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 be 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 tonight. 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."

"Are you sure you didn't drink anything else?"

"You know I'm a strict temperance man."

"I know you are," said Tom; "but I thought maybe you might have a cold, or something like that."

"No, I haven't taken a thing. I did have a drink of soda water before I came on duty, but that's all."

"Where'd you get it?" asked Tom.

"Well, a man treated me."

"Who?"

"I don't know his name. He met me on the street and asked me how to get to Plowden's hardware store. I showed him-- walked part of the way, in fact--and when I left he said he was going to have some soda, and asked me to have some. I did, and it tasted good."

"Well, don't go to sleep again," suggested Tom good- naturedly. "Did you hear anything at the side window a while ago?"

"Not a thing, Mr. Swift. I'll be all right now. I'll take a turn outside in the air."

"All right," assented the young inventor.

Then, as he turned to go into the house and was bidding Ned good-night, Tom said:

"I don't like this."

"What?" asked his chum.

"My sleepy watchman and the figure at the window. I more than half suspect that one of Blakeson's tools followed Kent for the purpose of buying him soda, only I think they might have put a drop or two of chloral in it before he got it. That would make him sleep."

"What are you going to do, Tom?"

"Put another man on guard. If they think they can get into the factory at night, and steal my plans, or get ideas from my tank, I'll fool 'em. I'll have another man on guard."

This Tom did, also telling Koku to sleep in the place, to be ready if called. But there was no disturbance that night, and the next day the work of completing the tank went on with a rush,

It was a day or so after this, and Tom had fixed on it as the time for taking the big machine apart for shipment, that Ned received a telephone message at the bank from Mr. Damon.

"Is Tom Swift over with you?" inquired the eccentric man.

"No. Why?" Ned answered.

"Well, I'm at his shop, and he isn't here. His father says he received a message from you a little while ago, saying to come over in a hurry, and he went. Says you told him to meet you out at that farmer Kanker's place. I thought maybe--"

"At Kanker's place!" cried Ned. "Say, something's wrong, Mr. Damon! Isn't Tom there?"

"No; I'm at his home, and he's been gone for some time. His father supposed he was with you. I thought I would telephone to make sure."

"Whew!" whistled Ned. "There's something doing here, all right, and something wrong! I'll be right over!" he added, as he hung up the receiver.