may have been disappointed
in perfecting a silent motor themselves, and think stealing my idea
would be the easiest way out of it."

"Do they know you are working on such a model as this Silent Sam of
yours, Tom?"

"Yes, I imagine they do. One of the firm members, as you recall,
overheard something, I think, that gave them a hint as to what my plans
were, though, thanks to the time I fooled the spy, they haven't any
real data to go by, I believe."

"Let us hope not," said Mr. Damon.

Tom and he made a thorough search of the big shed, but found no one,
nor was there any trace of an intruder. Tom notified Jackson, who, in
turn, told the guards and watchmen to be on the lookout for any
suspicious strangers, but none was seen in the vicinity of the Swift
works.

"Well, everything seems to be all right, so we'll have the test,"
remarked Torn, after a further search of the premises. "Now, Mr.
Damon, if all goes as I hope you will see what my new machine can do.
Strain your ears for a sound, and let me know how much you hear."

His men helping him, Tom started the new motor which was tried for the
first time attached to the new craft. No flight was to be made yet, the
motor being tested as though on the block, though, in reality, the
craft was ready for instant flight if need be.

Slowly the great propellers began to revolve, and then Tom, taking his
place in the cockpit, turned on more power. The new craft--Silent
Sam--was made fast so it could not progress even though the propellers
revolved at high speed.

"I'm not sending her to the limit," said Tom to his friend, as the
young inventor throttled down the motor. "If I did I'd tear her loose
from the holding blocks."

"Her!" cried Mr. Damon. "Bless my typewriter, Tom! but I thought Silent
Sam was a gentleman aeroplane.

"So he is!" laughed the young man, frankly. "I forgot about 'Silent
Sam.' Guess I'll have to say 'him' instead of 'her,' though the latter
sounds more natural. Anyhow what do you think?"

"I think it's wonderful!" exclaimed Mr. Damon. "There the motor is,
going at almost full speed, and I can hardly hear a thing. You can the
easier believe that when I say that I can hear you talk perfectly well.
And I guess you hear me, don't you?"

"Yes," replied Tom. "And we don't have to shout, either. This is the
best test ever! I think everything is a success."

"Are you going to take her aloft, Tom?" the eccentric man went on.

"Yes, now that I'm s