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TOM SWIFT AND HIS AIR SCOUT OR Uncle Sam's Mastery of the Sky

Part 3 out of 4

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"Did you think you heard some one moving around near the rudders
of Silent Sam, Mr. Damon?"

"No, I can't say that I did. Everything seems to me to be all

"Well, it doesn't to me," went on Tom grimly. "I think there
is an intruder in this shed, though how any one could get in when
the doors have been locked all day, is more than I can figure
out. But I'm going to have a look."

"I'll help you," offered Mr. Damon, and, in the bright glare
from many electric lights, the two began a search of the big
hangar where the new craft was kept.

But though the young inventor and his friend went around to the
rear of the aeroplane, walking in opposite directions, they saw
no one, nor did any one try to escape past them.

"And yet I was sure I heard some one in here," declared Tom,
when a search had revealed nothing. "It sounded as if some one
were scuffling softly about in rubber-soled shoes, trying to

"Bless my suspenders!" cried Mr. Damon, "who do you think it
could have been, Tom?"

"Who else but some spy trying to get possession of my secrets?"
was the answer. "But I guess I was too quick for them. They
couldn't learn much from looking at the outside of my muffler,
and it hasn't been disturbed, as far as I can see."

"Who would want to gain a knowledge of it in that unlawful
way?" asked Mr. Damon.

"Perhaps some of the Universal crowd. They 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

"Yes, now that I'm sure the engine is all right. Will you go
for a flight with me?"

"I certainly will! I only wish we could find him, though. I'd
go with a better heart."

"Oh! Mr. Nestor?"

"Yes, I can't imagine what has become of him. It is almost as
if the earth had opened and swallowed him. His disappearance is a
great mystery."

"It surely is," agreed Tom. "Can't seem to get any trace of
him. But if we hear another cry for help, when we have to land,
you can make up your mind I'll investigate more quickly than I
did at first."

"I agree with you," said Mr. Damon.

It was nearly evening then, and until it was dark enough for
his flight Tom spent the time tuning up the engine and seeing
that all was in readiness for the latest test. He had decided not
to go aloft while it was light enough for curiosity seekers to
note the flight.

Tom rather wished Mary Nestor might have a sail with him in his
latest improved silent Air Scout, but the girl was too much
occupied at home and in trying to find some trace of her father.

Tom, his father, and Mr. Damon had helped all they could, but
there were no results. A private detective had been engaged, but
he had no more of a clew than the regular police.

At last it was dark enough for the flight, and Tom and Mr.
Damon took their places in the machine. Once more the propellers
were turned around, and when the compression had been made, and
the spark switched on, around spun the big wooden blades, and the
great craft moved over the grass.

On and on and up and up sailed Tom and Mr. Damon, and as they
left behind them the shops and the Swift homestead, the two
passengers were aware of their almost silent flight. The big
aeroplane, the exhaust of which, ordinarily, would have nearly
deafened them, was now as silent as a bird.

"Silent Sam for Uncle Sam!" cried Tom in delight, as he went on
faster. "I'm sure the government ought to be glad to get this
plane for air scout work. It's a success! A great success!"

"Yes, so it is!" agreed Mr. Damon. "You do well to speak of it
so, Tom."

For, modest as the young inventor was, he felt, in justice to
himself, that he must acknowledge the fact that his craft was a
success. For it rose and sailed almost as silently as a bat, and
a few hundred feet away no one, not seeing it, would have
believed a big aeroplane was in motion.

Tom and Mr. Damon flew about twenty miles at a swift pace, and
all the fault Tom had to find was that the machine was not as
steady in flight as she should have been.

"But I can remedy that with the use of some of dad's gyroscope
stabilizers," he told Mr. Damon.

They returned to the hangar safely, and the first trip of the
new Silent Sam was an assured success.

It was the following day, when Tom was busy in the machine shop
installing the gyroscopes spoken of, that Jackson came to tell
him there was a visitor to see him.

"Who is it?" asked the young inventor.

"Mr. Gale of the Universal Company," was the answer.

"I don't want to see him!" declared Tom quickly. "I have
nothing to say to him after his clumsy threats."

"He seems very much in earnest," said Jackson. "Better see him,
if only for a minute or so."

"All right, I will," assented Tom. "Show him in."

Mr. Gale, as blusteringly bluff as ever, entered the shop. Tom
had carefully put away all papers and models, as well as the
finished machines, so he had no fear that his visitor might
discover some secret.

"Oh, Mr. Swift!" began the president of the Universal Company,
when he met the young inventor, "I wish to assure you that what
has been done was entirely without our knowledge. And, though
this man may have acted as our agent at one time, we repudiate
any acts of his that might

"What are you talking about?" asked Tom in surprise. "Have I
been so impolite as to sleep during part of your talk? I don't
understand what you are driving at."

"Oh, I thought you did," said Gale, and he showed surprise. "I
understood that the man who--"

"Do you mean there was some one here in the shed last night?"
cried the young inventor suddenly, all his suspicions aroused.

"Some one here last night?" repeated Mr. Gale. "No, I don't
refer to last night. But perhaps I am making a mistake.

"Some one is making a mistake!" said Tom significantly.


For perhaps a quarter of a minute Tom Swift and the president
of the Universal Flying Machine Company of New York sat staring
at one another. Mr. Gale's face wore a puzzled expression, and so
did Tom's. And, after the last remark of the young inventor, the
man who had called to see him said:

"Well, perhaps we are talking at cross purposes. I don't blame
you for not feeling very friendly toward us, and if I had had my
way that last correspondence with you would never have left our

"It wasn't very business-like," said Tom dryly, referring to
the veiled threats when he had refused to sell his services to
the rival company.

"I realize that," said Mr. Gale. "But we have some peculiar men
working for us, and sometimes there is so much to do, so many
possibilities of which to take advantage, that we may get a
little off our balance. But what I called for was not to renew
our offer to you. I understand that is definitely settled."

"As far as I am concerned, it is," said Tom, as his caller
seemed to want an answer.

"Yes. Well, then, what I called to say was that if you are
thinking of taking any legal action against us because of the
action of that man Lydane, I wish to state that he had absolutely
no authority to--"

"Excuse me!" broke in Tom, "but by Lydane do you mean the man
who also posed as Bower, the spy?"

"No, I do not. Though I regret to say that Bower once worked
for us. He, too, had no authority to come here and get a
position. He was still in our service when he did that."

"So I have suspected," said Tom. "I realize now that he was a
spy, who came here to try to find out for you some of my

"Not with my permission!" exclaimed Mr. Gale. "I was against
that from the first and I came to tell you so. But Bower really
did you no harm."

"No, he didn't get the chance!" chuckled Tom. "Nor did that
other spy--the one with the gold tooth. I wonder how he liked our
mud hole?"

"He was Lydane," said Mr. Gale. "It is about him I came."

"You might have saved yourself the trouble," returned Tom. "I
don't wish to discuss him."

"But I wish to make sure," said Mr. Gale, that what he has done
will not come back on us. We repudiate him entirely. His methods
we can not countenance. He is too daring--"

"Oh, don't worry!" interrupted Tom. "He hasn't done anything to
me--he didn't get the chance, as I guess he's told you. You
needn't apologize on his account. He did me no harm, and--"

"But I understood from him that--"

"Now I don't want to seem impolite!" broke in Tom, "nor do I
want to take pattern after some of your company's acts, if not
your own. But I am very busy. I have an important test to make
for the government, and my time is fully occupied. I am afraid I
shall have to bid you good-morning and--"

"But won't you give me a chance to--" began the president.

"Now, the less we discuss this matter the better!" interrupted
Tom. "Lydane, as you call the man with the gold tooth didn't
really do anything to me nor any great harm to any of my
possessions, as far as I can learn. His career is a closed book--
a book with muddy covers!" and the young inventor laughed.

"Oh, well, if you look at it that way, there is nothing further
for me to say" said Mr. Gale stiffly. "I understood-- But hasn't
my partner, Mr. Ware, seen you?" he asked Tom quickly.

"No. And I don't care to see him."

"Oh, then that accounts for it," was the quick answer. "Well,
if you regard the matter as closed I suppose we should also. We
are not to blame for what Lydane does when he is no longer in our
employ, and we repudiate anything he may do, or may have done."

This struck Tom, afterward, as being rather a queer remark, but
he did not think so at the time.

The truth was that the young inventor wished very much to try
out a new device on his noiseless aeroplane and wanted to get rid
of Mr. Gale before doing so. So he did not pay as much attention
to the remarks of the president as, otherwise, he might have

It was not until after Mr. Gale had taken his leave and Tom had
finished the particular work on which he was engaged when the
president of the rival company came in, that the young man did
some hard thinking. And this thinking was done after he had
received a telephone call from Mary Nestor, asking, if by any
chance, he had beard anything like a clew as to the whereabouts
of her father.

Tom had been obliged to tell her that he had not. Everything
possible was being done to find the missing man but he had
disappeared as completely as though he had ridden on his bicycle
into the crater of some extinct volcano on the meadow, and had
fallen to the bottom.

An effort was made to trace him through an automobile
association which had a large membership. That is, the members
were asked to make inquiries to ascertain, if possible, whether
any one had heard of an unreported accident--one in which Mr.
Nestor might have been carried away by persons who accidently ran
him down.

But this came to naught, and the police and other authorities
were at a loss how farther to proceed. It was a theory in some
quarters that Mr. Nestor was perfectly safe, but that he was out
of his mind, and was either wandering around, not knowing who he
was, or was, in this condition, detained somewhere, the persons
having him in charge not realizing that he was the missing man so
widely sought.

This belief was a relief to Mrs. Nestor and Mary in many ways
for it prevented them from giving way to the fear that Mr. Nestor
was dead. That he was alive was Tom Swift's firm opinion, and he
was doing all he could to prove it.

It was not until the day after the visit of Mr. Gale that Tom,
having concluded some intricate calculations about the strength
of cylinder valves, uttered an exclamation.

"I wonder if he could have meant that?" cried the young
inventor. "I wonder if he could have meant that? I must find out
at once! Queer I didn't think of that before!"

He put in a long distance call to New York, asking to speak to
Mr. Gale. But when, eventually, he was connected with the office
of the Universal Flying Machine Company he was told that Mr. Gale
and Mr. Ware had sailed for France that day, going over as
government representatives to investigate aeroplane motors.
Gale's visit to Tom had been just previous to taking the boat, it
was said.

"This is tough luck!" mused Tom, his suspicions doubly aroused
now. "I can't let this rest here! I've got to get after it! As
soon as I make this final test, and invite Uncle Sam's experts
out to see how my noiseless motor works, I'll get after Gale and
Ware if I have to follow them to the battlefields of France! I
wonder if it was that he was hinting at all the while! I begin to
believe it was!"

Tom Swift had decided on another flight for his new craft
before he would let the government experts see it.

"Silent Sam must do his very best work for Uncle Sam before I
turn him over," said the young inventor.

"And after this flight I'll offer the machine to the
government, and then devote all my time to finding Mr. Nestor,"
said Tom. "I'd do it now, but private matters, however deeply
they affect us, must be put aside to help win the war. But this
will end my inventive work until after Mr. Nestor is found--if
he's alive."

Preparations for the test flight went on apace, and one
afternoon Tom and Jackson took their places in the big, new
aeroplane. He no longer feared daylight crowds in case of an
accident. They made a good start, and the motor was so quiet that
as Tom passed over his own plant the men working in the yard, who
did not know of the flight, did not look up to see what was going
on. They could not hear the engine.

"I think we've got everything just as we want it, Jackson,"
said Tom, much pleased.

"I believe you," answered the mechanician. "It couldn't be
better. Now if--"

And at that moment there came a loud explosion, and Silent Sam
began drifting rapidly toward the earth, as falls a bird with a
broken wing.


"What happened?" cried Jackson to Tom, as he leaned forward in
his seat which was in the rear of the young inventor's.

"Don't know, exactly," was the answer, as Tom quickly shifted
the rudders to correct the slanting fall of his craft. "Sounded
as though there was a tremendous back-fire, or else the muffler
blew up. The engine is dead."

"Can you take her down safely?"

"Oh, yes, I guess so. She's a bit out of control, but the
stabilizer will keep her on a level keel. Good thing we installed

"You're right!" said Jackson.

Now they were falling earthward with great rapidity, but,
thanks to the gyroscope stabilizer, the "side-slipping," than
which there is no motion more dreaded by an aviator, had nearly
ceased. The craft was volplaning down as it ought, and Tom had it
under as perfect control as was possible under the

"We'll get down all right if something else doesn't happen," he
said to Jackson, with grim humor.

"Well, let's hope that it won't," said the mechanic. "We're a
good distance up yet."

They were, as a matter of fact, for the explosion, or whatever
had happened to the craft, had occurred at a height of over two
miles, and they at once began falling. As yet Tom Swift was
unaware of the exact nature of the accident or its cause. All he
knew was that there had been a big noise and that the engine had
stopped working. He could not see the silencer from where he sat,
as it was constructed on the underside of the motor, but he had
an idea that the same sort of mishap had occurred as on the
occasion when the test machine had sailed through the roof of his

"But, luckily, this wasn't as bad," mused Tom. "Anyhow the
motor is out of business."

And this was very evident. The young inventor had tried to
start the apparatus after its stoppage by the explosion, but it
had not responded to his efforts, and then he had desisted,
fearing to cause some further damage, or, perhaps, endanger his
own life and that of Jackson.

Down, down swept Silent Sam--doubly silent now, and Tom began
looking about for a good place to make a landing. This was
nothing new for either him or his mechanician, and they accepted
the outcome as a matter of course.

"Not a very lively place down there," remarked Jackson, as he
looked over the side of the cockpit.

"If we have to depend for help on any one down there, I guess
we'll be a long time waiting," agreed Tom. They were about to
land in a very lonely spot. It was one he had never before
visited, though he knew it could not be much more than twenty
miles from his own home, as they had not flown much farther than
that distance.

But, somehow or other, Tom had not visited this particular
section, and knew nothing of it. He saw below him, as Jackson had
seen, a lonely stretch of country--a big field, once a wood-lot,
evidently, as scattered about were some stumps and some second
growth trees. There were also a number of evergreens--Christmas
trees Jackson called them. And this was the only open place for
miles, the surrounding country being a densely wooded one. There
did not appear to be a house or other building in sight where
they might seek help.

"But maybe we can make the repairs ourselves and keep on," the
lad thought.

With practiced eye he picked out a smooth, grassy, level spot,
in the midst of scattered evergreen trees, and there Tom Swift
skillfully brought his Air Scout to rest. With a gentle thud the
rubber-tired wheels struck the Earth, rolled along a little
distance, and then called to a stop.

Hardly had the aeroplane ceased moving when Tom and his
companion jumped out and began eagerly to examine the machinery
to see the extent of damage.

"I thought so!" Tom exclaimed. "The silencer cracked under the
strain. Those exhaust gases have more pressure that I believed
possible. I increased the margin of safety on this muffler, too.
But she's cracked, and I can't use the machine until I put on a
new one. Good thing I didn't ask for a government inspection
until after this trial flight."

"That's so," agreed Jackson. "But can't you patch it up, or go
on without a muffler, so we can get back home?"

"I'm afraid not," Tom answered. "You see I removed all the old
exhaust pipe fittings when I put on my new silencer. Now if I
took off my attachment there wouldn't be anything to carry off
the discharged gases, and they'd form a regular cloud about us.
We couldn't stand it without gas masks, such as they use in the
trenches, and we haven't any of those with us."

"That's right," agreed Jackson. "Well, what do you want to do?
Have me stay here and guard the machine while you go for help? Or
shall I go?"

"I don't know why we both can't go," said Tom. "There is no use
trying to patch up this machine here. I'll have to send a truck
after it, and dismantle it before I can get it home.

"As for either of us staying here on guard, I don't quite see
the need of that. This looks like the jumping-off place to me. I
don't believe there's a native within miles. I didn't see any
houses as we came down, and I think Silent Sam will be perfectly
safe here. No one can run off with him, anyhow. He'd be as hard
to start as an automobile with all four wheels gone. Let's leave
it here and both walk back."

"All right," agreed Jackson. "That suits me. Might as well
leave our togs here, too. It will be easier walking without
them," and he began taking off the fur-lined suit, his cap, and
his goggles, such as he and Tom wore against the piercing cold of
the upper regions.

"We can stuff them in the cockpit and leave them," went on the
mechanician, as he divested himself of his garments. As he stowed
them away in his seat he gave one more look at the broken
muffler. As Tom Swift said, his new silencer had literally blown
up, a large piece having been torn from the gas chamber.

Something that Jackson saw caused him to utter an exclamation
that brought Tom Swift to his side.

"What is it?" asked the young inventor.

"Look!" was the answer. "See! Just at the edge of that break!
It's been filed to make the metal thinner there than anywhere
else. You didn't do that, did you?"

"I should say not!" cried Tom. "Why, to file there would mean
to weaken the whole structure."

"And that's exactly what's happened!" declared Jackson, as he
gave another look. "Some one has filed this nearly
throughleaving only a thin metal skin, and when the gas pressure
became too much it blew out. That's what happened!"

Tom Swift made a quick but thorough examination.

"You're right, Jackson!" he exclaimed. "That was filed
deliberately to cause the accident. And it must have been done
lately, for I carefully inspected the silencer when I put it on,
and it was in perfect order. There's been spy work here. Some one
got into the hangar and filed that casing. Then the accumulated
pressure of the gases did the rest."

"As sure as you're alive!" agreed Jackson. "Maybe that's what
Gale did when he called."

"No," returned Tom, shaking his head, "he didn't get a chance to
do anything like that. I watched him all the while. But perhaps
this is what he referred to when he said he and his company would
repudiate any act of that spy with the gold tooth--Lydane, so
Gale said his name was. Maybe that's what Lydane did."

"He was capable of it," agreed the mechanic, "but he couldn't
have done it that time you tripped him into the mud puddle. This
silencer wasn't built then."

"No, you're right," assented Tom. "Then he must have been
around since, doing some of his tricky work!"

"I don't see how that could have been," said Jackson slowly.
"We've kept a very careful watch, and your shop has been
specially guarded."

"I know it has," said Tom. "There couldn't much get past Koku;
but some one seems to have done it, or else how could that filing
have been done?"

Jackson shook his head. The problem was too much for him. He
looked carefully at the exploded and broken silencer, and Tom,
too, gave it a critical eye. There was no doubt but that it had
been filed in several places to weaken the structure of the

"When did you last see that it was in perfect condition?" asked

Tom named a certain date.

"That was just before Gale called," observed the mechanician.
"He might have known of it."

"I wish I'd known of it at the time," said Tom savagely. "He
wouldn't have gotten away as easily as he did. Well, there's no
use standing here talking about it. Let's get back to
civilization and we'll send back one of the trucks. Luckily I
have another silencer I can put on for the government test. This
one will never be of any more use, though I may be able to save
some of the valves and baffle plates."

Slowly they turned from the disabled aeroplane and started to
look for a path that would lead them out of the lonely place. Tom
as the first to strike what seemed to be a cow path, or perhaps
what had been a road into the wood lot in the early days.

As he tramped along it, followed by Jackson, the young inventor
suddenly stopped, as he came to a sandy place, and, stooping
over, looked intently at some queer marks in the soil.

"What is it?" asked the mechanician.

"Looks like the marks of an automobile," said Tom slowly. "And
I was just trying to remember where I'd seen marks like these


For several seconds the young inventor remained bending over
the queer marks in that little sandy path of the lonely field in
the midst of the silent woods. Jackson watched him curiously,
and then Tom straightened up, exclaiming as he did so:

"I have it! Now I know where it was! I saw marks like these the
night Mr. Nestor disappeared. Mr. Damon and I noticed the marks
in the dust on the road the time we made the forced landing the
first night we tried out the silent motor. That's it! They are
the same marks! I'm sure of it!"

"I wouldn't go so far as to say that," said Jackson slowly. He
was more deliberate than Tom Swift, a fact for which the young
inventor was often glad, as it saved him from impulsive mistakes.

"This may not be the same auto," went on the mechanician. "I'll
admit I never saw square tire marks like those before. Most of
the usual ones are circular, diamond-shape or oblong. Some tire
manufacturer must have tried a new stunt. But as for saying these
marks were made by the same machine you saw evidences of the
night Mr. Nestor disappeared, why, that's going a little too far,

"Yes, I suppose it is," admitted the young inventor. "But it's
a clew worth following. Maybe Mr. Nestor has been brought to some
lonely place like this, and is being held."

"Why would any one want to do that?" asked Jackson. "He had no

"Well, perhaps those who ran him down and injured him are
afraid to let him go for fear he will prosecute them and ask for
heavy damages," suggested Tom. "They may be holding him a captive
until he gets well, and aim on treating him so nicely that he
won't bring suit."

"That's a pretty far-fetched theory," said the mechanician as
he carefully looked at the tracks. "But of course it may be true.
Anyhow, these tire marks are rather recent, I should say, and
they are made by a new tire. Do you think we can follow them?"

"I'm going to try !" declared Tom. "The only trouble is we
can't tell whether it was going or coming--that is we don't know
which way to go."

"That's so," agreed his companion. "And so the only thing to do
is to travel a bit both ways. The path, or road, or whatever you
call it, is plainly enough marked here, though you can't always
pick out the tire marks. They show only on bare ground. The grass
doesn't leave any tracks that we can see, though doubtless they
are there.

"But as for thinking this car is the same one the marks of
which you saw on the lonely moor, the night you heard the call
for help--that's going too far, Tom Swift."

"Yes, I realize that. Of course there must be more than one car
with tires which have square protuberances. But it's worth taking
a chance on--following this clew."

"Oh, sure!" agreed Jackson.

"The only question is, then, which way to go," returned Tom.

They settled that, arbitrarily enough, by going on in the
direction they had started after leaving the stranded airship.
They followed a half-defined path, and were rewarded by getting
occasional glimpses on bare ground of the odd tire marks.

Through a devious winding way, now hidden amid a lane of trees,
and again cutting across an open space, the path led. They saw
the marks often enough to make sure they were on the right trail,
and in one place they saw several different patches of the odd

They went on perhaps half a mile more. when they came to a
lonely road and saw where the car had turned from that into the
wood-lot, as Tom called the place where his craft had settled

"Look!" cried the young inventor to Jackson. "They've been here
more than once, and have gone along the road in both directions.
They seem to have used this turning into the lot as a sort of
stopping place."

This was plain enough from an examination of the marks in the
sandy soil of the road, which was one not often used. The
automobile with the queer, square marks on the tires had turned
into the lot, coming and going in both directions.

"This settles it!" cried Tom, when he finished making an
examination. "There's something farther back in this lot that
we've got to see. This auto has been coming and going, and we
should have followed the tracks the other way from the point
where we first saw them, instead of coming this way."

"Except that we've learned the place of departure," suggested
Jackson. "Evidently the wood-lot is a blind alley. The car goes
in, but it can come out only just at this point, or, at least, it

"That's right!" agreed Tom. "Now the thing to do is to follow
our track back to where we started. There must be some place
where the car went to--some headquarters, or meeting place with
some one, farther back in the lot. If we can only follow the
trail back as well as we did coming, we may find out something."

"Well, let's try, anyhow," suggested Jackson.

They had no difficulty in making their way back to the spot
where they had first seen the queer marks. But from then on their
task was not so easy. For sandy or bare patches of earth were not
frequent, and they had to depend on these to give them direction,
for the road was overgrown and not well defined.

Often they would search about for some time after leaving one
patch of the marks before they found another that would justify
them in keeping on.

"They have headquarters, or a rendezvous, somewhere back in
this lot!" declared Tom, as they hurried on. "I think we're on
the track of a mystery."

"Unless it turns out that some farmer has treated himself to an
auto with new tires of square tread, and is hauling wood," said
Jackson. "It may turn out that way."

"Yes, it may," agreed Tom. "But, taking everything into
consideration, I think we're on the verge of finding out
something. Even if we do discover that the owner of this auto is
only hauling wood, he may be able to help us to a clew as to the
whereabouts of Mr. Nestor."


"Well, maybe he was in his machine on the moor the night the
call for help came. He may even have aided to carry Mr. Nestor
away. And if he doesn't know a thing about it--which, of course,
is possible--the man who bought these queer tires can tell us who
makes them, or who deals in them, and we can find out what
autoists around here have their cars equipped with this odd

"Yes," agreed Jackson, "that can be done."

And so they kept on, scouting here and there to either side of
the half-defined path, until they were far back from the spot
where they had left the Air Scout.

"We don't appear to be getting any warmer, as the children
say," remarked Jackson, as he straightened up and looked about,
for his back ached from so much stooping over to look for the odd

"We haven't seen anything yet, I'll admit," said Tom. "But it
won't be dark for another hour or so, and I vote that we keep

"Oh, I wasn't thinking of giving up!" exclaimed Jackson. "If
there's anything here--at the end of the route, as you might say
--we'll find it. Only I hope it doesn't turn out to be just a
wood pile, from which some farmer has been hauling logs."

"That would be a disappointment," assented Tom.

The day was waning, and they realized that they ought not to
spend too much time on what might turn out to be a wild goose
chase. They were in a lonely neighborhood, and while they were
not at all apprehensive of danger, they felt it would be best to
get to shelter before dark.

"We'll want to send word to Mr. Swift that we're all right."

"Yes," said Tom, "I'd like to get to a place where I can
telephone to him or Mrs. Baggert. Well, if we don't find
something pretty soon we'll have to turn back. I must complete
work on the new motor, for if I'm to offer it to Uncle Sam for
air scout purposes, the sooner I can do so the better. Things are
getting pretty hot over in Europe, and if ever the United States
needed aircraft on the western front they need them now. I want
to help all I can, and I also want to help Mary--you understand--
Miss Nestor."

"I understand," said Jackson simply. "I only hope you can help
her. But I'm afraid--this may turn out to be nothing--following
these marks, you know."

"And yet," said Tom slowly, "it would be strange if it was only
a coincidence--the two tire marks being the same--the night Mr.
Nestor disappeared and now."

And so they kept on, hoping.

The half-defined path through the wood-lot led them in a series
of turns and twists, and it extended through a dense patch of
woods, growing thickly, where it was so dark that it seemed as if
night had fallen.

"We can't spend much more time here," said Tom. "If we don't
find something in the next half mile we'll go back and take up
the search to-morrow. I'm going to find out what's at the end of
this road--even if it's only a wood pile."

For ten minutes more the two went on, making sure, by
occasional glimpses at the marks, that they were on the right
track. Then, suddenly, they saw something which made them feel
sure they had reached their goal.

In a clearing among the trees was a little cabin --a shack of
logs--and from the appearance it was deserted. There was not a
sign of life around


For a moment, at sight of the deserted cabin, staring at Tom
and his friend, as it were, from its hiding place amid the trees,
the young inventor and his companion did not move. They just
stood looking at the place.

"Well," said Tom,. at length, "we found it, didn't we

"We found something anyhow," agreed Jackson. "Whether it
amounts to anything or not, we've got to see."

"Come on!" cried Tom, impulsively. "I'm going to see what's

"There doesn't appear to be much of anything," said Jackson, as
he looked toward the lonely cabin with critical eyes. "I should
say that place hadn't been used, even as a chicken coop, in a
long while."

"We can soon tell!" exclaimed Tom, striding forward.

"Wait just a minute!" cried his companion, catching him by the
coat. "Don't be in such a hurry."

"Why not?" asked Tom. "There isn't any danger, is there?"

"I don't know about that. There's no telling who may be hidden
in that cabin, in spite of its deserted appearance. And though
there aren't any 'No Trespass' signs up, it may be that we
wouldn't be welcome. If there are some tramps there, which is
possible, they might take a notion to shoot at us first and ask
questions as to our peaceable intentions afterward--when it would
be too late."

"Nonsense!" exclaimed Tom. "There aren't any tramps there and,
if there were, they wouldn't dare shoot. I'm going to see what
the mystery is--if there is one."

But there was no sign of life, and, taking this as an
indication that their advance would not be disputed, Jackson
followed Tom. The latter advanced until he could take in all the
details of the shack. It was made of logs, and once had been
chinked with mud or clay. Some of this had fallen out, leaving
spaces between the tree trunks.

"It wasn't a bad little shack at one time," decided Tom. "Maybe
it was a place where some one camped out during the summer. But
it hasn't been used of late. I never knew there was such a place
around here, and I thought I knew this locality pretty well."

"I never heard of it, either," said Jackson. "Let's give a
shout and see if there's any one around. They may be asleep.
Hello, there !" he called in sufficiently vigorous tones to have
awakened an ordinary sleeper.

Put there was no answer, and as the shadows of the night began
to fall, the place took on a most lonely aspect.

"Let's go up and knock--or go in if the door's open," suggested
Tom. "We can't lose any more time, if we're to get out of here
before night."

"Go ahead," said Jackson, and together they went to the cabin

"Locked!" exclaimed Tom, as he saw a padlock attached to a
chain. It appeared to be fastened through two staples, driven one
into the door and the other into the jamb, at right angles to one
another and overlapping.

"Knock!" suggested Jackson. But when Tom had done so, and there
was no answer, the machinist took hold of the lock. To his own
surprise and that of Tom, one of the staples pulled out and the
door swung open. The place had evidently been forced before, and
the lock had not been opened by a key. The staple had been pulled
out and replaced loosely in the holes.

For a moment nothing could be made out in the dark interior of
the shack. But as their eyes became used to the gloom, Tom and
his companion were able to see that the shack consisted of two

In the first one there was a rusty stove, a table, and some
chairs, and it was evident, from pans and skillets hanging on the
wall, as well as from a small cupboard built on one side, that
this was the kitchen and living room combined.

"Anybody here?" cried Tom, as he stepped inside.

Only a dull echo answered.

The two could now see where a door gave entrance to an inner
room, and this, a quick glance showed, was the sleeping
apartment, two bunks being built on the side walls.

"Well, somebody had it pretty comfortable here," decided Tom,
as he looked around. "They've been cooking and sleeping here, and
not so very long ago, either. It wouldn't be such a bad place if
it was cleaned out."

"That's right," agreed Jackson. "Wouldn't mind camping here
myself, if there was any fishing near."

"The river can't be far away," suggested Tom. "And now let's
see what we can find, and see if we can get a line on who has
been here. But first we'll let in a little light."

He opened a window in the sleeping room, and pushed back the
heavy plank shutter that had been closed. When the light entered
it was seen that both bunks bore evidence of having been lately
slept in. The blankets were tossed back, as if the occupants had
risen, and in the outer room, on the stove, were signs that
indicated a meal had been served not many days gone by.

"Now," observed Tom musingly, as he wandered about the place,
"if we could only find out who owns this, and who has been here

Jackson stooped over, and, thrusting aside an end of the
blankets that trailed on the floor from one of the bunks, picked
up something.

"What is it?" asked Tom.

"Looks like a leather pocketbook," was the answer. "That's what
it is," the mechanic went on, as he held the object to the light.
"It's a wallet."

"Let me see it!" exclaimed Tom quickly. He took the wallet from
the hands of Jackson. Then the young inventor uttered a cry. "A
clew at last!" he exclaimed. "A clew at last! Mr. Nestor has been
in this cabin!"

"How do you know?" asked Jackson quickly.

"This is his wallet," said Tom excitedly. "I've often seen him
have it. In fact he had it with him on Earthquake Island, the
time I sent the wireless message for help. I saw it several times
then. He kept in it what few papers he had saved from the wreck.
And I've seen it often enough since. That's Mr. Nestor's wallet
all right. Besides, if you want any other evidence--look!" He
opened the leather flaps and showed Jackson on one, stamped in
gold letters, the name of Mary's father.

"Well, what do you make of it, Tom?" asked the mechanician, as
he finished his examination of the wallet. "What does it mean?
The pocket-book is empty and that--"

"Might mean almost anything," completed Tom. "But it's a clew
all right! He's been here, and I'm pretty certain he was brought
here in the auto with the odd tires--the one Mr. Damon and I saw
traces of the night we heard the cries for help."

"But that doesn't help us now," said Jackson. "The point is to
find out how lately Mr. Nestor was here, and what has happened to
him since. There isn't anything in the wallet, is there?"

"Nothing," answered Tom, making a careful examination so as to
be sure. "It's as empty as a last year's bird nest. He's been
robbed--that's what has happened to Mr. Nestor. He was waylaid
that night, instead of being run down as I thought--waylaid and
robbed and then his body was brought here."

"There you go again, Tom! Jumping to conclusions!" said
Jackson, with a friendly smile, and with the familiarity of an
old and valued helper. "Maybe he's in perfectly good health. Just
because you found his empty wallet doesn't argue that your friend
is in serious trouble. He may have dropped this on the road and
some one picked it up. I'll admit they may have taken whatever
was in it, but that doesn't prove anything. The thing for us to
do is to find out who knows about this shack; who owns it, on
whose land it is, and whether any one has been seen here lately."

"They've been here lately whether they've been seen or not,"
said Tom positively. "There are the auto tracks. It rained two
days ago, and the tracks were made since. Mr. Nestor must have
been here within two days."

"He may or may not," said Jackson. "Say, rather, that some one
was here and left his wallet after him. Now see if we can find
other clews!"

They looked about in the fast fading light, but at first could
discover nothing more than evidences that three or four persons
had been living in the shack and at some recent date--probably
within a day or two.

They had had their meals there and had slept there. But this
seemed to be all that could be established, other than that Mr.
Nestor's wallet was there, stripped of its contents.

Tom was looking through the closet, from which a frightened
chipmunk sprang as he opened the door. There were the remains of
some food, which accounted for the presence of the little striped
animal. And, as Tom poked about, his hand came in contact with
something wrapped in paper on an upper shelf. It was something
that clinked metallicly.

"What's that?" asked Jackson. "Knives, or some other weapons?"

"Neither," answered Tom. "It's a couple of files, and they've
been used lately. I can see something in the grooves yet and--"

Suddenly Tom ceased speaking and drew from his pocket a small
but powerful magnifying glass. Through this he looked at one of
the files, taking it out in front of the shack where the light
was better.

"I thought so!" he cried. "Look here, Jackson!"

"What is it?"

"Another clew!" answered Tom.


For a moment Jackson thought Tom had discovered a clew to, or
evidences of, some crime. He had an unpleasant suspicion, for an
instant, that there was blood on the files, and that it might
prove to be the blood of Mr. Nestor.

But the satisfaction that showed on Tom's face did not seem to
indicate such dire possibilities as these.

"What is it?" asked Jackson, unable to guess at what Tom was
looking through the powerful glass. "What do you see?"

"Metal filings on the grooves of these files," said the young
inventor. "And, unless I'm greatly mistaken, the particles of
filings are from the case of my aircraft silencer!"

"What!" cried the machinist. "Do you mean those are the files
used in weakening the outer case of your new machine, so that it
burst a little while ago?"

"That what I think," answered Tom. "I know it sounds pretty
far-fetched," he went on. "But take a look for yourself. If those
particles on, the files aren't exactly of the same color and
texture as the material of which the silencer case is made, I'll
never build another machine."

Jackson peered through the powerful glass moving out a little
farther from the shack, so as to get the best light possible on
the subject of his examination. It was fast getting dark, but
there was enough glow in the western sky for his purpose.

"Am I right?" asked Tom.

"You're right!" declared his helper. "This is exactly the same
metal as that of which your silencer case is made. It's a
peculiar mixture of aluminum and vanadium steel. I never knew it
used in any shop but yours, and these filings are certainly of
that metal. It would seem, Tom, that these were the files used to
cut a crease in the case of your silencer to weaken it so it
would burst."

"My idea exactly!" cried Tom. "The spy, who got into my shop in
some undiscovered manner, did his work and then fled here to
hide. He left his files behind. Mr. Nestor must have been here,
either before or after. No, I'll not say that, either. Finding
his wallet here doesn't prove that he was here. It might have
been brought here by one of the spies and dropped. But I'm sure
we're on the track of the men who damaged my airship, as well as
those who know something of the mystery of Mr. Nestor."

"I agree with you," said Jackson. "Of course there's a
possibility that the same peculiar metal you used in your
silencer case may have been used in some other machine shop, and
these files may have come from there, and have been employed in
perfectly regular work. But the chances are--"

"There's only one way to make sure," said Tom. "Let's take the
files with us and see if they fit in the grooves where the break
came. We'll take these back to where we left the Air Scout," and
he clinked the files he held.

"We can just about make it before it gets black dark," returned
Jackson. "But that won't give us any more time to look around
here," and he indicated the hut.

"I fancy we've seen all there is to see here," said Tom. "Mr.
Nestor isn't here, and whether he was or not is a question.
Anyhow, some one was here who had something to do with him after
his disappearance, I'm positive of that. And I'm sure some one
was here who damaged my airship. Now we'll run down both those
clews, find out who owns this place, who has been using it, and
all we can along that line. So, if you're ready, let's travel."

The two set out to make their way back to where they had left
the stranded airship. It was fast becoming dark, but they could
hurry along with more speed now, as they did not have to stop to
look for the marks of the peculiar automobile tires. They had
noticed the path along which they had traveled, and in half the
time they had spent coming they were back where the Air Scout
rested undisturbed in the meadow amid the trees.

Making sure that, as far as they could tell, no one had visited
the craft since they had left it, Tom and Jackson compared the
file marks on what was left of the broken silencer case with the
files they had found in the hut. They used a small, but powerful
electric lamp to aid them in this examination, as it was too dark
to see otherwise, and what they saw caused the young inventor to

"That settles it! These were the files used!"

"That's right!" agreed his assistant. "You've called the turn,
Tom. The next thing to do is to find who connects with the

"Yes. To do that and find Mr. Nestor," said Tom. "We have
plenty of work ahead of us. But let's get nearer civilization and
send some word to the folks at home. They'll be getting worried."

"It doesn't seem as if there was a way out of here without
using an airship," remarked Jackson.

But he and Tom finally reached the seldom-used road which ran
along the field that contained the lonely shack, and, following
this, they reached a farmhouse about a mile farther on. Greatly
to their relief, there was a telephone in the place. True it was
only a party line, set up by some neighboring farmers for their
own private use, but one of the subscribers, to whose home the
private line ran, had a long distance instrument, and after a
talk with him, this man promised Tom to call up Mr. Swift and
acquaint him with the fact that his son and Jackson were all
right, and would be home later.

"And now," said Tom, after thanking their temporary host, a
farmer named Bloise, "can you tell us anything about an old cabin
that stands back there?" and he indicated the location of the
mysterious shack.

"Well, yes, I can tell you a little about it, but not very
much," said Mr. Bloise. "It was built, some years ago, by a rich
New Yorker, who bought up a lot of land around here for a game
preserve. But it didn't pan out. This cabin was only the start of
what he was going to call a 'hunting lodge,' I believe it was.
There was to be a big building on the same order, but it never
was built.

"Some say the fellow lost all his money in Wall Street, and
others say the state wouldn't let him make a game preserve here.
However it was, the thing petered out, and the old shack hasn't
been used since."

"Oh, yes, it has!" exclaimed Tom. "We just came from there, and
there are signs which show some one has been sleeping there and
eating there."

"There has!" exclaimed the farmer. "Well, I didn't know that."

"I did," said his son, a young man about Tom's age. "I meant to
speak of it the other day. I saw an automobile turn into the old
road that the men used when they built the shack. I thought it
was kind of queer to see a touring car turn in there, and I meant
to speak of it, but I forgot. Yes, some one has been at the old
cabin lately."

"Do you know who they are?" asked Tom eagerly. "We are looking
for a Mr. Nestor, who disappeared mysteriously about two weeks
ago, and I just found his wallet there in the shack!"

"You did!" exclaimed Mr. Bloise. "That's queer! You relatives
of this Mr. Nestor?" he asked.

"Not exactly," Tom answered. "Just very close friends."

"Well, it's too bad about his being missing in that way," went
on the farmer. "I read about it in the paper, but I never
suspected he was around here."

"Oh, we're not sure that he was," said Tom quickly. "Finding
his wallet doesn't prove that," and he told the story of his own
and Jackson's appearance on the scene, to the no small wonder of
the farmer and his family. Tom said nothing about the finding of
the files, nor the evidence he deduced from them. That was
another matter to be taken up later.

"Who were in the auto you saw?" asked Tom of the farmer's son.
"Was Mr. Nestor in the car?"

"I couldn't be sure of that. There were two men in the machine,
and they were both strangers to me. They were talking together,
pretty earnestly, it seemed to me."

"One did not appear as if he was being taken away against his
will, did he?" asked Tom.

"No, I can't say that he did," was the answers "They looked to
me, and acted like, business men looking over land, or something
like that. They just turned in on the road that leads to the old
hunting cabin, as we call it around here, and didn't pay any
attention to me. Then I forgot all about them."

"Neither of them could have been Mr. Nestor," decided Tom. "At
least it doesn't seem as if he'd talk at all companionably to a
man who had treated him as we think Mr. Nestor has been treated.
I guess that clew isn't going to amount to much."

"It may!" insisted Jackson. "They may have had Mr. Nestor in
the car all the while--concealed in the back you know. We've got
to find out more about these men and their auto, Tom."

"Well, yes, perhaps we have. But how?"

"Station some one at the shack, or at the beginning of the
private road. The men may come back."

"That's so--they may. We'll do that!" cried the young inventor.
"We must tell the police and Mr. Nestor's folks what we have
learned. How can we get back to Shopton in a hurry?" he asked
the farmer.

"Well, I can drive you to the railroad station" was the answer.

"Thank you," remarked Tom. "We'll accept your offer. And as
soon as we get back we must send some one from the shop to stand
guard over the airship," he added in an aside to Jackson. "Those
file fellows may come back."

"That's so, we can't take any chances."

The farmer soon had his team at the door, and, after they had
had a hasty but satisfying supper at the farmhouse, the son drove
Tom and Jackson several miles to a railroad station, where they
could catch a train for Shopton.

In due season Tom's home was reached. He intended to stop but a
minute, to assure his father that everything was all right, and
then get out his speedy runabout to go to see Mary, to tell her
the news.

But when Tom sought his father in the library, he was told that
there was a visitor in the house.

"Tom," said his father, "this gentleman is from Washington. He
wants to arrange for a government test of your silent airship. I
told him I thought you were about ready for it."

"A government test !" cried Tom. "Why, I didn't think the
government even knew I was working on such an idea!" Tom was
greatly surprised.


With a reassuring smile the visitor from Washington looked at
Tom Swift.

"The government officials," he said, "know more than some
people give them credit for--especially in these war times. Our
intelligence bureau and secret service has been much enlarged of
late. But don't be alarmed, Mr. Swift," went on the caller, whose
name was Mr. Blair Terrill. "Your secret is safe with the
government, but I think the time is ripe to use it now--that is,
if you have perfected it to a point where we can use it."

"Yes," answered Tom slowly, "the invention is practically
finished and it is a success, except for a few minor matters that
will not take long to complete.

"Our accident this afternoon had nothing to do with the
efficiency of the silencer," Tom went on. "It was deliberately
damaged by some spy. I'll take that up later. That I am
interested to know how you heard of my Air Scout, as I call it."

"Well, we have agents, you know, watching all the inventors who
have helped us in times past, and we haven't forgotten your giant
cannon or big searchlight. I might say, to end your curiosity and
lull your suspicions, that your friend, Ned Newton, who has been
doing such good Liberty Bond work, informed us of your progress
on the silent motor."

"Oh, so it was Ned!" exclaimed Tom.

"Yes. He told us the time was about ripe for us to make you an
offer for your machine. I think we can use it to great advantage
in scout work on the western front," went on the agent, and he
soon convinced Tom that when it came to a knowledge of airships,
he had some very pertinent facts at his disposal.

"When can you give me a test?" Mr. Terrill asked Tom.

"As soon as I can get my craft back to the shop and fit on a
new outer case. That won't take long, as I have some spare ones.
But I must help the Nestors," he went on, speaking to his father.
"I didn't mention it over the wire," he added, "but we've found
in the cabin a clew to the missing man. I must tell Mary and her
mother, and help them all I can."

"And allow me to help, too," begged Mr. Terrill. "Since this
affects you, Mr. Swift, and since you are, in a way, working for
Uncle Sam, you must let him help you. This is the first I have
heard of the missing gentleman, of whom your father just told me
something, but you must allow me to help search for him. I will
get the United States Secret Service at work."

"That will be fine!" cried Tom. "I wanted to get their aid, but
I didn't see how I could, as I knew they were too busy with army
matters and tracing seditious alien enemies, to bother with
private cases. I'm sure the Secret Service men can get trace of
the persons responsible for the detention of Mr. Nestor, wherever
he is."

"They'll do their best," said Mr. Terrill. "I'm a member of
that body," he went on, "and I'll give my personal attention to
the matter."

Then followed a busy time. Tom did not get to bed until nearly
morning. For he had to arrange to send some of his men to guard
the stranded airship, and then he went to see Mary and her
mother, taking them the good news that the search for Mr. Nestor
would be prosecuted with unprecedented vigor.

"If it isn't too late!" sadly said the missing man's wife.

"Oh, I'm sure it isn't !" declared Tom.

In addition to sending a guard to the airship, other men, some
of them hastily summoned from the nearest federal agency, were
sent to keep watch in the vicinity of the lonely cabin. They had
orders to arrest whoever approached, and a relay of the men was
provided, so that watch could be kept up night and day. Besides
this, other men from the Secret Service began scouring the
country around the locality of the cabin, seeking a trace of the
two persons the farmer's son had seen in the automobile.

"If Mr. Nestor is to be found, they'll find him!" declared Tom

Mr. Damon, as might be expected, was very much excited and
wrought up over all these happenings.

"Bless my watch chain, Tom Swift!" cried the eccentric man,
"but something is always happening to you. And to think I wasn't
along when this latest happened!"

"Well, you can be in at the finish," promised Tom, and it was
strange how his promise was fulfilled.

Meanwhile there was much to do. During the time the Secret
Service men were busy looking up clews which might lead to the
finding of Mr. Nestor and keeping watch in the vicinity of the
hut, Tom had his airship brought back to the hangar, and a new
silencer was attached. While this work was going on the place was
guarded night and day by responsible men, so there was no chance
for an enemy spy to get in and do further damage.

An investigation was made of the Universal Flying Machine
Company, but nothing could be proved to link them with the
outrage. Gale and Ware were in Europe--ostensibly on government
business, but it was said that if anything could be proved
connecting them with the attempt made on Tom Swift's craft, they
would be deprived of all official contracts and punished.

All this took time, and the waits were wearisome, particularly
in the case of Mr. Nestor. No further trace of him was found,
though every effort was made. Tom began to feel that his boast of
his enemies having to get up early in the morning to get ahead of
him, had been premature, to say the least.

Tom Swift worked hard on his new Air Scout. He determined there
would be nothing lacking when it came to the government test, and
not only did he make sure that no enemy could tamper with his
machine, but he took pains to see that no inherent defect would
mar the test.

Jackson and the other men helped to the best of their ability,
and Mr. Swift suggested some improvements which were incorporated
in the new machine.

One of the puzzles the Secret Service men had to solve was that
of the connection, if any, between the men who had to do with the
missing Mr. Nestor and those who had damaged Tom's airship by
filing the muffler case so it was weakened and burst. That there
was some connection Tom was certain, but he could not work it
out, nor, so far, had the government men.

At last the day came when the big government test was to be
made. Tom had completed his Air Scout and had refined it to a
point where even his critical judgment was satisfied. All that
remained now was to give Mr. Terrill a chance to see how silently
the big craft could fly, and to this end a flight was arranged.

Tom had put the silencer on a larger machine than the one he
and Jackson had used. It held three easily, and, on a pinch, four
could be carried. Tom's plan was to take Mr. Damon and Mr.
Terrill, fly with them for some time in the air, and demonstrate
how quiet his new craft was. Then, by contrast, a machine without
the muffler and the new motor with its improved propellers would
be flown, making as much noise as the usual craft did.

"I only wish," said Tom, as the time arrived for the official
government test, "that Mary could be here to see it. She was the
one who really started me on this idea, so to speak, as it was
because I couldn't talk to her that I decided to get up a silent

But Mary Nestor was too grief-stricken over her missing father
to come to the test, which was to take place late one afternoon,
starting from the aerodrome of the Swift plant.

"First," said Tom, to Mr. Terrill, "I'll show you how the
machine works on the ground. I'll run the motor while the plane
is held down by means of ropes and blocks. Then we'll go up in

"That suits me," said the agent. "If it does all you say it
will do, and as much as I believe it will do, Uncle Sam will be
your debtor, Mr. Swift."

"Well, we'll see," said Tom with a smile.

Preparations were made with the greatest care, and Tom went
over every detail of the machine twice to make certain that, in
spite of the precautions, no spy had done any hidden damage, that
might be manifested at an inopportune moment. But everything
seemed all right, and, finally, the motor was started, while Mr.
Terrill, and some of his colleagues from the Army Aviation
department looked on.

"Contact!" cried Tom, as Jackson indicated that the compression
had been made.

The mechanic nodded, gave the big propeller blades a quarter
turn and jumped back. In an instant the motor was operating, and
the craft would have leaped forward and cleaved the air but for
the holding ropes and blocks. Tom speeded the machinery up to
almost the last notch, but those in the aerodrome hardly heard a
sound. It was as though some great, silent dynamo were working.



"Wouldn't have believed it possible!"

These were some of the comments of the government inspectors.

"And now for the final test--that in the air," said Mr.

Previous to this he and his colleagues had made a minute
examination of the machinery, and had been shown the interior
construction of the silencer by means of one built so that a
sectional view could be had. Tom's principles were pronounced
fundamental and simple.

"So simple, in fact, that it is a wonder no one thought of it
before," said a navy aviation expert. "It is the last word in
aircraft construction--a silent motor that will not apprise the
enemy of its approach! You have done wonders, Mr. Swift!"

"I'd rather hear you say that after the air test," replied Tom,
with a laugh. "Are you ready, Mr. Terrill?"

"Whenever you are."

"How about you, Mr. Damon?"

"Oh, I'm always ready to go with you, Tom Swift. Bless my
trench helmet, but you can't sail any too soon for me!"

There was a genial laugh at his impetuosity, and the three took
their seats in the big craft. Once more the engine was started.
It operated as silently as before, and the first good impressions
were confirmed. Even as the machine moved along the ground, just
previous to taking flight into the air, there was no noise, save
the slight crunch made by the wheels. This, of course, would be
obviated when Silent Sam was aloft.

Up and up soared the great craft, with Tom at the engine and
guide controls, while Mr. Terrill and Mr. Damon sat behind him,
both eagerly watching. Mr. Terrill was there to find fault if he
could, but he was glad he did not have to.

"The machine works perfectly, Mr. Swift," he said. "My report
cannot be otherwise than favorable."

"We mustn't be in too much of a hurry," said Tom, who had
learned caution some time ago. "I want to sail around for several
hours. Sometimes a machine will work well at first, but defects
will develop when it is overheated. I'm going to do my best to
make a noise with this new motor."

But it seemed impossible. The machinery worked perfectly, and
though Silent Sam took his passengers high and low, in big
circles and small ones, there was no appreciable noise from the
motor. The passengers could converse as easily, and with as
little effort, as in a balloon.

"Of course that isn't the prime requisite," said Mr. Terrill,
"but it is a good one. What we want is a machine that can sail
over the enemy's lines at night without being heard, and I think
this one will do it--in fact, I'm sure it will. Of course the
ability of the passengers to converse and not have to use the
uncertain tube is a great advantage."

As Tom Swift sailed on and on, it became evident that the test
was going to be a success. The afternoon passed, and it began to
grow dark, but a glorious full moon came up.

"Shall I take you down?" the young inventor asked Mr. Terrill.

"Not quite yet. I thoroughly enjoy this, and it isn't often I
get a chance for a moonlight airship ride. Go a little lower, if
you please, and we'll see if we attract any attention from the
inhabitants of the earth. We'll see if they can possibly hear the
machine, though I don't see how they can."

And they did not. Tom piloted the machine over Shopton, sailing
directly over the center of the town, where there was a big crowd
walking about. Though the airship sailed only a few hundred feet
above their heads, not a person was aware of it, since the
craft's lights were put out for this test.

"That settles it," said Mr. Terrill. "You have succeeded, Tom

But Tom was not yet satisfied. He wanted a longer test. Hardly
knowing why he did it he sent the craft in the direction of Mary
Nestor's home. As he sailed across her lawn he saw, in the
moonlight, that she and her mother were walking in the garden.
They did not look up as the aircraft passed over their heads, and
were totally unaware of its presence, unless they caught a
glimpse of it as it flitted silently along, like some great bird
of the night.

"It is perfectly wonderful!" declared Mr. Terrill, and he spoke
in ordinary tones, that carried perfectly to the ears of Tom and
Mr. Damon.

"Wonderful!" cried the eccentric man. "Bless my chimney, but
it's the greatest invention in the world! Yes, it is! Don't tell
me it 'isn't!"

And no one did.

Passing the Nestor home, the saddened occupants of which were
unaware of the passage, Tom sent the Air Scout about in a circle,
intending to proceed to the hangar. And then, some whim, perhaps,
caused him to guide Silent Sam out toward the lonely hut. Mr.
Damon and Mr. Tenrill seemed perfectly content to sail on and on
indefinitely in the moonlight. Tom thought he would take them
over a lonely neighborhood, and then bring them back.

In a little while the craft was directly over the stretch of
country where the aeroplane accident bad occurred, and where Tom
and Jackson had found the deserted hut.

Rather idly Tom looked down, wondering if the Secret Service
men were on the watch and if they had discovered anything.

Suddenly Tom was aware of an automobile moving along the field
path toward the cabin. There were two men in the car, both on
the front seat, and as Tom looked down the brilliant moonlight
showed him the figure of another man, behind, and huddled in the
tonneau of the car. The aeroplane was low enough for all these
details to be seen by the moon's gleam, but the men in the car,
not hearing any noise, did not look up, so they were unconscious
of this aerial espionage.

"Look! Look!" exclaimed Tom in a low voice to his companions.
"Doesn't that seem suspicious?"


Eagerly Mr. Damon and the government agent leaned over and
looked down. In the moonlight they saw the same sight that had
attracted Tom Swift. The touring car, the two men in front, and
the huddled, bound figure in the back.

"Can you go down, Tom, without letting them hear you?" asked
Mr. Damon, using a low voice, as if fearful the men in the
automobile would hear him.

"I guess so," answered the young inventor. "I can land nearer
to the cabin than Jackson and I did, and then we can see what
these fellows are up to. It looks suspicious to me. That is,
unless they're some of the Secret Service men, and have made a
capture," he added to Mr. Terrill.

"Those aren't any of Uncle Sam's men," declared the agent.
"That is, unless the bound one is. I can't see him very well.
Better go down, and we'll see if we can surprise them."

"My plan," voiced Tom.

Quickly he shifted the rudder, and then, shutting off the
motor, as he wanted to volplane down, he headed his craft for an
open spot that showed in the bright moonlight. By this time the
automobile and its occupants were out of sight behind a clump of
trees, but Tom and his companions felt sure of the destination of
the men--the deserted cabin in the wood.

As silently as a wisp of grass falling, the big craft came down
on a level spot, and then, leaping out, the young inventor and
his two companions crept along the path toward the cabin. Mr.
Terrill was armed, Tom carried a flashlight, while Mr. Damon
picked up a heavy club.

As soon as he came near a place where he thought the marks of
the automobile wheels would show, Tom flashed his light.

"I thought so!" he exclaimed, as he saw the square, knobby tread
marks left by the tires. "It's the same gang, or some of them in
the same car. If we can only capture them!"

"The Secret Service men ought to do that," returned Mr.
Terrill, but, as it developed later, they were not on hand,
though through no fault of theirs.

On and on crept Tom and the two men, until they came within
sight of the cabin. They saw a light gleaming in it, and Tom

"Now we have them! Work our way up quietly and make them
surrender, if we find they're what we think."

"Is there a rear door?" asked Mr. Terrill in a whisper.

Tom answered in the negative, and then all three, in fan shape,
crept up to the front portal. It was open, and silently reaching
a place where they could make an observation, Tom and his
companions looked in.

What they saw filled them with wild and righteous rage, and
brought to an end the mystery of the disappearance of Mr. Nestor.
For there he sat, bound in a chair, and at a table in front of
him were two forbidding-looking men.

"What do you intend to do now?" asked Mr. Nestor in a faint
voice. "I cannot stand this captivity much longer. You admit that
you don't want me--that you never wanted me--so why do you keep
me a prisoner? It cannot do the least good."

"There's no use going over that again !" exclaimed the harsh
voice of one of the men. told you that if you will promise to
keep still about what happened to you, and not to give the
police any information about us, we'll let you go gladly. We
don't want you. It was all a mistake, capturing you. You were the
wrong man. But we re not going to let you go and have you set the
police on us as soon as you get a chance. Give us your promise to
say nothing, and we'll let you join your friends. If you don't--"

"Make no promises, Mr. Nestor!" cried Tom Swift in a ringing
voice, as he leaped from his hiding place, followed by his
companions. "Your friends are here, and you can tell them

"Up with 'em!" called Mr. Terrill to the two conspirators as he
confronted them with his automatic pistol ready for firing. He
had no need to mention hands--they knew what he meant and took
the characteristic attitude.

"Tom! Tom Swift!" cried Mr. Nestor, struggling ineffectually at
his bonds. "Is it really you?"

"Well, I hope it isn't any imitation," was the grim answer.
"We'll tell you all about it later. Jove, but I'm glad we found
you! If it hadn't been for Silent Sam we might never have been
able to."

"Well, I don't know who Silent Sam is," said Mr. Nestor
faintly. "But I'm sure I'm much obliged to him and your other
friends. It has been very hard. Tell me, are my wife and Mary all

"In good health, yes, but, of course, worrying," said Tom. "We
saw them in the garden a little while ago. Now don't talk until I
set you free."

And as Tom cut the ropes from Mr. Nestor, Mr. Damon used them
to bind the two conspirators, while Mr. Terrill stood guard over
them. And when they were safely bound, and Mr. Nestor had
somewhat recovered from the shock, Tom had a chance to examine
the prisoners.

"What does it all mean? Who are you fellows, anyhow, and what's
your game?" he demanded.

"Guess it--since you're so smart!" snapped one.

And no sooner had he opened his mouth and Tom had a glance of
something gleaming brightly yellow, than the young inventor

"The gold tooth! So it's you again, is it, you spy?"

The man shrugged his shoulders with an assumption of
indifference. And, as Tom took a closer look, he became aware
that the man was surely none other than Lydane, the spy he had
chased into the mud puddle some weeks before. His companion was a
stranger to Tom.

"What does it all mean, Mr. Nestor ?" asked Tom. "Have these
men held you a prisoner ever since you called for help on the
moor that night?"

"Yes, Tom, they have. And I did call for help after they
attacked me as I was riding my wheel, but I didn't know any one
heard me. I began to be afraid no one would ever help me."

"We've been trying to, a long time," said Mr. Damon, "but we
couldn't find you. Where did they keep you?"

"Here, part of the time," was Mr. Nestor's answer. "And in
other lonely houses. They bound and gagged me when they took me
from place to place."

"But what was their object?" asked Tom, concluding it was
useless to question the two captives. "Why did they make you a
prisoner, Mr. Nestor?"

"Because they took me for you, Tom."

"For me?"

"Yes. The night I called at your house, and found you were not
at home, I put back in my pocket a bundle of papers I had brought
over to show you. They were plans of a little kitchen appliance a
friend of mine had invented, and I wanted to ask your opinion of

"These scoundrels must have followed me, or have seen the
bundle of papers, and, mistaking me for you, they followed,
attacked me in a lonely spot and, bundling me and my wrecked
wheel into an auto, carried me off. They first demanded that I
gave up the 'plans,' and when I wouldn't they choked off my cries
for help and knocked me into unconsciousness. Then they brought
me here, and kept me here for several days.

"They soon learned that the plans I had weren't those they
wanted, though what they were thin after I couldn't imagine.
Only, from what I laser overheard, I knew they mistook me for you
and that they were bitterly disappointed in not getting plans of
some new airship you were working on. They have kept me a
prisoner ever since, and though they offered to let me go if I
would keep silent, I refused. I did not think, to secure my own
comfort, I should let such men go unpunished if I could bring
about their arrest."

"I should say not!" cried Tom.

"Did they treat you brutally, Mr. Nestor?" asked Mr. Damon.

"Not after they found out who I was, by looking through my
wallet. Of course they didn't behave very decently, but they
weren't actually cruel, except that they bound and gagged me. Oh,
but I'm glad you came, Tom! How did it happen?"

Then they told Mr. Nestor their story, and how the test of the
new Air Scout had led to his rescue.

"But where are the Secret Service men?" asked Mr. Terrill, when
it became evident that none them was on guard at the cabin.

Later it developed that, by following a false clew, the Secret
Service men had been drawn miles away from the cabin. And only
that Tom and his companions in the silent airship saw the men.
Mr. Nestor might not have been rescued for some further time.

His version of what had happened was correct. He had been
mistaken for Tom, and the spy with the gold tooth and his
accomplice had waylaid Mary's father, under the belief that it
was Tom Swift with the plans of the new silent motor. Mr. Nestor
had been attacked while riding his wheel in a lonely place, and
had been carried off and kept in hiding, a prisoner even after
his identity became known.

"Well, this is a good night's work!" exclaimed Tom, when the
two rogues had been sent to jail and Mr. Nestor taken to the
Bloise farmhouse, to be refreshed before he went home. Word of
his rescue was telephoned to Mary and her mother, and it can be
imagined how they regarded Tom Swift for his part in the affair.

Little the worse for his experience, save that he was very
nervous, Mr. Nestor was taken home. He gave the details of his
being waylaid, and told how the men, for many days, were at their
wits' ends to keep him concealed when they found what a stir his
disappearance had created. The conspirators were well supplied
with money, and in the automobile they took their prisoner from
one place to another. They had usurped the use of the cabin and
had lived there nearly a week in hiding, leaving just before the
first visit of Tom and Jackson. The rifled wallet had been
dropped by accident.

And it did not take much delving to disclose the fact that,
Lydane, "Gold Tooth," as he was called, and his crony, were spies
in the pay of the Universal Flying Machine Company. As the men
went under several aliases there is no need of giving their
names. It is to be doubted if they ever used their real ones--or
if they had any.

Of course, there was quite a sensation when Mr. Nestor was
found, and a greater one when it became known the part the
Universal Flying Machine people had in his disappearance in
mistake for Tom. The officials of the company were indicted, and
several of the minor ones sent to jail but Gale and Ware escaped
by remaining abroad.

It came out that they both knew of the acts of Lydane and his
companion in crime, and that the two officials realized the
mistake that had been made by their clumsy operatives. It was
believed that this knowledge led to the visit of Gale to Tom, the
time the latter's suspicions were first aroused. Gale made a
clumsy attempt to clear his own skirts of the conspiracy, but in
vain, though he did escape his just punishment.

What had happened, in brief, was this. Gale and Ware, unable to
secure Tom's services, even by the offer of a large sum of money,
had stooped to the sending of spies to his shop, to get
possession of information about his silent motor. This was after
Gale had, by accident, heard Tom speaking of it to Mr. Damon.

But, thanks to Tom's vigilance, Bower was discovered. The man
tripped into the mud hole lost in the muck the plans Bower passed
to him. They were never recovered. Then Lydane tried again. He
managed, through bribery, to gain access to the hangar where the
new silent machine was kept, and, unable to get the silencer
apart, tried to file it. In doing so he weakened it so that it

The attempt to waylay Tom, and so get the plans from him, had
been tried before this, only a mistake had been made, and Mr.
Nestor was caught instead. Finding out their error, Lydane and
his companions did not tell the Universal people of their
mistake, though Gale and Ware knew the attempt was to be made
against Tom Swift.

Later, hearing that the young inventor was still at work on his
invention, Gale was much surprised, and paid his queer visit, in
an attempt to repudiate the actions of Lydane. At this time it
was assumed that Gale and his partner did not know that it was
Mr. Nestor who had been kidnapped by mistake or they might have
insisted on his release. As it was, Lydane had Mary's father, and
was afraid to let him go, though really their prisoner became a
white elephant on the hands of the conspirators and kidnappers.

And it was after all this was cleared up, and Mr. Nestor
restored to his family and friends, that one day, Tom Swift
received another visit from Mr. Terrill, the government agent.

"Well, Mr. Swift," was the genial greeting, "I have come to
tell you that the favorable report made by my friends and myself
as to the performance of your noiseless motor, has been accepted
by the War Department, and I have come to ask what your terms
are. For how much will you sell your patent to the United

Tom Swift arose.

"The United States hasn't money enough to buy my patent of a
noiseless motor," he said.

"Wha--what!" faltered Mr. Terrill. "Why, I understood--you
don't mean--they told me you were rather patriotic, and--"

"I hope I am patriotic!" interrupted Tom with a smile. "And
when I say that the United States hasn't money enough to buy my
latest invention I mean just that."

"My Air Scout is not for sale!"

"You mean," faltered the government agent. "You say--"

"I mean," went on Tom, "that Silent Sam is for Uncle Sam
without one cent of cost! My father and I take great pleasure in
presenting such machines as are already manufactured, those in
process of making, and the entire patents, and all other rights,
to the government for the winning of the war!"

"Oh!" said Mr. Terrill in rather a strange voice. "Oh!"

And that was all he could say for a little while.

But Tom Swift reckoned without a knowledge of a peculiar law
which prohibits the United States from accepting gifts totally
without compensation, and so, in due season, the young inventor
received a check for the sum of one dollar in full payment for
his silent motor, and the patent rights thereto. And Tom has that
check framed, and hanging over his desk.

And so the silent motor became an accomplished fact and a great
success. Those of you who have read of its work against the
Boches, and how it helped Uncle Sam to gain the mastery of the
sky, need not be reminded of this. By it many surprise attacks
were made, and much valuable information was obtained that
otherwise could not have been brought in.

One day, after the rogues had been sent to prison for long
terms, and Tom had turned over to his government his silent
aircraft--except one which he was induced to keep for his own
personal use--the young inventor went to call on Mary Nestor. The
object of his call, as I believe he stated it, was to see how Mr.
Nestor was, but that, of course, was camouflage.

"Would you like to come for a ride, Mary, in the silent
airship?" asked Tom, after he had paid his respects to Mr. Nestor
and his wife. "We can talk very easily on board Silent Sam
without the use of a speaking tube. Come on--we'll go for a
moonlight sky ride."

"It sounds enticing," said Mary, with a shy look at Tom. "But
wouldn't you just as soon sit on a bench in the garden? It's
moonlight there, and we can talk, and--and--"

"I'd just as soon!" said Tom quickly.

And out they went into the beautiful moonlight; and here we
will leave them and say good-bye.





These spirited tales. convey in a realistic way, the wonderful
advances in land and sea locomotion. Stories like these are
impressed upon the memory and their reading is productive
only of good.


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