d he's a wonderful mechanic. Knows a lot about gas
engines. I could let you have him--Bower his name is. The only thing
about it, though, is that I don't like to give you a man of whom I am
not dead certain, when you're working on a new device."

"Oh, that will be all right," said Tom. "There won't be any secrets he
can get, if you mean you think he might be up to spy work."

"That's what I did mean, Tom. You never can tell, you know, and you
have some bitter enemies."

"Yes, but I'll take care this man doesn't see the plans, or any of my
drawings. I only want some one to do the heavy assembling work on the
experimental muffler I'm getting up. We can let him think it's for a
new kind of automobile."

"Oh, then I guess it will be all right. I'll send Bower to you."

Tom rather liked the new workman, who seemed quiet and efficient. He
did not ask questions, either, about the machine on which he was
engaged, but did as he was told. As Tom had said, he kept his plans and
drawing under lock and key--in a safe to be exact--and he did not think
they were in any danger from his new helper.

But Tom Swift held into altogether too slight regard the powers of
those who were opposed to him. He did not appreciate the depths to
which they would stoop to gain their ends.

He had been working hard on his new device, and had reached a point
further along than when the other motor had exploded. He began to see
success ahead of him, and he was jubilant. Whether this made him
careless does not matter, but the fact was that he left Bower more to
himself, and alone in the experimental shop several times.

And it was on one of these occasions, when Tom had been for some time
in one of the other shops, where he and Jackson were in consultation
over a new machine, that as he came back to the test room unexpectedly,
he saw Bower move hastily away from in front of the safe. Moreover, Tom
was almost certain he had heard the steel door clang shut as he
approached the building.

And then, before he could ask his helper a question, Tom looked from a
window and saw a stranger running hastily along the side of the
building where his trial motor was being set up.

"Who's that? Who is that man? Did he come in here? Was he tampering
with my safe?" cried Tom. He saw Bower hesitate and change color, and
Tom knew it was time to act.

The window was open, and with one bound the young inventor was out and
running after the stranger he had seen de