"Well, no; not exactly, Rad. Just show Mr. Damon up to the house. I'd be glad to see him again, though I don't fancy he'll call. He's off on a little trip, and won't be back for a week. But watch out, Rad." And with that Tom turned toward the house, shaking his head over the puzzle of the missing plans.
"Did you find any one?" asked his father eagerly as the young inventor entered the library.
"No," was the gloomy answer. "There wasn't a sign of any one."
Tom went over to the window and looked about for clues. There was none that he could see, and a further examination of the ground under the window disclosed nothing. There was gravel beneath the casement, and this was not the best medium for retaining footprints. Nor were the gravel walks any better.
"Not a sign of any one," murmured Tom. "Are you sure you didn't hear any noise, dad, when you dozed off?"
"Not a sound, Tom. In fact, it's rather unusual for me to go to sleep like that, but I suppose it's because of my illness. But I couldn't have been asleep long—not more than two minutes."
"That's what I think. Yet in that time some one, who must have been on the watch, man-
