s there is no reason why a crew
of four or five could not run nights as well as days, two operating
while the others sleep in the hammocks. Cold foods can be cooked or
warmed up on the gas-stove when needed, and the enclosed cabin protects
all hands from the worst effects of bad storms."

"Wouldn't this glass break in a hailstorm?" asked Mr. Giddings. "It
seems to be pretty thin."

"It is thin," said Paul; "that is to give it lightness. It might check
some in a hailstorm, but it could not break out, as it is made of two
layers of glass between which is cemented a thin sheet of celluloid."

"I think you had two Liberty motors here in the hangar when I was here
last. I neglected to ask you the power of these, and what you need two
for," observed Mr. Giddings. "I thought you said in the beginning that
you considered one 400 horse-power engine of sufficient strength to
carry this plane at a fast clip."

"It is this way, sir," responded John. "The regular big biplane of the
bomber type carries two propellers with an engine for each propeller.
If one motor fails them when flying, about all the other is good for is
to make a landing with. By reason of the great lightness of our
airplane one good 400 horse-power motor is all we need for pulling
purposes. But suppose this should fail, as any motor might do? We
could not continue, any more than the other fellow, and would have to
volplane to the ground. Again, suppose we wished to fly continuously
more than twelve hours? We could not do so, as such a steady run would
heat the best motor and ruin it. These two Liberty motors, which we
have, overcome all these troubles. Both are so arranged that a simple
switch connects and disconnects either one with the propeller, and both
can be put at work at the one time if needed in a bad storm. If one
stalls, the other can immediately be thrown in and a forced landing
obviated. Moreover, if we could get fuel when needed, with this
arrangement I am safe in saying we could fly steadily day and night,
resting one motor and working its mate, for a week or more."

"What is this?" As he spoke the publisher touched a peculiar-looking
helmet hanging from a hook near the pilot's seat.

Bob laughed. "Why, don't you recognize the products of your talented
son, dad?" he cried, as he took the object down and clapped it over his
father's iron-gray head. "That's my new wireless telephone headpiece,
and right underneath it here is th