“There seems to be no doubt of it,” replied the Chief, calmly, and yet with a stiffening of his figure, as though conscious of having already discovered a most promising clue, that could not but reflect credit on his astuteness as an officer of the law.

“They knew all about Frank’s machine and mine too, then?” continued Percy, still grappling with the tremendous problem.

“Looks that way,” the official went on to remark, “and makes me think more than ever that they must have a friend right here in Bloomsbury who put them wise to lots of things.  Time’ll tell that.  But I don’t suppose you found anything around your place like Frank did, to tell that some strangers had been there while you slept?”

“Not a blessed thing; though, to tell the honest truth, I didn’t hang around long when I found my biplane was gone.  It was the best machine I ever owned, and as you know I’ve had several, all told.  And inside of three days I expected that the latest model of aluminum pontoons would be along, to turn it into a water as well as an air craft.  Now chances are, I’ll never see it again, because, like as not, nobody knows which way in creation they went.”

“We happen to have a pointer about that same thing,” Andy could not help saying, though he hardly liked the superior air of the other, not being able to overlook such things as easily as his cousin did.

“I hope, then, you’ll give it to the Chief, Andy,” the Carberry boy remarked, for the first time directly speaking to one of the cousins.

“Sure thing.  We want to see the rascals copped just as much as anybody does.  You see, Felix, he’s the farm hand up at Mr. Quackenboss’ place, and me, we thought it good policy to stay around, and keep an eye on our machine while it was lying overnight in that meadow.  I had had a long watch of it, and was taking my turn at sleeping when just at daybreak Felix shook me, and said there was a queer noise up aloft that kind of scared him, and which he rather believed must come from some sort of air craft.

“Oh!” exclaimed Percy, looking intensely interested, of course; “go on, please.”

“I jumped up, and sure enough I glimpsed a biplane passing over, and headed up the lake at a pretty good height, I thought it looked like your machine, but as I remarked to Frank later on, whoever steered it had a different way about him from your method.  While I was wondering what took you out so early, and I could see there were two in the machine, a big flock of crows passed over, and I lost track of it.

“So, you see, Percy,” broke in the eager Chief just at that point, “we’ve got a pretty good clue already about the direction the rascals took, who broke into the safe of the bank, and carried off a bagful of money, and valuable papers; and then followed that up by cribbing your biplane.  It was north they went, up the lake, in fact; and that’s the quarter we’ll have to look for them.  But let me tell you it’s putting it pretty hard over on a police officer to make him try to track a stolen flying machine.”