m, just where the bearer of the note would indicate. Koku, the
giant, and several of the machinists, who knew how to operate the big
machine, were to go with it, the note said.

"That made me sure everything was all right," said Mr. Swift. "I knew,
of course, Tom, that plotters might try to get hold of your war secret,
but I didn't see how they could if Koku and some of your own men were
in possession."

"They couldn't--as long as they remained in possession," Tom said. "But
that's the trouble. I'm afraid they haven't. What has probably
happened is that under the direction of this man, who brought the
forged note from me, Koku and the others took the tank where he
directed them, thinking to meet me. Then, reaching the place where the
rest of the plotters were concealed, they overpowered Koku and the
others and took possession of the machine."

"They'd have trouble with Koku," suggested Ned.

"Yes, but even a giant can't fight too big a crowd, especially if he is
taken by surprise, and that's probably what happened," remarked Tom.
"Now the question is where is the tank, and how can we get her back?
Every minute counts. If those German spies and their helpers remain in
possession long, they'll find out enough of my secrets to enable them
to duplicate the machine, and especially some of the most exclusive
features. We've got to get after 'em!"

"They imitated your writing pretty well, Tom," Observed Ned, as he
looked at the forged note.

"Yes; that's why they took all my papers away from me--to get specimens
of my handwriting. I half suspected that, but I didn't quite figure out
what their game was. Well, we know the worst now, and that's better
than working in the dark. Now I'm going to have a bath and get into
some decent clothes, and we'll see what we can do."

"Count on me, Tom!" exclaimed Ned. "I'll go the limit with you!"

"I knew you would, old man!"

"And me, too!" cried Mr. Damon. "Bless my open fireplace, but I'll send
word to my wife that I'm not coming home to-night, and we can start the
first thing in the morning, Tom."

"Yes; there isn't much use in going now, as it will soon be dark."

"How are you going to trace the tank, Tom?" asked Ned, when his chum
had bathed and gotten into fresh clothes.

"I'm going to tour the country around here in an auto. The tank can
make ten miles an hour, but that's nothing to what an auto can do. And
we oughtn't to have much trouble in tracing her. No one whos