Tom, old scout!"

The big battle-plane, soaring fully two thousand feet above the earth,
suddenly turned almost upside-down, so that its nose pointed at an angle
close to forty-five degrees. Like a hawk plunging after its prey it sped
through space, the two occupants held in their places by safety belts.

As they thus rushed downward the earth seemed as if rising to meet them.
Just at the right second Tom Raymond, by a skillful flirt of his hand,
brought the Yankee fighting aircraft back to an even keel, with a
beautiful gliding movement.

Immediately the steady throb of the reliable motor took up its refrain,
while the buzz of the spinning propellers announced that the plane was
once more being shot through space by artificial means.

The two occupants were Tom Raymond and Jack Parmly, firm friends and
chums who had been like David and Jonathan in their long association. It
was Tom who acted as pilot on the present occasion, while Jack took the
equally important position of observer and gunner.

Both were young Americans with a natural gift in the line of aviation.
They had won their spurs while serving under French leadership as members
of the famous Lafayette Escadrille. The adventures they encountered at
that time are related in the first book of this series, entitled: "Air
Service Boys Flying For France."

After America entered the war, like all other adventurous young Yankee
fliers, the two Air Service Boys offered their services to their own
country and joined one of the new squadrons then being formed.