Would he, like a desperate man, attempt to capture these venturesome lads, so as to keep them from informing the authorities at Bloomsbury? Either that, or else he would think that, since the game was up, and they could no longer loiter in the neighborhood of the aroused district in order to carry out the second part of the great scheme, they had better take to the aeroplane and vanish from view, leaving no trail behind by means of which they could be followed.

Frank had said all this in his mind when he lay there and waited to see what would turn up. He felt that they could surely afford to linger for some time, if there was any chance of learning whether the yeggmen meant to change their plans, or proceed to carry out their original scheme.

All seemed quiet at the farmhouse.

Sallie had come out on the porch, and looked rather disappointed to find that the two boys had strangely vanished. She stood there glancing around in a puzzled manner for several minutes, and then with a pretty shrug of her shoulders, and a pout of her lips whirled about and went back into the house again.

"Wow!" said Andy in a low tone, "she's got it in for you, Frank, because you dropped out of sight without even so much as saying goodbye."

But the other was thinking of weightier matters than the humor of a little coquette. He wondered whether Sallie would run across the professor and ask him if he had met two boys down the lane; which remark would excite his suspicions, and lead to other questions, now on his part.

If nothing happened inside of half an hour. Frank was of a mind to try the plan that had come to him—sending Andy off to try and reach some other farm where they would have a telephone; while he himself remained to keep watch.

That might necessitate taking Sallie into their confidence, for they would need to ask questions, and perhaps borrow a horse. On second thought Frank was now a little sorry he had not seen fit to tell the girl all. She seemed to be fairly clever, and could possibly keep a secret. At any rate, the chances of discovery would not be nearly so serious as now, when in her ignorance she was likely to blurt out all about the boys having been there, without knowing that in so doing she might be assisting clever yeggmen to avoid arrest.

The seconds moved along and changed into minutes.

If the professor had come to a window on that side of the house to look anxiously around, he must have been careful not to expose himself, for though Frank had kept a keen lookout he had failed to see anything of him.