Surprise, for the moment, held Mr. Damon, Ned and Lieutenant Marbury speechless. They looked from the heaving waters of the ocean below them to the young pilot of the Mars. He smiled at their astonishment.
"What—what does it mean, Tom?" asked Ned. "You never said you were going to take a trip as far as this."
"That's right," chimed in Mr. Damon. "Bless my nightcap! If I had known I was going to be brought so far away from home I'd never have come."
"You're not so very far from Waterford," put in Tom. "We didn't make any kind of speed coming from Shopton, and we could be back again inside of four hours if we had to."
"Then you didn't travel fast during the night?" asked the government man.
"No, we just drifted along," Tom answered. "I gave orders to run the machinery slowly, as I wanted to get it in good shape for the other tests that will come soon. But I told George, whom I left in charge when I turned in, to head for New York. I wanted to get out over the ocean to try the guns with the new recoil arrangement."
"Well, we're over the ocean all right," spoke Ned, as he looked down at the heaving waters.
"It isn't the first time," replied Tom cheerfully. "Koku, you may serve breakfast now," for the giant had been taken along as a sort of cook and waiter. Koku manifested no surprise or alarm when he found the airship floating over the sea. Whatever Tom did was right to him. He had great confidence in his master.
"No, it isn't the first time we've taken a water flight," spoke Ned. "I was only surprised at the suddenness of it, that's all."
"It's my first experience so far out above the water," observed Lieutenant Marbury, "though of course I've sailed on many seas. Why, we're out of sight of land."
"About ten miles out, yes," admitted Tom. "Far enough to make it safe to test the guns with real projectiles. That is what I want to do."
"And we've been running all night?" asked Mr. Damon.
"Yes, but at slow speed. The engines are in better shape now than ever before," Tom said. "Well, if you're ready we'll have breakfast."
The meal was served by Koku with as much unconcern as though they were in the Swift homestead back in Shopton, instead of floating near the clouds. And while it was being eaten in the main cabin, and while the crew was having breakfast in their quarters, the aerial warship was moving along over the ocean in charge of George Watson, one of Tom's engineers, who was stationed in the forward pilot-house.
"So you're going to give the guns a real test this time, is that it, Tom?" asked Ned, as he pushed back his plate, a signal that he had eaten enough.
"That's about it."
"But don't you think it's a bit risky out over the water this way. Supposing something should—should happen?" Ned hesitated.
"You mean we might fall?" asked Tom, with a smile.
"Yes; or turn upside down."
"Nothing like that could happen. I'm so sure that I have solved the problem of the recoil of the guns that I'm willing to take chances. But if any of you want to get off the Mars while the test is being made, I have a small boat I can lower, and let you row about in that until—"
"No, thank you!" interrupted Mr. Damon, as he looked below. There was quite a heavy swell on, and the ocean did not appear very attractive. They would be much more comfortable in the big Mars.
"I think you won't have any trouble," asserted Lieutenant Marbury. "I believe Tom Swift has the right idea about the guns, and there will be so small a shock from the recoil that it will not be noticeable."
"We'll soon know," spoke Tom. "I'm going to get ready for the test now."
They were now well out from shore, over the Atlantic, but to make certain no ships would be endangered by the projectiles, Tom and the others searched the waters to the horizon with powerful glasses. Nothing was seen and the work of loading the guns was begun. The bomb tubes, in the main cabin, were also to be given a test.
As service charges were to be used, and as the projectiles were filled with explosives, great care was needed in handling them.
"We'll try dropping bombs first," Tom suggested. "We know they will work, and that will be so much out of the way."
To make the test a severe one, small floating targets were first dropped overboard from the Mars. Then the aerial warship, circling about, came on toward them. Tom, seated at the range-finders, pressed the button that released the shells containing the explosives. One after another they dropped into the sea, exploding as they fell, and sending up a great column of salt water.
"Every one a hit!" reported Lieutenant Marbury, who was keeping "score."
"That's good," responded Tom. "But the others won't be so easy. We have nothing to shoot at."
They had to fire the other guns without targets at which to aim. But, after all, it was the absence of recoil they wanted to establish, and this could be done without shooting at any particular object.
One after another the guns were loaded. As has been explained, they were now made double, one barrel carrying the projectile, and the other a charge of water.
"Are you ready?" asked Tom, when it was time to fire. Lieutenant Marbury, Ned and Mr. Damon were helping, by being stationed at the pressure gauges to note the results.
"All ready," answered Ned.
"Do you think we'd better put on life preservers, Tom?" asked Mr. Damon.
"Nonsense! What for?"
"In case—in case anything happens."
"Nothing will happen. Look out now, I'm going to fire."
The guns were to be fired simultaneously by means of an electric current, when Tom pressed a button.
"Here they go!" exclaimed the young inventor.
There was a moment of waiting, and then came a thundering roar. The Mars trembled, but she did not shift to either side from an even keel. From one barrel of the guns shot out the explosive projectiles, and from the other spurted a jet of water, sent out by a charge of powder, equal in weight to that which forced out the shot.
As the projectile was fired in one direction, and the water in one directly opposite, the two discharges neutralized one another.
Out flew the pointed steel shells, to fall harmlessly into the sea, where they exploded, sending up columns of water.
"Well!" cried Tom as the echoes died away. "How was it?"
"Couldn't have been better," declared Lieutenant Marbury. "There wasn't the least shock of recoil. Tom Swift, you have solved the problem, I do believe! Your aerial warship is a success!"
"I'm glad to hear you say so. There are one or two little things that need changing, but I really think I have about what the United States Government wants."
"I am, also, of that belief, Tom. If only—" The officer stopped suddenly.
"Well?" asked Tom suggestively.
"I was going to say if only those foreign spies don't make trouble."
"I think we've seen the last of them," Tom declared. "Now we'll go on with the tests."
More guns were fired, singly and in batteries, and in each case the Mars stood the test perfectly. The double barrel had solved the recoil problem.
For some little time longer they remained out over the sea, going through some evolutions to test the rudder control, and then as their present object had been accomplished Tom gave orders to head back to Shopton, which place was reached in due time.
"Well, Tom, how was it?" asked Mr. Swift, for though his son had said nothing to his friends about the prospective test, the aged inventor knew about it.
"Successful, Dad, in every particular."
"That's good. I didn't think you could do it. But you did. I tell you it isn't much that can get the best of a Swift!" exclaimed the aged man proudly. "Oh, by the way, Tom, here's a telegram that came while you were gone," and he handed his son the yellow envelope.
Tom ripped it open with a single gesture, and in a flash his eyes took in the words. He read:
"Look out for spies during trial flights."
The message was signed with a name Tom did not recognize.
"Any bad news?" asked Mr. Swift.
"No—oh, no," replied Tom, as he crumpled up the paper and thrust it into his pocket. "No bad news, Dad."
"Well, I'm glad to hear that," went on Mr. Swift. "I don't like telegrams."
When Tom showed the message to Lieutenant Marbury, that official, after one glance at the signature, said:
"Pierson, eh? Well, when he sends out a warning it generally means something."
"Who's Pierson?" asked Tom.
"Head of the Secret Service department that has charge of this airship matter. There must be something in the wind, Tom."
Extra precautions were taken about the shops. Strangers were not permitted to enter, and all future work on the Mars was kept secret. Nevertheless, Tom was worried. He did not want his work to be spoiled just when it was about to be a success. For that it was a success, Lieutenant Marbury assured him. The government man said he would have no hesitation in recommending the purchase of Tom's aerial warship.
"There's just one other test I want to see made," he said.
"What is that?" Tom inquired.
"In a storm. You know we can't always count on having good weather, and I'd like to see how she behaves in a gale."
"You shall!" declared the young inventor.
For the next week, during which finishing touches were put on the big craft, Tom anxiously waited for signs of a storm. At last they came. Danger signals were put up all along the coast, and warnings were sent out broadcast by the Weather Bureau at Washington.
One dull gray morning Tom roused his friends early and announced that the Mars was going up.
"A big storm is headed this way," Tom said, "and we'll have a chance to see how she behaves in it."
And even as the flight began, the forerunning wind and rain came in a gust of fury. Into the midst of it shot the big aerial warship, with her powerful propellers beating the moisture-laden air.
"Say, Tom, are you sure you're all right?"
"Of course I am! What do you mean?"
It was Ned Newton who asked the question, and Tom Swift who answered it. The chums were in the pilot-house of the dipping, swaying Mars, which was nosing her way into the storm, fighting on an upward slant, trying, if possible, to get above the area of atmospheric disturbance.
"Well, I mean are you sure your craft will stand all this straining, pulling and hauling?" went on Ned, as he clung to a brass hand rail, built in the side of the pilot-house wall for the very purpose to which it was now being put.
"If she doesn't stand it she's no good!" cried Tom, as he clung to the steering wheel, which was nearly torn from his hands by the deflections of the rudders.
"Well, it's taking a big chance, it seems to me," went on Ned, as he peered through the rain-spotted bull's-eyes of the pilot-house.
"There's no danger," declared Tom. "I wanted to give the ship the hardest test possible before I formally offered her to the government. If she can't stand a blow like this she isn't what I thought her, and I'll have to build another. But I'm sure she will stand the racket, Ned. She's built strongly, and even if part of the gas bag is carried away, as it was when our propeller shattered, we can still sail. If you think this is anything, wait until we turn about and begin to fight our way against the wind."
"Are you going to do that, Tom?"
"I certainly am. We're going with the gale now, to see what is the highest rate of speed we can attain. Pretty soon I'm going to turn her around, and see if she can make any headway in the other direction. Of course I know she won't make much, if any speed, against the gale; but I must give her that test."
"Well, Tom, you know best, of course," admitted Ned. "But to me it seems like taking a big risk."
And indeed it did seem, not only to Ned, but to some of the experienced men of Tom's crew, that the young inventor was taking more chances than ever before, and Tom, as my old readers well know, had, in his career, taken some big ones.
The storm grew worse as the day progressed, until it was a veritable hurricane of wind and rain. The warnings of the Weather Bureau had not been exaggerated. But through the fierce blow the Mars fought her way. As Tom had said, she was going with the wind. This was comparatively easy. But what would happen when she headed into the storm?
Mr. Damon, in the main cabin, sat and looked at Lieutenant Marbury, the eccentric man now and then blessing something as he happened to think of it.
"Do you—do you think we are in any danger?" he finally asked.
"Not at present," replied the government expert.
"You mean we will be—later?"
"It's hard to say. I guess Tom Swift knows his business, though."
"Bless my accident insurance policy!" murmured Mr. Damon. "I wish I had stayed home. If my wife ever hears of this—" He did not seem able to finish the sentence.
In the engine-room the crew were busy over the various machines. Some of the apparatus was being strained to keep the ship on her course in the powerful wind, and would be under a worse stress when Tom turned his craft about. But, so far, nothing had given way, and everything was working smoothly.
As hour succeeded hour and nothing happened, the timid ones aboard began to take more courage. Tom never for a moment lost heart. He knew what his craft could do, and he had taken her up in a terrific storm with a definite purpose in view. He was the calmest person aboard, with the exception, perhaps, of Koku. The giant did not seem to know what fear was. He depended entirely on Tom, and as long as his young master had charge of matters the giant was content to obey orders.
There was to be no test of the guns this time. They had worked sufficiently well, and, if need be, could have been fired in the gale. But Tom did not want his men to take unnecessary risks, nor was he foolhardy himself.
"We'll have our hands full when we turn around and head into the wind," he said to his chum. "That will be enough."
"Then you're really going to give the Mars that test?"
"I surely am. I don't want any comebacks from Uncle Sam after he accepts my aerial warship. I've guaranteed that she'll stand up and make headway against a gale, and I'm going to prove it."
Lieutenant Marbury was told of the coming trial, and he prepared to take official note of it. While matters were being gotten in readiness Tom turned the wheel over to his assistant pilot and went to the engine-room to see that everything was in good shape to cope with any emergency. The rudders had been carefully examined before the flight was made, to make sure they would not fail, for on them depended the progress of the ship against the powerful wind.
"I rather guess those foreign spies have given up trying to do Tom an injury," remarked Ned to the lieutenant as they sat in the main cabin, listening to the howl of the wind, and the dash of the rain.
"Well, I certainly hope so," was the answer. "But I wouldn't be too sure. The folks in Washington evidently think something is likely to happen, or they wouldn't have sent that warning telegram."
"But we haven't seen anything of the spies," Ned remarked.
"No, but that isn't any sign they are not getting ready to make trouble. This may be the calm before the storm. Tom must still be on the lookout. It isn't as though his inventions alone were in danger, for they would not hesitate to inflict serious personal injury if their plans were thwarted."
"They must be desperate."
"They are. But here comes Tom now. He looks as though something new was about to happen."
"Take care of yourselves now," advised the young aero-inventor, as he entered the cabin, finding it hard work to close the door against the terrific wind pressure.
"Why?" asked Ned.
"Because we are going to turn around and fight our way back against the gale. We may be turned topsy-turvy for a second or two."
"Bless my shoe-horn!" cried Mr. Damon. "Do you mean upside down, Tom?"
"No, not that exactly. But watch out!"
Tom went forward to the pilot-house, followed by Ned and the lieutenant. The latter wanted to take official note of what happened. Tom relieved the man at the wheel, and gradually began to alter the direction of the craft.
At first no change was noticeable. So strong was the force of the wind that it seemed as though the Mars was going in the same direction. But Ned, noticing a direction compass on the wall, saw that the needle was gradually shifting.
"Hold fast!" cried Tom suddenly. Then with a quick shift of the rudder something happened. It seemed as though the Mars was trying to turn over, and slide along on her side, or as if she wanted to turn about and scud before the gale, instead of facing it. But Tom held her to the reverse course.
"Can you get her around?" cried the lieutenant above the roar of the gale.
"I—I'm going to!" muttered Tom through his set teeth.
Inch by inch he fought the big craft through the storm. Inch by inch the indicator showed the turning, until at last the grip of the gale was overcome.
"Now she's headed right into it!" cried Tom in exultation. "She's nosing right into it!"
And the Mars was. There was no doubt of it. She had succeeded, under Tom's direction, in changing squarely about, and was now going against the wind, instead of with it.
"But we can't expect to make much speed," Tom said, as he signaled for more power, for he had lowered it somewhat in making the turn.
But Tom himself scarcely had reckoned on the force of his craft, for as the propellers whirled more rapidly the aerial warship did begin to make headway, and that in the teeth of a terrific wind.
"She's doing it, Tom! She's doing it!" cried Ned exultingly.
"I believe she is," agreed the lieutenant.
"Well, so much the better," Tom said, trying to be calm. "If she can keep this up a little while I'll give her a rest and we'll go up above the storm area, and beat back home."
The Mars, so far, had met every test. Tom had decided on ten minutes more of gale-fighting, when from the tube that communicated with the engine-room came a shrill whistle.
"See what that is, Ned," Tom directed.
"Yes," called Ned into the mouthpiece. "What's the matter?"
"Short circuit in the big motor," was the reply. "We've got to run on storage battery. Send Tom back here! Something queer has happened!"
Ned repeated the message breathlessly.
"Short circuit!" gasped Tom. "Run on storage battery! I'll have to see to that. Take the wheel somebody!"
"Wouldn't it be better to turn about, and run before the wind, so as not to put too great a strain on the machinery?" asked Lieutenant Marbury.
"Perhaps," agreed Tom. "Hold her this way, though, until I see what's wrong!"
Ned and the government man took the wheel, while Tom hurried along the runway leading from the pilot-house to the machinery cabin. The gale was still blowing fiercely.
The young inventor cast a hasty look about the interior of the place as he entered. He sniffed the air suspiciously, and was aware of the odor of burning insulation.
"What happened?" he asked, noting that already the principal motive power was coming from the big storage battery. The shift had been made automatically, when the main motor gave out.
"It's hard to say," was the answer of the chief engineer. "We were running along all right, and we got your word to switch on more power, after the turn. We did that all right, and she was running as smooth as a sewing-machine, when, all of a sudden, she short-circuited, and the storage battery cut in automatically."
"Think you put too heavy a load on the motor?" Tom asked.
"Couldn't have been that. The shunt box would have taken that up, and the circuit-breaker would have worked, saving us a burn-out, and that's what happened—a burn-out. The motor will have to be rewound."
"Well, no use trying to fight this gale with the storage battery," Tom said, after a moment's thought. "We'll run before it. That's the easiest way. Then we'll try to rise above the wind."
He sent the necessary message to the pilot-house. A moment later the shift was made, and once more the Mars was scudding before the storm. Then Tom gave his serious attention to what had happened in the engine room.
As he bent over the burned-out motor, looking at the big shiny connections, he saw something that startled him. With a quick motion Tom Swift picked up a bar of copper. It was hot to the touch—so hot that he dropped it with a cry of pain, though he had let go so quickly that the burn was only momentary.
"What's the matter?" asked Jerry Mound, Tom's engineer.
"Matter!" cried Tom. "A whole lot is the matter! That copper bar is what made the short circuit. It's hot yet from the electric current. How did it fall on the motor connections?"
The engine room force gathered about the young inventor. No one could explain how the copper bar came to be where it was. Certainly no one of Tom's employees had put it there, and it could not have fallen by accident, for the motor connections were protected by a mesh of wire, and a hand would have to be thrust under them to put the bar in place. Tom gave a quick look at his men. He knew he could trust them—every one. But this was a queer happening.
For a moment Tom did not know what to think, and then, as the memory of that warning telegram came to him, he had an idea.
"Were any strangers in this cabin before the start was made?" he asked Mr. Mound.
"Not that I know of," was the answer.
"Well, there may be some here now," Tom said grimly. "Look about."
But a careful search revealed no one. Yet the young inventor was sure the bar of copper, which had done the mischief of short-circuiting the motor, had been put in place deliberately.
In reality there was no danger to the craft, since there was power enough in the storage battery to run it for several hours. But the happening showed Tom he had still to reckon with his enemies.
He looked at the height gauge on the wall of the motor-room, and noted that the Mars was going up. In accordance with Tom's instructions they were sending her above the storm area. Once there, with no gale to fight, they could easily beat their way back to a point above Shopton, and make the best descent possible.
And that was done while, under Tom's direction, his men took the damaged motor apart, with a view to repairing it.
"What was it, Tom?" asked Ned, coming back to join his chum, after George Ventor, the assistant pilot, had taken charge of the wheel.
"I don't exactly know, Ned," was the answer. "But I feel certain that some of my enemies came aboard here and worked this mischief."
"Your enemies came aboard?"
"Yes, and they must be here now. The placing of that copper bar proves it."
"Then let's make a search and find them, Tom. It must be some of those foreign spies."
"Just what I think."
But a more careful search of the craft than the one Tom had casually made revealed the presence of no one. All the crew and helpers were accounted for, and, as they had been in Tom's service for some time, they were beyond suspicion. Yet the fact remained that a seemingly human agency had acted to put the main motor out of commission. Tom could not understand it.
"Well, it sure is queer," observed Ned, as the search came to nothing.
"It's worse than queer," declared Tom, "it's alarming! I don't know when I'll be safe if we have ghosts aboard."
"Ghosts?" repeated Ned.
"Well, when we can't find out who put that bar in place I might as well admit it was a ghost," spoke Tom. "Certainly, if it was done by a man, he didn't jump overboard after doing it, and he isn't here now. It sure is queer!"
Ned agreed with the last statement, at any rate.
In due time the Mars, having fought her way above the storm, came over Shopton, and then, the wind having somewhat died out, she fought her way down, and, after no little trouble, was housed in the hangar.
Tom cautioned his friends and workmen to say nothing to his father about the mysterious happening on board.
"I'll just tell him we had a slight accident, and let it go at that," Tom decided. "No use in causing him worry."
"But what are you going to do about it?" asked Ned.
"I'm going to keep careful watch over the aerial warship, at any rate," declared Tom. "If there's a hidden enemy aboard, I'll starve him out."
Accordingly, a guard, under the direction of Koku, was posted about the big shed, but nothing came of it. No stranger was observed to sneak out of the ship, after it had been deserted by the crew. The mystery seemed deeper than ever.
It took nearly a week to repair the big motor, and, during this time, Tom put some improvements on the airship, and added the finishing touches.
He was getting it ready for the final government test, for the authorities in Washington had sent word that they would have Captain Warner, in addition to Lieutenant Marbury, make the final inspection and write a report.
Meanwhile several little things occurred to annoy Tom. He was besieged with applications from new men who wanted to work, and many of these men seemed to be foreigners. Tom was sure they were either spies of some European nations, or the agents of spies, and they got no further than the outer gate.
But some strangers did manage to sneak into the works, though they were quickly detected and sent about their business. Also, once or twice, small fires were discovered in outbuildings, but they were soon extinguished with little damage. Extra vigilance was the watchword.
"And yet, with all my precautions, they may get me, or damage something," declared Tom. "It is very annoying!"
"It is," agreed Ned, "and we must be doubly on the lookout."
So impressed was Ned with the necessity for caution that he arranged to take his vacation at this time, so as to be on hand to help his chum, if necessary.
The Mars was nearing completion. The repaired motor was better than ever, and everything was in shape for the final test. Mr. Damon was persuaded to go along, and Koku was to be taken, as well as the two government officials.
The night before the trip the guards about the airship shed were doubled, and Tom made two visits to the place before midnight. But there was no alarm.
Consequently, when the Mars started off on her final test, it was thought that all danger from the spies was over.
"She certainly is a beauty," said Captain Warner, as the big craft shot upward. "I shall be interested in seeing how she stands gun fire, though."
"Oh, she'll stand it," declared Lieutenant Marbury. The trip was to consume several days of continuous flying, to test the engines. A large supply of food and ammunition was aboard.
It was after supper of the first day out, and our friends were seated in the main cabin laying out a program for the next day, when sudden yells came from a part of the motor cabin devoted to storage. Koku, who had been sent to get out a barrel of oil, was heard to shout.
"What's up?" asked Tom, starting to his feet. He was answered almost at once by more yells.
"Oh, Master! Come quickly!" cried the giant. "There are many men here. There are stowaways aboard!"
For a moment, after hearing Koku's reply, neither Tom nor his friends spoke. Then Ned, in a dazed sort of way, repeated:
"Stowaways!"
"Bless my—" began Mr. Damon, but that was as far as he got.
From the engine compartment, back of the amidship cabin, came a sound of cries and heavy blows. The yells of Koku could be heard above those of the others.
Then the door of the cabin where Tom Swift and his friends were was suddenly burst open, and seven or eight men threw themselves within. They were led by a man with a small, dark mustache and a little tuft of whiskers on his chin—an imperial. He looked the typical Frenchman, and his words, snapped out, bore out that belief.
What he said was in French, as Tom understood, though he knew little of that language. Also, what the Frenchman said produced an immediate result, for the men following him sprang at our friends with overwhelming fierceness.
Before Tom, Ned, Captain Warner, Mr. Damon or Lieutenant Marbury could grasp any weapon with which to defend themselves, had their intentions been to do so, they were seized.
Against such odds little could be done, though our friends did not give up without a struggle.
"What does this mean?" angrily demanded Tom Swift. "Who are you? What are you doing aboard my craft? Who are—"
His words were lost in smothered tones, for one of his assailants put a heavy cloth over his mouth, and tied it there, gagging him. Another man, with a quick motion, whipped a rope about Tom's hands and feet, and he was soon securely bound.
In like manner the others were treated, and, despite the struggles of Mr. Damon, the two government men and Ned, they were soon put in a position where they could do nothing—helplessly bound, and laid on a bench in the main cabin, staring blankly up at the ceiling. Each one was gagged so effectively that he could not utter more than a faint moan.
Of the riot of thoughts that ran through the heads of each one, I leave you to imagine.
What did it all mean? Where had the strange men come from? What did they mean by thus assaulting Tom and his companions? And what had happened to the others of the crew—Koku, Jerry Mound, the engineer, and George Ventor, the assistant pilot?
These were only a few of the questions Tom asked himself, as he lay there, bound and helpless. Doubtless Mr. Damon and the others were asking themselves similar questions.
One thing was certain—whatever the stowaways, as Koku had called them, had done, they had not neglected the Mars, for she was running along at about the same speed, though in what direction Tom could not tell. He strained to get a view of the compass on the forward wall of the cabin, but he could not see it.
It had been a rough-and-tumble fight, by which our friends were made prisoners, but no one seemed to have been seriously, or even slightly, hurt. The invaders, under the leadership of the Frenchman, were rather ruffled, but that was all.
Pantingly they stood in line, surveying their captives, while the man with the mustache and imperial smiled in a rather superior fashion at the row of bound ones. He spoke in his own tongue to the men, who, with the exception of one, filed out, going, as Tom and the others could note, to the engine-room in the rear.
"I hope I have not had to hurt any of you," the Frenchman observed, with sarcastic politeness. "I regret the necessity that caused me to do this, but, believe me, it was unavoidable."
He spoke with some accent, and Tom at once decided this was the same man who had once approached Eradicate. He also recognized him as the man he had seen in the woods the day of the outing.
"He's one of the foreign spies," thought Tom "and he's got us and the ship, too. They were too many for us!"
Tom's anxiety to speak, to hold some converse with the captor, was so obvious that the Frenchman said:
"I am going to treat you as well as I can under the circumstances. You and your other friends, who are also made prisoners, will be allowed to be together, and then you can talk to your hearts' content."
The other man, who had remained with the evident ringleader of the stowaways, asked a question, in French, and he used the name La Foy.
"Ah!" thought Tom. "This is the leader of the gang that attacked Koku in the shop that night. They have been waiting their chance, and now they have made good. But where did they come from? Could they have boarded us from some other airship?"
Yet, as Tom asked himself that question, he knew it could hardly have been possible. The men must have been in hiding on his own craft, they must have been, as Koku had cried out—stowaways—and have come out at a preconcerted signal to overpower the aviators.
"If you will but have patience a little longer," went on La Foy, for that was evidently the name of the leader, "you will all be together. We are just considering where best to put you so that you will not suffer too much. It is quite a problem to deal with so many prisoners, but we have no choice."
The two Frenchmen conversed rapidly in their own language for a few minutes, and then there came into the cabin another of the men who had helped overpower Tom and his friends. What he told La Foy seemed to give that individual satisfaction, for he smiled.
"We are going to put you all together in the largest storeroom, which is partly empty," La Foy said. "There you will be given food and drink, and treated as well as possible under the circumstances. You will also be unbound, and may converse among yourselves. I need hardly point out," he went on, "that calling for help will be useless. We are a mile or so in the air, and have no intention of descending," and he smiled mockingly.
"They must know how to navigate my aerial warship," thought Tom. "I wonder what their game is, anyhow?"
Night had fallen, but the cabin was aglow with electric lights. The foreigners in charge of the Mars seemed to know their way about perfectly, and how to manage the big craft. By the vibration Tom could tell that the motor was running evenly and well.
"But what happened to the others—to Mound, Ventor and Koku?" wondered Tom.
A moment later several of the foreigners entered. Some of them did not look at all like Frenchmen, and Tom was sure one was a German and another a Russian.
"This will be your prison—for a while," said La Foy significantly, and Tom wondered how long this would be the case. A sharp thought came to him—how long would they be prisoners? Did not some other, and more terrible, fate await them?
As La Foy spoke, he opened a storeroom door that led off from the main, or amidship, cabin. This room was intended to contain the supplies and stores that would be taken on a long voyage. It was one of two, being the larger, and now contained only a few odds and ends of little importance. It made a strong prison, as Tom well knew, having planned it.
One by one, beginning with Tom, the prisoners were taken up and placed in a recumbent position on the floor of the storeroom. Then were brought in the engineer and assistant pilot, as well as Koku and a machinist whom Tom had brought along to help him. Now the young inventor and all his friends were together. It took four men to carry Koku in, the giant being covered with a network of ropes.
"On second thought," said La Foy, as he saw Koku being placed with his friends, "I think we will keep the big man with us. We had trouble enough to subdue him. Carry him back to the engine-room."
So Koku, trussed up like some roped steer, was taken out again.
"Now then," said La Foy to his prisoners, as he stood in the door of the room, "I will unbind one of you, and he may loose the bonds of the others."
As he spoke, he took the rope from Tom's hands, and then, quickly slipping out, locked and barred the door.
For a moment or two, after the ropes binding his hands were loosed, Tom Swift did nothing. He was not only stunned mentally, but the bonds had been pulled so tightly about his wrists that the circulation was impeded, and his cramped muscles required a little time in which to respond.
But presently he felt the tingle of the coursing blood, and he found he could move his arms. He raised them to his head, and then his first care was to remove the pad of cloth that formed a gag over his mouth. Now he could talk.
"I—I'll loosen you all in just a second," he said, as he bent over to pick at the knot of the rope around his legs. His own voice sounded strange to him.
"I don't know what it's all about, any more than you do," he went on, speaking to the others. "It's a fierce game we're up against, and we've got to make the best of it. As soon as we can move, and talk, we'll decide what's best to do. Whoever these fellows are, and I believe they are the foreign spies I've been warned about, they are in complete possession of the airship."
Tom found it no easy matter to loosen the bonds on his feet. The ropes were well tied, and Tom's fingers were stiff from the lack of circulation of blood. But finally he managed to free himself. When he stood up in the dim storeroom, that was now a prison for all save Koku, he found that he could not walk. He almost toppled over, so weak were his legs from the tightness of the ropes. He sat down and worked his muscles until they felt normal again.
A few minutes later, weak and rather tottery, he managed to reach Mr. Damon, whom he first unbound. He realized that Mr. Damon was the oldest of his friends, and, consequently, would suffer most. And it was characteristic of the eccentric gentleman that, as soon as his gag was removed he burst out with:
"Bless my wristlets, Tom! What does it all mean?"
"That's more than I can say, Mr. Damon," replied Tom, with a mournful shake of his head. "I'm very sorry it happened, for it looks as though I hadn't taken proper care. The idea of those men stowing themselves away on board here, and me not knowing it; and then coming out unexpectedly and getting possession of the craft! It doesn't speak very well for my smartness."
"Oh, well, Tom, anyone might have been fooled by those plotting foreigners," said Mr. Damon. "Now, we'll try to turn matters about and get the best of them. Oh, but it feels good to be free once more!"
He stretched his benumbed and stiffened limbs and then helped Tom free the others. They stood up, looking at each other in their dimly lighted prison.
"Well, if this isn't the limit I don't know what is!" cried Ned Newton.
"They got the best of you, Tom," spoke Lieutenant Marbury.
"Are they really foreign spies?" asked Captain Warner.
"Yes," replied his assistant. "They managed to carry out the plot we tried to frustrate. It was a good trick, too, hiding on board, and coming out with a rush."
"Is that what they did?" asked Mr. Damon.
"It looks so," observed Tom. "The attack must have started in the engine-room," he went on, with a look at Mound and Ventor. "What happened there?" he asked.
"Well, that's about the way it was," answered the engineer. "We were working away, making some adjustments, oiling the parts and seeing that everything was running smoothly, when, all at once, I heard Koku yell. He had gone in the oil room. At first I thought something had gone wrong with the ship, but, when I looked at the giant, I saw he was being attacked by four strange men. And, before I, or any of the other men, could do anything, they all swarmed down on us.
"There must have been a dozen of them, and they simply overwhelmed us. One of them hit Koku on the head with an iron bar, and that took all the fight out of the giant, or the story might have been a different one. As it was, we were overpowered, and that's all I know until we were carried in here, and saw you folks all tied up as we were."
"They burst in on us in the same way," Tom explained. "But where did they come from? Where were they hiding?"
"In the oil and gasoline storeroom that opens out of the motor compartment," answered Mound, the engineer. "It isn't half full, you know, and there's room for more than a dozen men in it. They must have gone in some time last night, when the airship was in the hangar, and remained hidden among the boxes and barrels until they got ready to come out and overpower us."
"That's it," decided Tom. "But I don't understand how they got in. The hangar was well guarded all night."
"Some of your men might have been bribed," suggested Ned.
"Yes, that is so," admitted Tom, and, later, he learned that such had been the case. The foreign spies, for such they were, had managed to corrupt one of Tom's trusted employees, who had looked the other way when La Foy and his fellow-conspirators sneaked into the airship shed and secreted themselves.
"Well, discussing how they got on board isn't going to do us any good now," Tom remarked ruefully. "The question is—what are we going to do?"
"Bless my fountain pen!" cried Mr. Damon. "There's only one thing to do!"
"What is that?" asked Ned.
"Why, get out of here, call a policeman, and have these scoundrels arrested. I'll prosecute them! I'll have my lawyer on hand to see that they get the longest terms the statutes call for! Bless my pocketbook, but I will!" and Mr. Damon waxed quite indignant.
"That's easier said than done," observed Tom Swift, quietly. "In the first place, it isn't going to be an easy matter to get out of here."
He looked around the storeroom, which was then their prison. It was illuminated by a single electric light, which showed some boxes and barrels piled in the rear.
"Nothing in them to help us get out," Tom went on, for he knew what the contents were.
"Oh, we'll get out," declared Ned confidently, "but I don't believe we'll find a policeman ready to take our complaint. The upper air isn't very well patrolled as yet."
"That's so," agreed Mr. Damon. "I forgot that we were in an airship. But what is to be done, Tom? We really are captives aboard our own craft."
"Yes, worse luck," returned the young inventor. "I feel foolish when I think how we let them take us prisoners."
"We couldn't help it," Ned commented. "They came on us too suddenly. We didn't have a chance. And they outnumbered us two to one. If they could take care of big Koku, what chance did we have?"
"Very little," said Engineer Mound. "They were desperate fellows. They know something about aircraft, too. For, as soon as Koku, Ventor and I were disposed of, some of them went at the machinery as if they had been used to running it all their lives."
"Oh, the foreigners are experts when it comes to craft of the air," said Captain Warner.
"Well, they seem to be running her, all right," admitted the young inventor, "and at good speed, too. They have increased our running rate, if I am any judge."
"By several miles an hour," confirmed the assistant pilot. "Though in which direction they are heading, and what they are going to do with us is more than I can guess."
"That's so!" agreed Mr. Damon. "What is to become of us? They may heave us overboard into the ocean!"
"Into the ocean!" cried Ned apprehensively. "Are we near the sea?"
"We must be, by this time," spoke Tom. "We were headed in that direction, and we have come almost far enough to put us somewhere over the Atlantic, off the Jersey coast."
A look of apprehension was on the faces of all. But Tom's face did not remain clouded long.
"We won't try to swim until we have to," he said. "Now, let's take an account of stock, and see if we have any means of getting out of this prison."