There was no doubt that the steamer was coming after the submarine. Several observations Captain Weston made confirmed this, and he reported the fact to Mr. Swift.
"Well, we'll change our plans, then," said the inventor. "Instead of sailing on the surface we'll go below. But first let them get near so they may have the benefit of seeing what we do. Tom, go below, please, and tell Mr. Sharp to get every thing in readiness for a quick descent. We'll slow up a bit now, and let them get nearer to us."
The speed of the submarine was reduced, and in a short time the strange steamer had overhauled her, coming to within hailing distance.
Mr. Swift signaled for the machinery to stop and the submarine came to a halt on the surface, bobbing about like a half-submerged bottle. The inventor opened a bull's-eye in the tower, and called to a man on the bridge of the steamer:
"What are you following us for?"
"Following you?" repeated the man, for the strange vessel had also come to a stop. "We're not following you."
"It looks like it," replied Mr. Swift. "You'd better give it up."
"I guess the waters are free," was the quick retort. "We'll follow you if we like."
"Will you? Then come on!" cried the inventor as he quickly closed the heavy glass window and pulled a lever. An instant later the submarine began to sink, and Mr. Swift could not help laughing as, just before the tower went under water, he had a glimpse of the astonished face of the man on the bridge. The latter had evidently not expected such a move as that.
Lower and lower in the water went the craft, until it was about two hundred feet below the surface. Then Mr. Swift left the conning tower, descended to the main part of the ship, and asked Tom and Captain Weston to take charge of the pilot house.
"Send her ahead, Tom," his father said. "That fellow up above is rubbing his eyes yet, wondering where we are, I suppose."
Forward shot the Advance under water, the powerful electrical plates pulling and pushing her on the way to secure the sunken gold.
All that morning a fairly moderate rate of speed was maintained, as it was thought best not to run the new machinery too fast.
Dinner was eaten about a quarter of a mile below the surface, but no one inside the submarine would ever have known it. Electric lights made the place as brilliant as could be desired, and the food, which Tom and Mr. Damon prepared, was equal to any that could have been served on land. After the meal they opened the shutters over the windows in the sides of the craft, and looked at the myriads of fishes swimming past, as the creatures were disclosed in the glare of the searchlight.
That night they were several hundred miles on their journey, for the craft was speedy, and leaving Tom and Captain Weston to take the first watch, the others went to bed.
"Bless my soul, but it does seem odd, though, to go to bed under water, like a fish," remarked Mr. Damon. "If my wife knew this she would worry to death. She thinks I'm off automobiling. But this isn't half as dangerous as riding in a car that's always getting out of order. A submarine for mine, every time."
"Wait until we get to the end of this trip," advised Tom. "I guess you'll find almost as many things can happen in a submarine as can in an auto," and future events were to prove the young inventor to be right.
Everything worked well that night, and the ship made good progress. They rose to the surface the next morning to make sure of their position, and to get fresh air, though they did not really need the latter, as the reserve supply had not been drawn on, and was sufficient for several days, now that the oxygen machine had been put in running order.
On the second day the ship was sent to the bottom and halted there, as Mr. Swift wished to try the new diving suits. These were made of a new, light, but very strong metal to withstand the pressure of a great depth.
Tom, Mr. Sharp and Captain Weston donned the suits, the others agreeing to wait until they saw how the first trial resulted. Then, too, it was necessary for some one acquainted with the machinery to remain in the ship to operate the door and water chamber through which the divers had to pass to get out.
The usual plan, with some changes, was followed in letting the three out of the boat, and on to the bottom of the sea. They entered a chamber in the side of the submarine, water was gradually admitted until it equaled in pressure that outside, then an outer door was opened by means of levers, and they could step out.
It was a curious sensation to Tom and the others to feel that they were actually walking along the bed of the ocean. All around them was the water, and as they turned on the small electric lights in their helmets, which lights were fed by storage batteries fastened to the diving suits, they saw the fish, big and little, swarm up to them, doubtless astonished at the odd creatures which had entered their domain. On the sand of the bottom, and in and out among the shells and rocks, crawled great spider crabs, big eels and other odd creatures seldom seen on the surface of the water. The three divers found no difficulty in breathing, as there were air tanks fastened to their shoulders, and a constant supply of oxygen was fed through pipes into the helmets. The pressure of water did not bother them, and after the first sensation Tom began to enjoy the novelty of it. At first the inability to speak to his companions seemed odd, but he soon got so he could make signs and motions, and be understood.
They walked about for some time, and once the lad came upon a part of a wrecked vessel buried deep in the sand. There was no telling what ship it was, nor how long it had been there, and after silently viewing it, they continued on.
"It was great!" were the first words Tom uttered when he and the others were once more inside the submarine and had removed the suits. "If we can only walk around the wreck of the Boldero that way, we'll have all the gold out of her in no time. There are no life-lines nor air-hose to bother with in these diving suits."
"They certainly are a success," conceded Mr. Sharp.
"Bless my topknot!" cried Mr. Damon. "I'll try it next time. I've always wanted to be a diver, and now I have the chance."
The trip was resumed after the diving chamber had been closed, and on the third day Captain Weston announced, after a look at his chart, that they were nearing the Bahama Islands.
"We'll have to be careful not to run into any of the small keys," he said, that being the name for the many little points of land, hardly large enough to be dignified by the name of island. "We must keep a constant lookout."
Fortune favored them, though once, when Tom was steering, he narrowly avoided ramming a coral reef with the submarine. The searchlight showed it to him just in time, and he sheered off with a thumping in his heart.
The course was changed from south to east, so as to get ready to swing out of the way of the big shoulder of South America where Brazil takes up so much room, and as they went farther and farther toward the equator, they noticed that the waters teemed more and more with fish, some beautiful, some ugly and fear-inspiring, and some such monsters that it made one shudder to look at them, even through the thick glass of the bulls-eye windows.
It was on the evening of the fourth day later that Captain Weston, who was steering the craft, suddenly called out:
"Land ho!"
"Where away?" inquired Tom quickly, for he had read that this was the proper response to make.
"Dead ahead," answered the sailor with a smile. "Shall we make for it, if I may be allowed the question?"
"What land is it likely to be?" Mr. Swift wanted to know.
"Oh, some small tropical island," replied the seafaring man. "It isn't down on the charts. Probably it's too small to note. I should say it was a coral island, but we may be able to find a spring of fresh water there, and some fruit."
"Then we'll land there," decided the inventor. "We can use some fresh water, though our distilling and ice apparatus does very well."
They made the island just at dusk, and anchored in a little lagoon, where there was a good depth of water.
"Now for shore!" cried Tom, as the submarine swung around on the chain. "It looks like a fine place. I hope there are cocoanuts and oranges here. Shall I get out the electric launch, dad?"
"Yes, you may, and we'll all go ashore. It will do us good to stretch our legs a bit."
Carried in a sort of pocket on the deck of the submarine was a small electric boat, capable of holding six. It could be slid from the pocket, or depression, into the water without the use of davits, and, with Mr. Sharp to aid him, Tom soon had the little craft afloat. The batteries were already charged, and just as the sun was going down the gold-seekers entered the launch and were soon on shore.
They found a good spring of water close at hand, and Tom's wish regarding the cocoanuts was realized, though there were no oranges. The lad took several of the delicious nuts, and breaking them open poured the milk into a collapsible cup he carried, drinking it eagerly. The others followed his example, and pronounced it the best beverage they had tasted in a long time.
The island was a typical tropical one, not very large, and it did not appear to have been often visited by man. There were no animals to be seen, but myriads of birds flew here and there amid the trees, the trailing vines and streamers of moss.
"Let's spend a day here to-morrow and explore it," proposed Tom, and his father nodded an assent. They went back to the submarine as night was beginning to gather, and in the cabin, after supper, talked over the happenings of their trip so far.
"Do you think we'll have any trouble getting the gold out of the wrecked vessel?" asked Tom of Captain Weston, after a pause.
"Well, it's hard to say. I couldn't learn just how the wreck lays, whether it's on a sandy or a rocky bottom. If the latter, it won't be so hard, but if the sand has worked in and partly covered it, we'll have some difficulties, if I may be permitted to say so. However, don't borrow trouble. We're not there yet, though at the rate we're traveling it won't be long before we arrive."
No watch was set that night, as it was not considered necessary. Tom was the first to arise in the morning, and he went out on the deck for a breath of fresh air before breakfast.
He looked off at the beautiful little island, and as his eye took in all of the little lagoon where the submarine was anchored he uttered a startled cry.
And well he might, for, not a hundred yards away, and nearer to the island than was the Advance, floated another craft—another craft, almost similar in shape and size to the one built by the Swifts. Tom rubbed his eyes to make sure he was not seeing double. No, there could be no mistake about it. There was another submarine at the tropical island.
As he looked, some one emerged from the conning tower of the second craft. The figure seemed strangely familiar. Tom knew in a moment who it was—Addison Berg. The agent saw the lad, too, and taking off his cap and making a mocking bow, he called out:
"Good morning! Have you got the gold yet?"
Tom did not know what to answer. Seeing the other submarine, at an island where he had supposed they would not be disturbed, was disconcerting enough, but to be greeted by Berg was altogether too much, Tom thought. His fears that the rival boat builders would follow had not been without foundation.
"Rather surprised to see us, aren't you?" went on Mr. Berg, smiling.
"Rather," admitted Tom, choking over the word.
"Thought you'd be," continued Berg. "We didn't expect to meet you so soon, but we're glad we did. I don't altogether like hunting for sunken treasure, with such indefinite directions as I have."
"You—are going to—" stammered Tom, and then he concluded it would be best not to say anything. But his talk had been heard inside the submarine. His father came to the foot of the conning tower stairway.
"To whom are you speaking, Tom?" he asked.
"They're here, dad," was the youth's answer.
"Here? Who are here?"
"Berg and his employers. They've followed us, dad."
Mr. Swift hurried up on deck. He was accompanied by Captain Weston. At the sight of Tom's father, Mr. Berg, who had been joined by two other men, called out:
"You see we also concluded to give up the trial for the Government prize, Mr. Swift. We decided there was more money in something else. But we still will have a good chance to try the merits of our respective boats. We hurried and got ours fitted up almost as soon as you did yours, and I think we have the better craft."
"I don't care to enter into any competition with you," said Mr. Swift coldly.
"Ah, but I'm afraid you'll have to, whether you want to or not," was the insolent reply.
"What's that? Do you mean to force this matter upon me?"
"I'm afraid I'll have to—my employers and I, that is. You see, we managed to pick up your trail after you left the Jersey coast, having an idea where you were bound, and we don't intend to lose you now."
"Do you mean to follow us?" asked Captain Weston softly.
"Well, you can put it that way if you like," answered one of the two men with Mr. Berg.
"I forbid it!" cried Mr. Swift hotly. "You have no right to sneak after us."
"I guess the ocean is free," continued the rascally agent.
"Why do you persist in keeping after us?" inquired the aged inventor, thinking it well to ascertain, if possible, just how much the men knew.
"Because we're after that treasure as well as you," was the bold reply. "You have no exclusive right to it. The sunken ship is awaiting the first comer, and whoever gets there first can take the gold from the wreck. We intend to be there first, but we'll be fair with you."
"Fair? What do you mean?" demanded Tom.
"This: We'll race you for it. The first one to arrive will have the right to search the wreck for the gold bullion. Is that fair? Do you agree to it?"
"We agree to nothing with you," interrupted Captain Weston, his usual diffident manner all gone. "I happen to be in partial command of this craft, and I warn you that if I find you interfering with us it won't be healthy for you. I'm not fond of fighting, but when I begin I don't like to stop," and he smiled grimly. "You'd better not follow us."
"We'll do as we please," shouted the third member of the trio on the deck of the other boat, which, as Tom could see, was named the Wonder. "We intend to get that gold if we can."
"All right. I've warned you," went on the sailor, and then, motioning to Tom and his father to follow, he went below.
"Well, what's to be done?" asked Mr. Swift when they were seated in the living-room, and had informed the others of the presence of the rival submarine.
"The only thing I see to do is to sneak away unobserved, go as deep as possible, and make all haste for the wreck," advised the captain. "They will depend on us, for they have evidently no chart of the wreck, though of course the general location of it may be known to them from reading the papers. I hoped I had thrown them off the track by the false chart I dropped, but it seems they were too smart for us."
"Have they a right to follow us?" asked Tom.
"Legally, but not morally. We can't prevent them, I'm afraid. The only thing to do is to get there ahead of them. It will be a race for the sunken treasure, and we must get there first."
"What do you propose doing, captain?" asked Mr. Damon. "Bless my shirt-studs, but can't we pull their ship up on the island and leave it there?"
"I'm afraid such high-handed proceedings would hardly answer," replied Mr. Swift. "No, as Captain Weston says, we must get there ahead of them. What do you think will be the best scheme, captain?"
"Well, there's no need for us to forego our plan to get fresh water. Suppose we go to the island, that is, some of us, leaving a guard on board here. We'll fill our tanks with fresh water, and at night we'll quietly sink below the surface and speed away."
They all voted that an excellent idea, and little time was lost putting it into operation.
All the remainder of that day not a sign of life was visible about the Wonder. She lay inert on the surface of the lagoon, not far away from the Advance; but, though no one showed himself on the deck, Tom and his friends had no doubt but that their enemies were closely watching them.
As dusk settled down over the tropical sea, and as the shadows of the trees on the little island lengthened, those on board the Advance closed the Conning tower. No lights were turned on, as they did not want their movements to be seen, but Tom, his father and Mr. Sharp took their positions near the various machines and apparatus, ready to open the tanks and let the submarine sink to the bottom, as soon as it was possible to do this unobserved.
"Luckily there's no moon," remarked Captain Weston, as he took his place beside Tom. "Once below the surface and we can defy them to find us. It is odd how they traced us, but I suppose that steamer gave them the clue."
It rapidly grew dark, as it always does in the tropics, and when a cautious observation from the conning tower did not disclose the outlines of the other boat, those aboard the Advance rightly concluded that their rivals were unable to see them.
"Send her down, Tom," called his father, and with a hiss the water entered the tanks. The submarine quickly sank below the surface, aided by the deflecting rudder.
But alas for the hopes of the gold-seekers. No sooner was she completely submerged, with the engine started so as to send her out of the lagoon and to the open sea, than the waters all about were made brilliant by the phosphorescent phenomenon. In southern waters this frequently occurs. Millions of tiny creatures, which, it is said, swarm in the warm currents, give an appearance of fire to the ocean, and any object moving through it can plainly be seen. It was so with the Advance. The motion she made in shooting forward, and the undulations caused by her submersion, seemed to start into activity the dormant phosphorus, and the submarine was afloat in a sea of fire.
"Quick!" cried Tom. "Speed her up! Maybe we can get out of this patch of water before they see us."
But it was too late. Above them they could hear the electric siren of the Wonder as it was blown to let them know that their escape had been noticed. A moment later the water, which acted as a sort of sounding-board, or telephone, brought to the ears of Tom Swift and his friends the noise of the engines of the other craft in operation. She was coming after them. The race for the possession of three hundred thousand dollars in gold was already under way. Fate seemed against those on board the Advance.
Directed by Captain Weston, who glanced at the compass and told him which way to steer to clear the outer coral reef, Tom sent the submarine ahead, signaling for full speed to the engine-room, where his father and Mr. Sharp were. The big dynamos purred like great cats, as they sent the electrical energy into the forward and aft plates, pulling and pushing the Advance forward. On and on she rushed under water, but ever as she shot ahead the disturbance in the phosphorescent water showed her position plainly. She would be easy to follow.
"Can't you get any more speed out of her?" asked the captain of the lad.
"Yes," was the quick reply; "by using the auxiliary screws I think we can. I'll try it."
He signaled for the propellers, forward and aft, to be put in operation, and the motor moving the twin screws was turned on. At once there was a perceptible increase to the speed of the Advance.
"Are we leaving them behind?" asked Tom anxiously, as he glanced at the speed gage, and noted that the submarine was now about five hundred feet below the surface.
"Hard to tell," replied the Captain. "You'd have to take an observation to make sure."
"I'll do it," cried the youth. "You steer, please, and I'll go in the conning tower. I can look forward and aft there, as well as straight up. Maybe I can see the Wonder."
Springing up the circular ladder leading into the tower, Tom glanced through the windows all about the small pilot house. He saw a curious sight. It was as if the submarine was in a sea of yellowish liquid fire. She was immersed in water which glowed with the flames that contained no heat. So light was it, in fact, that there was no need of the incandescents in the tower. The young inventor could have seen to read a paper by the illumination of the phosphorus. But he had something else to do than observe this phenomenon. He wanted to see if he could catch sight of the rival submarine.
At first he could make out nothing save the swirl and boiling of the sea, caused by the progress of the Advance through it. But suddenly, as he looked up, he was aware of some great, black body a little to the rear and about ten feet above his craft.
"A shark!" he exclaimed aloud. "An immense one, too."
But the closer he looked the less it seemed like a shark. The position of the black object changed. It appeared to settle down, to be approaching the top of the conning tower. Then, with a suddenness that unnerved him for the time being, Tom recognized what it was; it was the underside of a ship. He could see the plates riveted together, and then, as he noted the rounded, cylindrical shape, he knew that it was a submarine. It was the Wonder. She was close at hand and was creeping up on the Advance. But, what was more dangerous, she seemed to be slowly settling in the water. Another moment and her great screws might crash into the Conning tower of the Swifts' boat and shave it off. Then the water would rush in, drowning the treasure-seekers like rats in a trap.
With a quick motion Tom yanked over the lever that allowed more water to flow into the ballast tanks. The effect was at once apparent. The Advance shot down toward the bottom of the sea. At the same time the young inventor signaled to Captain Weston to notify those in the engine-room to put on a little more speed. The Advance fairly leaped ahead, and the lad, looking up through the bull's-eye in the roof of the conning tower, had the satisfaction of seeing the rival submarine left behind.
The youth hurried down into the interior of the ship to tell what he had seen, and explain the reason for opening the ballast tanks. He found his father and Mr. Sharp somewhat excited over the unexpected maneuver of the craft.
"So they're still following us," murmured Mr. Swift. "I don't see why we can't shake them off."
"It's on account of this luminous water," explained Captain Weston. "Once we are clear of that it will be easy, I think, to give them the slip. That is, if we can get out of their sight long enough. Of course, if they keep close after us, they can pick us up with their searchlight, for I suppose they carry one."
"Yes," admitted the aged inventor, "they have as strong a one as we have. In fact, their ship is second only to this one in speed and power. I know, for Bentley & Eagert showed me some of the plans before they started it, and asked my opinion. This was before I had the notion of building a submarine. Yes, I am afraid we'll have trouble getting away from them."
"I can't understand this phosphorescent glow keeping up so long," remarked Captain Weston. "I've seen it in this locality several times, but it never covered such an extent of the ocean in my time. There must be changed conditions here now."
For an hour or more the race was kept up, and the two submarines forged ahead through the glowing sea. The Wonder remained slightly above and to the rear of the other, the better to keep sight of her, and though the Advance was run to her limit of speed, her rival could not be shaken off. Clearly the Wonder was a speedy craft.
"It's too bad that we've got to fight them, as well as run the risk of lots of other troubles which are always present when sailing under water," observed Mr. Damon, who wandered about the submarine like the nervous person he was. "Bless my shirt-studs! Can't we blow them up, or cripple them in some way? They have no right to go after our treasure."
"Well, I guess they've got as much right as we have," declared Tom. "It goes to whoever reaches the wreck first. But what I don't like is their mean, sneaking way of doing it. If they went off on their own hook and looked for it I wouldn't say a word. But they expect us to lead them to the wreck, and then they'll rob us if they can. That's not fair."
"Indeed, it isn't," agreed Captain Weston, "if I may be allowed the expression. We ought to find some way of stopping them. But, if I'm not mistaken," he added quickly, looking from one of the port bull's-eyes, "the phosphorescent glow is lessening. I believe we are running beyond that part of the ocean."
There was no doubt of it, the glow was growing less and less, and ten minutes later the Advance was speeding along through a sea as black as night. Then, to avoid running into some wreck, it was necessary to turn on the searchlight.
"Are they still after us?" asked Mr. Swift of his son, as he emerged from the engine-room, where he had gone to make some adjustments to the machinery, with the hope of increasing the speed.
"I'll go look," volunteered the lad. He climbed up into the conning tower again, and for a moment, as he gazed back into the black waters swirling all about, he hoped that they had lost the Wonder. But a moment later his heart sank as he caught sight, through the liquid element, of the flickering gleams of another searchlight, the rays undulating through the sea.
"Still following," murmured the young inventor. "They're not going to give up. But we must make 'em—that's all."
He went down to report what he had seen, and a consultation was held. Captain Weston carefully studied the charts of that part of the ocean, and finding that there was a great depth of water at hand, proposed a series of evolutions.
"We can go up and down, shoot first to one side and then to the other," he explained. "We can even drop down to the bottom and rest there for a while. Perhaps, in that way, we can shake them off."
They tried it. The Advance was sent up until her conning tower was out of the water, and then she was suddenly forced down until she was but a few feet from the bottom. She darted to the left, to the right, and even doubled and went back over the course she had taken. But all to no purpose. The Wonder proved fully as speedy, and those in her seemed to know just how to handle the submarine, so that every evolution of the Advance was duplicated. Her rival could not be shaken off.
All night this was kept up, and when morning came, though only the clocks told it, for eternal night was below the surface, the rival gold-seekers were still on the trail.
"They won't give up," declared Mr. Swift hopelessly.
"No, we've got to race them for it, just as Berg proposed," admitted Tom. "But if they want a straightaway race we'll give it to 'em. Let's run her to the limit, dad."
"That's what we've been doing, Tom."
"No, not exactly, for we've been submerged a little too much to get the best speed out of our craft. Let's go a little nearer the surface, and give them the best race they'll ever have."
Then the race began; and such a contest of speed as it was! With her propellers working to the limit, and every volt of electricity that was available forced into the forward and aft plates, the Advance surged through the water, about ten feet below the surface. But the Wonder kept after her, giving her knot for knot. The course of the leading submarine was easy to trace now, in the morning light which penetrated ten feet down.
"No use," remarked Tom again, when, after two hours, the Wonder was still close behind them. "Our only chance is that they may have a breakdown."
"Or run out of air, or something like that," added Captain Weston. "They are crowding us pretty close. I had no idea they could keep up this speed. If they don't look out," he went on as he looked from one of the aft observation windows, "they'll foul us, and—"
His remarks were interrupted by a jar to the Advance. She seemed to shiver and careened to one side. Then came another bump.
"Slow down!" cried the captain, rushing toward the pilot house.
"What's the matter?" asked Tom, as he threw the engines and electrical machines out of gear. "Have we hit anything?"
"No. Something has hit us," cried the captain. "Their submarine has rammed us."
"Rammed us!" repeated Mr. Swift. "Tom, run out the electric cannon! They're trying to sink us! We'll have to fight them. Run out the stern electric gun and we'll make them wish they'd not followed us."
There was much excitement aboard the Advance. The submarine came to a stop in the water, while the treasure-seekers waited anxiously for what was to follow. Would they be rammed again? This time, stationary as they were, and with the other boat coming swiftly on, a hole might be stove through the Advance, in spite of her powerful sides.
They had not long to wait. Again there came a jar, and once more the Swifts' boat careened. But the blow was a glancing one and, fortunately, did little damage.
"They certainly must be trying to sink us," agreed Captain Weston. "Come, Tom, we'll take a look from the stern and see what they're up to."
"And get the stern electric gun ready to fire," repeated Mr. Swift. "We must protect ourselves. Mr. Sharp and I will go to the bow. There is no telling what they may do. They're desperate, and may ram us from in front."
Tom and the captain hurried aft. Through the thick plate-glass windows they could see the blunt nose of the Wonder not far away, the rival submarine having come to a halt. There she lay, black and silent, like some monster fish waiting to devour its victim.
"There doesn't appear to be much damage done back here," observed Tom. "No leaks. Guess they didn't puncture us."
"Perhaps it was due to an accident that they rammed us," suggested the captain.
"Well, they wouldn't have done it if they hadn't followed us so close," was the opinion of the young inventor. "They're taking too many chances. We've got to stop 'em."
"What is this electric gun your father speaks of?"
"Why, it's a regular electric cannon. It fires a solid ball, weighing about twenty-five pounds, but instead of powder, which would hardly do under water, and instead of compressed air, which is used in the torpedo tubes of the Government submarines, we use a current of electricity. It forces the cannon ball out with great energy."
"I wonder what they will do next?" observed the captain, peering through a bull's eye.
"We can soon tell," replied the youth. "We'll go ahead, and if they try to follow I'm going to fire on them."
"Suppose you sink them?"
"I won't fire to do that; only to disable them. They brought it on themselves. We can't risk having them damage us. Help me with the cannon, will you please, captain?"
The electric cannon was a long, steel tube in the after part of the submarine. It projected a slight distance from the sides of the ship, and by an ingenious arrangement could be swung around in a ball and socket joint, thus enabling it to shoot in almost any direction.
It was the work of but a few minutes to get it ready and, with the muzzle pointing toward the Wonder, Tom adjusted the electric wires and inserted the solid shot.
"Now we're prepared for them!" he cried. "I think a good plan will be to start ahead, and if they try to follow to fire on them. They've brought it on themselves."
"Correct," spoke Captain Weston.
Tom hurried forward to tell his father of this plan.
"We'll do it!" cried Mr. Swift. "Go ahead, Mr. Sharp, and we'll see if those scoundrels will follow."
The young inventor returned on the run to the electric cannon. There was a whir of machinery, and the Advance moved forward. She increased her speed, and the two watchers in the stern looked anxiously out of the windows to see what their rivals would do.
For a moment no movement was noticeable on the part of the Wonder. Then, as those aboard her appeared to realize that the craft on which they depended to pilot them to the sunken treasure was slipping away, word was given to follow. The ship of Berg and his employers shot after the Advance.
"Here they come!" cried Captain Weston. "They're going to ram us again!"
"Then I'm going to fire on them!" declared Tom savagely.
On came the Wonder, nearer and nearer. Her speed was rapidly increasing. Suddenly she bumped the Advance, and then, as if it was an unavoidable accident, the rear submarine sheered off to one side.
"They're certainly at it again!" cried Tom, and peering from the bull's-eye he saw the Wonder shoot past the mouth of the electric cannon. "Here it goes!" he added.
He shoved over the lever, making the proper connection. There was no corresponding report, for the cannon was noiseless, but there was a slight jar as the projectile left the muzzle. The Wonder could be seen to heel over.
"You hit her! You hit her!" cried Captain Weston. "A good shot!"
"I was afraid she was past me when I pulled the lever," explained Tom. "She went like a flash."
"No, you caught her on the rudder," declared the captain. "I think you've put her out of business. Yes, they're rising to the surface."
The lad rapidly inserted another ball, and recharged the cannon. Then he peered out into the water, illuminated by the light of day overhead, as they were not far down. He could see the Wonder rising to the surface. Clearly something had happened.
"Maybe they're going to drop down on us from above, and try to sink us," suggested the youth, while he stood ready to fire again. "If they do—"
His words were interrupted by a slight jar throughout the submarine.
"What was that?" cried the captain.
"Dad fired the bow gun at them, but I don't believe he hit them," answered the young inventor.
"I wonder what damage I did? Guess we'll go to the surface to find out."
Clearly the Wonder had given up the fight for the time being. In fact, she had no weapon with which to respond to a fusillade from her rival. Tom hastened forward and informed his father of what had happened.
"If her steering gear is out of order, we may have a chance to slip away," said Mr. Swift "We'll go up and see what we can learn."
A few minutes later Tom, his father and Captain Weston stepped from the conning tower, which was out of water, on to the little flat deck a short distance away lay the Wonder, and on her deck was Berg and a number of men, evidently members of the crew.
"Why did you fire on us?" shouted the agent angrily.
"Why did you follow us?" retorted Tom.
"Well, you've broken our rudder and disabled us," went on Berg, not answering the question. "You'll suffer for this! I'll have you arrested."
"You only got what you deserved," added Mr. Swift. "You were acting illegally, following us, and you tried to sink us by ramming my craft before we retaliated by firing on you."
"It was an accident, ramming you," said Berg. "We couldn't help it. I now demand that you help us make repairs."
"Well, you've got nerve!" cried Captain Weston, his eyes flashing. "I'd like to have a personal interview with you for about ten minutes. Maybe something besides your ship would need repairs then."
Berg turned away, scowling, but did not reply. He began directing the crew what to do about the broken rudder.
"Come on," proposed Tom in a low voice, for sounds carry very easily over water. "Let's go below and skip out while we have a chance. They can't follow now, and we can get to the sunken treasure ahead of them."
"Good advice," commented his father. "Come, Captain Weston, we'll go below and close the conning tower."
Five minutes later the Advance sank from sight, the last glimpse Tom had of Berg and his men being a sight of them standing on the deck of their floating boat, gazing in the direction of their successful rival. The Wonder was left behind, while Tom and his friends were soon once more speeding toward the treasure wreck.
"Down deep," advised Captain Weston, as he stood beside Tom and Mr. Swift in the pilot house. "As far as you can manage her, and then forward. We'll take no more chances with these fellows."
"The only trouble is," replied the young inventor, "that the deeper we go the slower we have to travel. The water is so dense that it holds us back."
"Well, there is no special need of hurrying now," went on the sailor. "No one is following you, and two or three days difference in reaching the wreck will not amount to anything."
"Unless they repair their rudder, and take after us again," suggested Mr. Swift.
"They're not very likely to do that," was the captain's opinion. "It was more by luck than good management that they picked us up before. Now, having to delay, as they will, to repair their steering gear, while we can go as deep as we please and speed ahead, it is practically impossible for them to catch up to us. No, I think we have nothing to fear from them."
But though danger from Berg and his crowd was somewhat remote, perils of another sort were hovering around the treasure-seekers, and they were soon to experience them.
It was much different from sailing along in the airship, Tom thought, for there was no blue sky and fleecy clouds to see, and they could not look down and observe, far below them, cities and villages. Nor could they breathe the bracing atmosphere of the upper regions.
But if there was lack of the rarefied air of the clouds, there was no lack of fresh atmosphere. The big tanks carried a large supply, and whenever more was needed the oxygen machine would supply it.
As there was no need, however, of remaining under water for any great stretch of time, it was their practice to rise every day and renew the air supply, also to float along on the surface for a while, or speed along, with only the conning tower out, in order to afford a view, and to enable Captain Weston to take observations. But care was always exercised to make sure no ships were in sight when emerging on the surface, for the gold-seekers did not want to be hailed and questioned by inquisitive persons.
It was about four days after the disabling of the rival submarine, and the Advance was speeding along about a mile and a half under water. Tom was in the pilot house with Captain Weston, Mr. Damon was at his favorite pastime of looking out of the glass side windows into the ocean and its wonders, and Mr. Swift and the balloonist were, as usual, in the engine-room.
"How near do you calculate we are to the sunken wreck?" asked Tom of his companion.
"Well, at the calculation we made yesterday, we are within about a thousand miles of it now. We ought to reach it in about four more days, if we don't have any accidents."
"And how deep do you think it is?" went on the lad.
"Well, I'm afraid it's pretty close to two miles, if not more. It's quite a depth, and of course impossible for ordinary divers to reach. But it will be possible in this submarine and in the strong diving suits your father has invented for us to get to it. Yes, I don't anticipate much trouble in getting out the gold, once we reach the wreck of course—"
The captain's remark was not finished. From the engine-room there came a startled shout:
"Tom! Tom! Your father is hurt! Come here, quick!"
"Take the wheel!" cried the lad to the captain. "I must go to my father." It was Mr. Sharp's voice he had heard.
Racing to the engine-room, Tom saw his parent doubled up over a dynamo, while to one side, his hand on a copper switch, stood Mr. Sharp.
"What's the matter?" shouted the lad.
"He's held there by a current of electricity," replied the balloonist. "The wires are crossed."
"Why don't you shut off the current?" demanded the youth, as he prepared to pull his parent from the whirring machine. Then he hesitated, for he feared he, too, would be glued fast by the terrible current, and so be unable to help Mr. Swift.
"I'm held fast here, too," replied the balloonist. "I started to cut out the current at this switch, but there's a short circuit somewhere, and I can't let go, either. Quick, shut off all power at the main switchboard forward."
Tom realized that this was the only thing to do. He ran forward and with a yank cut out all the electric wires. With a sigh of relief Mr. Sharp pulled his hands from the copper where he had been held fast as if by some powerful magnet, his muscles cramped by the current. Fortunately the electricity was of low voltage, and he was not burned. The body of Mr. Swift toppled backward from the dynamo, as Tom sprang to reach his father.
"He's dead!" he cried, as he saw the pale face and the closed eyes.
"No, only badly shocked, I hope," spoke Mr. Sharp. "But we must get him to the fresh air at once. Start the tank pumps. We'll rise to the surface."
The youth needed no second bidding. Once more turning on the electric current, he set the powerful pumps in motion and the submarine began to rise. Then, aided by Captain Weston and Mr. Damon, the young inventor carried his father to a couch in the main cabin. Mr. Sharp took charge of the machinery.
Restoratives were applied, and there was a flutter of the eyelids of the aged inventor.
"I think he'll come around all right," said the sailor kindly, as he saw Tom's grief. "Fresh air will be the thing for him. We'll be on the surface in a minute."
Up shot the Advance, while Mr. Sharp stood ready to open the conning tower as soon as it should be out of water. Mr. Swift seemed to be rapidly reviving. With a bound the submarine, forced upward from the great depth, fairly shot out of the water. There was a clanking sound as the aeronaut opened the airtight door of the tower, and a breath of fresh air came in.
"Can you walk, dad, or shall we carry you?" asked Tom solicitously.
"Oh, I—I'm feeling better now," was the inventor's reply. "I'll soon be all right when I get out on deck. My foot slipped as I was adjusting a wire that had gotten out of order, and I fell so that I received a large part of the current. I'm glad I was not burned. Was Mr. Sharp hurt? I saw him run to the switch, just before I lost consciousness."
"No, I'm all right," answered the balloonist. "But allow us to get you out to the fresh air. You'll feel much better then."
Mr. Swift managed to walk slowly to the ladder leading to the conning tower, and thence to the deck. The others followed him. As all emerged from the submarine they uttered a cry of astonishment.
There, not one hundred yards away, was a great warship, flying a flag which, in a moment, Tom recognized as that of Brazil. The cruiser was lying off a small island, and all about were small boats, filled with natives, who seemed to be bringing supplies from land to the ship. At the unexpected sight of the submarine, bobbing up from the bottom of the ocean, the natives uttered cries of fright. The attention of those on the warship was attracted, and the bridge and rails were lined with curious officers and men.
"It's a good thing we didn't come up under that ship," observed Tom. "They would have thought we were trying to torpedo her. Do you feel better, dad?" he asked, his wonder over the sight of the big vessel temporarily eclipsed in his anxiety for his parent.
"Oh, yes, much better. I'm all right now. But I wish we hadn't disclosed ourselves to these people. They may demand to know where we are going, and Brazil is too near Uruguay to make it safe to tell our errand. They may guess it, however, from having read of the wreck, and our departure."
"Oh, I guess it will be all right," replied Captain Weston. "We can tell them we are on a pleasure trip. That's true enough. It would give us great pleasure to find that gold."
"There's a boat, with some officers in it, to judge by the amount of gold lace on them, putting off from the ship," remarked Mr. Sharp.
"Ha! Yes! Evidently they intend to pay us a formal visit," observed Mr. Damon. "Bless my gaiters, though. I'm not dressed to receive company. I think I'll put on my dress suit."
"It's too late," advised Tom. "They'll be here in a minute."
Urged on by the lusty arms of the Brazilian sailors, the boat, containing several officers, neared the floating submarine rapidly.
"Ahoy there!" called an officer in the bow, his accent betraying his unfamiliarity with the English language. "What craft are you?"
"Submarine, Advance, from New Jersey," replied Tom. "Who are you?"
"Brazilian cruiser San Paulo," was the reply. "Where are you bound?" went on the officer.
"On pleasure," answered Captain Weston quickly. "But why do you ask? We are an American ship, sailing under American colors. Is this Brazilian territory?"
"This island is—yes," came back the answer, and by this time the small boat was at the side of the submarine. Before the adventurers could have protested, had they a desire to do so, there were a number of officers and the crew of the San Paulo on the small deck.
With a flourish, the officer who had done the questioning drew his sword. Waving it in the air with a dramatic gesture, he exclaimed:
"You're our prisoners! Resist and my men shall cut you down like dogs! Seize them, men!"
The sailors sprang forward, each one stationing himself at the side of one of our friends, and grasping an arm.
"What does this mean?" cried Captain Weston indignantly. "If this is a joke, you're carrying it too far. If you're in earnest, let me warn you against interfering with Americans!"
"We know what we are doing," was the answer from the officer.
The sailor who had hold of Captain Weston endeavored to secure a tighter grip. The captain turned suddenly, and seizing the man about the waist, with an exercise of tremendous strength hurled him over his head and into the sea, the man making a great splash.
"That's the way I'll treat any one else who dares lay a hand on me!" shouted the captain, who was transformed from a mild-mannered individual into an angry, modern giant. There was a gasp of astonishment at his feat, as the ducked sailor crawled back into the small boat. And he did not again venture on the deck of the submarine.
"Seize them, men!" cried the gold-laced officer again, and this time he and his fellows, including the crew, crowded so closely around Tom and his friends that they could do nothing. Even Captain Weston found it impossible to offer any resistance, for three men grabbed hold of him but his spirit was still a fighting one, and he struggled desperately but uselessly.
"How dare you do this?" he cried.
"Yes," added Tom, "what right have you to interfere with us?"
"Every right," declared the gold-laced officer.
"You are in Brazilian territory, and I arrest you."
"What for?" demanded Mr. Sharp.
"Because your ship is an American submarine, and we have received word that you intend to damage our shipping, and may try to torpedo our warships. I believe you tried to disable us a little while ago, but failed. We consider that an act of war and you will be treated accordingly. Take them on board the San Paulo," the officer went on, turning to his aides. "We'll try them by court-marital here. Some of you remain and guard this submarine. We will teach these filibustering Americans a lesson."