on the road the time we made the forced landing the first night we
tried out the silent motor. That's it! They are the same marks! I'm
sure of it!"

"I wouldn't go so far as to say that," said Jackson slowly. He was more
deliberate than Tom Swift, a fact for which the young inventor was
often glad, as it saved him from impulsive mistakes.

"This may not be the same auto," went on the mechanician. "I'll admit I
never saw square tire marks like those before. Most of the usual ones
are circular, diamond-shape or oblong. Some tire manufacturer must have
tried a new stunt. But as for saying these marks were made by the same
machine you saw evidences of the night Mr. Nestor disappeared, why,
that's going a little too far, Tom."

"Yes, I suppose it is," admitted the young inventor. "But it's a clew
worth following. Maybe Mr. Nestor has been brought to some lonely place
like this, and is being held."

"Why would any one want to do that?" asked Jackson. "He had no enemies.

"Well, perhaps those who ran him down and injured him are afraid to let
him go for fear he will prosecute them and ask for heavy damages,"
suggested Tom. "They may be holding him a captive until he gets well,
and aim on treating him so nicely that he won't bring suit."

"That's a pretty far-fetched theory," said the mechanician as he
carefully looked at the tracks. "But of course it may be true. Anyhow,
these tire marks are rather recent, I should say, and they are made by
a new tire. Do you think we can follow them?"

"I'm going to try!" declared Tom. "The only trouble is we can't tell
whether it was going or coming--that is we don't know which way to go."

"That's so," agreed his companion. "And so the only thing to do is to
travel a bit both ways. The path, or road, or whatever you call it, is
plainly enough marked here, though you can't always pick out the tire
marks. They show only on bare ground. The grass doesn't leave any
tracks that we can see, though doubtless they are there.

"But as for thinking this car is the same one the marks of which you
saw on the lonely moor, the night you heard the call for help--that's
going too far, Tom Swift."

"Yes, I realize that. Of course there must be more than one car with
tires which have square protuberances. But it's worth taking a chance
on--following this clew."

"Oh, sure!" agreed Jackson.

"The only question is, then, which way to go," returned Tom.

They settled that, arbitrarily enough, by