"And what are you doing here?" inquired the officer pleasantly.

"We came up to watch one of my chums experiment with a device he
believes he has discovered," replied Hugh. "For the last two nights
we have been puzzled to understand what that terrible roar and flash
meant. At first, we thought a meteor had fallen; but when it came
again last night and we saw the aeroplane swinging around up there
in the sky, I began to believe there was some connection between
them. And now that we've found this hole in the ground, I know
it shows where your bomb struck, Lieutenant."

"Yes, that is what happened," remarked the officer. "I came here
this morning to take notes, so that I could make a full report of
our practice. We have not thought it necessary to make use of our
searchlight so far when dropping a bomb; but now that we know
others besides ourselves are up here, we must be more careful.
Perhaps I would hesitate to say all this to most people whom I
happened to meet by accident, but I know what Boy Scouts are and how
devoted they have always proved to patriotic motives. I'm positively
certain that nothing could tempt one of you lads to betray any
confidence I placed in you."

"Thank you, sir," said Hugh, flushing with keen pleasure at hearing
such words of praise from an army officer. "And perhaps you may
not know that there are others up here who seem to be deeply
interested in all that you are doing."

"What is that, my boy?" exclaimed the other, showing sudden interest.

"Why, by chance my friend here, Ralph Kenyon, who has trapped all
through this section in years gone by, saw two men talking and acting
in a strange way. They've been spying on us, too, while we've
occupied the old shack close by. They even crept in while we were
off yesterday, to steal some plans of an aeroplane improvement which
this other scout, Bud Morgan, had carelessly left there."

"Two men, you say," the officer commented, knitting his brows with
sudden suspicion and uneasiness. "Could you tell whether they seemed
to look like natives or foreigners, son and he wheeled so as to face
Ralph as he asked this.

"I had an idea that one looked like a Japanese and the other a
German," the boy answered promptly.

At this, the army man rubbed his chin and seemed to consider.

"I've taken you into my confidence so far already, boys," he observed
presently, "that I suppose I might as well go right along and tell
you everything. We ar