"I left the gas on until all the furniture should be taken out," he explained. "But you will find nothing here."

It needed but a glance about the place to show that only some odds and ends of furniture was all that it contained.

"Where does this door lead to," asked Mr. Whitford, when he had made a tour of the place.

"Nowhere. Oh, that is only down into the cellar." was the reply.

"There is nothing there."

"We can't take anything for granted," went on the agent with a smile. "I'll take a look down there."

He descended with some of his men. Tom and Ned remained in the kitchen of the cottage, while Andy and his father conversed in low tones, occasionally casting glances at our heroes. Once Tom thought Mr. Foger looked apprehensively toward the door, through which the custom men had descended. He also appeared to be anxiously listening.

But when Mr. Whitford came back, with a disappointed look on his face, and said there was nothing to be found, Mr. Foger smiled:

"What did I tell you?" he asked triumphantly.

"Never mind," was the retort of Uncle Sam's man. "We are not through with Shopton yet."

"I'm sorry we gave you so much trouble on a false clew," said Tom, as he and Ned left the Foger premises with Mr. Whitford, the other deputies following.

"That's all right, Tom. We have to follow many false clews. I'm much obliged to you. Either we were on the wrong track, or the Fogers are more clever than I gave them credit for. But I am not done yet. I have something to propose to you. It has come to me in the last few minutes. I saw you in your airship once, and I know you know how to manage such craft. Now there is no question in my mind but what the smugglers are using airships. Tom, will you undertake a mission for Uncle Sam?"

"What do you mean?"

"I mean will you go to the border, in your airship, and try to catch the smugglers? I can promise you a big reward, and much fame if we catch them. An airship is just what is needed. You are the one to do it. Will you?"

CHAPTER VII

A SEARCHLIGHT IS NEEDED

For a few moments after the custom officer had made his appeal, Tom Swift did not reply. His thoughts were busy with many things.

Somehow, it seemed of late, there had been many demands on him, demands that had been hard and trying.

In the past he had not hesitated, but in those cases friendship, as well as a desire for adventures, had urged him. Now he thought he had had his fill of adventures.

"Well?" asked Mr. Whitford, gently. "What's your answer, Tom? Don't you think this is a sort of duty-call to you?"

"A duty-call?" repeated the young inventor.

"Yes. Of course I realize that it isn't like a soldier's call to battle, but Uncle Sam needs you just the same. When there is a war the soldiers are called on to repel an enemy. Now the smugglers are just as much an enemy of the United States, in a certain way, as an armed invader would be."

"One strikes at the life and liberty of the people, while the smugglers try to cheat Uncle Sam out of money that is due him. I'm not going to enter into a discussion as to the right of the government to impose duties. People have their own opinion as to that. But, as long as the law says certain duties are to be collected, it is the duty of every citizen, not only to pay those dues, but to help collect them. That's what I'm asking you to do, Tom."

"I don't want to get prosy, or deliver a lecture on the work of the custom house, Tom, but, honestly, I think it is a duty you owe to your country to help catch these smugglers. I admit I'm at the end of my rope. This last clew has failed. The Fogers seem to be innocent of wrong doing. We need your help, Tom."

"But I don't see how I can help you."

"Of course you can! You're an expert with airships. The smugglers are using airships, of that I'm sure. You tell me you have just perfected a noiseless aircraft. That will be just the thing. You can hover on the border, near the line dividing New York State from Canada, or near the St. Lawrence, which is the natural division for a certain distance, and when you see an airship coming along you can slip up in your noiseless one, overhaul it, and make them submit to a search."

"But I won't have any authority to do that," objected Tom, who really did not care for the commission.

"Oh, I'll see that you get the proper authority all right," said Mr.

Whitford significantly. "I made you a temporary deputy to-night, but if you'll undertake this work, to catch the smugglers in their airships, you will be made a regular custom official."

"Yes, but supposing I can't catch them?" interposed our hero. "They may have very fast airships, and--"

"I guess you'll catch 'em all right!" put in Ned, who was at his chum's side as they walked along a quiet Shopton street in the darkness. "There's not an aeroplane going that can beat yours, Tom."

"Well, perhaps I COULD get them," admitted the young inventor. "But--"

"Then you'll undertake this work for Uncle Sam?" interrupted Mr.

Whitford eagerly. "Come, Tom, I know you will."

"I'm not so sure of that," spoke Tom. "It isn't going to be as easy as you think. There are many difficulties in the way. In the first place the smuggling may be done over such a wide area that it would need a whole fleet of airships to capture even one of the others, for they might choose a most unfrequented place to cross the border."

"Oh, we would be in communication with you," said the agent. "We can come pretty near telling where the contrabrand goods will be shipped from, but the trouble is, after we get our tips, we can't get to the place before they have flown away. But with your airship, you could catch them, after we sent you, say a wireless message, about where to look for them. So that's no objection. You have a wireless outfit on your airships, haven't you, Tom?"

"Yes, that part is all right."

"Then you can't have any more objections, Tom."

"Well, there are some. For instance you say most of this smuggling is done at night."

"Practically all of it, yes."

"Well, it isn't going to be easy to pick out a contraband airship in the dark, and chase it. But I'll tell you what I'll do, Mr.

Whitford, I feel as if I had sort of 'fallen down' on this clew business, as the newspaper men say, and I owe it to you to make good in some way."

"That's what I want--not that I think you haven't done all you could," interposed the agent.

"Well, if I can figure out some way, by which I think I can come anywhere near catching these smugglers, I'll undertake the work!"

exclaimed Tom. "I'll do it as a duty to Uncle Sam, and I don't want any reward except my expenses. It's going to cost considerable, but--"

"Don't mind the expense!" interrupted Mr. Whitford. "Uncle Sam will stand that. Why, the government is losing thousands of dollars every week. It's a big leak, and must be stopped, and you're the one to stop it, Tom."

"Well, I'll try. I'll see you in a couple of days, and let you know if I have formed any plan. Now come on, Ned. I'm tired and want to get to bed."

"So do I," added the agent. "I'll call on you day after to-morrow, Tom, and I expect you to get right on the job," he added with a laugh.

"Have you any idea what you are going to do, Tom?" asked his chum, as they turned toward their houses.

"Not exactly. If I go I'll use my noiseless airship. That will come in handy. But this night business rather stumps me. I don't quite see my way to get around that. Of course I could use an ordinary searchlight, but that doesn't give a bright enough beam, or carry far enough. It's going to be quite a problem and I've got to think it over."

"Queer about the Fogers; wasn't it, Tom?"