"GOOD!" cried Tom admiringly. "You're coming right along in your
detective training. How do you make that out?"

"See here, where a piece of rubber has been broken or cut out of the
tire. It makes a peculiar mark in the dirt every time the wheel goes
around."

"That's right, and it will be a good thing to trace the carriage by.
Come on, we'll keep right after it."

"Hold on a bit," suggested Ned, who, though not so quick as Tom Swift,
frequently produced good results by his very slowness. "Are you going
off and leave the airship here for some one to walk off with?"

"Guess they wouldn't take it far," replied the young inventor, "but I'd
better make it safe. I'll disconnect it so they can't start it, though
if Andy Foger happens to come along he might slash the planes just out
of spite. But I guess he won't show up."

Tom took a connecting pin out of the electrical apparatus, making it
impossible to start the aeroplane, and then, wheeling it out of sight
behind a small barn, he and Ned went back to the carriage marks in the
road.

"Hurry!" urged Tom, as he started off in the direction of the village of
Hurdtown, near where the cottage stood. "We will ask people living along
the highway if they've seen a carriage pass."

"But what makes you think they went off that way?" asked Ned. "I should