumerable caves, many of which were of enormous depth. In fact the Dart once sailed into one of these nearly half a mile before it was discovered by the voyagers that they were in a cave. Then, of course, it was in order to turn about and sail out, but before this was done a thrilling experience was had. Prof. Von Bulow was greatly interested in this wonder of the ocean depths—this submarine cave of the great Atlantic Valley. “There is nothing like it on top of the earth,” he declared. “I would like very much to examine its structure, which has the appearance of being quartz.” “Quartz!” exclaimed Captain Bell. “Yes.” “Not of the gold-bearing species?” “It is not impossible.” At once everybody was interested, even Frank himself. “You shall have your desire, professor,” he declared. Accordingly the Dart was brought to a stop and rested upon the bed of the cavern. The diving suits were brought out. It was decided that Frank and Barney should accompany the professor this time. Pomp and Captain Bell were to remain on board the Dart. The searchlight illumined the walls of the cavern in beautiful style. They were of great beauty. Overhead they were crystal-like in their character, and the declaration by the professor that they were of quartz did not by any means seem far fetched. The diving suits were donned, and the three explorers, well armed with ax and knife, left the Dart. The floor of the cavern was tolerably smooth. They easily made their way over it, and Von Bulow was soon at work. It did not take the professor long to get to work with his hammer. In a very short time he had chipped off enough of the quartz to reveal a curious yellow vein which seemed to extend an indefinite distance into the ledge. The professor appeared excited. Seeing this, Frank put his helmet close to his and shouted: “Well, Von Bulow, what do you make of it?” “Gold!” shouted the excited scientist. Frank was astounded. “Gold?” he repeated. “Yes.” “A submarine gold mine?” “Exactly.” Barney had also placed his helmet close to the others and heard this. “Bejabers!” he cried; “then it’s a moighty fortune we’ve found.” “I think it would assay heavily,” declared the professor; “if it was only on the surface, now, what it would be worth!” Frank saw the point. “But it is of no value here?” The professor nodded. “Exactly. How could a stamp mill be operated down here at this depth? It would cost more than the ore is worth to mine it.” “But perhaps we might find some nuggets hereabouts.” “No,” replied Von Bulow, decidedly. “It is not likely. It is probable that all the gold hereabouts is secreted in these quartz walls. It is only a question of getting it out.” “Which is impracticable.” “Exactly.” The thought that they were really in a mighty submarine gold mine was a most thrilling one. However, the professor had other points to gain now, so he left the gold vein and began some further explorations of the submarine cave. This extended an unknown distance into the bowels of the earth. The party did not venture to go far beyond the rays of the searchlight. There would be great danger of getting lost in the labyrinth of passages, and certainly there would be no pleasure in this. In view of the experiences of the professor and the captain, this was an issue to be avoided. However, they carried the exploration as far as seemed safe. This was a number of hundred yards from the submarine boat, and they began to think of returning when Barney stumbled upon an exciting adventure. Suddenly he espied a curious-looking round body lying close to the wall of the cavern, and extending out of sight into dark depths. The Celt was nothing if not curious. It looked like a strange formation of some aquatic growth, and unthinkingly Barney jabbed the point of his knife into it. The result was thrilling. The round body instantly contracted and then rebounded, throwing Barney backward with great force. And then out of the darkness of a cavern passage came a great flat head with horrid jaws. It was a species of sea serpent. The huge coils were thrashing the water of the cavern furiously, and the divers stood for a moment paralyzed with terror. The sea serpent was undoubtedly the habitue of the ocean cavern. He seemed also disposed to resent this invasion upon his chosen territory. The situation was critical. Frank saw at once that quick action must be made, or serious consequences would be the result. The young inventor, therefore, at once signaled the others to follow him, and began a retreat for the Dart. But the sea serpent was following, and was certain to overtake them. Already Frank felt the creature right behind him. And he turned to see those horrid jaws wide open above him. If they should strike him, doubtless it would be a death blow. So Frank quickly dodged and made a blow at the monster with his ax. It missed the mark, and the next moment the creature’s jaws were right over Frank. It was a horrible moment. Only the young inventor’s rare presence of mind saved him then. Quick as a flash he drove the ax into the serpent’s jaws and down its throat. Then he was hurled half senseless to the floor of the cavern. The ax disappeared down the serpent’s throat instantly. It was undoubtedly not averse to a diet of the sort, for it did not seem to affect his snakeship. But Frank was for the nonce safe. He had been hurled into a small recess in the wall of the cavern, and the serpent passed on. It was now after Barney and Von Bulow. But Frank’s fracas with it had given them a chance to get a good lead. They were now quite near the Dart, and were enabled to reach it in time. On to the deck and into the vestibule they dashed. The next moment the submarine boat received a terrific shock. The sea serpent struck it full force, and for a moment it seemed as if the fate of the Dart was sealed. But, as good luck had it, the steel work of the boat was harder than the serpent’s head. It resisted the shock. But Pomp and Captain Bell were thrown across the cabin. They had seen the serpent coming in pursuit of Von Bulow and Barney, and it had given them a thrill. “Golly!” screamed Pomp. “De debbil am after dem. Shuah nuff dat big snake will swallow us all up!” “Great heavens!” gasped Captain Bell, “the creature means to strike us.” “Look out fo’ yo’sef!” Into the vestibule darted Barney and Von Bulow. Then came the shock. But the Dart was not demolished. On the contrary the sea serpent seemed for a moment stunned. Then it was that Barney recovered his senses. He remembered that Frank had been left behind, and with an inward cry darted out of the vestibule. “Bejabers! it’s not mesilf as will go off and lave Misther Frank in such a heap av trouble,” he muttered. “I’ll niver cum back widout him!” CHAPTER V. THE SUNKEN WRECK. Frank had recovered quickly and emerged from his place of safety just in time to see the sea serpent strike the Dart. The young inventor had seen and realized the awful risk which this entailed, and muttered: “My goodness! We are all lost!” But the result of the serpent’s attack was indeed gratifying. And he also saw what he believed to be his opportunity. Drawing his knife he darted after the monster. It was lying half dormant on the floor of the cavern from the shock which it had received. But as Frank ran toward the Dart he saw Barney coming toward him. Barney fairly embraced his young master, as he cried, placing his helmet close to Frank’s: “Och hone, Misther Frank, an’ I thought it was kilt entoirely ye was!” “I had a close call,” replied Frank. “But where is the captain?” “Shure, he’s safe aboard, sor.” “Good! Now, Barney, we’ve got to kill that monster some way.” The Celt looked at the dormant serpent a moment, and then swung his ax aloft, saying: “Shure, an’ it’s wid yez I am, Misther Frank. Say the worrud an’ I’ll go up on this side of him an’ cut his head off.” “Let me take your ax,” said Frank, resolutely. Barney complied and drew his knife. Frank made a motion for him to follow. The serpent was quickly recovering from his stupor. Frank saw that there was no time to lose, and at once made a bold attack. When near the monster’s head he rushed forward. The serpent reared its horrible jaws and seemed about to strike Frank; but the young inventor struck first. The keen blade of the ax swung around and took the serpent full in the jaw. It was a telling blow. It fairly sliced away a portion of the monster’s jaw and filled the water with blood. Again Frank swung the ax aloft. Barney attacked the body of the serpent, trying to cut the huge coil in two. The attack was a success. Again Frank’s ax struck the serpent full in the neck, cutting a huge gash. Then the maddened reptile made a savage blow at Frank. It just missed him by a narrow margin and proved the end of the struggle. Frank saw his opportunity, and gave the reptile a blow which almost severed its head from its body. The monster’s huge coils went writhing and twisting into the depths of the cavern. The struggle was over. Frank and Barney, somewhat exhausted by the struggle, climbed aboard the Dart. They were joyfully welcomed by the others, and mutual congratulations were exchanged over the success of the fight. “Begorra, I thought shure it was the ind av Misther Frank!” cried Barney. “Shure, it wud have been a sorry day for the loikes av us!” “Golly, if I had jes’ been out dere I would hab been happy!” declared Pomp. “I was jes’ itching fo’ to git a crack at dat ar big rapscallion of a snake.” “Well, as for me,” said Von Bulow, with a laugh, “I quite distinguished myself by running away. But I was never cut out for a fighting man anyway.” “And I stayed at home,” rejoined Bell. “Frank, you and Barney are the heroes.” All were intensely hungry, and Pomp served up a steaming repast. There was lovely steak from the swordfish, crabs on toast, fresh and nice, and many other saline delicacies, which were easily procured in the sea. The explorers regaled themselves sumptuously, and then all turned in for a sleep. Frank had decided to spend some hours longer in the cavern. When they awoke six hours later, Frank went into the pilot-house and started the Dart for the mouth of the immense ocean cavern. In due time this was reached, and soon they were not so very far from the spot where Captain Bell’s treasure ship had sunk. All were now eagerly on the lookout for the wreck. The searchlight’s rays were sent in every direction through the ocean depths. Suddenly Captain Bell, who was forward on the lookout, shouted: “Wreck ahoy!” The announcement went through the boat with startling force. Everybody was at once on the qui vive. And now dead ahead was seen a huge black mass looming up through the water. It was a sunken ship. Of course all believed it to be the Vestal Virgin. But the wreck was so covered with silt and seaweed that its character could not well be identified. The submarine boat sailed around it twice, then Frank allowed it to come to a rest on the ocean floor of white sand. “What do you make of it, skipper?” asked Captain Bell, as Frank came out of the pilot-house. “I hardly know,” replied Frank. “It looks to me, though, like a ship of more modern build than the pirate vessel.” “It’s mighty hard to tell for the seaweed over it.” “Yes.” “But I think it’s the Virgin!” “You do?” “Yes; she’s in about the right location. It must be her.” “I hope so.” Preparations were now made to go out and inspect the submarine wreck. This fell to the lot of Frank, Von Bulow and the captain. Barney and Pomp remained behind. They were very quickly equipped for the expedition; armed with axes and saws and such tools as were deemed necessary, they left the Dart. It was an easy matter to climb over the kelp-strewn rocks until the sunken vessel was reached. It lay half upon its side, and its port rail was nearly on a level with a drift of hard, white sand. This made it an easy matter for the explorers to reach the deck. They simply walked up the sandy slope and climbed over the rail. In the glare of the electric light, the deck was seen to be in a state of wild disorder. Rotting spars and heaps of debris covered it from stem to stern. It was easy to see that the vessel had passed through a terrible experience at sea. The storm which sent it to the bottom must have been a fearful one. It required no further examination to satisfy the party that this was not the treasure ship. Captain Bell saw at once that it was not the Vestal Virgin, and putting his helmet close to Frank’s, shouted: “This is not the ship.” “It looks like a merchantman,” replied Frank. “It is.” “Moreover, it was never sent to the bottom by shotted guns. It went down in a fearful storm.” “Without a doubt. But the Virgin must have gone down in this vicinity.” “Yes.” “We will probably find her not far from here.” “Well,” said Frank, doubtfully, “is it worth while to explore this hulk? She probably did not carry money.” Von Bulow, however, was in favor of exploring the sunken merchantman. “For curiosity, if nothing else,” he explained. “I’m quite anxious.” “Very well,” agreed Frank. “It shall be so.” With which the young inventor crossed the deck. He reached the companionway which led into the cabin. This was closed, but a blow with an ax forced it in. The stairs that led downward into the cabin were crumbling with decay. Frank led the way down. The light upon his helmet was sufficiently bright to reveal objects below quite plainly. Von Bulow and the captain followed. All stood at the foot of the companion ladder. The cabin was in a fearful state of dissolution. The elegant furnishings were all rotten and in shreds, and even the cabin table was shredded by sea worms. But the explorers did not pause here long. They passed through and into the forward cabin. Here was the long mess table, and upon it were dishes and eating utensils, just as the men had been served, which was the last ever eaten on board the ship. Frank took up one of the plates. In the china was the imperishable mark usually placed upon all ships’ ware with the name: “Ship Tempest, Baltimore.” This was all that could be learned of the identity of the vessel or of its mission. Yet it was reasonable to suppose that she was a merchantman. Little more of interest was found aboard her. A few skeletons of the members of the crew and some corroded coins. This was all of value. The party retraced their steps to the deck. Frank was the first to spring up out of the companionway, and as he did so he was given a startling shock. Until now the wreck had been flooded with a brilliant light from the searchlight of the Dart. But this was no longer so. All was the darkness of the ocean depths about. Nothing could be seen beyond the slight radius made by the light on their helmets. The Dart had left them. What did it mean? For a moment the explorers were appalled with the most startling realization. Left at the bottom of the ocean, upon a sunken wreck. There was no possible way of ever reaching the surface. That is unless the Dart should return from where it had gone, and why it should have left them in this manner was a mystery. Frank knew that Barney and Pomp would not leave the vicinity for any light reason. “Something has happened!” he exclaimed in dismay. “The Dart has met with a mishap.” “My goodness!” exclaimed Von Bulow; “then we are lost!” “What could have happened?” asked Bell in horror. Their three helmets were close together at this moment. The only logical conclusion that Frank could arrive at was that the Dart had received some fearful shock and had gone to the surface. If this was the case it would perhaps shortly return. But the one horrifying thought which oppressed Frank was that possibly Barney and Pomp would lose their bearings and would not be able to find the three divers. CHAPTER VI. IMPRISONED IN A WRECK. In this case their fate was certainly sealed. Lost at the bottom of the sea; lost in the great Atlantic Valley. What an awful thing to consider! Frank knew, however, that they could stay death for a number of days. There was enough material in the generators to keep them alive that length of time. But if the Dart should not return in that interval they were truly lost. It was some while before any one ventured to speak again. Then Bell said, despairingly: “How far is it to the land?” “Fully a thousand miles in any direction,” replied Frank. “We can hardly walk then?” “No, I think not.” “Is there any possibility of the Dart returning?” “We can only hope that it will. Our only way is to wait here.” Von Bulow sat down upon the rail of the sunken vessel, Captain Bell paced the deck, Frank tried to pierce the gloom of the ocean depths for some sign of the Dart. And now, at this critical moment, a new and thrilling peril confronted the trio. Suddenly Frank saw a long, sinuous body flash through the water some fifty feet distant. He saw its outlines and its shining silver scales, and at once recognized a deadly foe. “A swordfish,” he muttered. Then he made a motion of warning to the others. They leaped out of the way, but were not a moment too soon. The huge fish, with its keen lance of sharpest bone, had made a dive for them. As it dodged past him Frank struck at it with his ax. The blow nearly severed one of the fins of the huge fish and a cloud of blood spurted into the water. But instantly the swordfish turned and came again to the attack. And now the critical moment had come. In those depths the swordfish was a fearful foe. If he should strike any one of the party with his lance, it would mean instant death. The monster seemed savagely aggressive as well. On it came again at fearful speed and accuracy straight at Frank Reade, Jr. The young inventor waited until the fish had almost reached him; then quick as a flash he dodged under it. And as he did so he threw up his right hand, clutching the knife with the point upward. By the sheerest of good luck the knife struck the fish and ripped his abdomen open to a great length. This settled the contest. The fish’s entrails dropped out, and the monster lay upon the deck of the ship dead. But this did not by any means dispose of the fearful peril which surrounded the divers. A literal school of swordfish were seen bearing down upon the party. It was useless to think of coping with them in such numbers. It was necessary to make quick and definite action. Frank sprang toward the companionway and motioned the others to follow him. They were not a moment too soon in this, as the fish came about in a cloud, hovering over the hatchway, and trying to force an entrance. But the divers were safe for the nonce in their retreat, and it was deemed best to remain there until the fish should disperse. But they seemed in no disposition to do this. Indeed, they remained above the deck, besieging the party quite effectually. The position was by no means a pleasant one. “Well,” cried Frank, as they put their helmets together, “I don’t see but that we are obliged to stay here whether we will or no.” “That’s so,” agreed Bill. “I wish the beastly critters would clear out.” Von Bulow was getting depressed. “The most of us better make our peace with the Almighty,” he declared. “We shall never get out of this scrape.” And there the three divers were held imprisoned in the cabin of the sunken ship, while a rescue seemed indeed a hopeless thing. But let us return to the Dart, and learn the fate which had overtaken it. Barney and Pomp were faithful and reliable servants. They were well familiar with the workings of the craft, and no ordinary accident would have troubled them long. But the accident which befell the Dart was not an ordinary one. Left aboard the boat, Barney and Pomp fell to skylarking. They were as full of fun as a nut is of meat. After jibing each other for a while they got to wrestling. “Hi, dar, chile, don’ yo’ put yo’ han’s on me!” cried Pomp, as Barney closed with him. “If yo’ does yo’ shuah nuff get de wuss ob it!” “Begorra, I’ll have the best av yez or me name’s not O’Shea!” cried Barney, hilariously. “Shure, I’ll niver be downed by a naygur!” “Clar away dar, I’ish!” But Barney was in for a ruction. “Whurroo!” he cried. “Here’s at yez!” Then they went madly whirling about the cabin in a lively tussle. It was hard to say which had the best of it. It was certainly a lively contest, and honors were even until suddenly Barney tripped over a rug. Then down went Pomp’s head, and plump into the Celt’s stomach it went. Barney went down, and Pomp was on top of him. The darky hung to his man like a leech. “Ki, dar! Yo’ am not in it wif dis chile!” he shrieked. “Yo’ am beat, I’ish!” “Divil a bit!” screeched Barney. “I’ll have yez off yet!” But just at that moment something happened which terminated the friendly wrestle almost instantly. There was a sudden severe shock, and the two jokers were thrown half-way across the cabin. When they picked themselves up, both were dumbfounded to hear the electrical machinery buzzing furiously. The submarine boat was swaying madly, and they had hard work to keep their feet, so violent was the motion. “Massy Lordy!” gasped Pomp; “wha’ am de mattah, chile?” “Matther!” ejaculated Barney. “Shure, the divil is carrying us away.” “I don’ fink dat am jes’ a fac’!” Barney sprang into the pilot-house instantly. He tried to press the lever which shut off the speed current. It would not answer to his touch. The submarine boat was shooting like lightning through the water. How far they had run from the sunken wreck neither knew, but it was very likely several miles. Here was a fearful situation. The two looked at each other aghast. What was to be done? The risk was something awful. The Dart was not far from the bottom of the ocean. At any moment she might strike some projecting hillock or eminence. It would mean utter destruction. Barney was pale as a ghost, and Pomp’s eyes bulged like moons. “Golly, fo’ massy sakes!” wailed the affrighted darky. “We am done fo’!” “Begorra, it’s kilt we’ll be if we don’t sthop the boat!” “An’ Marse Frank am lef’ all alone behind dar. Mebbe we kain’t nebber find him no mo’.” It was a horrible thought which oppressed the two jokers. But they were not the kind to remain inactive. Something must be done. Barney realized this. If the machinery was out of order the cause must be found and remedied. He rushed down into the engine-room and began to examine it. At once he saw the trouble. One of the heavy dynamos had become unshelved, and the lever wire was twisted and broken. Barney instantly shouted: “Come down here, naygur!” Pomp at once responded. With their united effort the dynamo was relocated and the lever wire connected. Then Barney operated the lever and it worked all right. The boat came to a stop. And not a moment too soon. Just ahead was a mighty eminence, and the Dart would certainly have struck it at full speed. “Golly!” gasped Pomp. “Dat am jes’ de berry closest call I ebber knowed ob!” “Begorra, a miss is as good as a mile,” said Barney. “Shure, we must go back now.” “Does yo’ fink yo’ kin fin’ yo’ way back, chile?” This was quite a problem. The Dart had undoubtedly run many miles, and to find the way back, as no note had been taken of their course was all a matter of chance. “But fo’ de Lor’ sakes, whatebber struck the boat in de fust place?” asked Pomp. “Howebber did it git started?” “I’ll show yez,” said Barney. He led the way to the pilot-house. Upon the vessel’s bow was a huge specimen of fish. It was a swordfish. The monster had dashed against the vessel with such force that a part of the bulwark had been carried away, and the swordfish had been caught in the wire hamper of the rail. It was certainly the shock given the vessel by the huge fish which had dislocated the dynamo and disarranged the mechanism of the Dart. As the heavy body of the fish sagged the boat, Barney donned a diving suit, and going out, cut away the incumbrance. The damage was repaired as much as possible, and then the boat was turned about. The return course, as nearly as could be guessed, was taken. The Dart sailed on rapidly. But though miles were passed, not sign of the sunken wreck was seen. Barney doubled back on his course and sailed for miles. Hours passed and the anxious searchers were unrewarded. “Massy sakes!” gasped Pomp. “I done fear dat Marse Frank am done fo’ dis time. I jes’ fink he nebber come back no mo’!” “Begorra, he was a good, kind masther!” “Dat am so, honey!” “On me worrud, I’ll niver give up looking for him if I have to sail through these seas fer all me loife!” “I’m wid yo’, I’ish!” So they kept sailing about at random for a full day. Then Barney suddenly cried: “Look yonder, naygur. Phwat do yez call that?” It was a little star of light twinkling through the gloom. There was but one explanation for its presence in those depths. It was an electric light, and doubtless came from the helmet lamp of one of the lost divers. Barney at once shaped the course of the Dart for it. The two jokers anxiously awaited the result. CHAPTER VII. A CLOSE CALL. The three divers in the cabin of the sunken derelict were in by no means a cheerful or agreeable frame of mind. The swordfish would yet persist in hovering above the deck. They were apparently hoping that their would-be victims would come out. But they did not. Hours passed slowly by. Captain Bell sank down upon the rotting stairs and went to sleep. But Frank and the professor kept unwearying vigil. They were waiting for the welcome glare of the Dart’s searchlight. Should that appear they would know that they were saved. But it did not come. The Dart was far from the spot at the moment. The likelihood was not strong for an immediate return. But the state of siege was suddenly raised in an unexpected manner. There is a small fish which is a habitue of the ocean depths called the torpedo. It has all the power and characteristics of a powerful electrical battery, and can give a stunning shock to anybody which comes in contact with it. All manner of fishes, large and small, even the monster whale, stand in dread of the torpedo. It was a school of these odd fish which now proved the means of raising the siege. They came down upon the school of swordfish with demoralizing effects. In less time than it takes to tell it, every swordfish was far from the spot, and speeding for their lives to other depths. Prof. Von Bulow saw the torpedoes coming and realized their nature. He put his helmet against Frank’s and shouted: “Look out! If those little fiends hit one of us they will knock the breath away.” Frank aroused Captain Bell. Some loose planks were brought and the hatch covered. This was to prevent the torpedoes from entering; but the latter did not seem at all inclined to attack the divers. They were of a species which will not attack unless attacked. This was fortunate for our friends. Neither did they remain long in the vicinity. In fact they departed very soon, and with a breath of relief Frank opened the hatch and climbed out on deck. It was at this moment that Barney caught sight of the distant star of light, and this was Frank’s helmet. At almost the same moment Frank saw the distant glare of the searchlight on the Dart. A great cry burst from him. He rushed to the companionway and made excited signs to the others. At once they rushed upon deck. The excitement was intense. There was no doubt but that it was the Dart returning. All waited eagerly, hoping and praying that it would not pass them by. And as fortune had it, it did not. Presently its course seemed changed somewhat and it apparently bore down upon the hulk. “We are saved!” cried Frank. “Heaven has not deserted us,” said Von Bulow, joyously. And indeed it was a narrow escape for the trio of divers. There had been almost the moral certainty that they were doomed to find a grave at the bottom of the sea. But this danger had passed and rescue was at hand. Their joy cannot be fully imagined or expressed. Captain Bell was so overcome by it that he danced a hornpipe on the rotten deck of the old hulk. Just as soon as the hulk came within the radius of the searchlight’s glare Barney had seen it. It was the work of but a very few moments for the Celt to change the course of the Dart. He bore down for the hulk with all speed. As they drew nearer the trio of divers were seen upon the deck. “Glory fo’ goodness!” cried Pomp, wildly; “we am jes’ gwine fo’ to sabe dose chilluns, I’ish, shuah’s yo’ bo’n!” Barney whistled a jig, and Pomp stood on his head with glee. “We shall live!” cried Captain Bell. “We will find the Virgin next, and then the great treasure is ours.” Soon the Dart came to a stop not fifty yards away. The party left the wreck and quickly clambered aboard the submarine boat. Once more safely in the cabin of the Dart, joy and mutual congratulations followed. Barney told his story, and Frank spoke warm words of commendation of his course. “You did just right,” he declared; “the Dart is all right. I can see nothing the matter with her.” “Let us continue the search for the pirate ship,” said Captain Bell. “Which we will do!” declared Frank. But first refreshments were had, and all took a few hours of sleep. Much recuperated, the journey was continued some while later. The Dart went on an exploring tour now in the vicinity of the sunken wreck. In all directions the search for the Virgin was made. And fortune favored the searchers. Suddenly the wreck was sighted. It had been difficult to find for the fact that the shifting sands had nearly covered the hull. The many years which had elapsed had caused the masts and rigging to fall and partly decay. But Captain Bell declared it his confident belief that it was the Virgin. “I know her by the outline of her bow and her figurehead,” he declared; “that’s the old pirate, for sure!” At once the Dart anchored near the treasure ship. All became excitement, for it was indeed a thrilling thing to think that they were about to investigate a wreck with perhaps millions in gold aboard. As before, Barney and Pomp were to remain on board the Dart, while the others did the exploring. Soon they were all in readiness, and Frank led the way. They left the Dart and crossed the intervening distance without any mishap. Captain Bell made signs that his belief that this was the Virgin was confirmed when they reached the rail of the sunken vessel. This was certainly encouraging, and all clambered aboard not without some excitement. The deck of the pirate ship was deeply covered with seaweed and submarine growth. But the remains of old cannon and their charges were visible, and much of the paraphernalia of the ship was of an imperishable kind. Even some of the bones of human skeletons were scattered about. The Virgin had sunk, as Captain Bell had said, while in the heat of action. Therefore many of her fiendish crew had gone down with her. But their bodies were, of course, much consumed with the action of the water and of marine animals. A brief inspection of the deck was made; but one and all were thinking of the mighty wealth which undoubtedly existed below decks. And Frank led the way down through the hatches. The scene upon going into the cabin of the pirate ship was a thrilling one. Everywhere were skeletons in various positions, some expressing perfect horror and agony, faithfully showing how the wretched souls had departed. But there was no article of special value in the first cabin. Corroded cutlasses, muskets and other arms were lying about. Leaving all this for later inspection Frank pushed forward into the forward cabin. Here was a horrible sight. In the walls of the cabin were iron rings from which hung rusted iron chains inclosing the skeletons of unfortunate prisoners. It was a terrible thing to think of that these poor souls had thus gone down to their death in utter helplessness. In this cabin a way was found into the hold. Frank went boldly into this, and was not a little surprised to find that it was cleverly partitioned off in compartments. Breaking in the door of one of these compartments, it was found to be the powder magazine. Here were tons of saltpetre, ruined, of course, by the action of the water. Frank put his helmet against the others and said: “There was powder enough here to have blown the whole thing to the zenith.” “You are right,” agreed Von Bulow; “but the magazine was in too secure a place to stand any chance of being fired.” This was certainly true. “Let us go on to the next compartment and find the treasure,” said Captain Bell. “If there is any on board,” said Von Bulow, who was skeptical. “Of course there is,” declared Bell, with a positive air. “There is no doubt of it.” “I hope so,” rejoined the scientist. “At least we will try and find it,” said Frank Reade, Jr. “Come along; let us waste no time in argument.” So, with this, they passed on through the hold. The result was that they came to another compartment. But the door of this was much stronger, and Frank was compelled to use his ax to break it in. The heavy iron hinges, however, were so rusted that it was not a hard job. But the sight that was revealed to the divers was an astounding one. The compartment was, perhaps, a dozen feet square. On the floor there was piled a huge heap of coin, almost as perfect as the day it was placed there. Chests were piled one upon another about the place. For a moment the treasure hunters paused, overwhelmed at the sight. At last the pirates’ treasure had been found. There was no doubt of this. Then their helmets came together. “What did I tell you?” cried Bell, excitedly. “There are millions!” “It looks like gold,” gasped Von Bulow. “It is,” said Frank. “There is a mighty fortune in that heap! We are favored of fortune.” Then for a moment that peculiar malady, the gold fever, seemed to seize all. Even Frank Reade, Jr., who was wealthy enough, was constrained to fall to counting the gold. But this would have been an interminable task. So, after handling it awhile, they desisted and began to break open the chests which were piled about. These were in part filled with clothing which was remarkably well preserved, and consisted of gorgeous uniforms of all kinds, undoubtedly spoils from the prize ships captured and preserved by Longboots, who, as Captain Bell declared, was inordinately fond of rich display. But one of the chests contained something else. CHAPTER VIII. THE EARTHQUAKE. This consisted of heaps of rich jewels and precious stones. There was a mighty fortune in these alone. They were eagerly examined by the explorers. The pirates’ treasure was certainly a magnificent one. The find far exceeded the most sanguine expectations of any who were in the party, particularly Prof. Von Bulow. “It is beyond belief,” declared the scientist. “I cannot believe but that I am dreaming.” “No,” declared Captain Bell; “it is a reality. If you don’t believe me, professor, allow me to punch you.” “I will accept the fact and forego that test,” declared Prof. Von Bulow. “But what shall we do with it?” “What?” “The treasure.” “Take it aboard the submarine boat, of course; then we can return home as princes and roll in wealth all the rest of our lives.” Captain Bell’s eyes shone like stars. It was evident that he set more by the treasure than the others. Frank was wealthy, anyway, and Von Bulow was well-to-do. Captain Bell, on the other hand, was poor, which explained all. But before engaging in the transportation of the treasure to the Dart, it was decided to carry the examination of the ship further. This was done, and from one end to the other it was ransacked. But nothing more of value was found. At least nothing which could be transported. In the lower hold were discovered many casks of rich wine. But it could not, of course, even be removed. So the party finally returned to the treasure chamber. They took as much of the coin with them as they could carry, and started to return to the Dart. It was their intention to return later and make regular trips, until it had been all transported aboard the Dart. Leaving the sunken pirate they had soon reached the Dart. Going aboard, they were met by Barney and Pomp. The two jokers were wildly enthusiastic over the find. “Begorra, it’ll make the whole av us millionaires,” cried Barney. “Shure, I’ll wear a diamond in me shirt now as big as a cart wheel!” “I done fink dis chile git married!” declared Pomp. “Married!” declared Barney. “Shure, is it a Mormon yez are? Phwat’s the matther wid yer prisint woife?” “She jes’ don’ agree to agree wif me!” declared Pomp, succinctly. “And the only point we’s sartain sure agreed on is not to agree fo’ to lib togedder any more.” “Oh, yez have a divorce, eh?” Pomp looked scornful. “Wha’ fo’ I want a divorce?” he retorted. “Don’ yo’ fink cullud people am mo’ ’spectable dan dat?” “But, begorra, the law wud make yez support her!” “Golly, I don’ beliebe it. Dis chile hab got all he kin do to support hisse’f. No, sah! I jist go down to Kyarline an’ I find jes’ de most likely cullud gal I kin find dar. Den I say: Chloe, yo’ jes’ hitch hosses wif dis chile an’ I make yo’ wear diamonds. See! Lor’ sakes, chile! Money catch de best ob dem!” “Begorra, it’s a bigamist ye’d be!” declared Barney, contemptuously. “If yez do that, naygur, I’ll cut yez acquaintance.” “Suit yo’sef, sah,” declared Pomp; “but atween yo’ an’ me, I don’ beliebe eider one ob us will leabe Marse Frank right away.” “Yez are roight there,” cried Barney. “Shure, we’ll sthick to Misther Frank, for all av the foine gold.” Plans were at once made to transport the treasure to the Dart. But an incident now transpired to put a stop to the entire project. This happening was a most startling and unlooked for one. Suddenly the Dart received a shock which seemed to fairly hoist it a dozen feet from the bottom of the sea. Everybody on board were thrown from their feet. Then followed a distant rumble and a vibrating motion which lasted for full a minute. In some way the shock had disconnected the lever, and the electric lights were extinguished. All was darkness aboard the submarine boat. For a few moments a literal panic reigned. Frank Reade, Jr., was the first to recover. He ran into the pilot-house and quickly produced light. By this time the others had recovered. “For the love of Heaven! what has happened?” gasped Von Bulow. “We have been run into by a whale!” averred Captain Bell. But Frank shook his head. “No,” he said; “it is worse than that!” The young inventor knew well enough what the trouble was. “Well, what was it?” asked Von Bulow, rubbing his bruised shins. “An earthquake,” replied Frank, calmly. “An earthquake?” “Yes.” “Mercy on us! Is it possible?” “You shall see.” Frank quickly repaired the slight damage to the electric light apparatus. Then he turned on the searchlight. The region about was plainly illuminated, and it was seen that a great change had taken place in the bed of the ocean. In places it had been upheaved by the mighty forces of Nature, and vast ravines were created. All gazed in the direction of the treasure ship, and gave a start of surprise and dismay. “My goodness! What has become of it?” asked Von Bulow. Captain Bell looked aghast. “It has gone!” “Disappeared!” “Not a trace remains.” This was true. The Vestal Virgin had vanished as completely as if transported bodily to another sphere. Only a mound of sand remained where it had been. “Great Jericho!” exclaimed Captain Bell, in horror. “What has become of it?” “Golly, I done fink dat it hab been blowed to pieces!” declared Pomp. “Bejabers, maybe it’s buried!” said Barney, at a venture. “Yes,” replied Frank. “It has been buried by the earthquake. No doubt the great revulsion of Nature’s forces has covered it many feet deep with sand.” “And the treasure ——” began Von Bulow. “Is gone!” groaned Bell. For a time there was a painful silence. All stood looking at each other with dismay depicted upon their faces. Bell was now completely disgusted. “It’s only a sample of my dad-gasted luck,” he declared. “Every time I get a fortune within my grasp it is whisked away.” “Hard luck,” said Frank. “Perhaps we can dig down to the wreck,” ventured Von Bulow. But Frank shook his head. “I’m afraid the pirates’ gold will never do any human being any good,” he declared. “It’s buried forever.” Captain Bell was completely overwhelmed. He was so confident from the first of reclaiming the treasure, that it was a terrible disappointment. But Frank said, cheerily: “Don’t get downcast, captain. Perhaps we may find another treasure ship somewhere in the Atlantic Valley.” Bell’s face brightened. “Do you think so?” he asked. “It is not at all impossible.” But the captain shook his head. “If we do,” he said, “I would have no just claim upon it. It would be yours.” “You shall have your share,” replied Frank; “so cheer up, man.” The captain became a little more cheerful. Von Bulow, on the whole, did not care greatly. But Frank yielded to Bell’s desire to first inspect the spot where the pirate ship was buried. There was a lingering hope in the captain’s mind that the treasure might yet be reached. So Frank and Bell put on diving suits and went out to examine the locality. The work accomplished by the earthquake was marvelous. It seemed as if the whole bed of the ocean had undergone a transformation. Great hills and ridges were raised, deep valleys created, and countless forms of fish and marine life lay dead upon the white sands. Truly, it had been a terrible action of Nature’s forces. The Vestal Virgin had seemed to literally sink into the shifting sands which now were high over her. It was a wonder that the Dart had not been buried also. But she had rested upon a more rocky and solid foundation. Bell was wholly satisfied that the treasure could never be recovered. “I give it up,” he declared. “Let us go back.” They were soon aboard the Dart again. Frank took his bearings as well as he could. He was not exactly sure whether he was half way through the valley or not. It was, however, decided to go on and explore the valley thoroughly. Then they would make for the English Channel and pay a visit to London and the Thames. The spirits of all revived greatly. The Dart once more shot forward on her way. A good outlook was kept for sunken vessels. “We will search every one of them we find,” declared Frank. “There certainly are vast treasures under the sea, and we are not brilliant if we do not find them.” This revived Bell’s hopes greatly, and he was once more glib and gay. For miles, however, the Dart now sailed on over unknown depths into which it was not safe to descend. These were the lowermost depths of the great deep where the pressure would be so great that a huge ship sunken there would be crushed into a shapeless mass. But it was not likely that many interesting things would be found down there even if the Dart was able to go. So none were much disappointed. The sea soon began to change again. The water seemed a peculiar olive tint, and Frank, who had studied the phenomena, said: “We are coming to a submarine forest. You shall see.” His prediction proved correct. Soon the tops of trees were seen far below. At least they looked like trees, with branches, foliage and all, but Frank said: “It is a queer coral formation. A very common mistake is made by divers who consider them petrified.” Von Bulow was deeply interested in the submarine forest. But soon a new scene spread before their view. It was such a scene as none of them had ever seen before. One and all gave expression to startled cries of interest and wonderment, and Frank slackened speed. CHAPTER IX. THE SUNKEN CITY. “A city under the sea!” cried Prof. Von Bulow. “Wonderful thing!” All gazed upon what certainly seemed to be a mighty city, built upon a plain. Mighty buildings lined wide streets, which traversed the plain in every direction. There were minarets and spires, domes and obelisks and huge public squares with giant statuary. The city, buildings, streets, and all, were as white as driven snow. It was a most bewildering sight. But all was as quiet and deserted as the tomb. It was a city without people. Frank brought the Dart to a stop, and all gazed upon the scene for a time with deep interest. “The lost Atlantis!” declared Prof. Von Bulow. “It is not a myth, after all.” “Do you suppose there is any treasure in the place?” asked Captain Bell, with sudden inspiration. All laughed at this, and Frank said: “Bell, you will yet gain the reputation of treasure hunter.” “That is what I am,” acknowledged the captain. “I have been hunting for a fortune all my life, and I mean to have it before I die, if I have luck.” “Which I hope you will.” “I shall not give up trying.” “Well,” said Von Bulow, wistfully, “are we to pay a visit of exploration to that city or not?” “I think we will,” replied Frank. “I shall sail the Dart down into that large square in the center. It looks like a central point.” “So it is,” cried the scientist, joyfully. “Oh, what a splendid opportunity to advance exploration now!” No time was lost. The Dart was allowed to sail down into the large square in the heart of the sunken city. Here it was securely anchored, and all the explorers were now brought in close proximity to the buildings. And these were of a wonderful style of architecture, and their white color did not arise from the nature of the stone employed, but, as was now seen, owing to a thick formation of coral which encrusted all. It was a scene of great beauty, and all gazed upon it spellbound. But Von Bulow was anxious to begin work at once. So after arrangements had been hastily concluded the party donned diving suits and set out for a “walk about town.” Only one was left aboard the Dart, and this was Pomp. Truly it was a novel experience to walk the streets of a submarine city, but such it was. The city was evidently constructed long before the days of Moses and the patriarchs, and was an excellent bit of proof of the existence of quite an advanced stage of civilization in that part of the world at that time. The explorers could almost fancy the shops still filled with rich goods and stuffs in vogue then. They could imagine the appearance the city must have borne when its streets were thronged with busy people, and all was life and activity. Truly it was a wonderful thing to think of. But that such a state of affairs did once exist there was no doubt. Across the great paved square the explorers walked. Before them swam beautiful vari-colored fish. At their feet crept crabs and shell fish of a strange and beautiful variety. Before them was a mighty building which seemed to have once been a palace or temple. “Let us explore that,” said Von Bulow, in signs. The others nodded an acquiescence. Frank and Barney, armed with axes, led the way into the temple. They passed through a high arched door. It was a mammoth hall with high pillars of stone which they now stood in. There was a grandeur about the mammoth structure which reminded one of the Roman temples in Italy. The hall had evidently been some sort of a public auditorium or council chamber. At the lower end was a dais of stone, and upon it was a high chair or throne of the same material. But all articles of furniture or decoration which had been made of wood or the metals were gone. Undoubtedly the worm of decay had long since eaten them up. Neither were there any skeletons or like remains of human beings to be found. When it was remembered that this city was perhaps twenty centuries old, this was not to be wondered at. Passing through the temple, the explorers came to a spacious court, beyond which was a peristyle. Whoever the inhabitants of the ancient city had been, they were certainly a people of gifts and much genius. This was evident in the construction and architecture of the city. It was a magnificent monument to their great talents, and though buried under the sea many leagues would yet exist through all time. Beyond the peristyle court the explorers came to a mighty marble paved basin, which had evidently been a bath or large lake. From one part of the sunken city to another the explorers wandered. Upon every hand new sights were seen and new wonders unfolded. Upon one building was a marine growth greatly resembling English ivy. It had a most beautiful effect. Every building had its colony of submarine creatures. There were all manner of rainbow-hued fish, and monster eels like huge serpents wriggling in the sand. But thus far nothing had been encountered of a dangerous size and character. For miles the explorers walked in the glare of the searchlight, which quite illumined the whole city. At length, however, it was decided to return. Von Bulow was highly delighted with the result of the expedition. He had recovered many valuable specimens and was in high feather. But Captain Bell was disappointed. There had been no sign of a treasure about the sunken city. If gold had ever existed there, time and the water had consumed it, beyond a doubt. Without mishap the party reached the Dart in safety. Pomp had a rousing, hearty meal ready for them, of which all partook with avidity. Then they fell to discussing the situation. “It is established beyond all doubt,” said Von Bulow, “that this part of the Atlantic was once a continent above the sea.” “That seems certain,” agreed Frank; “and it was undoubtedly inhabited by a most powerful nation.” “But though we may see this evidence of their handiwork, we do not know how they may have looked.” “I imagine that they resembled the ancient Greeks,” said Captain Bell; “though I have no particular reason for that idea.” “There was an old tradition among the Mediterranean sailors that to the west of the coast of Spain was a great continent known as Atlantis, and inhabited by a powerful and intelligent race of people.” “Then it was no myth, but the truth,” cried Von Bulow. “We have indeed found the lost Atlantis.” “Be not so sure,” said Frank. “Why?” “The continent may have been only an island, and this is possibly the only city upon it.” All reflected that this might be true. Thus the discussion progressed for some time, no definite conclusion being reached. At length it was decided to leave the sunken city and proceed on the way to the end of the valley. Accordingly Frank went into the pilot-house and started the Dart. The submarine boat floated away over the housetops and soon left the sunken city behind. As the Dart went on now many traces of a once powerful civilization were to be seen. There were many buildings which might have been country houses or farms once. Also there were actually seen traces of roads and paths and many other things to prove that this had been a nation above the surface. For many miles this sort of thing continued. Then the Dart came once more to a wild and desolate expanse of sand. It extended many miles. Frank held the Dart down for a close run over this. He hoped then to reach a point in the Atlantic Valley which was merely an island in the midst of the vast water. On the chart the island was known under the name of Gull Island. Here Frank had thought of going to the surface for a brief time. For hours the submarine boat ran on at full speed. The bed of the sea here afforded no new features for study, and Von Bulow had no desire to stop. So the Dart kept on until at length the end of the plain was reached. Then there came a rocky and rough region entirely different from that which Frank had expected. “How is this?” he exclaimed, in surprise. “Where is Gull Island?” Once more he examined the chart. As near as Frank could reckon, he ought to be just at the spot where Gull Island should be. But instead, the water seemed deeper here than anywhere else. There surely was no sign of an island. Of course it was not possible to take bearings in the usual way, being so far under the sea. “Bejabers, it’s off our course we are, Misther Frank!” said Barney. “I’m afraid you are right, Barney,” agreed the young inventor. “What shall we do about it?” “Go to the surface and make sure where we are,” said Von Bulow. “It won’t do any of us harm to take another look at the sky and the outer air.” “You are right,” said Frank, with sudden decision. “We will do it.” With which the young inventor went into the pilot-house and opened wide the pneumatic valve, which expelled the water from the tank. This should cause the Dart to at once rise to the surface. But it did not. It arose twenty feet or more, and then stopped with a jar. Frank was dumbfounded. What did it mean? Again he opened the valve. But it was of no use. The boat would not go up a single peg further. Here was a dilemma. CHAPTER X. BURIED UNDER THE SEA. Frank Reade, Jr., was greatly puzzled at this very singular action of the pneumatic valve. “What is the matter?” he exclaimed in sheer astonishment. “Something is wrong somewhere.” He went hurriedly below and examined the electrical apparatus. It seemed to be all right. Then he went into the tank-room and instantly saw what was the matter. It gave him a shock. The outer lining of the tank had become perforated, and water had flooded the forward compartment. This was of sufficient weight to hold the boat in suspension. It could be sunk by letting water into the tank as usual. But though the tank was emptied as readily as usual, it was not sufficient in buoyancy to carry the boat to the surface. In other words, the extra water in the forward compartment overcame this needed buoyancy and held the Dart in suspension. It was most unfortunate that the water had invaded this part of the boat. Frank was bathed in a cold perspiration. He knew that it was impossible to expel this water by any ordinary means. It would be necessary for the Dart to reach the surface in order to do this. As matters stood then the submarine boat would never be able to reach the surface again. It was buried forever at the bottom of the sea. Confronted by this almost appalling truth, Frank Reade, Jr., stood aghast. Not until footsteps sounded in his ears did he recover. The other voyagers had come down to join him. “Well, Frank, have you found out what is the matter?” asked Von Bulow. “Yes,” replied the inventor. “What?” “We are lost!” “Lost?” “Yes; buried forever at the bottom of the ocean. Truly lost in the great Atlantic Valley!” Stupefied with horror at these words, the others were for a time unable to speak. Then Frank proceeded to explain the situation exactly. It was a terrible truth. “Great Heaven!” exclaimed Captain Bell; “then the Dart can never again reach the surface!” “Never!” “And we must die in these depths?” “We won’t say that,” said Frank, resolutely. “The Dart will never return to the upper world, but I shall try and devise a method by which we may.” With this the young inventor went into his own cabin. He was in earnest in his purpose. A hundred different plans occurred. With their bearings lost he knew not what direction to take to reach the upward slope of the shore of some island or continent. If this could be done there would be a chance for escape, as they could leave the Dart, and in their diving suits stand a good chance of reaching land. But the quest for the land must be a random one. In such a vast space they might cruise about for months, possibly for a lifetime, without chancing to reach shore. Every possible expedient to reach the upper air was considered by Frank. But he could think of no better plan than to attempt the random quest for a shore. He consulted with the others. “That seems the only logical plan,” he said. “We may succeed very quickly and we may not.” “I think we had better adopt it,” said Captain Bell. “But what a pity that we should be obliged to leave this wonderful invention behind us.” “Never mind that,” said Frank. “I suppose you can build another one.” “If I do I shall provide for the contingency which has just arisen.” “Begorra, it was the earthquake shock that did it,” declared Barney. “Shure, it was enough to break anything.” “I agree with you there, Barney,” agreed Frank. But Pomp, who had been listening with interest, now came forward. “Shuah, now, yo chillun hab not got de right plan,” he declared. “Jes’ yo’ heah what dis chile hab to say.” “Well, Pomp,” said Frank; “what is it?” “If yo’ wants jes’ to git to de surface why don’t yo’ swim?” “Swim?” “Yas, sah! Dat am a berry easy mattah. Jes swim up!” Everybody looked at Pomp in surprise for a moment, and then laughed. “I am afraid your plan is not the best kind of a one,” declared Frank. “It would be of little use to gain the surface and have no ship there to pick you up, or be out of sight of land. I am afraid you would come down for a permanent thing.” Pomp looked somewhat aggrieved, at which Barney began to jolly him. “Begorra, yez are a ganius, naygur!” he cried, hilariously. “Shure, yez take the cake. That’s a foine plan yez have!” Pomp was angry. “Shut up, yo’ no ’count I’ishman!” he cried, indignantly. “Yo’ amn’t got no plan fo’ to propose at all.” “Bejabers, I’d rather not have thin to put out the loikes av that,” roared Barney. “It’s a foine brain yez have!” Pomp made a dive for Barney, but the Celt dodged him. There would have been a lively ruction between the two, however, but for Frank, who checked them. “Hold on!” he cried. “None of that. We have too many serious matters on hand just now.” So the two jokers refrained from any more of this sort of thing. All returned to the cabin. Bell was exceedingly uneasy. “I think we made a mistake in coming on this expedition,” he said. “We have sacrificed our lives and gained nothing!” “You cannot say that,” said Von Bulow. “I have gained many valuable discoveries for science.” “Which science will never get.” “Yet, if I die now, I shall not feel that I have thrown my life away.” “I don’t see how you regard it in that light. My wife told me I would meet disaster. I had ought to have stayed at home.” “Shure ye had ought to,” said Barney, bluntly. “You don’t mean to insult me?” flashed the captain. “Bejabers, thot wud be impossible!” “What do you mean?” But Frank put an end to the jar quickly. “Tut, tut!” he cried. “Don’t let me hear anything of that kind. This is a poor time for quarreling!” “I am sure,” said Von Bulow; “I think we are well fixed for the emergency before us.” “So do I,” said Frank; “the chances for our own escape are very good.” “About one in a million,” said Bell, sarcastically. “At least we can preserve life for a good long period aboard the Dart,” said Von Bulow. “We have provisions enough for a year, eh, Frank?” “I think so,” agreed the young inventor. “And much longer if we economize.” “But we could never live a year in these close quarters on this artificial air,” growled Bell. This was the real horror of their situation. It was not at all unlikely that the chemicals would give out before many weeks. It was liable to give out at any time, and then a horrible death by asphyxiation must be the result. Truly this was a dreadful thing to contemplate. But Frank compressed his lips tightly and went resolutely into the pilot-house. As nearly as he was able to plan it, he started the Dart in what he believed was a direct course out of the valley. The boat shot onward through the water like an arrow. Miles were covered, but yet there was no indication that they were approaching a coast. A week passed thus. It was a period of anxiety, of mental worriment and of almost despair. Heretofore no thought had been given to the chemical generators, for had they failed it was always known that a supply of fresh air could be obtained by almost instantly rising to the surface. But now that it seemed certain that the boat could not rise, all depended upon the efficacy of the generators. Thus far they had evinced no signs of giving out. Yet there was the dreadful uncertainty. In every other respect except that of buoyancy the Dart seemed as seaworthy as ever. She made rapid speed through the limitless waste of water, and her engines worked to perfection. But it did not seem possible that the vessel could long proceed without coming to land in some direction. Yet there was the fatal possibility of traveling about in a mighty circle for an indefinite length of time. The keenest outlook was kept, and the spirits of all on board the Dart were much in the same channel. There was the same strained, anxious feeling, the dreadful sense of uncertainty, the horror of impending death in an awful form. Barney was constantly at the wheel in the pilot-house, keeping the keenest sort of an outlook. And one day there was seen to be a sudden change in the color of the sea water. All noticed it with a thrill, and a great cry went up. “We are coming to land!” The peculiar greenish hue, and many significant changes in the character of the ocean bed would seem to indicate this to be a certain fact. At once all became excitement. Everybody crowded to the windows and kept a lookout for—what they hardly knew, unless it might be some certain indication of land. Suddenly the Dart came to a stop. She was facing a succession of ascending reefs. Further progress in that direction was barred. But all were confident. “I tell you we are close to land,” cried Von Bulow. “We have only to ascend those reefs to reach it,” declared Bell. But Frank Reade, Jr., was not so sanguine. “We shall see,” he said. “Put out the anchors.” Barney and Pomp hastened to do this. The Dart rested upon the verge of one of the reefs. Then preparations were quickly made for leaving the Dart. The diving suits were quickly on hand and all were soon in readiness. CHAPTER XI. ON THE REEF. Not one of the party but felt quite confident that they would soon stand on terra firma above the sea. There was every indication that land was just before them. “Bejabers, I hope its a civilized land we’ll foind, and divil a cannibal,” said Barney. “I’ve no taste for bein’ ate up in mishtake fer a lobster as soon as iver I cum out av the wather!” “Golly, dey would neber eat yo’ fo’ dat, I’ish!” grunted Pomp. “I’se dead suah ob dat.” “Shure, they’d run for their loives if iver they saw you coming out av the say.” But there was no time for argument, so it was dropped for the time being, and all made ready. The Dart was securely anchored, and then lots were drawn to see who should remain aboard. As chance had it, it fell to the lot of Captain Bell. The terrified captain turned white as a corpse and groaned aloud. Barney saw this and said: “Shure, sor, yez kin go along with the rist. I’ll sthay.” And so the cowardly captain was relieved in a measure of his fears. But the respect of the others for him was greatly diminished. However, Frank had arranged it so that the one left aboard the Dart should not be cut off from communication with the others. He carried a small spool of thin wire and a battery. As he would proceed, this could be paid out, and with a small ticker a message could be easily sent to the Dart. This was a certain way of informing Barney when they should reach the land, and also the Celt could easier gain the shore by simply following up the wire. The searchlight’s glare was thrown as far as possible up over the reefs, so that the course could easily be seen. If the shore was successfully reached and it was not far distant, all of the valuable effects of the Dart could thus be saved. At last all was ready, and then the party left the anchored boat. Quickly they began to climb the reefs. Up and up they went. It was fearfully slow work, and they were obliged to pause many times to rest. But at length they saw what they believed was the light of day above. Then the reefs began to assume a smoother character. There was a regular motion to the waves, which was a certainty that they were nearing the surface. Frank Reade, Jr., and Pomp were in the advance. Indeed, they would have reached the surface much quicker but for the necessity of constantly turning to look out for the two older men. They came along more slowly. In fact, Bell was hardly able to climb the reefs. But after awhile the motion of the water became such that they were able plainly to realize that the surface was but a few feet above. Frank was the first to emerge from the water. His head came above the surface suddenly. He looked about. The scene which met his gaze was far different from what he had expected. There was no long line of coast, no inviting shore with tropical foliage and high cliffs of stone. Naught but the dreary, boundless, tossing waste of waters was to be seen as far as the eye could reach. The reef cropped up just high enough so that the lightest waves combed over it. Frank crawled upon it and stood in several inches of water. It was a solitary reef in the midst of the ocean. Just this and nothing more. So far as offering an asylum or means of rescue to the explorers, this was out of the question. It would not be even safe for them to remain upon the reef long. For a stiff gale was threatening, and they could hardly hope to cling to the reef without harm. Not a sail was in sight. Neither was there much likelihood that this was in the path of sailing vessels, else it would have been marked with a buoy. All drew themselves out of the water and stood for a time upon the submerged reef looking blankly around. They removed their helmets, and for the first time in many weeks took a breath of pure air. “Well, this is not just what we expected, is it?” said Frank. “Well, hardly,” growled Bell. “I tell you luck is against me.” “Against you?” asked Von Bulow. “Yes.” “Why you more than the rest of us?” “It’s harder for me.” “Well,” said the scientist, emphatically, “I can’t agree with you. Take my advice, Bell. Think less of yourself and you will be more cheerful.” The captain did not see fit to reply to this shot, which was a telling and deserved one. “Golly, Marse Frank!” cried Pomp, as he looked about, “I don’t fink we cud swim dat stretch berry easy.” “No, I think not,” agreed Frank. “It is a little too vast.” Then the situation was discussed. “I don’t see that we have gained anything by this discovery,” said Von Bulow. “Have we?” “Not a thing,” agreed Frank. “We are no better off than before.” “But very little.” “Do you think there is any possibility of hailing a passing vessel?” “There is perhaps in time. It may be a lifetime, though.” “Then we had better return to the Dart and make another try.” “Yes.” “Hold on!” said Bell. “I object to that.” “Oh, do you?” “Yes.” “What plan have you to propose?” “Stay right here and look for a passing ship. Set a signal. If we go back to the bottom of the sea we’ll never find land again.” “But we must take the chances.” “They are against us.” “Yet I think they are the best.” Captain Bell demurred, but the majority were with Frank Reade, Jr., and they ruled. It was decided to return at once to the Dart. Then they would go again in quest of land. “I feel sure we shall succeed,” said Frank. “It is only a question of time.” “I shall-not go!” said Bell, obdurately. “You may if you choose!” “What!” cried Frank, in surprise; “you mean to remain here?” “Yes.” All looked astonished. “That will be suicide.” “Then you will be responsible for my life!” Frank looked at Von Bulow, and the latter winked. “Come on, friends,” he said; “we wish you luck, captain. No doubt you will succeed in hailing a ship.” Von Bulow proceeded to adjust his helmet. The others did the same and slid under the water. Half-way down the reef Von Bulow pressed Frank’s arm. The young inventor looked back. Bell was just behind. The captain’s little game of bluff did not work worth a cent. Everybody was onto his ways after that. Very soon the glare of the searchlight was seen below. Frank had signaled Barney several times, and knew that all was well. Very soon the party came in sight of the Dart. Then they safely reached the vestibule and were soon in the cabin after some thrilling experiences. Another discussion was now held as to what it was best to do. Frank settled it by going into the pilot-house and backing the Dart off the reef. Then he started to make a circuit of the reef. Suddenly, as the boat was gliding smoothly along, an object loomed up in the gloom. The searchlight was brought to bear upon it, and it was seen to be a sunken hulk. No doubt it had fallen a victim to the treacherous reef. “A sunken vessel!” cried Von Bulow. “Here, Bell, here’s a chance to get your treasure.” The captain was now all eagerness. “Hurrah!” he cried; “that is so!” Frank brought the Dart to a stop. “Golly, Marse Frank!” exclaimed Pomp, in surprise, “am yo’ gwine to visit dat wreck?” “Yes,” replied Frank. “Wha’ fo’, sah?” “To satisfy Captain Bell.” “But fo’ goodness sake, sah, if dar was any treasure on bo’d, yo’ cudn’t take it away wif yo’!” But Frank’s word was law; the Dart was anchored. “Barney,” he said, “you and the captain may go. Look out for the captain.” “All right, sor.” Captain Bell was elated. He had a queer sort of mania for treasure hunting, and he forgot all about the perils lately threatening in this desire. Barney was not loth to go. The Celt was inordinately fond of adventure, and here was a chance to distinguish himself. So he put on his diving suit, and with Captain Bell left the Dart. They soon reached the wreck and clambered aboard. She was evidently some sort of a trading vessel, and had not been many months under the water. Her rigging and spars were strewn about the deck. There was every indication that she had gone down in a storm, and by striking on the reef. Barney put his helmet close to Bell’s and cried: “Shure phwat do yez think av it now, me frind?” “I don’t know hardly,” replied Bell. “It looks to me as if she was a trader.” “Yis, sor.” “But there may be treasure aboard her, all the same.” “Yez are roight!” “We will take a good look.” “I’m wid yez.” “Let us go down into the cabin.” “Lead on, sor.” This Bell proceeded to do. He led the way to the hatch, and then began to descend the stairs. All had been dark in the cabin, but the lights on their helmets displaced the gloom. And as they reached the bottom stair and their helmet lights illumined the place, a horrible sight was revealed. The cabin seemed literally filled with dead bodies. CHAPTER XII. A FEARFUL SITUATION. These were bloated and swelled to a horrible extent by the water. They had in many cases become decomposed, but many of them floated and, attracted by the current caused by the entrance of the divers, came straight toward them. Then Barney made a dash for the next cabin. Bell followed him. And then the bodies, attracted again by the current, came piling after them. Bell shrieked and flung the cabin door shut behind him. This shut off pursuit. The two terrified divers were in the second cabin. Barney drew close to Bell and shouted: “Begorra, if they’d been aloive I’d not have been afraid av thim!” “Nor I,” agreed Bell; “but I am mighty afraid of a dead man under the water. It is horrible!” “Begorra, ye’re roight. Shure, we’d niver make soldiers.” “I don’t care if we don’t, if we only find the treasure.” “Do you believe there’s any aboord av this ship?” “Of course I do.” “Phwere the divil will we foind it, thin, I’d loike to know?” “Probably in the captain’s cabin.” “An’ that’s jest forward av this?” “Yes.” “Begorra, let’s go there!” “We will.” With which Bell opened the door leading into the captain’s cabin. As he did so he gave a great start of horror. Grasping the knob of the door upon the other side was the corpse of a man. The captain gave a yell and bolted to the other end of the cabin. But he finally recovered himself sufficiently to see that the corpse had not followed him. He also saw that it had not the power to do so. The grip of its fingers upon idle knob held it. The dead man undoubtedly was the captain of the brig. Bell made a motion to Barney, who came near. “We are fools,” he said. “These dead people can’t hurt us!” “Arrah, but it’s the looks av thim!” declared Barney. “Hang the looks! They can’t kill. Let us go into the cabin.” “I’m agreeable, sor.” “There is no doubt but that he is the captain of the ship.” “Yis, sor.” “Then, if there is any treasure aboard, it is in his cabin.” “I believe yez.” With this Bell hesitated no longer. He boldly arose and approached the door. The corpse swung toward him, and he hesitated a moment. But he quickly recovered and summoned up enough courage to push it aside. Then he entered the compartment. The captain’s cabin was richly furnished, and in one corner was a huge steel safe. As luck had it, this appeared to be open. Bell advanced and peered in. And as he did so, he gave a gasping cry which brought Barney to the spot. “Look!” he cried. “It is gold!” There were a number of small white bags piled upon the floor of the safe. Upon each of these was a figure of value. Bell took up one of these and opened it. A heap of shining coin rolled out upon the floor. They were American eagles. Upon the bag was the mark, five hundred dollars. “What a find!” gasped Bell. “There are fully two hundred of these bags; at least one hundred thousand dollars in gold. That is not equal to the treasure of the Vestal Virgin, but it will do.” “Begorra, I should say so,” agreed the Celt. “It will make me rich after a fair division,” declared Bell. “We must get it aboard the Dart at once.” It was a trying ordeal to pass through the next cabin with its complement of grinning corpses. But the two treasure hunters did so, and they reached the deck in safety. The glare of the searchlight was full upon them, and those on board the Dart were waiting for them to appear. When they did come in sight, they were seen to be bearing the bags of gold. “Hurrah!” cried Von Bulow. “Bell has got his treasure!” “You’re right,” agreed Frank. “But what good will it do him?” “No good, unless he can get it ashore, which is not likely.” Barney and Bell now came hastily toward the Dart. A moment later they were in the vestibule. The water was expelled, and then they staggered into the cabin. They dropped their precious load upon the floor of the cabin, and then removed their helmets quickly. “Well,” cried Frank; “you made a rich find?” “You’re right we did!” cried Bell, with great jubilance. “There is more left there—fully a hundred thousand dollars, and we want to rig up some way to get it.” “That will be easy,” said Frank. “What!” exclaimed Von Bulow, disappointedly. “Shall we waste the time?” “It is a large treasure,” he said. “I am going to get it and take it ashore.” “I hope you will,” said Von Bulow, dubiously. Frank and Pomp now put on diving suits and went with Barney and Bell aboard the brig. They soon succeeded in conveying the one hundred bags aboard the Dart. Then the gold was all poured out in a heap and counted. There was fully one hundred thousand dollars. It was a rich find. Bell occupied himself in counting the gold and replacing it in the bags. Then the Dart once more went on its way. The reef was left far behind. Days passed and the Dart still kept on her swift course. Still there was no sign of land. The situation had become a hundred-fold more serious. Every moment matters were becoming more complicated. In the first place the water supply had given out. Then the chemical generators began to show signs of failing. The appalling truth was presented to the submarine travelers that every moment was drawing them rapidly nearer to the end. Their lives would be cut short very speedily unless land was reached at no very distant time. Bell was in a fearful state of mind. He had earned and well merited the euphonious name of “kicker,” and in many ways excited the ire of the others. “There’s one thing about it, Bell,” said Von Bulow, severely, “nothing is to be gained by your chronic fault-finding. We shall get out of the woods no sooner.” “I suppose I lack your sublime philosophy which enables you to meet fate with supreme indifference,” sneered Bell. “I’m not a kicker, anyway!” averred Von Bulow. Frank meanwhile was busily trying to find some way out of the dilemma. The young inventor studied plan after plan, but without hitting upon anything at all favorable. At length he came in from the chemical room one day with a white face. “Shure, what is it, sor?” asked Barney, with alarm. “We have but a few more hours to live,” said Frank, with a ghastly smile. The fearless Irishman scratched his head coolly and said: “Faith, an’ I don’t think we’d betther tell the others.” “Ah, but that would not be right.” “Shure, if that Captain Bell knows av it he’ll have a fit.” A short while later all were congregated in the cabin and Frank told them the exact truth. Contrary to the general expectation, Captain Bell was singularly silent. After awhile he came to Frank and said: “Do you give up all hope?” “I fear so,” said Frank. “I don’t.” “What do you mean?” “I think we are very near land at this moment.” “I see no indication of it,” said Frank. “Then you are blind. I have seen many. How long will our diving generators last?” “Well charged, twenty-four hours.” “Let us get them ready, and when the Dart’s generators fail us let us leave her and strike out.” It was the most forlorn hope that Frank had ever heard of, but he at once saw that it was the only one. CHAPTER XIII. THE END. Still the Dart kept on her course. Frank looked in vain for the signs of land described by Captain Bell. To him they did not exist. He had no means of knowing at what depth they were. But he knew that their situation was hourly growing more critical. Then Prof. Von Bulow came to him. “I have a request to make. “If you should succeed in reaching home alive tell my wife that I sent her my love in my dying breath.” Frank took the scientist’s hand. “Of course I would do that,” he said. “But there is no more chance for me to reach home safely than for you.” “I understand,” said Von Bulow, sadly; “but it is a comfort to me.” “Then I will promise,” said Frank. Just at this moment came the climax. Barney came running into the cabin with his face as pale as chalk. “Misther Frank!” he cried, “the chemical generator has failed to worruk, an’ the air is all going, sor!” At once active measures were taken to meet the end. The helmets were hurriedly brought and donned. It was none too soon, for the air in the cabin was quickly exhausted. Then the Dart came to a stop, for it was useless to attempt to run it without the aid of the pneumatic engine. The Dart was securely anchored, and then, as lightly equipped as possible, the explorers set forth upon their apparently hopeless quest for land. On and on they wandered. What seemed like an interminable period elapsed. Still there was no sign of land. Von Bulow had begun to give out. All the others were more or less affected; at length the scientist sank down helpless. But at the eleventh hour rescue came. Suddenly Barney sprang up with a sharp cry. It was not heard by the others, but his action was seen. He pointed to an object not many feet away and advancing toward them. It was a man in a diver’s costume, with life line and rope. He came toward them with astonishment. Putting his helmet to Frank’s, he shouted: “Who are you?” “We are the crew of the submarine boat Dart.” And Frank told his story, to which the diver listened with amazement. “And I am John Frisbie, of the Thames Diving Company,” said the diver. “I am down here looking for the brig Enterprise, sunk here two weeks ago.” “What part of the sea is this?” asked Frank. “We are in the English Channel.” What followed needs but a few words to relate. Frank and the others were safely drawn up and aboard the English tug Fortune. A few days later they were safe in London. The great submarine expedition was at an end. All hands returned to America. Frank Reade, Jr., and Barney and Pomp went back to Readestown. Frank at once began work upon a new invention. Captain Bell recovered his gold by diving for it, but the Dart was never raised, and to-day sleeps at the bottom of the English Channel. And this, dear reader, brings to a propitious end our story of submarine adventure. The End