A NIGHT TRIP
Taking a lesson from what had happened, Tom was very much more careful
in the following experiments on his new, silent motor. He made some
changes in his shop, and took Jackson in to help on the new machine,
thus insuring perfect secrecy as the apparatus developed.
Tom also changed the safe in which he kept his plans, for the one he
had used previous to the episode in which Bower and the stranger who
took the mud bath figured, was one the combination of which could
easily be ascertained by an expert. The new safe was more complicated,
and Tom felt that his plans, specifications, and formulae which he had
worked out were in less danger.
"I can just about figure out what happened," said Ned Newton to Tom,
when told of the circumstances. "These Universal people were provoked
because you wouldn't give them the benefit of your experience on their
flying machines, and so they sent a spy to get work with you. They,
perhaps, hoped to secure some of your ideas for their own, or they may
have had a deeper motive."
"What deeper motive could they have, Ned?"
"They might have hoped to disable you, or some of your machines, so that
you couldn't compete with them. They're unscrupulous, I hear, and will
do anything to succeed and make money. So be on your guard against
them."
"I will," Tom promised. "But I don't believe there's any more danger
now. Anyhow, I have to take some chances."
"Yes, but be as careful as you can. How is the silent motor coming on?"
"Pretty good. I've had a lot of failures, and the thing isn't so easy
as I at first imagined it would be. Noise is a funny thing, and I'm
just beginning to understand some of the laws of acoustics we learned
at high school. But I think I'm on the right track with the muffler and
the cutting down of the noise of the explosions in the cylinders. I'm
working both ends, you see--making a motor that doesn't cause as much
racket as those now in use, and also providing means to take care of
the noise that is made. It isn't possible to make a completely silent
motor of an explosive gas type. The only thing that can be done is to
kill the noise after it is made."
"What about the propeller blades?"
"Oh, they aren't giving me any trouble. The noise they make can't be
heard a hundred feet in the air, but I am also working on improvements
to the blades. Take it altogether, I'll have an almost silent aeroplane
if my plans come out all right."
"Have you said anything to the government yet?"
"No; I want to have it pretty well perfected before I do. Besides, I
don't want any publicity about it until I'm ready. If these Universal
people are after me I'll fool 'em."
"That's right, Tom! Well, I must go. Another week of this Liberty Bond
campaign!"
"I suppose you'll be glad when it's over."
"Well, I don't know," said Ned slowly. "It's part of my small
contribution to Uncle Sam. I'm not like you--I can't invent things."
"But you have an awful smooth line of talk, Ned!" laughed his chum. "I
believe you could sell chloride of sodium to some of the fishes in the
Great Salt Lake--that is if it has fishes."
"I don't know that it has, Tom. And, anyhow, I'm not posing as a salt
salesman," and Ned grinned. "But I must really go. Our bank hasn't
reached its quota in the sale of Liberty Bonds yet, and it's up to me
to see that it doesn't fall down."
"Go to it, Ned! And I'll get busy on my silent motor."
"Getting busy" was Tom Swift's favorite occupation, and when he was
working on a new idea, as was the case now, he was seldom idle, night
or day.
"I have hardly seen you for two weeks," Mary Nestor wrote him one day.
"Aren't you ever coming to see me any more, or take me for a ride?"
"Yes," Tom wrote back. "I'll be over soon. And perhaps on the next ride
we take I won't have to shout at you through a speaking tube because
the motor makes so much noise."
From this it may be gathered that Tom was on the verge of success.
While not altogether satisfied with his progress, the young inventor
felt that he was on the right track. There were certain changes that
needed to be made in the apparatus he was building--certain refinements
that must be added, and when this should be done Tom was pretty certain
that he would have what would prove to be a very quiet aeroplane, if
not an absolutely silent one.
The young inventor was engaged one day with some of the last details of
the experiment. The new motor, with the silencer and the changed
cylinders, had been attached to one of Tom's speedy aeroplanes, and he
was making some intricate calculations in relation to a new cylinder
block, to be used when he started to make a completely new machine of
the improved type.
Tom had set down on paper some computations regarding the cross-section
of one of the cylinders, and was working out the amount of stress to
which he could subject a shoulder strut, when a shadow was cast across
the drawing board he had propped up in his lap.
In an instant Tom pulled a blank sheet over his mass of figures and
looked up, a sudden fear coming over him that another spy was at hand.
But a hearty voice reassured him.
"Bless my rice pudding!" cried Mr. Damon, "you shut yourself up here,
Tom, like a hermit in the mountains. Why don't you come out and enjoy
life?"
"Hello! Glad to see you!" cried Tom, joyfully. "You're just in time!"
"Time for what--dinner?" asked the eccentric man, with a chuckle. "If
so, my reference to rice pudding was very proper."
"Why, yes, I imagine there must be a dinner in prospect somewhere, Mr.
Damon," said Tom with a smile. "We'll have to see Mrs. Baggert about
that. But what I meant was that you're just in time to have a ride with
me, if you want to go."
"Go where?"
"Oh, up in cloudland. I have just finished my first sample of a silent
motor, and I'm going to try it this evening. Would you like to come
along?"
"I would!" exclaimed Mr. Damon. "Bless my onion soup, Tom, but I would!
But why fly at night? Isn't it safer by daylight?"
"Oh, that doesn't make much difference. It's safe enough at any time.
The reason I'm going to make my first flight after dark is that I don't
want any spies about."
"Oh, I see! Are they camping on your trail?"
"Not exactly. But I can't tell where they may be. If I should start out
in daylight and be forced to make a landing-- Well, you know what a
crowd always collects to see a stranded airship."
"That's right, Tom."
"That decided me to start off after dark. Then if we have to come down
because of some sort of engine trouble or because my new attachment
doesn't work right, we sha'n't have any prying eyes."
"I see! Well, Tom, I'll go with you. Fortunately I didn't tell my wife
where I was going when I started out this afternoon, so she won't worry
until after it's over, and then it won't hurt her. I'm ready any time
you are."
"Good! Stay to dinner and I'll show you what I've made. Then we'll take
a flight after dark."
This suited the eccentric man, and a little later, after he had eaten
one of Mrs. Baggert's best meals, including rice pudding, of which he
was very fond, Mr. Damon accompanied Tom to one of the big hangars
where the new aeroplane had been set up.
"So that's the Air Scout, is it, Tom?" asked Mr. Damon, as he viewed
the machine.
"Yes, that's the girl. 'Air Scout' is as good a name as any, until I
see what she'll do."
"It doesn't look different from one of your regular craft of the skies,
Tom."
"No, she isn't. The main difference is here," and Tom showed his friend
where a peculiar apparatus had been attached to the motor. This was the
silencer--the whole secret of the invention, so to speak.
To Mr. Damon it seemed to consist of an amazing collection of pipes,
valves, baffle-plates, chambers, cylinders and reducers, which took the
hot exhaust gases as they came from the motor and "ate them up," as he
expressed it.
"The cylinders, too, and the spark plugs are differently arranged in
the motor itself, if you could see them," said Tom to his friend. "But
the main work of cutting down the noise is done right here," and he put
his hand on the steel case attached to the motor, the case containing
the apparatus already briefly described.
"Well, I'm ready when you are, Tom," said Mr. Damon.
"We'll go as soon as it's dark," was the reply. "But first I'll give
you a demonstration. Start the motor, Jackson!" Tom called to his chief
helper.
Mr. Damon had ridden in aeroplanes before, and had stood near when Tom
started them; so he was prepared for a great rush of air as the
propellers whirled about, and for deafening explosions from the engine.
The big blades, of new construction, were turned until the gas in the
cylinders was sufficiently compressed. Then Jackson stepped back out of
danger while Tom threw over the switch.
"Contact!" cried the young inventor.
Jackson gave the blades a quarter pull, and, a moment later, as he
leaped back out of the way, they began to revolve with the swiftness of
light. There was the familiar rush of air as the wooden wings 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?