"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. He's mean enough to do a thing like
that, but I didn't think he'd have the nerve. However, I'll see if I can
learn anything about him. He may have been sneaking around, and if he
has my plans he'd ask nothing better than to make a sky racer and beat
me."

"Oh, Tom, I'm so sorry!" exclaimed Mr. Swift "I--I feel very bad about
it!"

"There, never mind!" spoke the lad, seeing that his father was looking
ill again. "Don't think any more about it, dad. I'll get back those
plans. Come, now. It's time for your medicine, and then you must lie
down." For the aged inventor was looking tired and weak.

Wearily he let Tom lead him to his room, and after seeing that the
invalid was comfortable Tom called up Dr. Gladby, to have him come and
see Mr. Swift. The doctor said his patient had been overdoing himself a