smuggling, and--"

"Smuggling!" interrupted Ned.

"Yes, over from Canada. Maybe you have seen something in the papers about our department thinking airships were used at night to slip the goods over the border."

"We saw it!" cried Tom eagerly. "But how does that concern me?"

"I'll come to that, presently," replied Mr. Whitford. "In the first place, we have been roundly laughed at in some papers for proposing such a theory. And yet it isn't so wild as it sounds. In fact, after seeing your airship, Tom Swift, I'm convinced--"

"That I've been smuggling?" asked Tom with a laugh.

"Not at all. As you have read, we confiscated some smuggled goods the other day, and among them was a scrap of paper with the words Shopton, New York, on it."

"Was it a letter from someone here, or to someone here?" asked Ned. "The papers intimated so."

"No. they only guessed at that part of it. It was just a scrap of paper, evidently torn from a letter, and it only had those three words on it. Naturally we agents thought we could get a clew here. We imagined, or at least I did, for I was sent to work up this end, that perhaps the airships for the smugglers were made here. I made inquiries, and found that you, Tom Swift, and one other, Andy Foger, had made, or owned, airships in Shopton."

"I came here, but I soon exhausted the possibility of Andy Foger making practical airships. Besides he isn't at home here any more, and he has no facilities for constructing the craft as you have. So I came to look at your place, and I must say that it looks a bit suspicious, Mr. Swift. Though, of course, as I said," he added with a smile, "you may be able to explain everything."

"I think I can convince you that I had no part in the smuggling," spoke Tom, laughing. "I never sell my airships. If you like you may talk with my father, the housekeeper, and others who can testify that since my return from taking moving pictures, I have not been out of town, and the smuggling has been going on only a little while."

"That is true," assented the custom officer. "I shall be glad to listen to any evidence you may offer. This is a very baffling case. The government is losing thousands of dollars every month, and we can't seem to stop the smugglers, or get much of a clew to them. This one is the best we have had so far."

It did not take Tom many hours to prove to the satisfaction of Mr. Whitford that none of our hero's airships had taken any part in cheating Uncle Sam out of custom duties.

"Well, I don't know what to make of it," said the government agent, with a disappointed air, as he left the office of the Shopton chief of police, who, with others, at Tom's request, had testified in his favor. "This looked like a good clew, and now it's knocked into a cocked hat. There's no use bothering that Foger fellow," he went on, "for he has but one airship, I understand."

"And that's not much good." put in Ned. "I guess it's partly wrecked, and Andy has kept it out in the barn since he moved away."

"Well, I guess I'll be leaving town then," went on the agent. "I can't get any more clews here, and there may be some new ones found on the Canadian border where my colleagues are trying to catch the rascals. I'm sorry I bothered you, Tom Swift. You certainly have a fine lot of airships," he added, for he had been taken through the shop, and shown the latest, noiseless model. "A fine lot. I don't believe the smugglers, if they use them, have any better."

"Nor as good!" exclaimed Ned. "Tom's can't be beat."

"It's too late for our noiseless trial now," remarked Tom, after the agent had gone. "Let's put her back in the shed, and then I'll take you down street, and treat you to some ice cream, Ned. It's getting quite summery now."

As the boys were coming out of the drug store, where they had eaten their ice cream in the form of sundaes, Ned uttered a cry of surprise at the sight of a man approaching them.

"It's Mr. Dillon, the carpenter whom we saw in the Foger house, Tom!" exclaimed his chum. "This is the first chance I've had to talk to him. I'm going to ask him what sort of repairs he's making inside the old mansion." Ned was soon in conversation with him.

"Yes, I'm working at the Foger house," admitted the carpenter, who had done some work for Ned's father. "Mighty queer repairs, too. Something I never did before. If Andy wasn't there to tell me what he wanted done I wouldn't know what to do."

"Is Andy there yet?" asked Tom quickly.

"Yes, he's staying in the old house. All alone too, except now and then, he has a chum stay there nights with him. They get their own meals. I bring the stuff in, as Andy says he's getting up a surprise and doesn't want any of the boys to see him, or ask questions. But they are sure queer repairs I'm doing," and the carpenter scratched his head reflectively.

"What are you doing?" asked Ned boldly.

"Fixing up Andy's old airship that was once busted," was the unexpected answer, "and after I get that done, if I ever do, he wants me to make a platform for it on the roof of the house, where he can start it swooping through the air. Mighty queer repairs, I call 'em. Well, good evening, boys," and the carpenter passed on.

Chapter IV Searching For Smugglers

"Well, of all things!"

"Who in the world would think such a thing?"

"Andy going to start out with his airship again!"

"And going to sail it off the roof of his house!"

These were the alternate expressions that came from Tom and Ned, as they stood gazing at each other after the startling information given them by Mr. Dillon, the carpenter.

"Do you really think he means it?" asked Tom, after a pause, during which they watched the retreating figure of the carpenter. "Maybe he was fooling us."

"No, Mr. Dillon seldom jokes," replied Ned, "and when he does, you can always tell. He goes to our church, and I know he wouldn't deliberately tell an untruth. Oh. Andy's up to some game all right."

"I thought he must be hanging around here the way he has been, instead of being home. But I admit I may have been wrong about the police being after him. If he'd done something wrong, he would hardly hire a man to work on the house while he was hiding in it. I guess he just wants to keep out of the way of everybody but his own particular cronies. But I wonder what he is up to, anyhow; getting his airship in shape again?"

"Give it up, unless there's an aero meet on somewhere soon," replied Ned. "Maybe he's going to try a race again."

Tom shook his head.

"I'd have heard about any aviation meets, if there were any scheduled," he replied. "I belong to the national association, and they send out circulars whenever there are to be races. None are on for this season. No, Andy has some other game."

"Well, I don't know that it concerns us," spoke Ned.

"Not as long as he doesn't bother me," answered the young inventor. "Well, Ned, I suppose you'll be over in the morning and help me try out the noiseless airship?"

"Sure thing. Say, it was queer, about that government agent, wasn't it? suspecting you of supplying airships to the smugglers?"

"Rather odd," agreed Tom. "He might much better suspect Andy Foger."

"That's so, and now that we know Andy is rebuilding his old airship, maybe we'd better tell him."

"Tell who?"

"That government agent. Tell him he's wrong in thinking that Andy is out of the game. We might send him word that we just learned that Andy is getting active again. He has as much right to suspect and question him, as he had you."

"Oh, I don't know," began Tom slowly. He was not a vindicative youth, nor, for that matter, was Ned. And Tom would not go out of his way to give information about an enemy, when it was not certain that the said enemy meant anything wrong. "I don't believe there's anything in it," finished our hero. "Andy may have a lot of time on his hands, and, for want of something better to do, he's