in the clear sky.

By this time it was noticeable that they had somehow divided into two
squads or escadrilles; and at a signal from Commander Byers down below
they began maneuvering like two hostile squadrons about to engage in
aerial battle. Thereupon ensued a display of battle tactics that would
have been bewildering to an unaccustomed spectator.

These vicious little fighting planes reminded one more of air insects
than of birds. In their forward rushes many of them were doing more
than two miles a minute.

"Watch out!" said the Commander, his glass at his eyes. "The Sergeant
is going to loop."

True enough, Blaine's machine took a nose flip. He was riding upside
down. Then he was level again. The rest of his squad followed suit,
then followed their leader at a daring angle, all of them straight and
level again. The first plane in the other line, driven by Erwin, began
to loop the loop sidewise, rolling over and over, not unlike a horse
rolls over when turned out to grass. The others behind him began much
the same tactics while the first line drew away as if preparing for
counter moves.

Beyond, in the further sky, two opposing machines having detached
themselves from the rest were playing with each other like kittens with
wings. One was making rapid evolutions, the other following, and
clinging to the set course in a series of whirls with its own wing-tip
as a pivot.