en before, and
I know something about airships. It has some new wrinkles on it, and I
thought you might have evolved them yourself. Not that it's an amateur
affair, by any means!" he added hastily, as if fearing the young
inventor might resent the implication that his machine was a home-made
product.

"Yes, I originated this," answered Tom, as he put a new turn-buckle in
place; "but I didn't actually construct it--that is, except for some
small parts. It was made in the shop--"

"Over at the army construction plant, I presume," interrupted the man
quickly, as he motioned toward the big factory, not far from Shopton,
where aircraft for Uncle Sam's Army were being turned out by the
hundreds.

"Might as well let him think that," mused Tom; "at least until I can
figure out who he is and what he wants."

"This is different from most of those up there," and the stranger
pointed toward the circling craft on high. "A bit more speedy, I guess,
isn't it?"

"Well, yes, in a way," agreed Tom, who was lending over his craft. He
stole a side look at the man. The face was becoming more and more
familiar, yet something about it puzzled Tom Swift.

"I've seen him before, and yet he didn't look like that," thought the
young inventor. "It's different, somehow. Now why should my memory play
me a trick like this? Who in the world can he be?"

Tom straightened up, and tossed a monkey wrench into the tool box.

"Get everything fixed?" asked the stranger.

"I think so," and the young inventor tried to make his answer pleasant.
"It was only a small break, easily fixed."

"Then you'll be on your way again?"

"Yes. Are you ready?" called Tom to Mr. Damon.

"Bless my timetable, yes! I didn't think you'd start back again so
soon. There's one young fellow up there who has looped the loop three
times, and I expect him to fall any minute."

"Oh, I guess he knows his business," Tom said easily. "We'll be
getting back now."

"One moment!" called the man. "I beg your pardon for troubling you, but
you seem to be a mechanic, and that's just the sort of man I'm looking
for. Are you open to an offer to do some inventive and constructive
work?"

Tom was on his guard instantly.

"Well, I can't say that I am," he answered. "I am pretty busy--"

"This would pay well," went on the man eagerly. "I am a stranger around
here, but I can furnish satisfactory references. I am in need of a good
mechanic, an inventor as well, who can do what you s