trembling like a leaf," answered Jimmie. "If they see you it'll be a
dead give-away. Can't you stop shaking so? What's the matter?"

"I'm going to stop. I was just thinking about what would happen to you
if they saw you at the machine. I'm all right now."

"You'd better be. If they start any questions, just remember that you
never saw an aeroplane nor a Boy Scout in your life."

"There he is now," said Dave, pointing toward the machine.

"He's going to try to make a start," said Jimmie. "But for goodness'
sake," the boy went on, "get your mind off it. Look away."

By this time the aviator had reached the machine and was preparing for
another flight. Willing hands had been stretched forth from the crowd
of soldiers who had but a moment before ignored the machine entirely,
and the plane was turned about and headed away from the station.

A preliminary explosion or two from the motors announced to all that
the aviator intended leaving the place. Other explosions rapidly
succeeded the first. Then came a silence. The aviator was examining
his machine, evidently seeking for the cause of some trouble.

The exhausts of his motor had been regular, but something had gone
wrong, and he was trying to locate the difficulty.

Presently he again started the engine in an effort to warm it up.
Becoming impatient at his failure to readily locate the cause of the
uneven running of his motor, the aviator turned on full power.

For an instant the clatter of the motor drowned all other sounds.
Throughout the roar of the exhaust the sharp ears of the two boys could
discover a strange vibration that told of trouble.

Before they could again turn to examine the aeroplane that had been
wheeled along the ground for some distance, there came a crash,
followed by a rending, tearing sound. Then all was still again.

As Jimmie and Dave turned they saw the aeroplane lying a wreck, torn by
its own propellers.

CHAPTER XVI

UNDER FALSE COLORS

"Well, let 'em come," declared Harry, hastening toward the Eagle with
the last load of gasoline. "We are ready for a quick start now, and if
they want to see a correct imitation of three boys beating it down the
road they'd better hurry. We can't wait much longer."

"Sure!" put in Ned. "Shall we whistle a warning signal to hurry them
up a little, or shall we let them miss the boat?"

"Let 'em miss the boat if they can't get here on time," laughed Jack,
carrying out the jok