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.

It was getting very much of a bore to Andy.  He changed his position restlessly several times, as though he wished Frank would make some sort of a move, he hardly cared what its nature so long as it meant action.

But although Andy could not see it at that moment, there were lively enough times ahead of them to please even his impetuous nature.  And the passage of every minute brought the crisis closer and closer.

Once Frank believed he heard loud voices inside the farmhouse; and at the same time some one was certainly hurrying back and forth.  But then possibly that might be only Sallie, obeying another call from the kitchen, where the good woman was so busily engaged with her canning operations.

Something like twenty minutes must have passed since the boys made their change of base.  To Andy it was much longer, for he felt the time pass as though it had leaden wings.

Then Frank, watching, saw some one come hastily out of the front door, pass quickly down to the path, and move away in the direction of the lane.

“He’s going off, Frank!” exclaimed Andy, all excitement, just as though he half expected that his companion would give the word that meant an immediate pursuit.

“Yes; keep quiet, Andy!”

“But he’ll give us the slip, don’t you see?” persisted the other.

“Let him, then; we can’t help it.  You can see that he’s made quite a change in his looks, as though he’s thrown the mask off, and doesn’t expect to play the part of a collegeman and a bug collector any more,” Frank whispered.

“That’s so, he hasn’t got the brown glasses on, and that old butterfly net is missing; but Frank, just notice, won’t you, how he hangs to that little camera-like black box.  Say, perhaps I was right after all; perhaps Casper Blue is carrying all that stuff cribbed from the Bloomsbury bank, inside the same.”

The two boys crouched there behind the woodshed and by cautiously peeping around the corner could watch the late boarder of the Hoskins hurrying down the lane, as though he had received a hasty summons from the president of his college demanding an immediate return.