in Europe, and if ever
the United States needed aircraft on the western front they need them
now. I want to help all I can, and I also want to help Mary--you
understand--Miss Nestor."

"I understand," said Jackson simply. "I only hope you can help her. But
I'm afraid--this may turn out to be nothing--following these marks, you
know."

"And yet," said Tom slowly, "it would be strange if it was only a
coincidence--the two tire marks being the same--the night Mr. Nestor
disappeared and now."

And so they kept on, hoping.

The half-defined path through the wood-lot led them in a series of
turns and twists, and it extended through a dense patch of woods,
growing thickly, where it was so dark that it seemed as if night had
fallen.

"We can't spend much more time here," said Tom. "If we don't find
something in the next half mile we'll go back and take up the search
to-morrow. I'm going to find out what's at the end of this road--even
if it's only a wood pile."

For ten minutes more the two went on, making sure, by occasional
glimpses at the marks, that they were on the right track. Then,
suddenly, they saw something which made them feel sure they had reached
their goal.

In a clearing among the trees was a little cabin--a shack of logs--and
from the appearance it was deserted. There was not a sign of life
around.

CHAPTER XXII

CLEWS AT LAST

For a moment, at sight of the deserted cabin, staring at Tom and his
friend, as it were, from its hiding place amid the trees, the young
inventor and his companion did not move. They just stood looking at the
place.

"Well," said Tom, at length, "we found it, didn't we?"

"We found something anyhow," agreed Jackson. "Whether it amounts to
anything or not, we've got to see."

"Come on!" cried Tom, impulsively. "I'm going to see what's there."

"There doesn't appear to be much of anything," said Jackson, as he
looked toward the lonely cabin with critical eyes. "I should say that
place hadn't been used, even as a chicken coop, in a long while."

"We can soon tell!" exclaimed Tom, striding forward.

"Wait just a minute!" cried his companion, catching him by the coat.
"Don't be in such a hurry."

"Why not?" asked Tom. "There isn't any danger, is there?"

"I don't know about that. There's no telling who may be hidden in that
cabin, in spite of its deserted appearance. And though there aren't any
'No Trespass' signs up, it may be that we wouldn't be welcome. If