Once Tom Swift had made up his mind to do a thing he did it—even though it was against his better judgment. His word, passed, was his bond.
In conformity then with his decision to take Mr. Damon and the latter's friend, Mr. Hardley, on an undersea search for treasure, Tom at once proceeded to make his preparations. Ned, too, had his work to do, since the decision to make what might be a long trip would necessitate a change in Tom's plans. But, as in everything he did, he threw himself into this whole-heartedly and with enthusiasm.
Not once did Tom Swift admit to himself that he was going into this scheme because he thought well of it. It was all for Mr. Damon, after Tom had learned that his friend had invested considerable money in a company Mr. Hardley had formed to pay half the expenses of the trip.
Tom even tried to buy Mr. Damon off, by offering the latter back all the money the eccentric man had invested with his new friend. But Mr. Damon exclaimed:
"Bless my gasolene tank, Tom! I'm in this thing as much for the love of adventure, as I am for the money. Now let's go on with it. You will like Hardley better when you know him better."
"Perhaps," said Tom dryly, but he did not think so.
The young inventor insisted, before making any preparations for the trip, that all the cards be laid on the table. That is, he wanted to be sure there had been such a ship as the Pandora, that she was laden with gold, and that she had sunk where Mr. Hardley said she had. The latter was perfectly willing to supply all needful proofs, even though some were difficult, because of the nature of the voyage of the treasure craft. As a filibuster she was not trading openly.
"Here are all the records," said Mr. Hardley to Tom one day, when the young inventor, Ned, and Mr. Damon were gathered in Tom's office. "You may satisfy yourself."
And, with Ned's help, Tom did.
There was no question but what the Pandora had sailed from a certain port on a certain date. The official reports proved that. And that she did carry a considerable treasure in gold was also established to the satisfaction of Tom Swift. Because the gold was to be used for furthering ends against one of the South American governments, the gold shipment was not insured and, in consequence, no recovery could be made.
"Then you are satisfied, are you, Mr. Swift, that the ship, set out with over two millions in gold on board?" asked Mr. Hardley. "Yes, that seems to be proved," Tom admitted, and Ned nodded. "The next thing to prove is that she foundered in a storm about the position I am going to tell you," went on Mr. Damon's friend.
"He doesn't tell you the exact location now, Tom," explained Mr. Damon, "because it might leak out. He'll disclose it to us as soon as we are out of sight of land in the submarine."
"I'm willing to agree to that proposition," Tom said. "But I want to be sure she really did sink."
This was proved to him by official records. There was no question but that the Pandora had gone down in a big storm. And Mr. Hardley was on board. He proved that, too, a not very difficult task, since the official passenger list was open to inspection.
Mr. Hardley repeated his story about having overheard the exact location of the ship a few minutes before she sank, and he also told of the captain and several members of the ship's company having been drowned. This, too, was confirmed.
"Then," went on Mr. Hardley, "all that remains for me to do is to deposit at some bank my half of the expenses and await your word to go aboard the submarine."
"I believe that is all," returned Tom. "But, on my part, it will take some little time to fit the submarine out as I want to have her. There are some special appliances I want to take along which will aid us in the search for the gold, if we find the place where the Pandora is sunk."
"Oh, we'll find that all right," declared Mr. Hardley, "if you will only follow my directions."
Tom looked slightly incredulous, but said nothing.
Then followed busy days. The submarine Advance, which had made several successful trips, as related in the book bearing the title, "Tom Swift and His Submarine Boat," was hauled into dry dock and the work of overhauling her begun. Tom put his best men to work, and, after a consultation with his father, decided on some radical changes in the craft.
"Tom, my boy," said the aged Mr. Swift, "I wish you weren't going on this trip."
"Why, Dad?" asked the young inventor.
"Because I fear something will happen. We don't really need this money, and suppose—suppose—"
"Oh, I'm not worrying, Dad," was the answer. "I've taken worse risks than this, many a time. I'm really doing it as a favor to Mr. Damon. He's got too much money invested to let him lose it. And we can use a million dollars ourselves. It will enable me to put in operation a plan to pension our workmen. I've long had that in mind, but I've never had enough capital to carry it out."
"Well, of course, Tom, that's a worthy object, and I won't make any further objections. But take my advice, and strengthen the submarine."
"Why, Dad?" asked Tom in some surprise. "Because you'll find the water there of a greater depth than you think," was the answer. "I know you have the official hydrographic charts, but there's a mistake, I'm sure. I once made a study of that part of the ocean, and there are currents there at certain seasons of the year that no one suspects, and deep caverns that aren't charted. If the Pandora lies in one of these you'll need a great strength of walls to your submarine to withstand the pressure of deep water."
The craft Tom Swift proposed to use in searching for the treasure ship Pandora was of the regular cigar-shape, but inside it had many special features. It was more comfortable than the usual submarine, not being intended for fighting, though it did carry guns and a torpedo tube. Tom intended renaming the craft, which had been called Advance, and one day, when there had been some discussion as to what the undersea craft ought to be called, Ned explained:
"Why don't you name it after her?"
"After whom?" inquired Tom, in some surprise, looking up from a letter he was writing.
"Your friend and future wife, Mary Nestor," answered Ned. "I'm sure she'd appreciate it."
"That isn't such a bad idea," conceded Tom musingly. "The only thing about it is that I don't want Mary's name bandied about that way."
"Use her initials, then," suggested Ned.
"How do you mean?"
"Why not call it the M. N. 1.? Isn't that a good name?"
"The M. N. 1." mused Tom. "Not so bad. If the N. C. 4 flew over the ocean the M. N. 1 ought to be able to navigate under it. I think I'll do that, Ned."
So the Advance, rebuilt and refitted in many ways, was christened the M. N. 1, and a wonderful craft she proved to be. Mary Nestor was quite pleased when Tom told her what he had done. She appreciated the delicate compliment he had paid her.
Busy and more busy were the days that passed. As the M. N. 1 had to be refitted some miles from Tom's home, where it was feasible to launch her for the trip, he had to make the journey between the drydock and his shop either by automobile or aeroplane. Often he choose the latter, since he had a number of small, speedy craft in his hangars. Sometimes Ned or Mr. Damon went with him, but Mr. Hardley could never be induced to ride in an airship.
"I'll travel on the ocean or under it," he said, "but I'm not going to take a chance in the air. I'm too afraid of falling."
"Tom, what's this?" asked Ned one day, when he and Tom had come to see how the work of remodeling the submarine was getting along. "It looks like something you used when you dug your big tunnel."
"That's a new kind of diving bell," Tom answered. "You know it isn't easy to get treasure out of a sunken ship. It isn't like picking it off the bottom of the ocean. We've got to get it out from inside—perhaps from inside a strong box or a safe. This bell may come in useful."
"Can't you use the special diving suits that you always used to carry?" the financial manager wanted to know.
"We might, if the water isn't too deep," replied Tom. "But you know there is a limit to how far down a man in even my kind of diving dress can go. With this diving bell a much greater depth can be reached. And this diving bell is not like any you have ever seen or read about. My father gave me the idea for it. I'll demonstrate it to you some day."
A diving bell is shaped like its name. A common glass tumbler thrust down into a pail of water, with the open side down, will show exactly the principle on which a diving bell works. It illustrates the fact that two things cannot occupy the same place at the same time.
Pushing the tumbler, open end down, into the pail of water, leaves a space in the upper end of the tumbler which the water cannot fill, because it is already occupied with air. Imagine a big tumbler, made of thick steel, lowered into the water. Air pumped into the upper part not only keeps the water from entering, but also enables a man inside to breathe and to move about inside the bell which may be lowered to the floor of the ocean. But, as Tom told Ned, his diving bell was a big improvement over those commonly used.
The two young men inspected the progress made in refitting the submarine, and Tom expressed himself as satisfied.
"How soon do you think you can start?" asked Ned.
"In about two weeks," was the answer. "I'll want to get to the West Indies before the fall storms start. Not only will it be impossible to make a search then, but the very location of the sunken wreck may be changed."
"How so?" asked Ned.
"Because of undersea currents. They are strong enough, not only to sweep a wreck away from the place where it may have settled, but they may cover it with sand, and then it is hopeless to try to dig it out. So we've got to go soon, if we go at all."
"Well, I'm with you!" exclaimed Ned. "Hello! here's some one looking for you, I guess," he added, as a boy came hurrying down to the dock from the temporary office Tom had set up there.
"You're wanted on the telephone, Mr. Swift," said the messenger. "It's important, too."
"All right. I'll come at once," was the answer. "Hope it isn't bad news," mused Ned, as his chum hurried on in advance. "Maybe Hardley has found out he hasn't a right to search for that sunken gold after all. That would be too bad for Mr. Damon!"
"Hello! Hello! Yes, this is Tom Swift. What's that? You've had an accident? Great Scott, Mary! I hope you aren't hurt."
Ned overheard these words as he stood outside the temporary office, from inside which Tom Swift was telephoning.
"There's been an accident!" thought the financial manager. "I wonder if I can help?"
He was about to hurry in to offer his services when he heard Tom laugh, and then he knew it was all right. He heard his chum say:
"I'll be right over and get you. Just where are you?"
Then followed a period of listening on the part of Tom, to be broken by the words:
"All right, I'll be right with you. Lucky I have my Air Scout with me. You aren't afraid to ride in that, are you? No, that's good! I'll be right over. Ned is here with me, and I'll have him telephone to your father and mother."
With that Tom hung up the receiver and joined his chum.
"Mary had a slight automobile accident about five miles from here," Tom told his chum. "Some green driver ran into her and dished one of her wheels. No one hurt, but she hasn't a spare wheel and can't navigate. She called me up at the house, not wishing to alarm her father, and Mrs. Baggert told her you and I had come down to the dock, so she reached me here. I'll go in the small aeroplane and get her. Luckily I left it here the last time I made a trip. Will you call up Mary's home and let them know she's all right and that I'll soon be home with her? They might hear an exaggerated account of the accident."
Ned promised to do this, and at once put in a call for the home of his chum's fiancee, while Tom had one of his men run out the Air Scout. This was an aeroplane recently perfected by the young inventor which slipped through space with scarcely a sound. So silent was it that the craft had been dubbed "Silent Sam," and it stood Tom in good stead as those of you know who have read the volume just before the present book. This sky glider Tom would now use in going to the rescue of Mary Nestor was not, however, the same large craft that figured in the previous story. That airship had been given to the United States government for war purposes. But Tom had built himself a smaller one for his own use. It had the advantage of enabling him to carry on a conversation with his passenger when he took one aloft.
About a week before Tom and Ned had flown from Shopton to the dry dock where the submarine was being reconstructed in this small airship. Engine trouble had developed after they had landed, and they had gone back by automobile, leaving the Air Scout to be repaired. This had been done, and now Tom intended to use it in going to Mary's rescue.
Now, when the Air Scout had been run out of the hangar, Tom climbed into it.
"Sorry I can't take you along," he called to Ned, who had finished telephoning to Mary's home, "but, under the circumstances—"
"Two's company and three's a crowd!" laughed Ned. "I know!"
"No, I didn't mean that," Tom said. "You know Mary likes you, but this will carry only two."
"I know!" answered his chum. "On your way!"
And with an almost noiseless throb of her engine and a whirr of her propeller, the aeroplane rolled swiftly over the level starting ground and took the air like a swan leaving its lake.
Tom did not rise to a great height, as he would need only a few minutes to reach the place where Mary was stalled by the accident to her machine. Soon he was hovering over a level field, one of several that lined the country highways in that section. A small crowd on the turnpike gathered about an evidently disabled automobile gave Tom the clew he needed, and presently he made a landing. Instantly the throng of country people who had gathered to look at the automobile crash deserted that for a view of something more sensational—an airship.
Cautioning the boys who gathered about not to "monkey" with any of the mechanism, Tom hastened over to where Mary was standing near her car.
"Are you sure you aren't hurt?" he asked her anxiously.
"Oh, yes, very sure," she replied, smiling at him. "It isn't much of an accident—only one wheel smashed. We were both going slowly."
"But it was all my fault!" insisted a young fellow who had been driving the car that crashed into Mary's. "I'm all kinds of sorry, and of course I'll pay all damages. I wanted this young lady to let me drive her home and then send a garage man to tow her car, but she said she had other plans. I don't blame her for not wanting to ride in my jitney bus when I see what kind of car you have," and he looked over toward Tom's aeroplane.
"Thank you, just the same," murmured Mary. "I'm not quite sure that it was all your fault. But if you will be so good as to send a man after my machine I'll go back with Mr. Swift. Wait until I get my bag," she added, and she extracted it from the seat in her automobile. "There'll be room for this, won't there?" she asked. "I've been shopping."
"You must have made some large purchases," laughed Tom, looking critically at the small bag. "Yes, there'll be room for that, all right."
He made a brief examination of Mary's machine, ascertaining that the dished wheel was the main damage, and then, having given the young man who caused the accident directions for the garage attendant, Tom led his pretty companion across the field to the waiting airship.
Of course a crowd gathered to see them start off, and this was not long delayed, as Tom was not fond of curiosity seekers. In a few minutes he and Mary were soaring aloft.
"Well, how are you?" he asked Mary, when they were alone well above the earth.
"Fine and dandy," she answered, smiling at him, for they were riding side by side and could converse with little difficulty owing to the silent running of Tom's latest invention. "I'm sorry to have called you away from your work," she added, "but when Mrs. Baggert told me you were at the submarine dock I thought perhaps you could run out and get me in your machine. I didn't expect you to fly to me."
"I'm always ready to do that!" exclaimed Tom, as he shot upward to avoid a bank of low-lying clouds. "Were you frightened at the crash in the machine?"
"Not greatly. I saw it coming, and knew it was unavoidable. That chap hasn't been running autos very long, I imagine, and he lost his head in the emergency. But I had my brakes on and he just coasted into me. I was lucky in that it wasn't worse."
"I should say so! Do you want to get right home?"
"I think I'd better. Mother and father may be a little worried about me. And they've had trouble enough of late."
"Trouble!" exclaimed Tom, in a questioning voice. "Anything serious?"
"No, just family financial matters. Not ours," she hastened to add, as she saw Tom look quickly at her. "A relative. I shouldn't have mentioned it, but father and mother are a little worried, and I don't want to add to it."
"Of course not," agreed Tom. "If there's anything I can do?"
"Oh, I expected you to say that!" laughed Mary. "Thanks. If there is we'll call on you. But it may all be straightened out. Father was expecting a message from Uncle Barton today. So, though I'd like to take a cloud-ride with you, I think I'd better get home."
"All right," agreed Tom. "I told Ned to telephone that you were all right, so they won't worry. And now try to enjoy yourself."
"I'll try," promised Mary, but it was obvious, even from the quick glances Tom gave her, that she was worried about something. Mary was not her usual, spontaneous, jolly self, and Tom realized it.
"Well, here we are!" he announced a little later, as they soared above a level field not far from her home. "Sorry I can't let you down right on your roof, but it isn't flat enough nor big enough."
"Oh, I don't mind a little walk, especially as I didn't have to hike it all the way in from Bailey Corners," she said, referring to the place of the automobile accident. "I suppose the time will come when everybody who now has an auto will have an airship and a landing place, or a starting place, for it at his own door," she added.
"Either that, or else we'll have airships so compact that they can set off and land in as small a space as an auto now requires," said Tom. "The latter would be the best solution, as one great disadvantage of airships now is the manner of starting and stopping. It's too big."
Tom left his Air Scout in a field owned by Mr. Nestor, where he had often landed before, and walked up to the house with Mary.
"Oh, I'm glad you're back!" exclaimed Mrs. Nestor, when she saw the two coming up the steps.
"You weren't worried, were you, after Ned telephoned?" asked Tom.
"Not exactly worried, but I thought perhaps he was making light of it. Do tell me what happened, Mary!"
Thereupon the girl related all the circumstances of the smash, and Tom added his share of the story.
"Did father hear anything from Uncle Barton?" asked Mary, after her mother's curiosity had been satisfied.
"Yes," was the answer, in rather despondent tones, "he did, but the news was not encouraging. The papers cannot be found."
"It's mother's brother we're talking about," Mary explained to Tom. "Barton Keith in his name. Perhaps you remember him?"
"I've heard you speak of him," Tom admitted.
"Well," resumed Mary, "Uncle Barton is in a peck of trouble. He was once very rich, and he invested heavily in oil lands, in Oklahoma, I believe."
"No, in Texas," corrected Mrs. Nestor.
"Yes, it was Texas," agreed Mary. "Well he bought, or got, somehow, shares in some valuable oil lands in Texas, and expected to double his fortune. Now, instead, he's probably lost it all."
"That's too bad!" exclaimed Tom. "How did it happen?"
"In rather an odd way," went on Mary. "He really owns the lands, or at least half of them, but he cannot prove his title because the papers he needs were taken from him, and, he thinks, by a man he trusted. He's been trying to get the documents back, and every day we've been expecting to hear that he has them, but mother says there has been no result."
"No," said Mrs. Nestor. "My brother thought sure he had a trace of the man he believes has the papers, or who had them, but he lost track of him. If we could only find him—"
At that moment a maid came into the room to announce that Tom Swift was wanted at the telephone.
"This is my busy day!" announced the young inventor as he went into the Nestor sitting room, where the telephone was installed.
"Perhaps it is some one else who wants you to come to their rescue," suggested Mary.
But it was not, as Tom related a little later when he had finished his talk over the wire.
"Just a business matter," he announced to Mary and her mother, when he rejoined them. "A gentleman with whom I expect to make a submarine trip is at the house, and wants to consult with me about details. He is getting anxious to start. Mr. Damon is there, too."
"Blessing every thing he lays eyes on, I suppose," remarked Mrs. Nestor, with a smile.
"Yes, and some things he doesn't see," agreed Tom. "He is going with us on this submarine trip."
"Oh, Tom, are you going to undertake another of those dangerous voyages?" asked Mary, in some alarm.
"Well, I don't know that they are particularly dangerous," replied Tom, with a smile. "But we expect to make a search for a sunken treasure ship in a submarine. That's the vessel I'm working on now," he added. "We're rebuilding the Advance, you know, making her more up-to-date, and adding some new features, including her name—M. N. 1."
"I suppose Mr. Damon's friend is getting anxious to make a start, particularly as he has already invested several thousand dollars in the project," went on the young inventor. "He formed a company to pay half the expenses of the search, and they will share in the treasure—if we find it," Tom said. "I wish Mr. Damon, who holds most of the shares the promoter let out of his own hands, had not gone into it, but, since he has, I'm going to do the best I can for him."
"Then aren't you friendly with the other man?" asked Mary.
"I don't especially care for him," the young inventor admitted. "He isn't just my style—too fond of himself, and all that. Still I may be misjudging him. However, I'm in the game now, and I'm going to stick. I'll have to be traveling on," he said. "Mr. Damon and his friend are at my house, and they've been telephoning all over to find me. I guess this was one of the first places they tried," he said with a smile, referring to the fact that he spent considerable time at Mary's home.
"Well, I'm glad they found you, but I'm sorry you have to go," Mary said with a smile.
A little later Tom Swift, with Ned, for whom he called, was on his way back home in his Air Scout, having said goodbye to Mary and her mother and expressing the hope that Mr. Keith would soon be over his business troubles.
"Oil wells are queer, anyhow," mused Tom.
Then Tom got to thinking about Dixwell Hardley: "I don't like the man, and the more I see of him the less I like him. But I'm in for it now, and I'll stick to the finish. I only wish I could locate the treasure ship, give him his share, and get back to my work. I'm going to try to turn out an airship that a man can use as handily as he does a flivver now."
Musing on the possibilities in this field, Tom, having left Ned at the latter's home, soared down from aloft, and a little later, having told Koku to look after the Air Scout, much to the delight of the giant and the discomfiture of Rad, the young inventor was closeted with Mr. Damon and Dixwell Hardley.
"Bless my straw hat, Tom!" exclaimed the eccentric man, "but we just couldn't wait any longer. How are you coming on, and when can we start on this treasure-hunting trip? I declare it makes me feel young again to think about it!"
"Well, it won't be long now," was the answer. "The men are working hard to get the submarine in shape, and I should say that in another week, or two weeks at the most, we could set off!"
"Good!" exclaimed Mr. Hardley. "I have received additional information," he went on, "to the effect that the amount of gold on board the Pandora was even greater than we at first thought."
"That sounds encouraging," replied Tom. "It only remains to find the sunken ship now. But what interests me greatly is whether, after we have gotten this gold, supposing we are successful, we shall be allowed to keep it."
"Bless my bank book! why not?" asked Mr. Damon. "Isn't it wealth abandoned at the bottom of the sea, and isn't finding keeping?"
"Not always," answered Tom. "There are certain rules and laws about treasure, and it might happen that after we got this—if we do—it could be taken away from us."
"I think there will be no difficulty on this score," said Mr. Hardley. "In the first place, two attempts were made to get this wealth, and were unsuccessful. Then it was practically abandoned, and I believe under the law the persons who now find it will be entitled to keep it. Besides the persons who gathered it together did so for an unlawful purpose—that of starting a revolution in a friendly country—and they would not dare claim it for fear of giving their secret away."
"Well, perhaps you are right," assented Tom. "We'll make a try for it, anyhow."
"You say the submarine is nearly ready?" asked Mr. Hardley.
"She will be ready for a trial trip at the end of this week," said Tom, "and be fitted up for the voyage within another seven days, I hope. Then for the great adventure!" and he laughed, though, truth to tell, he had no real liking for his task. The more he saw of Mr. Hardley the less he liked him.
"I shall begin getting my affairs in shape," said the latter, as he gathered up some papers he had brought to attempt to prove to Tom that the wealth of the Pandora was greater than had been supposed. "I have many large interests," he went on, rather pompously, "and they need looking after; especially if I undertake anything so extra hazardous as a submarine trip."
"Yes, there always is some danger," admitted Tom. "But then there is danger walking along the street."
"Oh, there's no danger with Tom Swift!" exclaimed Mr. Damon. "I've been under the sea and above the clouds with him, and, bless my rainbow! he always brought us safe home."
"And I'll try to do the same this time," said the young inventor.
Busy days followed for Tom Swift and his friends. The force at work on the submarine turned night into day to rush her completion, and in due season she was set afloat in the dry dock basin and formally rechristened the M. N. 1.
Mary blushed as she gave the boat her new name, and there was a little cheer from the group of workmen gathered at the dock. There was no launching in the real sense of the word, since as the Advance that ceremony had been gone through with for the undersea craft.
She had been greatly changed interiorly and outwardly. Her skin, or plates, having been doubled and strengthened. For Tom proposed to go to a much greater depth than ever before.
In addition to using the submarine herself in a search for the gold on the Pandora, Tom had installed on board some new kinds of diving apparatus and also a diving bell. If one would not serve, the other might, he reasoned.
"Well, Tom," remarked his aged father the night before they were to start on the trial trip, "I understand you have practically rebuilt the Advance."
"Yes; and I think she's a much better craft, too, Father."
"Glad to hear that, Tom. Of course you kept the gyroscope rudder feature?"
"No, I didn't," replied Tom. "If I had left that installed it would have meant carrying a smaller diving bell, and I think that last will be more useful than the gyroscope. I put in a set of double-acting depth rudders instead."
Mr. Swift shook his head.
"I'm sorry for that, Tom," he remarked. "There's nothing like the gyroscope rudder in a tight pinch—say when there's a storm. And for holding the boat steady, if you have to make a sudden turn under water, to avoid an obstruction you come upon unexpectedly, a gyroscope can't be improved on. It holds you steady and prevents your turning turtle."
"I've put side fin-keels to correct that," Tom explained.
But still his father was not satisfied.
"I'd rather you had kept the gyroscope," he said, and the time was to come when Tom Swift wished that himself.
But it was too late to make the change now, and so, with more than usual confidence in his own designing abilities, the next day the young inventor and his friends went aboard the M. N. 1 for the trial trip.
"You don't easily get seasick, do you?" Tom asked Mr. Hardley, as they descended the hatchway into the interior of the craft.
"No, I'm considered a good sailor."
"Well, you'll need to be," went on Tom, with a smile. "Not that we are likely to strike any rough water now, though the reports say a stiff breeze is blowing in the bay. But when we once start for the West Indies you are likely to experience a new sensation. I've known sailors who never had any qualms, even in terrible storms, to get ill in a submarine when she went through only a small blow. The motion is different from that on a surface boat."
"I can imagine so," returned Mr. Hardley. "But I'll be thinking of the millions in gold on the Pandora, and that will keep my mind off being seasick."
"Let us hope so," murmured Tom.
He gave the word, they all descended, the hatch covers were closed down, and the M. N. 1 was ready to start on a trial trip.
"What's that noise?" asked Mr. Hardley.
Mr. Hardley, Tom Swift, Mr. Damon, Ned Newton, Koku, and one or two navigating officers of the craft, were gathered in the operating cabin of the M. N. 1.
"That's water being pumped into the tanks," explained Tom. "We are now going down. If you'll watch the depth gauge you can note our progress."
"Going down, are we?" remarked Mr. Hardley. "Well, it's interesting to say the least," and he observed the gauge, which showed them to be twenty feet under the surface.
"Bless my hydrometer, but he's got nerve for a first trip in a submarine! He's all right, isn't he?" whispered Mr. Damon to Tom.
"Well, I'm glad to see he isn't nervous," remarked Tom, honest enough to give his visitor credit for what was due him. And indeed many a person is nervous going down in a submarine for the first time. "Still we can't go more than thirty feet down in this water," went on Tom. "A better test will be when we get about five hundred feet below the surface. That's a real test, though as far as knowing it is concerned, a person can't tell ten feet from ten hundred in a submarine under water, unless he watches the gauge."
"Well, I think you'll find Mr. Hardley all right," said Mr. Damon, who seemed to have taken a strong liking to his new friend.
Certainly the latter showed no signs of nervousness as the craft slowly settled to the proper depth. He asked numberless questions, showing his interest in the operation of the M. N. 1, but he showed not the least sign of fear. However, as Tom said, that might come later.
"We are going down now," Tom explained, as he pointed out to Mr. Hardley the various controlling wheels and levers, "by filling our ballast tanks with water. We can rise, when needful, by forcing out this water by means of compressed air. When we are on the ocean we can go down by using our diving rudders, and in much quicker time than by filling our tanks."
"How is that?" asked the seeker after the Pandora's gold.
"Filling the tanks is slow work in itself," replied Tom, "and they have to be filled very carefully and evenly, so we don't stand on our stern or bow in going down. We want to sink on an even keel, and sometimes this is hard to accomplish. But we are doing it now," and he called attention to an indicator which told how much the M. N. 1 might be listing to one side or to one end or the other.
A submarine, as everyone knows, is essentially a water-tight tank, shaped like a cigar, with a propeller on one end. It can sink below the surface and move along under water. It sinks because rudders force it down, and water taken into tanks in its interior hold it to a certain depth. It can rise by ejecting this extra water and by setting the rudders in the proper position.
A submarine moves under water by means of electric motors, the current of which is supplied by storage batteries. On the surface when the hatches can be opened, oil or gasolene engines are used. These engines cannot be used under water because they depend on a supply of air, or oxygen, and when the submarine is tightly sealed all the air possible is needed for her crew to breathe. While cruising on the surface a submarine recharges her storage batteries to give her motive power when she is submerged.
There are many types of submarines, some comparatively simple and small, and others large and complex. In some it is possible for the crew to live many days without coming to the surface.
Tom Swift's reconstructed craft compared favorably with the best and largest ever made, though she was not of exceptional size. She was very strong, however, to allow her to go to a great depth, for the farther down one goes below the surface of the sea, the greater the pressure until, at, say, six miles, the greatest known depth of the ocean, the pressure is beyond belief. And yet is possible that marine monsters may live in that pressure which would flatten out a block of solid steel into a sheet as thin as paper.
"Well, we are as deep down as it is safe to go in the river," announced Tom, as the gauge showed a distance below the surface of a little less than twenty-nine feet. "Now we'll move into the bay. How do you like it, Mr. Hardley?"
"Very well, so far. But it isn't very exciting yet."
"Bless my accident policy!" exclaimed Mr. Damon, "I hope you aren't looking for excitement."
"I'm used to it," was the answer. "The more there is the better I like it."
"Well, you may get your wish," said Tom.
He turned a lever, and those on board the submarine became conscious of a forward motion. She was no longer sinking.
She trembled and vibrated as the powerful electric motors turned her propellers, and Tom, having seen that all was running smoothly in the main engine room, called Mr. Damon, Ned, and Mr. Hardley to him.
"We'll go into the forward pilot house and give Mr. Hardley a view under water," he announced. "Of course, you'll see nothing like what you'll view when we're in the ocean," added the young inventor, "but it may interest you."
The four were soon in the forward compartment of the craft. She could be directed and steered from here when occasion arose, but now Tom was letting his navigator direct the craft from the controls in the main engine room. A conning tower, rising just above the deck of the craft, gave the pilot the necessary view.
"Here you are!" exclaimed Tom, as he switched out the lights in the cabin. For a moment they were in darkness, and then, with a click, steel plates, guarding heavy plate glass bull's-eyes, moved back, and Mr. Hardley for the first time looked out on an underwater scene. He saw the murky waters of river down which they were proceeding to the bay moving past the glass windows. Now and then a fish swam up, looking in, and, with a swirl of its tail, shot away again, apparently frightened well-nigh to death.
"Bless my shoe laces, Tom!" exclaimed Mr. Damon, "this isn't a marker compared to some of the sights we've seen, is it?"
"I can imagine not," said Mr. Hardley. "But it is interesting. I shall be anticipating more wonderful sights."
"And you'll get them!" exclaimed Ned. "Do you remember, Tom, the time the big octopus tried to hold us back?"
"Yes, indeed," answered the young inventor. "That gave us a scare for the time being."
Steadily the M. N. 1 kept on her way under water. Her path was illuminated to a considerable degree by a broad, diffused beam of light from a powerful searchlight that was fixed just back of the conning tower, giving the helmsman a certain degree of vision. This light also served to illuminate the water, so that those in the forward cabin could see what was going on around them.
"There isn't much of interest in the river," said Tom. "No big fish, or anything else of moment. Even in the bay we won't see much to attract our attention. But I want to make sure everything is working smoothly before we start for the West Indies."
"That's right!" agreed Mr. Hardley. "We want to make a success of this trip."
He remained at the glass bull's-eyes, now and then exclaiming as some shad or other fair-sized fish came into view. Suddenly, however, his exclamation was sharper than usual.
"Look!" he exclaimed. "There's part of a wreck!"
Ned, Mr. Damon, and Tom looked out and saw, sweeping past them, the ribs and worm-eaten timbers of some craft, lying on the bottom of the river.
"Yes, that's the remains of an old brick scow," the young inventor explained. "That's one of our water-marks, so to speak. It is at the bend of the river. We turn now, and head for the bay."
As he spoke they all became aware of a sudden swerve in the course of the submarine. The helmsman had, doubtless, noted the "water-mark," as Tom termed it, and as an automobilist on land might swing at the cross-roads, the steersman was changing the course of his craft.
"We'll go deeper," said Tom a moment later, as the wreck passed out of view. "We can go about fifty feet down now. Yes, he's sinking her," he added, as a gauge showed the craft to be descending. "Nelson knows his business all right."
"He is your captain?" asked Mr. Hardley.
"One of the best, yes. He'll go with us on the search for the Pandora."
They talked of various matters, Tom relating to Mr. Hardley how a tug had rammed the brick scow some years ago, and sunk it in the river.
The submarine was now about forty-eight feet below the surface, and suddenly they all became aware that her speed had increased.
"Guess he's going to give the motors a good try-out," observed Tom. "I think I'll go back to the engine room. You may remain here, if you like, and you'll probably see—"
A cry from Mr. Damon interrupted him.
"Bless my rubber boots, Tom! Look!" cried the eccentric man. "We're going to ram a mud bank!"
As he spoke they all became aware of a solid black mass looming in front of the bull's-eye window. An instant later the submarine came to a jarring stop, as if she had struck some soft, yielding substance. There was a confused shouting throughout the craft, the noise of machinery, a trembling and vibration, and then ominous quiet.
Characteristic it was of Tom Swift to act calmly in times of stress and danger, and he ran true to form now. Only for an instant did he show any sign of perturbation. Then with calmness and deliberation the young inventor quickly did a number of things to the controls within his reach.
First of all he signaled to the engine room that he was going to take charge of the boat. This meant that the navigator in the conning tower was to keep his hands off the various levers and wheel-valves. It was possible to operate the M. N. 1 from three positions, but Tom wanted no triplicate handling of his craft now.
Almost the instant Tom signaled that he would take charge back came flashing the electrical signal from the conning tower that his orders were understood. The next thing that those aboard the craft became aware of was a tremor that seemed to run through the whole under-sea ship. The quiet had changed to a subdued humming, and the ominous lack of motion was succeeded by violent vibration.
"Backing her up, Tom?" asked Ned, in a low voice.
"Trying to," was the answer. "But I'm afraid her nose has gone in pretty deep. I've reversed the propellers."
For perhaps a minute this vibration continued, showing that the powerful electric motors were turning over the twin propellers at the blunt stern of the craft. But she did not change her position.
With a touch of his hand, and still almost as cool as the proverbial cucumber (though why they should be cool it is hard to say), Tom stopped the motors. Once again the craft was quiet, but now, instead of the occupants being able to see clearly from the thick, glass windows in the forward cabin, the water showed muddy and murky in the glare of the underwater searchlight.
"Bless my postage stamps, Tom! what has happened?" exclaimed Mr. Damon. "Has a giant squid attacked us, as one did some time ago, and is he roiling up the water?"
"No, it isn't a squid, Mr. Damon," replied the young inventor easily; "though the water does look as if a squid had spilled a lot of his ink in it. This is just the effect of mud stirred up by our propellers. There may be more of it."
Ned looked toward Mr. Hardley to see how he was taking it. The seeker after gold apparently had good control of his nerves, or else he was ignorant of what was going on. For he asked, casually enough:
"Have we stopped?"
"We have," answered Tom. "I thought I'd give you a view of the scenery."
Perhaps he spoke sarcastically, but, if he did, Mr. Damon's friend did not seem to be aware of it. Coolly enough he replied:
"Well, if this is a fair sample of underwater scenery I prefer something up above, though I appreciate that this may be needful."
"We'll soon be traveling along," announced Tom. "Koku," he added to the giant, who had been calmly sitting during the excitement, "go to the engine room and help with the big levers."
"Yes, Master," was the answer. Koku had implicit faith in Tom.
Waiting a moment for his faithful servant to reach the post assigned to him, Tom again signaled to his helpers and then quickly turned a wheel which produced startling results. For all within the submarine suddenly slid forward across the cabin floor.
"Bless my hammock hooks, Tom! are you standing her on her head?" cried Mr. Damon.
"That's exactly what I'm doing," was the answer. "I've started to empty one of the after ballast tanks, and that, naturally, raises the stern while the nose is held down."
The submarine was indeed in a peculiar position. She was on a slant in the water, her nose held fast in the soft mud bank, and it was Tom's idea that by making the stern buoyant it might help to pull her free.
To this end he also gave what assistance the propellers were capable of adding by starting the motors again, so that the craft once more trembled and vibrated.
But it all seemed to no purpose. Aside from the slanting position, there was no change in the M. N. 1. Ned, looking out into the murky water, which had cleared slightly, saw that the craft was still held fast. And then, for the first time, Mr. Hardley seemed to become aware that something serious was the matter. Up to now he seemed to think that all that had occurred was done for the purpose of testing the newly outfitted underseas boat.
"Is there anything wrong?" he asked sharply of Tom. "Why are we in this position, and why don't we go on out to the open ocean and make a test at considerable depth? We'll have to go down deeper than this if we find the Pandora!"
"I suppose so," agreed Tom. "But we have had an accident, and—"
"An accident!" interrupted the gold-seeker, and then Ned saw him turn pale. "Do you mean to say this is not part of the test?"
"We have run into a mud bank," said Tom. "The steersman must have become confused, or else, since we last used the submarine, there has been a shift of the mud banks in this river and one exists where there was none before. At any rate, we ran our nose deep into it, and here we are—stuck!"
"Can't we get loose—go up to the surface?" demanded Mr. Hardley.
"I'm trying to bring that about," announced Tom calmly. "So far her engines haven't been able to pull her loose."
"But Great Scott, man, we can't stay here!" cried the now excited adventurer. "We'll be drowned like rats in a trap! Let me out! Isn't there some way? I'll be shot through a torpedo tube, if necessary! I must get out! I can't stay here to be drowned! I have too much at stake!"
"Now wait a minute!" calmly advised Tom Swift. "You haven't any more at stake than the rest of us. None of us wants to be drowned, and there is only a remote possibility that we shall be. I haven't played all my cards yet. We can live on this boat for a week, if need be."
"You mean under water as we are now?" asked Mr. Hardley.
"Yes. I always keep the boat provisioned and with plenty of air and water for a long stay, if need be," replied Tom. "And I did not overlook the fact that we might have an accident on the trial trip."
"I don't see how you let an accident happen before we even got started," complained the gold-seeker. "I should think your steersman would have been more careful."
"He is very careful," explained Tom. "But we have not used the craft for some time, and, meanwhile, there have been changes in the river, due, I suppose, to heavy tides. But we may get out of the grip of the mud bank soon."
"And if we don't, what then?" asked Mr. Hardley.
"Then there is always the torpedo tube," said Tom calmly. "And we are not very deep down. I think I can save you all."
"I certainly hope so!" was the fretful comment of the adventurer. "I have too much at stake to be drowned like a rat in a trap! You must send me up first if it becomes necessary to use the tube."
Tom did not answer. But as he looked out of the observation windows to see if possible the conformation of the mud bank, the young inventor whispered to Ned one word. And that word was:
"Yellow!"
"You said it!" was Ned's whispered rejoinder.
Tom Swift arrived at a sudden determination. Once again the motors were stopped, and the boat gradually assumed an even keel.
"What are you going to try, Tom?" asked Ned.
"I'm going to shove her farther into the mud bank," announced the young inventor. "I think that's the only way to get her loose."
"Bless my apple pie, Tom!" cried Mr. Damon, "doesn't that seem a foolish thing to do?"
"It's the only thing to do, I believe," was the answer. "This mud is of a peculiar sticky and holding kind. The sub's nose is in it like a peg in a hole. What I propose to do now is to enlarge the hole, and then our nose will come loose—I hope."
"But you haven't any right to shove our nose further in!" cried Mr. Hardley. "I won't allow it! I demand to be put on the surface! I won't be drowned down here before I get the gold that's coming to me—the gold and—"
"Now look here!" suddenly cried Tom. "I'm in command of this boat, and you'll do as I say. I'll gladly set you on the surface if I can, and this is the only way it can be brought about—it's the only way to save all of us. I'm going to enlarge the mud hole so we can pull out. Please keep still!"
Mr. Hardley stared at the young inventor a moment, seemed about to say something, and then changed his mind.
"Hold fast, everybody!" suddenly called Tom. The next moment the M. N. 1 began behaving in a most peculiar manner.
She appeared to be acting like a corkscrew. While her bow was comparatively steady, her stern described a circle in the water which was churned to mud by the two propellers, each being revolved in a different direction.
"I'm trying to make the hole bigger just as an amateur carpenter makes a nail hole bigger, so he can pull out the nail, by twisting it around," explained Tom. "The motion may be a bit unpleasant, but it is needful."
And indeed the motion was unpleasant. Tom, veteran airman and sailor that he was, began to feel a trifle seasick, and Mr. Hardley was in very evident distress.
Suddenly, however, something happened. The M. N. 1 gave a lurch to one side and then shot upward so quickly that Ned and Mr. Damon lost their balance and slumped over on the bench that ran around three sides of the room.
"Are we free?" cried Mr. Hardley.
"We have come loose from the mud bank," said Tom quietly. "By boring into it the hole was enlarged sufficiently to enable us to pull loose. There is no more danger!"
His announcement was received in momentary silence, and then Ned exclaimed:
"Hurray!"
"Bless my accident policy!" voiced Mr. Damon.
Mr. Hardley appeared dazed, and then, as the submarine was again moving through the water, seemingly none the worse for the accident, the gold seeker approached Tom Swift.
"I want to apologize, Mr. Swift, for my actions and words," said Mr. Hardley frankly. "I admit that I lost my head. But it's my first trip in a submarine."
"I realize that," said Tom, equally frank, "and we'll forget all about it. It was a strain on you—on all of us—though there really was no very great danger. Now, are you game enough to continue the trip?"
"Try me!" exclaimed the adventurer. "You won't find me acting so like a baby again."
Nor did he, even when the craft reached the open ocean and went down to a considerable depth, where, had any accident occurred, there would have been grave danger to all. But Mr. Hardley seemed to enjoy it.
"Maybe I've misjudged him," Tom said to Ned, when they were getting ready to go back.
"It's possible," agreed the financial manager. This trial, which so nearly ended disastrously, was only one of several. No damage resulted from the collision with the river mud bank, and that trip and the ones following gave Tom some new ideas in interior construction which he followed out.
About a month later all was ready for the trip to the West Indies to look for the ill-fated Pandora. Tom's affairs were put in shape, the submarine was laden with stores and provisions, the new diving bell and other wonderful apparatus were put aboard, and the crew and officers picked. Ned, Mr. Damon, Koku, and Tom were, of course, together, and though Mr. Hardley was a stranger, he seemed to become more friendly as the days passed.
"Well, we start in the morning," said Tom to Ned one evening. "I'm going over to tell Mary goodbye."
"Give her my regards," requested Ned, and Tom said he would.