otion."

"I used to be," murmured Mr. Damon; "but I gave it up."

"After his machine climbed a tree," Tom explained, with a smile,
remembering how he had originally met Mr. Damon, and bought the damaged
machine from him, as told in the first volume of this series.

"So, when I got your letter," continued the General, "I naturally
jumped on my machine and came over. Now I find that it is all a hoax."

"I am very sorry, I assure you," said Tom. "We did have a sort of test
today; but it was a failure, owing to the fact that someone tampered
with my powder. From what you tell me, I am inclined to the belief that
the same person may have sent you that letter. Let me look at it
again," he requested.

Carefully he scanned it.

"I should say that was written in a sort of German hand; would you not
also?" he asked of Mr. Damon.

"I would, Tom."

"A German!" exclaimed General Waller.

At the mention of the word "German" Koku, the giant, who had entered
the room, to be stared at in amazement by the officer, exclaimed:

"That he, Master! That he!"

"What do you mean?" inquired Tom.

"German man give me stuff for to put in your powder. I 'member now, he
talk like Hans who make our garden here; and he say 'yah' just the same
like. That man German sure."

"What does this mean?" inquired the officer.

Quickly Tom told of the visit of an unknown man who had prevailed on
the simple-minded giant to "dope" Tom's new powder under the impression
that he was doing his master a favor. Then the flight of the spy on a
motor-cycle, just as the experiment failed, was related.

"We have a German gardener," went on Tom, "and Koku now recalls that
our mysterious visitor had the same sort of speech. This ought to give
us a clue."

"Let me see," murmured General Waller. "In the first place your test
fails--you learn, then, that your powder has been tampered with--you
see a man riding away in haste after having, in all likelihood, spied
on your work--your giant servant recalls the visit of a mysterious man,
and, when the word 'German' is pronounced in his hearing he recalls
that his visitor was of that nationality. So far so good.

"I come to this vicinity for my health. That fact, as are all such
regarding officers, was doubtless published in the Army and Navy
Journal, so it might easily become known to almost anyone. I receive a
letter which I think is from Tom Swift, asking me to attend the test.
As the distance is short I go, o