The man suddenly turned, and gave a shrill whistle.  Instantly, from the hut, came several men who had been in the motor boat.  One or two of them had weapons.

“I guess you’d better go now,” said the first man sharply.  “You’re not in the United States now, you know.”

“It’s easy to see that, by the politeness of the residents of this section,” put in Tom.

“None of your back talk!  Get away from here!” cried the man.  “If you don’t go peaceably—­”

“Oh, we’re going,” interposed Mr. Whitford calmly.  “But that isn’t saying we won’t come back.  Come on, boys.  We’ll get over on Uncle Sam’s territory.”

The group of men stood silently watching them, as they filed back through the woods.

“What do you make of it?” asked Tom of the agent.

“I’m positive that I’m right, and that they’re the smugglers.  But I can’t do anything on this side of the line.  If ever I can catch them across the border, though, there’ll be a different story to tell.”

“What had we better do?” inquired Ned.

“Go back to our airship, and leave for Logansville.  We don’t need to land until night, though, but we can make a slow trip.  Is the gas machine all right again, Tom?”

“Practically so.  If that hadn’t gone back on me we would have had those fellows captured by this time.”

“Never mind.  We did our best.”

It did not take Tom and his chum long to complete the repairs, and soon they arose in the air.

“Let’s take a flight over where those fellows are, just to show them what we can do,” proposed Ned, and Tom and Mr. Whitford agreed to it.  Soon they were circling over the hut.  The launch was just starting out again, when a cry from the man who seemed to be a sort of guard, drew the attention of his confederates to the noiseless airship.

Once more the launch was turned about, and sent back to shore, while those in it shook their fists at Tom and his friends.

“We can play tag with ’em up here!” chuckled Ned.

“There’s the small vessel that pulled up anchor a while ago,” remarked Mr. Whitford, pointing to the vessel which had steamed around a wooded point.  “They thought we had gone for good, and they were getting ready to land the stuff.  Well, we’ll know where to head for next time, when we watch for the smugglers at night.”

Realizing that nothing more could be done, Tom sent his airship toward the camp, just outside of Loganville.  But he did not land until after dark, when, making out the spot by means of the electric lights, which were set aglow automatically at dark, he descended.

“We won’t try anything to-night,” said Mr. Whitford.  “I doubt if the smugglers will themselves, after their experience last night.  I’ll get into town, see some of my men, and come out here to-morrow night again.”

Tom and Ned spent the following day in going carefully over the Falcon, making some slight repairs.  The great searchlight was cleaned and adjusted, and then, as dusk came on once more Tom remarked: