of two dollars and a half a mile--pretty expensive riding. But if
you are in earnest I will let you have the machine for fifty
dollars, and then I fear that I will be taking advantage of you."

"I'll give you fifty dollars," said Tom quickly, and Mr. Damon
exclaimed:

"Bless my liver--that is, if I have one. Do you mean it?"

Tom nodded. "I'll fetch you the money right away," he said, starting
for his room. He got the cash from a small safe he had arranged,
which was fitted up with an ingenious burglar alarm, and was on his
way downstairs when he heard his father call out:

"Here! What do you want? Go away from that shop! No one is allowed
there!" and looking from an upper window, Tom saw his father running
toward a stranger, who was just stepping inside the shop where Mr.
Swift was constructing his turbine motor. Tom started as he saw that
the stranger was the same black-mustached man whom he had noticed in
the post-office, and, later, in the restaurant at Mansburg.




CHAPTER V.

MR. SWIFT IS ALARMED


Stuffing the money which he intended to give to Mr. Damon in his