t was German."

Dick's eyes twinkled.

"Come out of your trance," he chuckled. "I don't make that kind of
mistakes."

For answer Frank led the way to the wrecked and partly burned plane and
pointed out the markings.

But despite the evidence, Dick still seemed unabashed and his chuckle
broke into a laugh.

"That's one on you fellows," he snorted. "Those markings are pure
camouflage. Just another cute little German trick that went wrong.
That fellow set out to take photographs over our lines and he didn't
want to be disturbed, so he painted out his own markings, and put the
French in their place. If you'll come a little closer you can see the
Hun marks under their coat of white."

The boys did so and, now that their attention had been called to it,
they could readily see the tracings that had been almost obliterated.

"That's evidence enough," remarked Dick, "but to make assurance doubly
sure we'll go over to where the aviator fell and you'll see that he was
a German all right."

The body had been decently covered up before the boys reached there,
but the clothing and the effects found proved beyond a doubt that the
aviator had been one of their foes.

"Take it all back, Dick," said Frank. "You knew what you were about.
And I'm glad that you came out of the scrap safe and sound. But it
certainly was some scrap while it lasted."

"It sure was," replied Dick. "That fellow was as skilful and plucky as
they make them. He kept my hands full, and there was one time when he
came within an ace of raking me. But luck was with me. Poor fellow!
I'm sorry for him, but I'd have been still more sorry if it had been
myself."

"What beats me is the way you tumbled to him," puzzled Billy. "You
surely couldn't have read the German markings under their coat of
paint. How did you know he was a German?"

Dick smiled.

"Simple enough," he answered. "We Allied aviators have a secret system
of signals, something like Freemasonry. When we come near another
plane that seems to be one of our own, we make a certain dip of our
plane. That's like asking for the countersign. If the other fellow's
all right he makes a certain signal in return. If he doesn't do it the
first time, we try again, because there's always a chance that he
hasn't noticed our signal, or is too busy in handling his plane to give
the reply. But if after two or three times we don't get the
countersign, we know the fellow's a Hun and we open up o