ntered 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 someone, who must have been on
the watch, managed to get in here and take my plans for the new sky
racer. I don't see how they got the wire screen open from the outside,
though. It fastens with a strong hook."

"And was the screen open?" asked Mr. Swift

"Yes, it was unhooked. Either they pushed a wire in through the mesh,
caught it under the hook, and pulled it up from the outside, or else
the screen was opened from the inside."

"I don't believe they could get inside to open the screen without some
of us seeing them," spoke the older inventor. "More likely, Tom, it
wasn't hooked, and they found it an easy matter to simply pull it open."

"That's possible. I'll ask Mrs. Baggert if the screen was unhooked."

But the housekeeper could not be certain on that point, and so that
part of the investigation amounted to nothing.

"It's too bad!" exclaimed Mr. Swift. "It's my fault, for dozing off
that way."

"No, indeed, it isn't!" declared Tom stoutly.

"Is the loss a serious one?" asked his father. "Have you no copy of the
plans?"

"Yes, I have a rough draft from which I made the completed drawings,
and I can easily make another set. But that isn't what worries me--the
mere loss of the plans."

"What is it, then, Tom?"

"The fact that whoever took them must know what they are the plans for
a sky racer that is to take part in the big meet. I have worked it out
on a new principle, and it is not yet patented. Whoever stole my plans
can make the same kind of a sky racer that I intended to construct, and
so stand as good a chance to win the prize of ten thousand dollars as I
will."

"That certainly is too bad, Tom. I never thought of that. Do you
suspect any one?"

"No one, unless it's Andy Foger.