"He did?" cried Mr. Nestor.

"That's what he did. Talk about doing your bit—"

"I didn't know that," observed Mary's father slowly. "Do you suppose it's a test of another gas helmet that Tom has asked us out to see to-night?"

"I hardly think so," said Ned. "He wouldn't wait until after dark for that This is something big, and Tom must intend to have it out in the open. He probably waited until after sunset so the neighbors wouldn't come out in flocks. There's been a lot of talk about what is going on in Shop Thirteen, especially since the arrest of the German spies, and the least hint that a test is under way would bring out a big crowd."

"I suppose so," agreed Mr. Nestor. "Well, I'm glad to know that Tom is doing something for Uncle Sam, even if it's only helping with gas helmets. Those Germans are barbarians, if ever there were any, and we've got to fight them the same way they fight us! That's the only way to end the war! Now if I had my way, I'd take every German I could lay my hands on—"

"Father, pretzels!" exclaimed Mary.

"Eh? What's that, my dear?"

"I said pretzels!"

"Oh!" and Mr. Nestor's voice lost its sharpness.

"That's my way of quieting father down when he gets too strenuous in his talk about the war," explained Mary. "We agreed that whenever he got excited I was to say 'pretzels' to him, and that would make him remember. We made up our little scheme after he got into an argument with a man on the train and was carried past his station."

"That's right," admitted Mr. Nestor, with a laugh. "But that fellow was the most obstinate, pig-headed Dutchman that ever tackled a plate of pig's knuckles and sauerkraut, and if he had the least grain of common sense he'd—"

"Pretzels!" cried Mary.

"Eh? Oh, yes, my dear. I was forgetting again."

There was a moment of merriment, and then, after the talk had run for a while in other and safer channels, Mr. Damon made the announcement:

"I think we're about there. We'll be at Tom's place when we make the turn and—"

He was interrupted by a low, heavy rumbling.

"What's that?" asked Mr. Nestor.

"It's getting louder—the noise," remarked Mary. "It sounds as if some big body were approaching down the road—the tramp of many feet. Can it be that troops are marching away?"

"Bless my spark plug!" suddenly cried Mr. Damon. "Look!"

They gazed ahead, and there, seen in the glare of the automobile headlights, was an immense, dark body approaching them from across a level field. The rumble and roar became more pronounced and the ground shook as though from an earthquake.

A glaring light shone out from the ponderous moving body, and above the roar and rattle a voice called:

"Out out of the way! We've lost control! Look out!"

"Bless my steering wheel!" gasped Mr. Damon, "that was Tom Swift's voice! But what is he doing in that—thing?"

"It must be his new invention!" exclaimed Ned.

"What is it?" asked Mr. Nestor.

"A giant," ventured Ned. "It's a giant machine of some sort and—"

"And it's running away!" cried Mr. Damon, as he quickly steered his car to one side—and not a moment too soon! An instant later in a cloud of dust, and with a rumble and a roar as of a dozen express trains fused into one, the runaway giant—of what nature they could only guess—flashed and lumbered by, Tom Swift leaning from an opening in the thick steel side, and shouting something to his friends.



Chapter XI

Tom's Tank

"What was it?" gasped Mary, and, to her surprise, she found herself close to Ned, clutching his arm.

"I have an idea, but I'd rather let Tom tell you," he answered.

"But where's it going?" asked Mr. Nestor. "What in the world does Tom Swift mean by inviting us out here to witness a test, and then nearly running us down under a Juggernaut?"

"Oh, there must be some mistake, I'm sure," returned his daughter. "Tom didn't intend this."

"But, bless my insurance policy, look at that thing go! What in the world is it?" cried Mr. Damon.

The "thing" was certainly going. It had careened from the road, tilted itself down into a ditch and gone on across the fields, lights shooting from it in eccentric fashion.

"Maybe we'd better take after it," suggested Mr. Nestor. "If Tom is—"

"There, it's stopping!" cried Ned. "Come on!"

He sprang from the automobile, helped Mary to get out, and then the two, followed by Mr. Damon and Mr. Nestor, made their way across the fields toward the big object where it had come to a stop, the rumbling and roaring ceasing.

Before the little party reached the strange machine—the "runaway giant," as they dubbed it in their excitement—a bright light flashed from it, a light that illuminated their path right up to the monster. And in the glare of this light they saw Tom Swift stepping out through a steel door in the side of the affair.

"Are you all right?" he called to his friends, as they approached.

"All right, as nearly as we can be when we've been almost scared to death, Tom," said Mr. Nestor.

"I'm surely sorry for what happened," Tom answered, with a relieved laugh. "Part of the steering gear broke and I had to guide it by operating the two motors alternately. It can be worked that way, but it takes a little practice to become expert."

"I should say so!" cried Mr. Damon. "But what in the world does it all mean, Tom Swift? You invite us out to see something—"

"And there she is!" interrupted the young inventor. "You saw her a little before I meant you to, and not under exactly the circumstances I had planned. But there she is!" And he turned as though introducing the metallic monster to his friends.

"What is she, Tom?" asked Ned. "Name it!"

"My latest invention, or rather the invention of my father and myself," answered Tom, and his voice showed the love and reverence he felt for his parent. "Perhaps I should say adaptation instead of invention," Tom went on, "since that is what it is. But, at any rate, it's my latest—dad's and mine—and it's the newest, biggest, most improved and powerful fighting tank that's been turned out of any shop, as far as I can learn.

"Ladies—I mean lady and gentlemen—allow me to present to you War Tank A, and may she rumble till the pride of the Boche is brought low and humble!" cried Tom.

"Hurray! That's what I say!" cheered Ned.

"That's what I have been at work on lately. I'll give you a little history of it, and then you may come inside and have a ride home."

"In that?" cried Mr. Damon.

"Yes. I can't promise to move as speedily as your car, but I can make better time than the British tanks. They go about six miles an hour, I understand, and I've got mine geared to ten. That's one improvement dad and I have made."

"Ride in that!" cried Mr. Nestor. "Tom, I like you, and I'm glad to see I've been mistaken about you. You have been doing your bit, after all; but—"

"Oh, I've only begun!" laughed Tom Swift.

"Well, no matter about that. However much I like you," went on Mr. Nestor, "I'd as soon ride on the wings of a thunderbolt as in Tank A, Tom Swift."

"Oh, it isn't as bad as that!" laughed the young scientist. "But neither is it a limousine. However, come inside, anyhow, and I'll tell you something about it. Then I guess we can guide it back. The men are repairing the break."

The visitors entered the great craft through the door by which Tom had emerged. At first all they saw was a small compartment, with walls of heavy steel, some shelves of the same and a seat which folded up against the wall made of like powerful material.

"This is supposed to be the captain's room, where he stays when he directs matters." Tom explained. "The machinery is below and beyond here."

"How'd you come to evolve this?" asked Ned. "I haven't seen half enough of the outside, to say nothing of the inside."

"You'll have time enough," Tom said. "This is my first completed tank. There are some improvements to be made before we send it to the other side to be copied.

"Then they'll make them in England as well as here, and from here we'll ship them in sections."

"I don't see how you ever thought of it!" exclaimed the girl, in wonder.

"Well, I didn't all at once," Tom answered, with a laugh. "It came by degrees. I first got the idea when I heard of the British tanks.

"When I had read how they went into action and what they accomplished against the barbed wire entanglements, and how they crossed the trenches, I concluded that a bigger tank, one capable of more speed, say ten or twelve miles an hour, and one that could cross bigger excavations—the English tanks up to this time can cross a ditch of twelve feet—I thought that, with one made on such specifications, more effective work could be done against the Germans."

"And will yours do that?" asked Ned. "I mean will it do ten miles an hour, and straddle over a wider ditch than twelve feet?"

"It'll do both," promptly answered Tom. "We did a little better than eleven miles an hour a while ago when I yelled to you to get out of the way just now. It's true we weren't under good control, but the speed had nothing to do with that. And as for going over a big ditch, I think we straddled one about fourteen feet across back there, and we can do better when I get my grippers to working."

"Grippers!" exclaimed Mary.

"What kind of trench slang is that, Tom Swift?" asked Mr. Damon.

"Well, that's a new idea I'm going to try out It's something like this," and while from a distant part of the interior of Tank A came the sound of hammering, the young inventor rapidly drew a rough pencil sketch.

It showed the tank in outline, much as appear the pictures of tanks already in service—the former simile of two wedge-shaped pieces of metal put together broad end to broad end, still holding good. From one end of the tank, as Tom drew it, there extended two long arms of latticed steel construction.

"The idea is," said Tom, "to lay these down in front of the tank, by means of cams and levers operated from inside. If we get to a ditch which we can't climb down into and out again, or bridge with the belt caterpillar wheels, we'll use the grippers. They'll be laid down, taking a grip on the far side of the trench, and we'll slide across on them."

"And leave them there?" asked Mr. Damon.

"No, we won't leave them. We'll pick them up after we have passed over them and use them in front again as we need them. A couple of extra pairs of grippers may be carried for emergencies, but I plan to use the same ones over and over again."

"But what makes it go?" asked Mary. "I don't want all the details, Tom," she said, with a smile, "but I'd like to know what makes your tank move."

"I'll be able to show you in a little while," he answered. "But it may be enough now if I tell you that the main power consists of two big gasolene engines, one on either side. They can be geared to operate together or separately. And these engines turn the endless belts made of broad, steel plates, on which the tank travels. The belts pass along the outer edges of the tank longitudinally, and go around cogged wheels at either end of the blunt noses.

"When both belts travel at the same rate of speed the tank goes in a straight line, though it can be steered from side to side by means of a trailer wheel in the rear. Making one belt—one set of caterpillar wheels, you know—go faster than the other will make the tank travel to one side or the other, the turn being in the direction of the slowest moving belt. In this way we can steer when the trailer wheels are broken."

"And what does your tank do except travel along, not minding a hail of bullets?" asked Mr. Nestor.

"Well," answered Tom, "it can do anything any other tank can do, and then some more. It can demolish a good-sized house or heavy wall, break down big trees, and chew up barbed-wire fences as if they were toothpicks. I'll show you all that in due time. Just now, if the repairs are finished, we can get back on the road—"

At that moment a door leading into the compartment where Tom and his friends were talking opened, and one of the workmen said:

"A man outside asking to see you, Mr. Swift."

"Pardon me, but I won't keep you a moment," interrupted a suave voice. "I happened to observe your tank, and I took the liberty of entering to see—"

"Simpson!" cried Ned Newton, as he recognized the man who had been up the tree. "It's that spy, Simpson, Tom!"



Chapter XII

Bridging a Gap

Such surprise showed both on the face of Ned Newton and that of the man who called himself Walter Simpson that it would be hard to say which was in the greater degree. For a moment the newcomer stood as if he had received all electric shock, and was incapable of motion. Then, as the echoes of Ned's voice died away and the young bank clerk, being the first to recover from the shock, made a motion toward the unwelcome and uninvited intruder, Simpson exclaimed.

"I will not bother now. Some other time will do as well."

Then, with a haste that could be called nothing less than precipitate, he made a turn and fairly shot out of the door by which he had entered the tank.

"There he goes!" cried Mr. Damon. "Bless my speedometer, but there he goes!"

"I'll stop him!" cried Ned. "We've got to find out more about him! I'll get him, Tom!"

Tom Swift was not one to let a friend rush alone into what might be danger. He realized immediately what his chum meant when he called out the identity of the intruder, and, wishing to clear up some of the mystery of which he became aware when Schwen was arrested and the paper showing a correspondence with this Simpson were found, Tom darted out to try to assist in the capture.

"He went this way!" cried Ned, who was visible in the glare of the searchlight that still played its powerful beams over the stern of the tank, if such an ungainly machine can be said to have a bow and stern. "Over this way!"

"I'm with you!" cried Tom. "See if you can pick up that man who just ran out of here!" he cried to the operator of the searchlight in the elevated observation section of what corresponded to the conning tower of a submarine. This was a sort of lookout box on top of the tank, containing, among other machines, the searchlight. "Pick him up!" cried Tom.

The operator flashed the intense white beam, like a finger of light, around in eccentric circles, but though this brought into vivid relief the configuration of the field and road near which the tank was stalled, it showed no running fugitive. Tom and Ned were observed—shadows of black in the glare—by Mary and her friends in the tank, but there was no one else.

"Come on!" cried Ned. "We can find him, Tom!"

But this was easier said than done. Even though they were aided by the bright light, they caught no glimpse of the man who called himself Simpson.

"Guess he got away," said Tom, when he and Ned had circled about and investigated many clumps of bushes, trees, stumps and other barriers that might conceal the fugitive.

"I guess so," agreed Ned. "Unless he's hiding in what we might call a shell crater."

"Hardly that," and Tom smiled. "Though if all goes well the men who operate this tank later may be searching for men in real shell holes."

"Is this one going to the other side?" asked Ned, as the two walked back toward the tank.

"I hope it will be the first of my new machines on the Western front," Tom answered. "But I've still got to perfect it in some details and then take it apart. After that, if it comes up to expectations, we'll begin making them in quantities."

"Did you get him?" asked Mr. Damon eagerly, as the two young men came back to join Mary and her friends.

"No, he got away," Tom answered.

"Did he try to blow up the tank?" asked Mr. Nestor, who had an abnormal fear of explosives. "Was he a German spy?"

"I think he's that, all right," said Ned grimly. "As to his endeavoring to blow up Tom's tank, I believe him capable of it, though he didn't try it to-night—unless he's planted a time bomb somewhere about, Tom."

"Hardly, I guess," answered the young inventor. "He didn't have a chance to do that. Anyhow we won't remain here long. Now, Ned, what about this chap? Is he really the one you saw up in the tree?"

"I not only saw him but I felt him," answered Ned, with a rueful look at his fingers. "He stepped right on me. And when he came inside the tank to-night I knew him at once. I guess he was as surprised to see me as I was to see him."

"But what was his object?" asked Mr. Nestor.

"He must have some connection with my old enemy, Blakeson," answered Tom, "and we know he's mixed up with Schwen. From the looks of him I should say that this Simpson, as he calls himself, is the directing head of the whole business. He looks to be the moneyed man, and the brains of the plotters. Blakeson is smart, in a mechanical way, and Schwen is one of the best machinists I've ever employed. But this Simpson strikes me as being the slick one of the trio."

"But what made him come here, and what did he want?" asked Mary. "Dear me! it's like one of those moving picture plots, only I never saw one with a tank in it before—I mean a tank like yours, Tom."

"Yes, it is a bit like moving picture—especially chasing Simpson by searchlight," agreed the young inventor. "As to what he wanted, I suppose he came to spy out some of my secret inventions—dad's and mine. He's probably been hiding and sneaking around the works ever since we arrested Schwen. Some of my men have reported seeing strangers about, but I have kept Shop Thirteen well guarded.

"However, this fellow may have been waiting outside, and he may have followed the tank when we started off a little while ago for the night test. Then, when he saw our mishap and noticed that we were stalled, he came in, boldly enough, thinking, I suppose, that, as I had never seen him, he would take a chance on getting as much information as he could in a hurry."

"But he didn't count on Ned's being here!" chuckled Mr. Damon.

"No; that's where he slipped a cog," remarked Mr. Nestor. "Well, Tom, I like your tank, what I've seen of her, but it's getting late and I think Mary and I had better be getting back home."

"We'll be ready to start in a little while," Tom said, after a brief consultation with one of his men. "Still, perhaps it would be just as well if you didn't ride back with me. She may go all right, and then, again, she may not. And as it's dark, and we're in a rough part of the field, you might be a bit shaken up. Not that the tank minds it!" the young inventor hastened to add "She's got to do her bit over worse places than this—much worse—but I want to get her in a little better working shape first. So if you don't mind, Mary, I'll postpone your initial trip."

"Oh, I don't mind, Tom! I'm so glad you've made this! I want to see the war ended, and I think machines like this will help."

"I'll ride back with you, Tom, if you don't mind," put in Ned. "I guess a little shaking up won't hurt me."

"All right—stick. We're going to start very soon."

"Well, I'm coming over to-morrow to have a look at it by daylight," said Mr. Damon, as he started toward his car.

"So am I," added Mary. "Please call for me, Mr. Damon."

"I will," he promised.

Mr. Nestor, his daughter, and Mr. Damon went back to the automobile, while Ned remained with Tom. In a little while those in the car heard once more the rumbling and roaring sound and felt the earth tremble. Then, with a flashing of lights, the big, ungainly shape of the tank lifted herself out of the little ditch in which she had come to a halt, and began to climb back to the road.

Ned Newton stood beside Tom in the control tower of the great tank as she started on her homeward way.

"Isn't it wonderful!" murmured Mary, as she saw Tank A lumbering along toward the road. "Oh, and to think that human beings made that To think that Tom should know how to build such a wonderful machine!"

"And run it, too, Mary! That's the point! Make it run!" cried her father. "I tell you, that Tom Swift is a wonder!"

"Bless my dictionary, he sure is!" agreed Mr. Damon.

Along the road, back toward the shop whence it had emerged, rumbled the tank. The noise brought to their doors inhabitants along the country thoroughfare, and some of them were frightened when they saw Tom Swift's latest war machine, the details of which they could only guess at in the darkness.

"She'll butt over a house if it gets in her path, knock down trees, chew up barbed-wire, and climb down into ravines and out again, and go over a good-sized stream without a whimper," said Tom, as he steered the great machine.

There was little chance then for Ned to see much of the inside mechanism of the tank. He observed that Tom, standing in the forward tower, steered it very easily by a small wheel or by a lever, alternately, and that he communicated with the engine room by means of electric signals.

"And she steers by electricity, too," Tom told his friend. "That was one difficulty with the first tanks. They had to be steered by brute force, so to speak, and it was a terrific strain on the man in the tower. Now I can guide this in two ways: by the electric mechanism which swings the trailer wheels to either side, or by varying the speed of the two motors that work the caterpillar belts. So if one breaks down, I have the other."

"Got any guns aboard her—I mean machine guns?" asked Ned.

"Not yet. But I'm going to install some. I wanted to get the tank in proper working order first. The guns are only incidental, though of course they're vitally necessary when she goes into action. I've got 'em all ready to put in. But first I'm going to try the grippers."

"Oh, you mean the gap-bridgers?" asked Ned.

"That's it," answered Tom. "Look out, we're going over a rough spot now."

And they did. Ned was greatly shaken up, and fairly tossed from side to side of the steering tower. For the tank contained no springs, except such as were installed around the most delicate machinery, and it was like riding in a dump cart over a very rough road.

"However, that's part of the game," Tom observed.

Tank A reached her "harbor" safely—in other words, the machine shop enclosed by the high fence, inside of which she had been built.

Tom and Ned made some inquiries of Koku and Eradicate as to whether or not there had been any unusual sights or sounds about the place. They feared Simpson might have come to the shop to try to get possession of important drawings or data.

But all had been quiet, Koku reported Nor had Eradicate seen or heard anything out of the ordinary.

"Then I guess we'll lock up and turn in," decided Tom. "Come over to-morrow, Ned."

"I will," promised the young bank clerk. "I want to see more of what makes the wheels go round." And he laughed at his own ingenuousness.

The next day Tom showed his friends as much as they cared to see about the workings of the tank. They inspected the powerful gasolene engines, saw how they worked the endless belts made of plates of jointed steel, which, running over sprocket wheels, really gave the tank its power by providing great tractive force.

Any self-propelled vehicle depends for its power, either to move itself or to push or to pull, on its tractive force—that is, the grip it can get on the ground.

In the case of a bicycle little tractive power is needed, and this is provided by the rubber tires, which grip the ground. A locomotive depends for its tractive power on its weight pressing on its driving wheels, and the more driving wheels there are and the heavier the locomotive, the more it can pull, though in that case speed is lost. This is why freight locomotives are so heavy and have so many large driving wheels. They pull the engine along, and the cars also, by their weight pressing on the rails.

The endless steel belts of a tank are, the same as the wheels of a locomotive. And the belts, being very broad, which gives them a large surface with which to press on the ground, and the tank being very heavy, great power to advance is thus obtained, though at the sacrifice of speed. However, Tom Swift had made his tank so that it would do about ten miles and more an hour, nearly double the progress obtained up to that time by the British machines.

His visitors saw the great motors, they inspected the compact but not very attractive living quarters of the crew, for provision had to be made for the men to stay in the tank if, perchance, it became stalled in No Man's Land, surrounded by the enemy.

The tank was powerfully armored and would be armed. There were a number of machine guns to be installed, quick-firers of various types, and in addition the tank could carry a number of riflemen.

It was upon the crushing power of the tank, though, that most reliance was placed. Thus it could lead the way for an infantry advance through the enemy's lines, making nothing of barbed wire that would take an artillery fire of several days to cut to pieces.

"And now, Ned," said Tom, about a week after the night test of the tank, "I'm going to try what she'll do in bridging a gap."

"Have you got her in shape again?"

"Yes, everything is all right. I've taken out the weak part in the steering gear that nearly caused us to run you down, and we're safe in that respect now. And I've got the grippers made. It only remains to see whether they're strong enough to bear the weight of my little baby," and Tom affectionately patted the steel sides of Tank A.

While his men were getting the machine ready for a test out on the road, and for a journey across a small stream not far away, Tom told his chum about conceiving the idea for the tank and carrying it out secretly with the aid of his father and certain workmen.

"That's the reason the government exempted me from enlisting," Tom said. "They wanted me to finish this tank. I didn't exactly want to, but I considered it my 'bit.' After this I'm going into the army, Ned."

"Glad to hear it, old man. Maybe by that time I'll have this Liberty Bond work finished, and I'll go with you. We'll have great times together! Have you heard anything more of Simpson, Blakeson and Scoundrels?" And Ned laughed as he named this "firm."

"No," answered Tom. "I guess we scared off that slick German spy."

Once more the tank lumbered out along the road. It was a mighty engine of war, and inside her rode Tom and Ned. Mary and her father had been invited, but the girl could not quite get her courage to the point of accepting, nor did Mr. Nestor care to go. Mr. Damon, however, as might be guessed, was there.

"Bless my monkey wrench, Tom!" cried the eccentric man, as he noted their advance over some rough ground, "are you really going to make this machine cross Tinkle Creek on a bridge of steel you carry with you?"

"I'm going to try, Mr. Damon."

A little later, after a successful test up and down a small gully, Tank A arrived at the edge of Tinkle Creek, a small stream about twenty feet wide, not far from Tom's home. At the point selected for the test the banks were high and steep.

"If she bridges that gap she'll do anything," murmured Ned, as the tank came to a stop on the edge.



Chapter XIII

Into a Trench

Tom cast a hasty glance over the mechanism of the machine before he started to cross the stream by the additional aid of the grippers, or spanners, as he sometimes called this latest device.

Along each side, in a row of sockets, were two long girders of steel, latticed like the main supports of a bridge. They were of peculiar triangular construction, designed to support heavy weights, and each end was broadly flanged to prevent its sinking too deeply into the earth on either side of a gully or a stream.

The grippers also had a sort of clawlike arrangement on either end, working on the principle of an "orange-peel" shovel, and these claws were designed to grip the earth to prevent slipping.

The spanners would be pulled out from their sockets on the side of the tank by means of steel cables, which were operated from within. They would be run out across the gap and fastened in place. The tank was designed to travel along them to the other side of the gap, and, once there, to pick tip the girders, slip them back into place on the sides, and the engine of war would travel on.

"You are mightily excited, Tom.

"I admit it, Ned. You see, I have not tried the grippers out except on a small model. They worked there, but whether they will work in practice remains to be seen. Of course, at this stage, I'm willing to stake my all on the results, but there is always a half-question until the final try-out under practical conditions."

"Well, we'll soon see," said one of the workmen. "Are you ready, Mr. Swift?"

"All ready," answered Tom.

Tank A, as she was officially known, had come to a stop, as has been said, on the very edge of Tinkle Creek. The banks were fairly solid here, and descended precipitously to the water ten feet below. The shores were about twenty feet apart.

"Suppose the spanners break when you're halfway over, Tom?" asked his chum.

"I don't like to suppose anything of the sort. But if they do, we're going down!"

"Can you get up again?"

"That remains to be seen," was the non-committal reply. "Well, here goes, anyhow!"

Going up into the observation tower, which was only slightly raised above the roof of the highest part of the tank, Tom gave the signal for the motors to start. There was a trembling throughout the whole of the vast structure. Tom threw back a lever and Ned, peering from a side observation slot, beheld a strange sight.

Like the main arm of some great steam shovel, two long, latticed girders of steel shot out from the sides of the tank. They gave a half turn, as they were pulled forward by the steel ropes, so that they lay with their broader surfaces uppermost.

Straight across the stream they were pulled, their clawlike ends coming to a rest on the opposite bank. Then they were tightened into place by a backward pull on the operating cables, and Tom, with a sigh of relief, announced:

"Well, so far so good!"

"Do we go over now?" inquired Ned.

"Over the top—yes, I hope," answered Tom, with a laugh. "How about you down there?" he called to the engine room through a telephone which could only be used when the machinery was not in action, there being too much noise to permit the use of any but visual signals after that.

"All right," came back the answer. "We're ready when you are."

"Then here we go!" said Tom. "Hold fast, Ned! Of course there's no real telling what will happen, though I believe we'll come out of it alive."

"Cheerful prospect," murmured Ned.

The grippers were now in place. It only remained for the tank to propel herself over them, pick them up on the other side of Tinkle Creek, and proceed on her course.

Tom Swift hesitated a moment, one hand on the starting lever and the other on the steering wheel. Then, with a glance at Ned, half whimsical and half resolute, Tom started Tank A on what might prove to be her last journey.

Slowly the ponderous caterpillar belts moved around on the sprocket wheels. They ground with a clash of steel on the surface of the spanners. So long was the tank that the forward end, or the "nose," was halfway across the stream before the bottom part of the endless belts gripped the latticed bridge.

"If we fall, we'll span the creek, not fall into it," murmured Ned, as he looked from the observation slot.

"That's what I counted on," Tom said. "We'll get out, even if we do fall."

But Tank A was not destined to fall. In another moment her entire weight rested on the novel and transportable bridge Tom Swift had evolved. Then, as the gripping ends of the girders sank farther into the soil, the tank went on her way.

Slowly, at half speed, she crawled over the steel beams, making progress over the creek and as safely above the water as though on a regularly constructed bridge.

On and on she went. Now her entire weight was over the middle of the temporary structures. If they were going to give way at all, it would be at this point But they did not give. The latticed and triangular steel, than which there is no stronger form of construction, held up the immense weight of Tank A, and on this novel bridge she propelled herself across Tinkle Creek.

"Well, the worst is over," remarked Ned, as he saw the nose of the tank project beyond the farthermost bank.

"Yes, even if they collapse now nothing much can happen," Tom answered. "It won't be any worse than wallowing down into a trench and out again. But I think the spanners will hold."

And hold they did! They held, giving way not a fraction of an inch, until the tank was safely across, and then, after a little delay, due to a jamming of one of the recovery cables, the spanners were picked up, slid into the receiving sockets, and the great war engine was ready to proceed again.

"Hurrah!" cried Ned. "She did it, Tom, old man!" and he clapped his chum resoundingly on the back.

"She certainly did!" was the answer. "But you needn't knock me apart telling me that. Go easy!"

"Bless my apple pie!" cried Mr. Damon, who was as much pleased as either of the boys, "this is what I call great!"

"Yes, she did all that I could have hoped for," said Tom. "Now for the next test."

"Bless my collar button! is there another?"

"Just down into a trench and out again." Tom said. "This is comparatively simple. It's only what she'll have to do every day in Flanders."

The tank waddled on. A duck's sidewise walk is about the only kind of motion that can be compared to it. The going was easier now, for it was across a big field, and Tom told his friends that at the other end was a deep, steep and rocky ravine in which he had decided to give the tank another test.

"We'll imagine that ravine is a trench," he said, "and that we've got to get on the other side of it. Of course, we won't be under fire, as the tanks will be at the front, but aside from that the test will be just as severe."

A little later Tank A brought her occupants to the edge of the "trench."

"Now, little girl," cried Tom exultingly, patting the rough steel side of his tank, "show them what you can do!"

"Bless my plum pudding!" cried Mr. Damon, "are you really going down there, Tom Swift?"

"I am," answered the young inventor. "It won't be dangerous. We'll crawl down and crawl out. Hold fast!"

He steered the machine straight for the edge of the ravine, and as the nose slipped over and the broad steel belts bit into the earth the tank tilted downward at a sickening angle.

She appeared to be making the descent safely, when there was a sudden change. The earth seemed to slip out from under the broad caterpillar belts, and then the tank moved more rapidly.

"Tom, we're turning over!" shouted Ned. "We're capsizing!"



Chapter XIV

The Ruined Factory

Only too true were the words Ned Newton shouted to his chum. Tank A was really capsizing. She had advanced to the edge of the gully and started down it, moving slowly on the caterpillar bands of steel. Then had come a sudden lurch, caused, as they learned afterward, by the slipping off of a great quantity of shale from an underlying shelf of rock.

This made unstable footing for the tank. One side sank lower than the other, and before Tom could neutralize this by speeding up one motor and slowing down the other the tank slowly turned over on its side.

"But she isn't going to stop here!" cried Ned, as he found himself thrown about like a pill in a box. "We're going all the way over!"

"Let her go over!" cried Tom, not that he could stop the tank now. "It won't hurt her. She's built for lust this sort of thing!"

And over Tank A did go. Over and over she rolled, sidewise, tumbling and sliding down the shale sides of the great gully.

"Hold fast! Grab the rings!" cried Tom to his two companions in the tower with him. "That's what they're for!"

Ned and Mr. Damon understood. In fact, the latter had already done as Tom suggested. The young inventor had read that the British tanks frequently turned turtle, and he had this in mind when he made provision in his own for the safety of passengers and crew.

As soon as he felt the tank careening, Tom had pressed the signal ordering the motors stopped, and now only the force of gravity was operating. But that was sufficient to carry the big machine to the bottom of the gulch, whither she slid with a great cloud of sand, shale and dust.

"Bless my—bless my—" Mr. Damon was murmuring, but he was so flopped about, tossed from one side to the other, and it took so much of his attention and strength to hold on to the safety ring, that he could not properly give vent; to one of his favorite expressions.

But there comes an end to all things, even to the descent of a tank, and Tom's big machine soon stopped rolling, sliding, and turning improvised somersaults, and rested in a pile of soft shale at the bottom of the gully. And the tank was resting on her back!

"We've turned turtle!" cried Ned, as he noted that he was standing on what, before, had been the ceiling of the observation tower. But as everything was of steel, and as there was no movable furniture, no great harm was done. In fact, one could as well walk on the ceiling of the tank as on the floor.

"But how are you going to get her right side up?" asked Mr. Damon.

"Oh, turning upside down is only one of the stunts of the game. I can right her," was the answer.

"How?" asked Ned.

"Well, she'll right herself if there's ground enough for the steel belts to get a grip on.

"But can the motors work upside down?"

"They surely can!" responded Tom. "I made 'em that way on purpose. The gasolene feeds by air pressure, and that works standing on its head, as well as any other way. It's going to be a bit awkward for the men to operate the controls, but we won't be this way long. Before I start to right her, though, I want to make sure nothing is broken."

Tom signaled to the engine room, and, as the power was off and the speaking tube could be used, he called through it:

"How are you down there?"

"Right-o!" came back the answer from a little Englishman Tom had hired because he knew something about the British tanks. "'Twas a bit of nastiness for a while, but it won't take us long to get up ag'in."

"That's good!" commented Tom. "I'll come down and have a look at you."

It was no easy matter, with the tank capsized, to get to the main engine room, but Tom Swift managed it. To his delight, aside from a small break in one of the minor machines, which would not interfere with the operation or motive force of the monster war engine, everything was in good shape. There was no leak from the gasolene tanks, which was one of the contingencies Tom feared, and, as he had said, the motors would work upside down as well as right side up, a fact he had proved more than once in his Hawk.

"Well, we'll make a start," he told his chief engineer. "Stand by when I give the signal, and we'll try to crawl out of this right side up."

"How are you going to do it?" asked Ned, as his chum crawled back into the observation tower.

"Well, I'm going to run her part way up the very steepest part of the ravine I can find—the side of a house would do as well if it could stand the strain. I'm going to stand the tank right up on her nose, so to speak, and tip her over so she'll come right again."

Slowly the tank started off, while Tom and his friends in the observation tower anxiously awaited the result of the novel progress. Ned and Mr. Damon clung to the safety rings. Tom put his arm through one and hung on grimly, while he used both hands on the steering apparatus and the controls.

Of course the trailer wheels were useless in a case of this kind, and the tank had to be guided by the two belts run at varying speeds.

"Here we go!" cried Tom, and the tank started. It was a queer sensation to be moving upside down, but it did not last very long. Tom steered the tank straight at the opposite wail of the ravine, where it rose steeply. One of the broad belts ran up on that side. The other was revolved in the opposite direction. Up and up, at a sickening angle, went Tank A.

Slowly the tank careened, turning completely over on her longer axis, until, as Tom shut off the power, he and his friends once more found themselves standing where they belonged—on the floor of the observation tower.

"Right side up with care!" quoted Ned, with a laugh. "Well, that was some stunt—believe me!"

"Bless my corn plaster, I should say so!" cried Mr. Damon.

"Well, I'm glad it happened," commented Tom. "It showed what she can do when she's put to it. Now we'll get out of this ditch."

Slowly the tank lumbered along, proper side up now, the men in the motor room reporting that everything was all right, and that with the exception of a slight unimportant break, no damage had been done.

Straight for the opposite steep side of the gully Tom directed his strange craft, and at a point where the wall of the gulch gave a good footing for the steel belts, Tank A pulled herself out and up to level ground.

"Well, I'm glad that's over," remarked Ned, with a sigh of relief, as the tank waddled along a straight stretch. "And to think of having to do that same thing under heavy fire!"

"That's part of the game," remarked Tom. "And don't forget that we can fire, too—or we'll be able to when I get the guns in place. They'll help to balance the machine better, too, and render her less likely to overturn."

Tom considered the test a satisfactory one and, a little later, guided his tank back to the shop, where men were set to work repairing the little damage done and making some adjustments.

"What's next on the program?" asked Ned of his chum one day about a week later. "Any more tests in view?"

"Yes," answered Tom. "I've got the machine guns in place now. We are going to try them out and also endeavor to demolish a building and some barbed wire. Like to come along?"

"I would!" cried Ned.

A little later the tank was making her way over a field. Tom pointed toward a deserted factory, which had long been partly in ruins, but some of the walls of which still stood.

"I'm going to bombard that," he announced, and then try to batter it down and roll over it like a Juggernaut. Are you game?"

"Do your worst!" laughed Ned. "Let me man one of the machine guns!"

"All right," agreed Tom. "Concentrate your fire. Make believe you're going against the Germans!"

Slowly, but with resistless energy, the tank approached the ruined factory.

"Are you sure there's no one in it, Tom?"

"Sure! Blaze away!"



Chapter XV

Across Country

Ned Newton sighted his machine gun. Tom had showed him how to work it, and indeed the young bank clerk had had some practice with a weapon like this, erected on a stationary tripod. But this was the first time Ned had attempted to fire from the tank while it was moving, and he found it an altogether different matter.

"Say, it sure is hard to aim where you want to!" he shouted across to Tom, it being necessary, even in the conning tower, where this one gun was mounted, to speak loudly to make one's self heard above the hum, the roar and rattle of the machinery in the interior of Tank A, and below and to the rear of the two young men.

"Well, that's part of the game," Tom answered. "I'm sending her along over as smooth ground as I can pick out, but it's rough at best. Still this is nothing to what you'll get in Flanders."

"If I get there!" exclaimed Ned grimly. "Well, here goes!" and once more he tried to aim the machine gun at the middle of the brick wall of the ruined factory.

A moment later there was a rattle and a roar as the quick-firing mechanism started, and a veritable hail of bullets swept out at the masonry. Tom and Ned could see where they struck, knocking off bits of stone, brick and cement.

"Sweep it, Ned! Sweep it!" cried Tom. "Imagine a crowd of Germans are charging out at you, and sweep 'em out of the way!"

Obeying this command, the young man moved the barrel of the machine gun from side to side and slightly up and down. The effect was at once apparent. The wall showed spatter-marks of the bullets over a wider area, and had a body of Teutons been before the factory, or even inside it, many of them would have been accounted for, since there were several holes in the wall through which Ned's bullets sped, carrying potential death with them.

"That's better!" shouted Tom. "That'll do the business! Now I'm going to open her up, Ned!"

"Open her up?" cried the young bank clerk, as he ceased firing.

"Yes; crack the wall of that factory as I would a nut! Watch me take it on high—that is, if the old tank doesn't go back on me!"

"You mean you're going to ride right over that building, Tom?"

"I mean I'm going to try! If Tank A does as I expect her to, she'll butt into that wall, crush it down by force and weight, and then waddle over the ruins. Watch!"

Tom sent some signals to the motor room. At once there was noticed an increase in the vibrations of the ponderous machine.

"They're giving her more speed," said Tom. "And I guess we'll need it."

Straight for the old factory went Tank A. In spite of its ruined condition, some of the walls were still firm, and seemed to offer a big obstacle to even so powerful an engine of war as this monstrous tank.

"Get ready now, Ned," Tom advised. "And when I crack her open for you cut loose with the machine gun again. This gun is supposed to fire straight ahead and a little to either side. There are other guns at left and right, amidships, as I might say, and there's also one in the stern, to take care of any attack from that direction.

"The men in charge of them will fire at the same time you do, and it will be as near like a real attack as we can make it—with the exception of not being fired back at. And I wouldn't mind if such were the case, for I don't believe anything, outside of heavy artillery, will have any effect on this tank."

Tank A was now almost at her maximum speed as she approached closer to the deserted factory. Ned and Tom, in the conning tower, saw the largest of the remaining walls looming before them. Straight at it rushed the ponderous machine, and the next moment there came a shock which almost threw Ned away from his gun and back against the steel wall behind him.

"Hold fast!" cried Tom. "Here we go! Fire. Ned! Fire!"

There was a crash as the blunt nose of the great war tank hit the wall and crumpled it up.

A great hole was made in the masonry, and what was not crushed under the caterpillar belts of the tank fell in a shower of bricks, stone and cement on top of the machine.

Like a great hail storm the broken masonry pelted the steel sides and top of the tank. But she felt them no more than does an alligator the attacks of a colony of ants. Right on through the dust the tank crushed her way. Added to the noise of the falling walls was that of the machine guns, which were barking away like a kennel of angry hounds eager to be unleashed at the quarry.

Ned kept his gun going until the heat of it warned him to stop and let the barrel cool, or he knew he would jam some of the mechanism. The other guns were firing, too, and the bullets sent up little spatter points of dust as they hit.

"Great jumping hoptoads!" yelled Ned above the riot of racket outside and inside. "Feel her go, Tom!"

"Yes, she's just chewing it up, all right!" cried the young inventor, his eyes shining with delight.

The tank had actually burst her way through the solid wall of the old factory, permission to complete the demolition of which Tom had secured from the owners. Then the great machine kept right on. She fairly "walked" over the piles of masonry, dipped down into what had been a basement, now partly filled with debris, and kept on toward another wall.

"I'm going through that, too!" cried Tom.

And he did, knocking it down and sending his tank over the piled-up ruins, while the machine guns barked, coughed and spluttered, as Ned and the others inside the tank held back the firing levers.

Right through the opposite wall, as through the one she had already demolished, the tank careened on her way, to emerge, rather battered and dust-covered, on the other side of what was left of the factory. And there was not much of it left. Tank A had well-nigh completed its demolition.

"If there'd been a nest of Germans in there," said Tom, as he brought the machine to a stop in a field beyond the factory, "they'd have gotten out in a hurry."

"Or taken the consequences," added Ned, as he wiped the sweat from his powder-blackened and oil-smeared face. "I certainly kept my gun going."

"Yes, and so did the others," reported one of the mechanics, as he emerged from the "cubby hole," where the great motors had now ceased their hum and roar.

"How'd she stand it?" asked Tom.

"All right inside," answered the man. "I was wondering how she looks from the outside."

"Oh, it would take more than that to damage her," said Tom, with pardonable pride. "That was pie for her! Solid concrete, which she may have to chew up on the Western front, may present another kind of problem, but I guess she'll be able to master that too. Well, let's have a look."

He and Ned, with some of the crew and gunners, went outside the tank. She was a sorry-looking sight, very different from the trim appearance she had presented when she first left the shop. Bricks, bits of stone, and piles of broken cement in chunks and dust lay thick on her broad back. But no real damage had been done, as a hasty examination showed.

"Well, are you satisfied, Tom?" asked his chum.

"Yes, and more," was the answer. "Of course this wasn't the hardest test to which she could have been submitted, but it will do to show what punishment she can stand. Being shot at from big guns is another matter. I'll have to wait until she gets to Flanders to see what effect that will have. But I know the kind of armor skin she has, and that doesn't worry me. There's one thing more I want to do while I have her out now."

"What's that?" asked Ned.

"Take her for a long trip cross country, and then shove her through some extra heavy barbed wire. I'm certain she'll chew that up, but I want to see it actually done. So now, if you want to come along, Ned, we'll go cross country."

"I'm with you!"

"Get inside then. We'll let the dust and masonry blow and rattle off as we go along."

The tank started off across the fields, which stretched for many miles on either side of the deserted factory, when suddenly Ned, who was again at his post in the observation tower, called:

"Look, Tom!"

"What at?"

"That corner of the factory which is still standing. Look at those men coming out and running away!"

Ned pointed, and his chum, leaning over from the steering wheel and controls, gave a start of surprise as he saw three figures clambering down over the broken debris and making their way out of what had once been a doorway.

"Did they come out of the factory, Ned?"

"They surely did! And unless I miss my guess they were in it, or around it, when we went through like a fellow carrying the football over the line for a touchdown."

"In there when the tank broke open things?"

"I think so. I didn't see them before, but they certainly ran out as we started away."

"This has got to be looked into!" decided Tom. "Come on, Ned! It may be more of that spy business!"

Tom Swift stopped the tank and prepared to get out



Chapter XVI

The Old Barn

"There's no use chasing after 'em, Tom," observed Ned, as the two chums stood side by side outside the tank and gazed after the three men running off across the fields as fast as they could go. "They've got too much a start of us."

"I guess you're right, Ned," agreed Tom. "And we can't very well pursue them in the tank. She goes a bit faster than anything of her build, but a running man is more than a match for her in a short distance. If I had the Hawk here, there'd be a different story to tell."

"Well, seeing that you haven't," replied Ned, "suppose we let them go—which we'll have to, whether we want to or not—and see where they, were hiding and if they left any traces behind."

"That's a good idea," returned Tom.

The place whence the men had emerged was a portion of the old factory farthest removed from the walls the tank had crunched its way through. Consequently, that part was the least damaged.

Tom and Ned came to what seemed to have been the office of the building when the factory was in operation. A door, from which most of the glass had been broken, hung on one hinge, and, pushing this open, the two chums found themselves in a room that bore evidences of having been the bookkeeper's department. There were the remains of cabinet files, and a broken letter press, while in one corner stood a safe.

"Maybe they were cracking that," said Ned.

"They were wasting their time if they were," observed Tom, "for the combination is broken—any one can open it," and he demonstrated this by swinging back one of the heavy doors.

A quantity of papers fell out, or what had been papers, for they were now torn and the edges charred, as if by some recent fire.

"They were burning these!" cried Ned. "You can smell the smoke yet. They came here to destroy some papers, and we surprised them!"

"I believe you're right," agreed Tom. "The ashes are still warm." And he tested them with his hand. "They wanted to destroy something, and when they found we were here they clapped the blazing stuff into the safe, thinking it would burn there.

"But the closing of the doors cut off the supply of air and the fire smouldered and went out. It burned enough so that it didn't leave us very much in the way of evidence, though," went on Tom ruefully, as he poked among the charred scraps.

"Maybe you can read some of 'em," suggested Ned.

"Part of the writing is in German," Tom said, as he looked over the mass. "I don't believe it would be worth while to try it. Still, I can save it. Here, I'll sweep the stuff into a box, and if we get a chance we can try to patch it together," and finding a broken box in what had been the factory office the young inventor managed to get into it the charred remains of the papers.

A further search failed to reveal anything that would be useful in the way of evidence to determine what object the three men could have had in hiding in the ruins, and Tom and Ned returned to the tank.

"What do you think about them, Tom?" asked Ned, as they were about to start off once more for the cross-country test.

"Well, it seems like a silly thing to say—as if I imagined my tank was all there was in this part of the country to make trouble—but I believe those men had some connection with Simpson and with that spy Schwen!"

"I agree with you!" exclaimed Ned. "And I think if we could get head or tail of those burned papers we'd find that there was some correspondence there between the man I saw up the tree and the workman you had arrested."

"Too bad we weren't a bit quicker," commented Tom. "They must have been in the factory when we charged it—probably came there to be in seclusion while they talked, plotted and planned. They must have been afraid to go out when the tank was walking through the walls."

"I guess that's it," agreed Ned. "Did you recognize any of the men, Tom?"

"No, I didn't see 'em as soon as you did, and when they were running they had their backs toward me. Was Simpson one?"

"I can't be sure. If one was, I guess he'll think we are keeping pretty closely after him, and he may give this part of the country a wide berth."

"I hope he does," returned Tom. "Do you know, Ned, I have an idea that these fellows—Schwen Simpson, and those back of them, including Blakeson—are trying to get hold of the secret of my tank for the Germans."

"I shouldn't be surprised. But you've got it finished now, haven't you? They can't get your patents away from you."

"No, it isn't that," said Tom. "There are certain secrets about the mechanism of the tank—the way I've increased the speed and power, the use of the spanners, and things like that—which would be useful for the Germans to know. I wouldn't want them to find out these secrets, and they could do that if they were in the tank a while, or had her in their possession."

"They couldn't do that, Tom—get possession of her—could they?"

"There's no telling. I'm going to be doubly on the watch. That fellow Blakeson is in the pay of the plotters, I believe. He has a big machine shop, and he might try to duplicate my tank if he knew how she was made inside."

"I see! That's why he was inquiring about a good machinist, I suppose, though he'll be mightily surprised when he learns it was you he was talking to the time your Hawk met with the little mishap."

"Yes, I guess maybe he will be a bit startled," agreed Tom. "But I haven't seen him around lately, and maybe he has given up."

"Don't trust to that!" warned Ned.

The tank was now progressing easily along over fields, hesitating not at small or big ditches, flow going uphill and now down, across a stretch of country thinly settled, where even fences were a rarity. When they came to wooden ones Tom had the workmen get out and take down the bars. Of course the tank could have crushed them like toothpicks, but Tom was mindful of the rights of farmers, and a broken fence might mean strayed cows, or the letting of cattle into a field of grain or corn, to the damage of both cattle and fodder.

"There's a barbed-wire fence," observed Ned, as he pointed to one off some distance across the field. "Why don't you try demolishing that?"

"Oh, it would be too easy! Besides, I don't want the bother of putting it up again. When I make the barbed-wire test I want some set up on heavy posts, and with many strands, as it is in Flanders. Even that won't stop the tank, but I'm anxious to see how she breaks up the wire and supports—just what sort of a breach she makes. But I have a different plan in mind now.

"I'm going to try to find a wooden building we can charge as we did the masonry factory. I want to smash up a barn, and I'll have to pick out an old one for choice, for in these war days we must conserve all we can, even old barns."

"What's the idea of using a barn, Tom?"

"Well, I want to test the tank under all sorts of conditions—the same conditions she'll meet with on the Western front. We've proved that a brick and stone factory is no obstacle."

"Then how could a flimsy wooden barn be?"

"Well, that's just it. I don't think that it will, but it may be that a barn when smashed will get tangled up in the endless steel belts, and clog them so they'll jam. That's the reason I want to try a wooden structure next."

"Do you know where to find one?"

"Yes; about a mile from here is one I've had my eyes on ever since I began constructing the tank. I don't know who owns it, but it's such a ramshackle affair that he can't object to having it knocked into kindling wood for him. If he does holler, I can pay him for the damage done. So now for a barn, Ned, unless you're getting tired and want to go back?"

"I should say not! Speaking of barns, I'm with you till the cows come home! Want any more machine gun work?"

"No, I guess not. This barn isn't particularly isolated, and the shooting might scare horses and cattle. We can smash things up without the guns."

The tank was going on smoothly when suddenly there was a lurch to one side, and the great machine quickly swung about in a circle.

"Hello!" cried Ned. "What's up now? Some new stunt?"

"Must be something wrong," answered the young inventor. "One of the belts has stopped working. That's why we're going in a circle."

He shut off the power and hastened down to the motor room. There he found his men gathered about one of the machines.

"What's wrong?" asked Tom quickly.

"Just a little accident," replied the head machinist. "One of the boys dropped his monkey wrench and it smashed some spark plugs. That caused a short circuit and the left hand motor went out of business. We'll have her fixed in a jiffy."

Tom looked relieved, and the machinist was as good as his word. In a few minutes the tank was moving forward again. It crossed out to the road, to the great astonishment of some farmers, and the fright of their horses, and then Tom once more swung her into the fields.

"There's the old barn I spoke of," he remarked to Ned. "It's almost as bad a ruin as the factory was. But we'll have a go at it."

"Going to smash it?" asked Ned.

"I'm going right through it!" Tom cried



Chapter XVII

Veiled Threats

Like some prehistoric monster about to charge down upon another of its kind, Tank A, under the guidance of Tom Swift, reeled and bumped her way over the uneven fields toward the old barn. Within the monster of steel and iron were raucous noises: the clang and clatter of the powerful gasolene motors; the rattle of the wheels and gears; all making so much noise that, in the engine room proper, not a word could be heard. Every order had to be given by signs, and Tom sent his electric signals from the conning tower in the same way. When running at full speed, it was almost impossible, even in the tower, which was some distance removed from the engine room, to hear voices unless the words were shouted.

"Why don't you go at it?" cried Ned to his "friend, who was peering through the observation slot in the tower."

"I'm getting in good position," Tom answered. "Or rather, the worst position I can find. I want to give the tank a good try-out, and I'm going at the barn on the assumption that this is in enemy country and that I can't pick and choose my advance.

"So I want to come up through that gully, and go at the barn from the long way. That will be the worst possible way I could do it, and if old Tank A stands the gaff I'll know she's a little bit nearer all right."

"I think she's all right as she is!" asserted Ned in a yell, for just then Tom signaled for more speed, and the consequent increase in the rattling and banging noises made it correspondingly difficult for talk to be heard.

The big machine now tipped into the little gully spoken of by Tom. This meant a dip downward, and then a climb out again and an attack on the barn going uphill and at an angle. But, as the young inventor had said, it would make a severe test and that was what he wanted to give his ponderous machine.

Ned grasped one of the safety rings, as, with a reel to one side, almost as if it were going to capsize, the tank rumbled on. Tom cast a half-amused smile at his chum, and then threw over the guiding lever.

The tank rolled down into the gully. It was rough and filled with stones and boulders, some of considerable size. But Tank A made less than nothing even of the largest rocks. Some she crushed beneath her steel belts. Others she simply "walked" over, smashing them down into the soil.

Now the big machine reached the bottom of the gulch and started up the sides, which, though not as steep as the trench in which she had capsized, still were not easy going.

"Now for it!" cried Tom, as he signaled for full speed.

Up climbed the tank. Now she was halfway. A moment later, and she was at the top, and then a forward careening motion told that she had passed over the summit and was ready for the attack proper.

Ned gave a quick glance through the slot nearest him. He had a glimpse of the barn, and then he saw something else. This was the sight of a man running away from the dilapidated structure—a man who glanced toward the tank with a face that showed great fright.

"Stop! Stop!" yelled Ned. "There may be folks in there, Tom! I just saw a man run out!"

"All right!" Tom cried, though Ned could hardly hear him. "Tell me when we get on the other side! We're going through now!"

"But," shouted Ned, "don't you understand? I saw a man come out of there! Maybe there's more inside! Wait, Tom, and—"

But it was too late. The next instant there was a smashing, grinding, splintering crash, a noise as of a thunder-clap, and Tank A fairly ate her way through the old barn as a rat might eat his way into a soft cheese, only infinitely more quickly.

On and on and through and through went the tank, knocking beams, boards, rafters and timbers hither and thither. Minding not at all the weight of great beams on her back, caring nothing for those that got in the way of her steel belts, heeding not the wall of wood that reared itself before her in a barrier of splinters and slivers, Tank A went on and on until finally, with another grinding crash, as she smashed her way through the farthermost wall, the great engine of war emerged on the other side and came panting into the field, dragging with her a part of the structure clinging to her steel sides.

"Well," cried Tom, with a laugh, as he signaled for the power to be shut off, thereby making it possible for ordinary conversation to be heard, "I guess we didn't do a thing to that barn!"

"Not much left of it, for a fact, Tom," agreed Ned, as he looked through the after observation slots at the ruin in the rear. "But didn't you hear what I was saying?"

"I heard you yelling something to me, but I was too anxious to go at it as fast as I could. I didn't want to stop then. What was the trouble?"

"That's what I'm afraid of, Tom—there may be trouble. Just before you tackled the barn for a knockdown, instead of a touchdown, as we might say, I saw a man running out of it. I thought if there was one there, perhaps there might be more. That's why I yelled to you."

"A man running from the old barn!" cried Tom. "Whew!" he whistled. "I wish I had seen him. But, Ned, if one ran out of harm's way, any others who might possibly be in there would do the same thing, wouldn't they?"

"I hope so," returned Ned doubtfully.

"Great Scott!" cried Tom, as the possibility was borne home to him. "If anything has happened—"

He sprang for the door of the tower and threw over the catch, springing out, followed by Ned. From the engine room of the armored tank the men came, smiles of gratification on their faces.

"We certainly busted her wide open, Mr. Swift!" called the chief mechanician.

"Yes," assented the young inventor; but there was not as much gratification in his voice as there should have been. "There isn't much of a barn left, but Ned thinks he saw some one run out, and if there was one man there may have been more. We'd better have a look around, I guess."

The engineering force exchanged glances. Then Hank Baldwin, who was in charge of the motors, said:

"Well, if there was anybody in that barn when we chewed her up I wouldn't give much for his hide, German or not."

"Let us hope no one was in there," murmured Tom.

They turned to go back to the demolished structure, fear and worry in their hearts. No more complete ruin could be imagined. If a cyclone had swept over the barn it could not have more certainly leveled it. And, not only was it leveled, crushed down in the center by the great weight of the tank, but the boards and beams were broken into small pieces. Parts of them clung in long, grotesque splinters to the endless steel belts.

"I don't see how we're going to find anybody if he's in there," remarked Hank.

"We'll have to," insisted Tom. "We can look about and call. If any one is there he may have been off to one side or to one end, and be protected under the debris. I wish I had heard you call, Ned."

"I wish you had, Tom. I yelled for all I was worth."

"I know you did. I was too eager to go on, and, at the same time, I really couldn't stop well on that hill. I had to keep on going. Well, now to learn the worst!"

They walked back toward the demolished barn. But they had not reached it when from around the corner swung a big automobile. In it were several men, but chief, in vision at least, among them, was a burly farmer who had a long, old-fashioned gun in his hands. On his bearded face was a grim look as he leaped out before the machine had fairly stopped, and called:

"Hold on, there! I guess you've done damage enough! Now you can pay for it or take the consequences!" And he motioned to Tom, Ned, and the others to halt.



Chapter XVIII

Ready for France

Such was the reaction following the crashing through of the barn, coupled with the sudden appearance of the men in the automobile and the threat of the farmer, that, for the moment, Tom, Ned, or their companions from the tank could say nothing. They just stood staring at the farmer with the gun, while he grimly regarded them. It was Tom who spoke first.

"What's the idea?" asked the young inventor. "Why don't you want us to look through the ruins?"

"You'll learn soon enough!" was the grim answer.

But Tom was not to be put off with undecided talk.

"If there's been an accident," he said, "we're sorry for it. But delay may be dangerous. If some one is hurt—"

"You'll be hurt, if I have my way about it!" snapped the farmer, "and hurt in a place where it always tells. I mean your pocketbook! That's the kind of a man I am—practical."

"He means if we've killed or injured any one we'll have to pay damages," whispered Ned to Tom. "But don't agree to anything until you see your lawyer. That's a hot one, though, trying to claim damages before he knows who's hurt!"

"I've got to find out more about this," Tom answered. He started to walk on.

"No you don't!" cried the farmer, with a snarl. "As I said, you folks has done damage enough with your threshing machine, or whatever you call it. Now you've got to pay!"

"We are willing to," said Tom, as courteously as he could. "But first we want to know who has been hurt, or possibly killed. Don't you think it best to get them to a doctor, and then talk about money damages later?"

"Doctor? Hurt?" cried the farmer, the other men in the auto saying nothing. "Who said anything about that?"

"I thought," began Tom, "that you—"

"I'm talkin' about damages to my barn!" cried the farmer. "You had no right to go smashing it up this way, and you've got to pay for it, or my name ain't Amos Kanker!"

"Oh!" and there was great relief in Tom's voice. "Then we haven't killed any one?"

"I don't know what you've done," answered the farmer, and his voice was not a pleasant one. "I'm sure I can't keep track of all your ructions. All I know is that you've ruined my barn, and you've got to pay for it, and pay good, too!"

"For that old ramshackle?" cried Ned.

"Hush!" begged Tom, in a low voice. "I'm willing to pay, Ned, for the sake of having proved what my tank could do. I'm only too glad to learn no one was hurt. Was there?" he asked, turning to the farmer.

"Was there what?"

"Was there anybody in your barn?"

"Not as I knows on," was the grouchy answer. "A man who saw your machine coming thought she was headed for my building, and he run and told me. Then some friends of mine brought me here in their machine. I tell you I've got all the evidence I need ag'in you, an' I'm going to have damages! That barn was worth three thousand dollars if it was worth a cent, and—"

"This matter can easily be settled," said Tom, trying to keep his temper. "My name is Swift, and—"

"Don't get swift with me, that's all I ask!" and the farmer laughed grimly at his clumsy joke.

"I'll do whatever is right," Tom said, with dignity. "I live over near Shopton, and if you want to send your lawyer to see mine, why—"

"I don't believe in lawyers!" broke in the farmer. "All they think of is to get what they can for theirselves. And I can do that myself. I'll get it out of you before you leave, or, anyhow, before you take your contraption away," and he glanced at the tank.

The same suspicion came at once to Tom and Ned, and the latter gave voice to it when he murmured in a low voice to his chum:

"This is a frame-up—a scheme, Tom. He doesn't care a rap for the barn. It's some of that Blakeson's doing, to make trouble for you."

"I believe you!" agreed Tom. "Now I know what to do."

He looked toward the collapsed barn, as if making a mental computation of its value, and then turned toward the farmer.

"I'm very sorry," said Tom, "if I have caused any trouble. I wanted to test my machine out on a wooden structure, and I picked your barn. I suppose I should have come to you first, but I did not want to waste time. I saw the barn was of practically no value."

"No value!" broke in the farmer. "Well, I'll show you, young man, that you can't play fast and loose with other people's property and not settle!"

"I'm perfectly willing to, Mr. Kanker. I could see that the barn was almost ready to fall, and I had already determined, before sending my tank through it, to pay the owner any reasonable sum. I am willing to do that now."

"Well, of course if you're so ready to do that," replied the farmer, and Ned thought he caught a glance pass between him and one of the men in the auto, "if you're ready to do that, just hand over three thousand dollars, and we'll call it a day's work. It's really worth more, but I'll say three thousand for a quick settlement."

"Why, this barn," cried Ned, "isn't worth half that! I know something about real estate values, for our bank makes loans on farms around here—"

"Your bank ain't made me no loans, young man!" snapped Mr. Kanker. "I don't need none. My place is free and clear! And three thousand dollars is the price of my barn you've knocked to smithereens. If you don't want to pay, I'll find a way to make you. And I'll hold you, or your tank, as you call it, security for my damages! You can take your choice about that."

"You can't hold us!" cried Tom. "Such things aren't done here!"

"Well, then, I'll hold your tank!" cried the farmer. "I guess it'll sell for pretty nigh onto what you owe me, though what it's good for I can't see. So you pay me three thousand dollars or leave your machine here as security."

"That's the game!" whispered Ned. "There's some plot here. They want to get possession of your tank, Tom, and they've seized on this chance to do it."

"I believe you," agreed the young inventor. "Well, they'll find that two can play at that game. Mr. Kanker," he went on, "it is out of the question to claim your barn is worth three thousand dollars."

"Oh, is it?" sneered the farmer. "Well, I didn't ask you to come here and make kindling wood of it! That was your doings, and you've had your fun out of it. Now you can pay the piper, and I'm here to make you pay!" And he brought the gun around in a menacing manner.

"He's right, in a way," said Ned to his chum. "We should have secured his permission first. He's got us in a corner, and almost any jury of farmers around here, after they heard the story of the smashed barn, would give him heavy damages. It isn't so much that the barn is worth that as it is his property rights that we've violated. A farmer's barn is his castle, so to speak."

"I guess you're right," agreed Tom, with a rather rueful face. "But I'm not going to hand him over three thousand dollars. In fact, I haven't that much with me."

"Oh, well, I don't suppose he'd want it all in cash."

But, it appeared, that was just what the farmer wanted. He went over all his arguments again, and it could not be denied that he had the law on his side. As he rightly said, Tom could not expect to go about the country, "smashing up barns and such like," without being willing to pay.

"Well, what you going to do?" asked the farmer at last. "I can't stay here all day. I've got work to do. I can't go around smashing barns. I want three thousand dollars, or I'll hold your contraption for security."

This last he announced with more conviction after he had had a talk with one of the men in the automobile. And it was this consultation that confirmed Tom and Ned in their belief that the whole thing was a plot, growing out of Tom's rather reckless destruction of the barn; a plot on the part of Blakeson and his gang. That they had so speedily taken advantage of this situation carelessly given them was only another evidence of how closely they were on Tom's trail.

"That man who ran out of the barn must have been the same one who was in the factory," whispered Ned to his chum. "He probably saw us coming this way and ran on ahead to have the farmer all primed in readiness. Maybe he knew you had planned to ram the barn."

"Maybe he did. I've had it in mind for some time, and spoken to some of my men about it."

"More traitors in camp, then, I'm afraid, Tom. We'll have to do some more detective work. But let's get this thing settled. He only wants to hold your tank, and that will give the man, into whose hands he's playing, a chance to inspect her."

"I believe you. But if I have to leave her here I'll leave some men on guard inside. It won't be any worse than being stalled in No Man's Land. In fact, it won't be so bad. But I'll do that rather than be gouged."

"No, Tom, you won't. If you did leave some one on guard, there'd be too much chance of their getting the best of him. You must take your tank away with you."

"But how can I? I can't put up three thousand dollars in cash, and he says he won't take a check for fear I'll stop payment. I see his game, but I don't see how to block it."

"But I do!" cried Ned.

"What!" exclaimed Tom. "You don't mean to say, even if you do work in a bank, that you've got three thousand in cash concealed about your person, do you?"

"Pretty nearly, Tom, or what is just as good. I have that amount in Liberty Bonds. I was going to deliver them to a customer who has ordered them but not paid for them. They are charged up against me at the bank, but I'm good for that, I guess. Now I'll loan you these bonds, and you can give them to this cranky old farmer as security for damages. Mind, don't make them as a payment. They're simply security—the same as when an autoist leaves his car as bail. Only we don't want to leave our car, we'd rather have it with us," and he looked over at the tank, bristling with splinters from the demolished barn.

"Well, I guess that's the only way out," said Tom. "Lucky you had those bonds with you. I'll take them, and give you a receipt for them. In fact, I'll buy them from you and let the farmer hold them as security."

And this, eventually, was done. After much hemming and hawing and consultation with the men in the automobile, Mr. Kanker said he would accept the bonds. It was made clear that they were not in payment of any damages, though Tom admitted he was liable for some, but that Uncle Sam's war securities were only a sort of bail, given to indicate that, some time later, when a jury had passed on the matter, the young inventor would pay Mr. Kanker whatever sum was agreed upon as just.

"And now," said Tom, as politely as he could under the circumstances, "I suppose we will be allowed to depart."

"Yes, take your old shebang offen my property!" ordered Mr. Kanker, with no very good grace. "And if you go knocking down any more barns, I'll double the price on you!"

"I guess he's a bit roiled because he couldn't hold the tank," observed Ned to Tom, as they walked together to the big machine. "His friends—our enemies—evidently hoped that was what could be done. They want to get at some of the secrets."

"I suppose so," conceded Tom. "Well, we're out of that, and I've proved all I want to."

"But I haven't—quite," said Ned.

"What's missing?" asked his chum, as they got back in the tank.

"Well, I'd like to make sure that the fellow who ran from the factory was the same one I saw sneaking out of the barn. I believe he was, and I believe that Simpson's crowd engineered this whole thing."

"I believe so, too," Tom agreed. "The next thing is to prove it. But that will keep until later. The main thing is we've got our tank, and now I'm going to get her ready for France."

"Will she be in shape to ship soon?" asked Ned.

"Yes, if nothing more happens. I've got a few little changes and adjustments to make, and then she'll be ready for the last test—one of long distance endurance mainly. After that, apart she comes to go to the front, and we'll begin making 'em in quantities here and on the other side."

"Good!" cried Ned. "Down with the Huns!"

Without further incident of moment they went back to the headquarters of the tank, and soon the great machine was safe in the shop where she had been made.

The next two weeks were busy ones for Tom, and in them he put the finishing touches on his machine, gave it a long test over fields and through woods, until finally he announced:

"She's as complete as I can make her! She's ready for France!"



Chapter XIX

Tom is Missing

With Tom Swift's announcement, that his tank was at last ready for real action, came the end of the long nights and days given over on the part of his father, himself, and his men to the development and refinement of the machine, to getting plans and specifications ready so that the tanks could be made quickly and in large numbers in this country and abroad and to the actual building of Tank A. Now all this was done at last, and the first completed tank was ready to be shipped.

Meanwhile the matter of the demolished barn had been left for legal action. Tom and Ned, it developed, had done the proper thing under the circumstances, and they were sure they had foiled at least one plan of the plotters.

"But they won't stop there," declared Ned, who had constituted himself a sort of detective. "They're lying back and waiting for another chance, Tom."

"Well, they won't get it at my tank!" declared the young inventor, with a smile. "I've finished testing her on the road. All I need do now is to run her around this place if I have to; and there won't be much need of that before she's taken apart for shipment. Did you get any trace of Simpson or the men who are with him—Blakeson and the others?"

"No," Ned answered. "I've been nosing around about that farmer, Kanker, but I can't get anything out of him. For all that, I'm sure he was egged on to his hold-up game by some of your enemies. Everything points that way."

"I think you're right," agreed Tom. "Well, we won't bother any more about him. When the trial comes on, I'll pay what the jury says is right. It'll be worth it, for I proved that Tank A can eat up brick, stone or wooden buildings and not get indigestion. That's what I set out to do. So don't worry any more about it, Ned."

"I'm not worrying, but I'd like to get the best of those fellows. The idea of asking three thousand dollars for a shell of a barn!"

"Never mind," replied Tom. "We'll come out all right."

Now that the Liberty Loan drive had somewhat slackened, Ned had more leisure time, and he spent parts of his days and not a few of his evenings at Tom Swift's. Mr. Damon was also a frequent visitor, and he never tired of viewing the tank. Every chance he got, when they tested the big machine in the large field, so well fenced in, the eccentric man was on hand, with his "bless my—!" whatever happened to come most readily to his mind.

Tom, now that his invention was well-nigh perfected, was not so worried about not having the tank seen, even at close range, and the enclosure was not so strictly guarded.

This in a measure was disappointing to Eradicate, who liked the importance of strutting about with a nickel shield pinned to his coat, to show that he was a member of the Swift & Company plant. As for the giant Koku, he really cared little what he did, so long as he pleased Tom, for whom he had an affection that never changed. Koku would as soon sit under a shady tree doing nothing as watch for spies or traitors, of whose identity he was never sure.

So it came that there was not so strict a guard about the place, and Tom and Ned had more time to themselves. Not that the young inventor was not busy, for the details of shipping Tank A to France came to him, as did also the arrangements for making others in this country and planning for the manufacture abroad.

It was one evening, after a particularly hard day's work, when Tom had been making a test in turning the tank in a small space in the enclosed yard, that the two young men were sitting in the machine shop, discussing various matters.

The telephone bell rang, and Ned, being nearest, answered.

"It's for you, Tom," he said, and there was a smile on the face of the young bank clerk.

"Um!" murmured Tom, and he smiled also.

Ned could not repress more smiles as Tom took up the conversation over the wire, and it did not take long for the chum of the youthful inventor to verify his guess that Mary Nestor was at the other end of the instrument.

"Yes, yes," Tom was heard to say. "Why, of course, I'll be glad to come over. Yes, he's here. What? Bring him along? I will if he'll come. Oh, tell him Helen is there! 'Nough said! He'll come, all right!"

And Tom, without troubling to consult his friend, hung up the receiver.

"What's that you're committing me to?" asked Ned.

"Oh, Mary wants us to come over and spend the evening. Helen Sever is there, and they say we can take them downtown if we like."

"I guess we like," laughed Ned. "Come along! We've had enough of musty old problems," for he had been helping Tom in some calculations regarding strength of materials and the weight-bearing power of triangularly constructed girders as compared to the arched variety.

"Yes, I guess it will do us good to get out," and the two friends were soon on their way.

"What's this?" asked Mary, with a laugh, as Tom held out a package tied with pink string. "More dynamite?" she added, referring to an incident which had once greatly perturbed the excitable Mr. Nestor.

"If she doesn't want it, perhaps Helen will take it," suggested Ned, with a twinkle in his eyes. "Halloran said they were just in fresh—"

"Oh, you delightful boy!" cried Helen. "I'm just dying for some chocolates! Let me open them, Mary, if you're afraid of dynamite."

"The only powder in them," said Tom, "is the powdered sugar. That can't blow you up."

And then the young people made merry, Tom, for the time being, forgetting all about his tank.

It was rather late when the two young men strolled back toward the Swift home, Ned walking that way with his chum. Tom started out in the direction of the building where the tank was housed.

"Going to have a good-night look at her?" asked Ned.

"Well, I want to make sure the watchman is on guard. We'll begin taking her apart in a few days, and I don't want anything to happen between now and then."

They walked on toward the big structure, and, as they approached from the side, they were both startled to see a dark shadow—at least so it seemed to the youths—dart away from one of the windows.

"Look!" gasped Ned.

"Hello, there!" cried Tom sharply. "Who's that? Who are you?"

There was no answer, and then the fleeing shadow was merged in the other blackness of the night.

"Maybe it was the watchman making his rounds," suggested Ned.

"No," answered Tom, as he broke into a run. "If it was, he'd have answered. There's something wrong here!"

But he could find nothing when he reached the window from which he and Ned had seen the shadow dart. An examination by means of a pocket electric light betrayed nothing wrong with the sash, and if there were footprints beneath the casement they indicated nothing, for that side of the factory was one frequently used by the workmen.

Tom went into the building, and, for a time, could not find the watchman. When he did come upon the man, he found him rubbing his eyes sleepily, and acting as though he had just awakened from a nap.

"This isn't any way to be on duty!" said Tom sharply. "You're not paid for sleeping!"

"I know it, Mr. Swift," was the apologetic answer. "I don't know what's come over me to-night. I never felt so sleepy in all my life. I had my usual sleep this afternoon, too, and I've drunk strong coffee to keep awake."