Hugh immediately turned to the army man and expressed his pleasure.

"I've often hoped to have a chance to go up," he said, "but hardly thought it would happen so soon. And we'll all be only too glad to accept your invitation."

"I should say so," added Ralph.

Bud did not say a single word, and turning to ascertain why, the officer found a smile of the "kind that won't come off" spreading all the way across his face. It was evident that Bud was too happy for words. He had long dreamed of spinning through the upper currents in one of those bustling airships that are becoming more common every day; but, like Hugh, he had not expected the golden opportunity to be sprung upon him so soon.

As they walked along, the officer once more started to question them regarding the two strange men who seemed to be hanging about without any known business to keep them up in this unsettled region.

"I think you said that one of them looked in through the window of your shack night before last, and then fled when you let him see that he had been discovered?" he remarked to Hugh.

"Yes, and we made sure that he had been there by examining the soil under the window. It is a part of a scout's education, you know, sir, looking for signs. We found them, too, marks of a long narrow shoe, that told us the man could never be a hobo but must be a gentleman. After they had rummaged through our cabin while we were away, we found the same marks before the door, and indenting tracks of our own, so that proved just when the fellows must have been around."

The army officer nodded his head and laughed softly.

"I understand what you mean, son," he remarked, "and it quite tickles me to know how clever our boys are getting under the influence of this new scout movement. It is bound to wake up most lads and set them to thinking for themselves, years before they would have been aroused under the old way. And I must say I'm heartily in sympathy with the work of the association. It's the finest thing that ever happened for the boys of America. If I had sons, they should everyone of them join one of your troops as soon as they were old enough."

"We forgot to tell you, sir, about hearing those two men rushing through the dense woods and thickets just after the explosion last night. They seemed to act as if more or less frightened; and I guessed that they may have had a narrow escape from being struck by your bomb."