"Yes, but they are both devoted to you, Tom," said the aged
inventor. "But what is this you hinted at--a silent motor you
called it, I believe? Are you really serious in trying to invent
one?"

"Yes, Dad, I am. I think there's a big field for an aeroplane
that could travel along over the enemy's lines--particularly at
night--and not be heard from below. Think of the scout work that
could be done.

"Well, yes, it could be done if you could get a silent motor,
or propellers that made no noise, Tom. But I don't believe it can
be done."

"Well, maybe not, Dad. But I'm going to try!" and Tom, after a
further talk with his father, began work in earnest on the big
problem. That it was a big one Tom was not disposed to deny, and
that it would be a valuable invention even his somewhat skeptical
father admitted.

"How are you going to start, Tom?" asked Mr. Swift, several
days after the big idea had come to the young man.

"I'm going to experiment a bit, at first. I've got a lot of old
motors, that weren't speedy enough for any of my flying machines,
and I'm going to make them over. If I spoil them the loss won't
amount to anything, and if I succeed --well, maybe I can help out
Uncle Sam a bit more."

As Tom had said he would do, he began at the very foundation,