? Oh, Hugh, that was why the old aeroplane kept
circling all around, wasn't it? They were picking out some place
to make a big hole! Whee! No wonder then they came up here to
this lonely place to try things out. A farmer'd be apt to kick
like a steer if he waked up some fine morning and found holes like
this in his garden or field. It's good we didn't happen to be
standing here when they dropped the bomb, as you call it."

"I had an idea of something like this last night," Hugh said; "but
thought best not to mention it until I could see my way clearer.
But now the last doubt has gone, and I know the truth."

"But Hugh, who could it be trying out this awful explosive, and
wanting to do it where no curious eyes could watch the operation?"

"I don't know that, Bud, but we can guess. It must be either some
company in the market with explosives, or else the Government itself
trying to see how the Flying Squadron, as they call their aerial arm
of the service, could work in time of actual war."

"Say, if they could drop bombs like that just, where they wanted,"
remarked Bud admiringly, "I'd pity the enemy, whether Japanese
or German or anything else. Just think of a great big bat circling
around in the darkness of night, sending down a searchlight, maybe,
to pick out the right spot, and then, bang! Good-by to your old fort
or battleship! It would be all over before you could wink twice.
And let me tell you, fellows, we've got the bully boys in the army
to do this same stunt, if anybody on earth can!"

"Thank you for the compliment, my boy!"

A quiet voice said this, and the three scouts looked up hastily to
discover that a man clad in a faded suit of khaki was standing close
by, watching them with an expression of amusement on his clear-cut
face.

There was something about his make-up that instantly convinced Hugh
of his connection with the aviation corps of the Government service.
This, then, would seem to prove that it was the army engaged in
making these secret experiments with the new explosive, perhaps from
a war aeroplane that may have been given over into the charge of the
Flying Corps for trial.

Hugh immediately advanced toward the officer and gave the regular
salute, as every scout is taught to do when he meets one who is above
him in rank. To his delight, the other acknowledged the salute
immediately.

"We are Boy Scouts belonging to a town some miles away from here,"
Hugh started to explain.