at the rate of
fifteen hundred revolutions a minute. When operated at full speed the
airship was capable of making eighty miles an hour, against a moderate
wind.

But if the use of the peculiarly-shaped planes and the gas container,
with the secret but powerful vapor in it were something new in airship
construction, so was the car in which the operator and travelers were
to live during a voyage. It was a complete living room, with the engine
and other apparatus, including that for generating the gas, in a
separate compartment, and the whole was the combined work of Tom and
Mr. Sharp. There were accommodations for five persons, with sleeping
berths, a small galley or kitchen, where food could be prepared, and
several easy chairs where the travelers could rest in comfort while
skimming along high in the air, as fast as the fastest railroad train.

There was room enough to carry stores for a voyage of a week or more,
and enough gas could be manufactured aboard the ship, in addition to
that taken in the aluminum case before starting, to sustain the ship
for two weeks. The engine, steering apparatus, and the gas machine were
within easy reach and control of the pilot, who was to be stationed in
a small room in the "bow" of the ship. An electric stove served to warm
the interior of the car, and also provided means for cooking the food.

The airship could be launched either by starting it along the ground,
on rubber-tired wheels, as is done in the case of the ordinary
aeroplane, or it could be lifted by the gas, just as is done with a
balloon. In short there were many novel features about the ship.

The gas test, which took place a few days later, showed that the young
inventor and Mr. Sharp had made no mistake this time. No explosion
followed, the needle valve controlling the powerful vapor perfectly.

"Well," remarked Mr. Sharp, one afternoon, "I think we shall put the
ship together next week, Tom, and have a trial flight. We shall need a
few more aluminum bolts, though, and if you don't mind you might jump
on your motor-cycle and run to Mansburg for them. Merton's machine shop
ought to have some."

Mansburg was the nearest large city to Shopton, and Merton was a
machinist who frequently did work for Mr. Swift.

"All right," agreed Tom. "I'll start now. How many will you need?"

"Oh, a couple of dozen."

Tom started off, wheeling his cycle from the shed where it was kept.
As he passed the building where the big fr