of machine gun fire from the ground ahead. There came a reply higher
up, and he felt that this must come from Lafe.

Mounting swiftly, he presently became conscious that a machine was
hovering above and behind, "getting on his tail" as the slang runs
among aviators at the front. The quickest way to avert the danger was
first to try the "side loop" which is a kind of "loop-the-loop"
sideways, a risky trick, yet a good thing if rightly done. Buck tried
it instantly. When upside down he darted ahead swiftly but in a
reversed course, bringing him fairly behind the other plane as he,
righted.

As he came up to a level again, now behind his opponent, he saw for an
instant that the shadow looming scarce fifty yards ahead looked
strangely like Blaine's machine. What to do next -- before firing?
Use his private signal, of course. No sooner thought than done. Two
peculiar flares shot forth, each glowing brightly for an instant, then
vanishing.

"But -- hey?" Bangs was ejaculating to himself excitedly. "Will he
answer?"

Up, up climbed Buck, his pulses throbbing for one long instant, the
nose of his machine settling rapidly on the tail of the other plane.
Then came an answering flash. After that another.

"Bully for you, Lafe! My, that was a close call! I mustn't lose track
of him again. We'll be there with the goods yet, if we stick
together." This to himself.