given her a partial
shop-tryout, and she works well. But there is still plenty to do. Did I
tell you about meeting Blakeson?"

"Yes, and I can't understand why he should be in this vicinity. Do you
think he has had any intimation of what you are doing?"

"It's hard to say, and yet I would not be surprised. When Uncle Sam
couldn't keep secret the fact of our first soldiers sailing for France.
How can I expect to keep this secret? But they won't get any details
until I'm ready, I'm sure of that."

"Koku is a good discourager," said Mr. Swift, with a chuckle. "You
couldn't have a better guard, Tom."

"No, and if I can keep him and Eradicate from trying to pull off rival
detective stunts, or 'deteckertiff,' as Rad calls it, I'll be all
right. Now let's have another go at that carburetor. There's our weak
point, for it's getting harder and harder all the while to get
high-grade gasolene, and we'll have to come to alcohol of low proof, or
kerosene, I'm thinking."

"I wouldn't be surprised, Tom. Well, perhaps we can get up a new style
of carburetor that will do the trick. Now look at this needle valve;
I've given it a new turn," and father and son went into technical
details connected with their latest invention.

These were busy days at the Swift plant. Men came and went--men with
queerly shaped parcels frequently--and they were admitted to the big
new building after first passing Eradicate and then Koku, and it would
be hard to say which guard was the more careful. Only, of course, Koku
had the final decision, and more than one person was turned back after
Eradicate had passed him, much to the disgust of the negro.

"Pooh! Dat giant don't know a workman when he sees 'im!" snorted
Eradicate. "He so lazy his own se'f dat he don't know a workman! Ef I
sees a spy, Massa Tom, or a crook, I's gwine git him, suah pop!"

"I hope you do, Rad. We can't afford to let this secret get out," said
the young inventor.

It was one evening, when taking a short cut to his home, that Mr.
Nestor, the father of Mary Nestor, in whom Tom was more than ordinarily
interested, passed not far from the big enclosure which was guarded, on
the factory side, day and night. Inside, though out of sight and hidden
by the high fence, were other guards.

As Mr. Nestor passed along the fence, rather vaguely wondering why it
was so high, tight and strong, he felt the ground trembling beneath his
feet. It rumbled and shook as though a distant train wer