“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.

“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.