"I don't know about that," returned the other, stepping back a pace to where he could glance through the open door. "He's gone straight to the drawer where we keep some of our stuff. There, he's taken out the marine glasses that I just put away. What under the sun do you suppose Andy wants with them? He doesn't look up at the summit of Old Thunder Top, where we landed from our monoplane last summer, being the first human being ever to step there above the big cliffs. No, Andy has gone to a window with the glass. He seems to want to keep out of sight. Now, I wonder why?"
"Three to one he just saw your sister Janet going along the further road; and couldn't keep from wanting to admire her at close range," chuckled Larry.
"But now he's elevating the glasses," Frank went on. "He seems to be interested in that old mill you can see yonder above the trees. I declare, I did see something moving then in one of the upper windows. That beats everything. To think of Andy having such sharp eyes."
"Oh! the boys used to play there last summer," ventured Elephant; "though since then nobody goes near the old place. I was told it had become the haunt of hoboes this summer. Anyway, the boys fight shy of it right along now."
"Here comes Andy; now we'll know," said Nat, just as smartly as any of them could have spoken, for his hurry spell was over, and he had command of his vocal chords once more.
"Wondering what took you inside to get the glasses," remarked Frank, as the other joined them, a frown marked on his usually placid face. "And then, what made you go to a window instead of standing outside openly, and looking?"
"I'll tell you," returned Andy, solemnly. "I didn't want 'em to see me peeking."
"You mean the fellows in the old deserted mill?" asked Larry.
"No other," came the quick reply, "I don't know how it came to strike me, because you know as a rule I ain't suspicious; but something about the way those two men in the touring car looked so greedily at our new aeroplane gave me an idea it might be them."
"Goodness gracious!" gasped Elephant, his eyes round with wonder and excitement.