point the gun at him, is a thing they
can't well get away from. That Hartford type of hunter just over
from home is rigged up that way, and I can get the little gun on
her pointed anyway I like. But all guns fixed that way fire through
the propeller, and just exactly how all those bullets manage to get
through those whirring blades without hitting one of them is not
quite clear to me yet."

"Go it, Joe," said Harry Corwin. "You spent a good time listening
to what that French pilot said about Garros the other day."

"The Frenchman told me that a very well known pilot of the early days
of the war, named Garros, invented the arrangement whereby a gun could
be so mounted that the bullets went through the arc of the
revolving propeller blades," answered Joe. "He said, too, that
Garros had the bad luck to be taken prisoner, and the Germans got
his machine before he had any chance to destroy it. That was the
way the Germans got hold of the idea. Garros simply designed a bit
of mechanism that automatically stops the gun from firing when the
propeller blade is passing directly in front of the gun-barrel. He
placed the gun-barrel directly behind the propeller. He then made a
cam device so regulated as to fire the gun with a delay not exceeding
one five-hundredth of a second. As soon as the blade of the
propeller passes the barrel the system liberates the firing mechanism
of the gun until another blade passes, or is about to pass, when
the bullets that would pierce it are held up, just for that
fraction of a second, again. So it goes on, like clockwork. You
have noticed that on the new planes all the pilot has to do when
he wants to fire his machine-gun is to press a small lever which
is set, on most planes, in the handle of the directing lever. That
small lever acts, by the mechanism I have told you about, on the
trigger of the gun. It is simple enough."

"Yes," admitted Bob, "it does not sound very complicated, but it seems
very wonderful, all the same. Most things out here are wonderful when
you first run into them, though."

Of the group of Brighton boys selected by the squadron commander to
study the finer points of aerial acrobatics, Joe Little was the star,
with Harry Corwin a very close second and Jimmy Hill a good third.
Their education, as the days went past, became a series of experiments
that were nothing short of hair-raising to any onlookers save most
experienced ones.

To see Joe, in a wasp of