s cut
through the atmosphere, but there was scarcely any noise. Mr. Damon
could hardly believe his ears.

"I'm not running her at full speed," said Tom. "If I did she'd tear
loose from the holding blocks. But you can see what little racket she
makes."

"Bless my fountain pen!" cried Mr. Damon. "You are right, Tom Swift!
Why, I can hear you talk almost as easily as if no engine were going.
And I don't have to shout my head off, either."

This was perfectly true. Tom could converse with Mr. Damon in almost
ordinary tones. The exhaust from the motor was nearly completely
muffled.

"Out in the air it will seem even more quiet," said Tom. "I'll soon
give you a chance to verify that statement."

He ran the engine a little longer, the aeroplane quivering with the
vibrations, but remaining almost silent.

"I'm anxious to see what she'll do when in motion," said Tom, as he
shut off the gas and spark.

Soon after supper, when the shades of evening were falling, he and Mr.
Damon took their places in the first of the Air Scouts, to give it the
preliminary test in actual flying.

Would Tom's hopes be justified or would he be disappointed?

CHAPTER XII

THE CRY FOR HELP

"All ready, Mr. Damon?" asked Tom, as he looked to see that all the
levers, wheels, valves, and other controls were in working order on his
Air Scout.

"As ready as I ever shall be, Tom," was the answer. "I don't know why
it is, but somehow I feel that something is going to happen on this
trip."

"Nonsense!" laughed Tom. "You're nervous; that's all."

"I suppose so. Don't think I'm going to back out, or anything like
that, but I wish it were successfully over with, Tom Swift, I most
certainly do."

"It will be in a little while," returned Tom, as he settled himself
comfortably in his seat and pulled the safety strap tight. "You've gone
up in this same plane before, when it didn't have the silent motor
aboard."

"Yes, I know I have. Oh, I dare say it will be all right, Tom. And
yet, somehow, I can't help feeling--"

But Tom Swift felt that the best way to set Mr. Damon's premonitions to
rest was to start the motor, and this he gave orders to have done,
Jackson and some others of the men from the shops congregating about
the craft to see the beginning of the night flight. Mr. Swift was there
also, and Eradicate. Mary Nestor had been invited, but her Red Cross
work engaged her that evening, she said. Ned Newton was away from town
on Li