“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?”