ut no
such alarming report circulated in Shopton. In fact having made some
inquiries that day of Ned, he learned that no trace had been seen of
the mysterious men. The police had been on the lookout, but they had
seen nothing of them.

"Maybe, after all, they weren't the same ones," suggested Ned, when he
paid Tom another visit the next night.

"Well, of course it's possible that they weren't," admitted the young
inventor. "I'd be very glad to think so. Even if they were, your
encounter with them may have scared them off; and that would be a good
thing."

The next two weeks were busy ones for Tom and Mr. Sharp. Aided
occasionally by Mr. Swift, and with Garret Jackson, the engineer, to
lend a hand whenever needed, the aeronaut and the owner of the speedy
Arrow made considerable progress on their airship.

"What is your father so busy over?" asked Mr. Sharp one day, when the
new aluminum gas holder was about completed.

"I don't know," answered Tom, with a somewhat puzzled air. "He doesn't
seem to want to talk about it, even to me. He says it will
revolutionize travel along a certain line, but whether he is working on
an airship that will rival ours, or a new automobile, I can't make out.
He'll tell us in good time. But when do you think we will finish
the--well, I don't know what to call it--I mean our aeroplane?"

"Oh, in about a month now. That's so, though, we haven't a name for it.
But we'll christen it after it's completed. Now if you'll tighten up
some of those bolts I'll get the gas generating apparatus in readiness
for another test."

A short description of the new airship may not be out of place now. It
was built after plans Mr. Sharp had shown to Tom and his father soon
after the thrilling rescue of the aeronaut from the blazing balloon
over Lake Carlopa. The general idea of the airship was that of the
familiar aeroplane, but in addition to the sustaining surfaces of the
planes, there was an aluminum, cigar-shaped tank, holding a new and
very powerful gas, which would serve to keep the ship afloat even when
not in motion.

Two sets of planes, one above the other, were used, bringing the
airship into the biplane class. There were also two large propellers,
one in front and the other at the rear. These were carefully made, of
different layers of wood "built up" as they are called, to make them
stronger. They were eight feet in diameter, and driven by a
twenty-cylinder, air-cooled, motor, whirled around