Hugh shook his head as though, try as he would, as yet he could see no way of solving the puzzle. Just then Bud came back, having fixed the door the same way he had found it, with the loose board used as a prop to keep it in position.
"Just as you said, Hugh," he announced, "it's clear as a bell, with a young moon hanging low in the western sky and the stars shining like all get-out. No siree, thunder never yet was heard on a night like this. So I guess it must have been a blast. They do say dynamite shakes the ground a heap more than powder, because its force is always directed downward. If you put a cartridge on top of a big rock and fire it, the boulder is shattered to pieces. Powder you've got to put underneath every time."
"Correct, Bud, you go up to the head of the class," laughed Hugh.
"I wanted to ask Ralph if when he used to camp around here last winter he ever knew the air to be clear enough to hear the noise of the mill over at town?"
"Why, it's a good many miles away," returned Ralph, "and I don't know that I ever did hear what you say. But what makes you ask that, Bud?"
"Oh! the atmosphere must be doing its prettiest then, to-night," came the answer. "While I was standing just outside the door I could hear the plain rattle of the machinery, though it died away quick enough. I understand that business is so good that they're running a night shift at the mills. And sounds can be heard a long way off after sunset, can't they, Hugh?"
"That's all as true as anything, Bud, though if you'd asked me my opinion before you spoke, I would have said it was foolish to think we could hear the mills so far away as this, no matter how clear the frosty air might be."
"Well, that may be," remarked the other boy doggedly; "but I did hear machinery pounding away at a right merry pace, give you my word on that. I even stepped out further and looked around, but there wasn't a thing in sight, only the stars shining up there and the little horned moon dropping down close to the horizon."
"We came up here thinking we'd be all alone and could do what we'd planned without being interrupted," observed Hugh, "but seems as though we've dropped on the queerest sort of a mystery the very first thing. And as scouts always stand to investigate what they don't understand, I reckon we'll have our hands full prying into this thing."
"But don't let it make my affairs take second place, Hugh," pleaded Bud. "What if some fellow does happen to be using up explosives by the cartload, that oughtn't to interfere with the trying out of the little invention which the brain of a Morgan has conjured up, and which, if successful, will be a blessing to science, as well as to aviators in particular."