“Well, say, that’s the limit!” cried Ned, as Tom finished reading.  “What do you know about that?”

“It brings it right home to us,” agreed the young inventor.  “But who is there in Shopton who would be in league with the smugglers?”

“That’s hard to say.”

“Of course we don’t know everyone in town,” went on Tom, “but I’m pretty well acquainted here, and I don’t know of a person who would dare engage in such work.”

“Maybe it’s a stranger who came here, and picked out this place because it was so quiet,” suggested Ned.

“That’s possible.  But where would he operate from?” asked Tom.  “There are few in Shopton who would want to buy smuggled goods.”

“They may only ship them here, and fix them so they can’t be recognized by the custom authorities, and then send them away again,” went on Ned.  “This may be a sort of clearing-house for the smugglers.”

“That’s so.  Well, I don’t know as we have anything to do with it.  Only if those fellows are using an airship I’d like to know what kind it is.  Well, come on out to the shop now, and we’ll see how the silent motor works.”

On the way Tom passed his father, and, telling him not to work too hard in the sun, gave his parent the piece of paper to read, telling about the smugglers.

“Using airships! eh?” exclaimed Mr. Swift.  “And they think there’s a clew here in Shopton?  Well, we’ll get celebrated if we keep on, Tom,” he added with a smile.

Tom and Ned spent the rest of the day working over the motor, which was set going, and bore out all Tom claimed for it.  It was as silent as a watch.

“Next I want to get it in the airship, and give it a good test,” Tom remarked, speeding it up, as it was connected on a heavy base in the shop.

“I’ll help you,” promised Ned, and for the next few days the chums were kept busy fitting the silent motor into one of Tom’s several airships.

“Well, I think we can make a flight to-morrow,” said the young inventor, about a week later.  “I need some new bolts though, Ned.  Let’s take a walk into town and get them.  Oh, by the way, have you seen anything more of Andy Foger?”

“No. and I don’t want to.  I suppose he’s gone back home after his visit to Sam.  Let’s go down the street, where the Foger house is, and see if there’s anything going on.”

As the two lads passed the mansion, they saw a man, in the kind of suit usually worn by a carpenter, come out of the back door and stand looking across the garden.  In his hand he held a saw.

“Still at the repairs, I guess,” remarked Ned.  “I wonder what—­”

“Look there!  Look!  Quick!” suddenly interrupted Tom, and Ned, looking, saw someone standing behind the carpenter in the door.  “If that isn’t Andy Foger, I’ll eat my hat!” cried Tom.

“It sure is,” agreed Ned.  “What in the world is he doing there?”

But his question was not answered, for, a moment later, Andy turned, and went inside, and the carpenter followed, closing the door behind them.