Tom Swift and His Air Scout; Or, Uncle Sam's Mastery of the Sky

TOM SWIFT AND HIS AIR SCOUT

CHAPTER I

A SKY RIDE

"Oh Tom, is it really safe?"

A young lady--an exceedingly pretty young lady, she could be

called--stood with one small, gloved hand on the outstretched wing of

an aeroplane, and looked up at a young man, attired in a leather,

fur-lined suit, who sat in the cockpit of the machine just above her.

"Safe, Mary?" repeated the pilot, as he reached in under the hood of

the craft to make sure about one of the controls. "Why, you ought to

know by this time that I wouldn't go up if it wasn't safe!"

"Oh, yes, I know, Tom. It may be all right for you, but I've never been

up in this kind of airship before, and I want to know if it's safe for

me."

The young man leaned over the edge of the padded cockpit, and clasped

in his rather grimy hand the neatly gloved one of the young lady. And

though the glove was new, and fitted the hand perfectly, there was no

attempt to withdraw it. Instead, the young lady seemed to be very glad

indeed that her hand was in such safe keeping.

"Mary!" exclaimed the young man, "if it wasn't safe--as safe as a

church--I wouldn't dream of taking you up!" and at the mention of

"church" Mary Nestor blushed just the least bit. Or perhaps it was that

the prospective excitement of the moment caused the blood to surge into

her cheeks. Have it as you will.

"Come, Mary! you're not going to back out the last minute, are you?"

asked Tom Swift. "Everything is all right. I've made a trial flight,

and you've seen me come down as safely as a bird. You promised to go

up with me. I won't go very high if you don't like it, but my

experience has been that, once you're off the ground, it doesn't make

any difference how high you go. You'll find it very fascinating. So

skip along to the house, and Mrs. Baggert will help you get into your

togs."

"Shall I have to wear all those things--such as you have on?" asked

Mary, blushing again.

"Well, you'll be more comfortable in a fur-lined leather suit,"

asserted Tom. "And if it does make you look like an Eskimo, why I'm

sure it will be very becoming. Not that you don't look nice now," he

hastened to assure Miss Nestor, "but an aviation suit will be

very--well, fetching, I should say."

"If I could be sure it would 'fetch' me back safe, Tom--"

"That'll do! That'll do!" laughed the young aviator. "One joke like

that is enough in a morning. It was pretty good, though. Now go on in

and tog up."

"You're sure it's safe, Tom?"

"Positive! Trot along now. I want to fix a wire and--"

"Oh, is anything broken?" and the girl, who had started away from the

aeroplane, turned back again.

"No, not broken. It's only a little auxiliary dingus I put on to make

it easier to read the barograph, but I think I'll go back to the old

system. Nothing to do with flying at all, except to tell how high up

one is."

"That's just what I don't care to know, Tom," said Mary Nestor, with a

smile. "If I could imagine I was sailing along only about ten feet in

the air I wouldn't mind so much."

"Flying at that height would be the worst sort of danger. You leave it

to me, Mary. I won't take you up above the clouds on this sky ride;

though, later, I'm sure you'll want to try that. This is only a little

flight. You've been promising long enough to take a trip with me, and

now I believe you're trying to back out."

"No, really I'm not, Tom! Only, at the last minute, the machine looks

so small and frail, and the sky is so--big--"

She glanced up and seemed to shiver just a trifle.

"Don't be thinking of those things, Mary!" laughed Tom Swift. "Trot

along and get ready. The motor never worked better, and we may break a

few speed records this morning. No traffic cops to stop us, either, as

there might be if we were in an auto."

"There you go, Mary!" exclaimed Tom, as if struck with a new thought.

"You've ridden in an auto with me many a time, and you never were a bit

afraid, though we were in more danger than we'll be this morning."

"Danger, Tom, in an auto? How?"

"Why, danger of a wheel collapsing as we were going full speed; or the

steering knuckle breaking and sending us into a tree; danger of running

into a stone wall or a ditch; danger of some one running into us, or of

us running into some one else. There isn't one of these dangers on a

sky ride."

"No," said Mary slowly. "But there's the danger of falling."

"One against twenty. That's the safety margin. And, if we do fall, it

will be like landing in a feather bed! There, don't wait any longer. Go

and get ready."

Mary sighed, and then, seeming to summon her nerve to her aid, she

smiled brightly, waved her hand to Tom, and hastened toward his home,

where Mrs. Baggert the matronly housekeeper, was waiting to help the

girl attire herself in a flying-suit of leather.

Mary Nestor, who had a very warm place in the heart of Tom Swift, had,

as he stated, some time since promised to take a trip in the air with

the young inventor. But she had kept putting it off, for one reason or

another, until Tom began to despair of ever getting her to accompany

him. To-day, however, when she had called to inquire about his father,

who had been slightly ill, Tom had, after the social visit, insisted on

the promise being kept.

He had his mechanic get out one of the safest, though a speedy, double

machine, and, with Mary to watch, Tom had taken a trial flight, just to

show her how easy it was. It was not the first time she had seen him

take to the air, but now she watched with different emotions, for she

was vitally interested.

Tom had sailed down from aloft, making a landing in the aviation field

he had constructed near his home, and then he had insisted that Mary

should keep her promise to take a sky ride with him.

"Don't be too long now!" called Tom to the girl, as she hurried toward

the house. "Never mind about your hair, or whether your hat's on

straight. You're going to wear a cap, anyhow, and tuck your hair up

under that. It's hot down here, but it will be cold up above; so tell

Mrs. Baggert to see that you're warmly dressed."

"All right," and gaily she waved her hand to him. Now that she had made

her decision, and was really going up, she was not half so frightened

as she had been in the contemplation of it.

As Tom climbed out of the machine, to give it a careful inspection,

though he was certain there was nothing wrong, an aged colored man

shuffled toward him.

"Yo'--yo'll be mighty careful ob Miss Nestor now, won't yo', Massa

Tom?" asked the man.

"Of course I will, Eradicate," was the young inventor's answer.

"Case we ain't got many laik her no mo', an' dat's de truf, Massa Tom,"

went on the old man. "So be mighty careful laik!"

"That's what I will, Rad! And, while I'm up in the air, don't you and

Koku have any trouble."

"Ho! Trouble wif dat onery no-'count giant! I guess not!" and the

colored man limped off, highly indignant.

Satisfied, from an inspection of his machine, that it was as nearly

mechanically perfect as it was possible to be, Tom Swift finished his

trip around it and stood near the big propeller, waiting for Mary

Nestor to reappear. Presently she did so, and Tom gaily waved his hand

to her.

"You're a picture!" he cried, as he saw how particularly "fetching" she

looked in the aviator's costume which was like his own. Because of the

danger of entanglement, Miss Nestor had doffed her skirts, and wore the

costume of all aviators--men and women.

"I wish I had my camera!" cried Tom. "You look--stunning!"

"I hope that isn't any comment on how I'm going to feel if we have to

make a--forced landing, I believe you call it," she retorted.

"Oh, I'll take care of that!" exclaimed Tom. "Now up you go, and we'll

start," and he helped her to climb into the padded seat of the cockpit,

behind where he was to sit.

"Oh, Tom! Don't be in such a hurry!" expostulated Mary. "Let me get my

breath!"

"No!" laughed the young inventor. "If I did you might back out. Get

in, fasten the strap around you and sit still. That's all you have to

do. Don't be afraid, I'll be very careful. And don't try to yell at me

to go slower or lower once we're up in the air.

"Why not?" Mary wanted to know, as she settled herself in her seat.

"Because I can't very well hear you, or talk to you. The motor makes so

much noise, you know. We can do a little talking through this speaking

tube," and he indicated one, "but it isn't very satisfactory. So if you

have anything to say--"

"In the language of the poets," interrupted Mary, "if I have words to

spill, prepare to spill them now. Well, I haven't! Now I'm here, go

ahead! I shall probably be too frightened to talk, anyhow."

"Oh, no you won't--after the first little sensation," Tom assured her.

"You'll be crazy about it. Come on, Jackson!" he called to the

mechanician. "Start the ball rolling!"

Tom was in his place, his goggles and cap well down over his face, and

he was adjusting the switch as the mechanic prepared to spin the

propellers.

Suddenly a man came running from the Swift house, waving his arms not

unlike the blades of an aircraft propeller, he also shouted, but Tom,

whose ears were covered with his fur cap, could not hear. However,

Jackson did, and stopped whirling the blades, turning about to see what

was wanted.

"Why, it's Mr. Damon!" exclaimed Tom, as he caught sight of the excited

man. "Hello, what's the matter?" the youth asked, pulling aside one

flap of his head-covering so he might hear the answer.

"Tom! Wait a minute! Bless my mouse trap!" exclaimed Mr. Damon, "I want

to speak to you!" He was panting from his run across the field. "I just

got to your house--saw your father--he said you were going up with Miss

Nestor, but--bless my dog biscuit--"

"Can't stop now, Mr. Damon!" answered Tom, with a laugh. "I have only

just succeeded, by hard work, in getting Mary to a point where she has

consented to take a sky ride. If I stop now she'll back out and I'll

never get her in again. See you when I come back," and Tom pulled the

covering over his ear once more.

"But, Tom, bless my shoe laces! This is important!"

"So's this!" answered Tom, with a grin. He saw, by the motion of Mr.

Damon's lips, what the latter had said.

Around swung the propeller blades. The gasoline vapor in the cylinders

was being compressed.

"Contact!" called Tom sharply, as he pressed the switch to give the

igniting spark at the proper moment. The mechanic had stepped back out

of the way, in case there should be a premature starting of the

powerful engine, in which event the blades would have cut him to pieces.

"Wait, Tom! Wait! This is very important! Bless my collar button, Tom

Swift, but this is--"

Bang! Bang! Bang!

With a series of explosions, like those of a machine gun, the motor

started, and further talk was out of the question. Tom turned on more

gas. The propellers became almost invisible blades of light and shadow,

and the aeroplane began moving over the grassy field. The mechanic had

sprung out of the way, pulling Mr. Damon with him.

"Come back! Come back! Wait a minute, Tom Swift! Bless my pansy

blossoms, I want to tell you something!" cried the little man.

But Tom Swift was away and out of hearing. He had started on his sky

ride with Mary Nestor.

CHAPTER II

A NEW IDEA

Any one who has taken a flight in an aeroplane or gone up in a balloon,

will know exactly how Mary Nestor felt on this, her first sky ride of

any distance. For a moment, as she looked over the side of the machine,

she had a distinct impression, not that she was going up, but that some

one had pulled the earth down from beneath her and, at the same time,

given her a shove off into space. Such is the first sensation of going

aloft. Then the rush of air all about her, the slightly swaying motion

of the craft, and the vibration caused by the motor took her attention.

But the sensation of the earth dropping away from beneath her remained

with Mary for some time.

This sensation is much greater in a balloon than in an aeroplane, for a

balloon, unless there is a strong wind blowing, goes straight up, while

an aeroplane ascends on a long slant, and always into the teeth of the

wind, to take advantage of its lifting power on the underside of the

planes. The reason for this sensation--that of the earth's dropping

down, instead of one's feeling, what really happens, that one is

ascending--is because there are no objects by which comparison can be

made. If one starts off on the earth's surface at slow, or at great

speed, one passes stationary objects--houses, posts, trees, and the

like--and judges the speed by the rapidity with which these are left

behind.

Going up is unlike this. There is nothing to pass. One simply cleaves

the air, and only as it rushes past can one be sure of movement. And as

the air is void of color and form, there is no sensation of passing

anything.

So Mary Nestor, as she shot into the air with Tom Swift, had a

sensation as though the earth were dropping from beneath her. For a

moment she felt as though she were in some vast void--floating in

space--and she had a great fear. Then she calmed herself. She looked at

Tom sitting in front of her. Of course, all she could see was his back,

but it looked to be a very sturdy back, indeed, and he sat there in the

aircraft as calmly as though in a chair on the ground. Then Mary took

courage, and ceased to grasp the sides of the cockpit with a grip that

stiffened all her muscles. She was beginning to "find herself."

On and on, and up and up, went Mary and Tom, in this the girl's first

big sky ride. The earth below seemed farther and farther away. The

wide, green fields became little emerald squares, and the houses like

those in a toy Noah's ark.

Down below, Mr. Wakefield Damon, who had hurried over from his home in

Waterfield to see Tom Swift, gazed aloft at the fast disappearing

aeroplane and its passengers.

"Bless my coal bin!" cried the eccentric man, "but Tom is in a hurry

this morning. Too bad he couldn't have stopped and spoken to me. It

might have been greatly to his advantage. But I suppose I shall have to

wait."

"You want to see Master?" asked a voice behind Mr. Damon, and, turning,

he beheld a veritable giant.

"Yes, Koku, I did," Mr. Damon answered, and he did not appear at all

surprised at the sight of the towering form beside him. "I wanted to

see Tom most particularly. But I shall have to wait. I'll go in and

talk to Mr. Swift."

"Yaas, an' I go talk to Radicate," said the giant. "Him diggin' up

ground where Master told me to make garden. Radicate not strong enough

for dat!"

"Huh! there's trouble as soon as those two get to disputing," mused Mr.

Damon, as he went toward the house.

Meanwhile, Mary was beginning to enjoy herself. The sensation of moving

rapidly through the air in a machine as skillfully guided as was the

one piloted by Tom Swift was delightful. Up and up they went, and then

suddenly Mary felt a lurch, and the plane, which was now about a

thousand feet high, seemed to slip to one side.

Mary screamed, and began reaching for the buckle of the safety belt

that fastened her to her seat. She saw that something unusual had

occurred, for Tom was working frantically at the mechanism in front of

him.

But, in spite of this, he seemed aware that Mary was in danger, not so

much, perhaps, from what might happen to the machine, as what she might

do in her terror.

"Oh! Oh!" cried the girl, and Tom heard her above the terrific noise of

the motor, for she was speaking with her lips close to the tube that

served as a sort of inter-communicating telephone for the craft. "Oh,

we are falling! I'm going to jump!"

"Sit still! Sit still for your life!" cried Tom Swift. "I'll save you

all right! Only sit still! Don't jump!"

Mary, her red cheeks white, sank back, and the young inventor redoubled

his efforts at the controls and other mechanisms.

And that Tom was perfectly qualified to make a safe landing, even with

engine trouble, Mary Nestor well knew. Those of you who have read the

previous books of this series know it also, but, for the benefit of my

new readers, I shall state that this was by no means Tom's first ride

in an aeroplane.

He had operated and built gasoline engines ever since he was about

sixteen years old. As related in the initial volume of this series,

entitled, "Tom Swift and His Motorcycle," he became possessed of this

machine after it had started to climb a tree with Mr. Damon on board.

After that experience the eccentric man--blessing everything he could

think of--had no liking for the speedy motorcycle and sold it to Tom at

a low price.

That was the beginning of a friendship between the two, and also

started Tom on his career as an inventor and a possessor of many

gasoline craft. For he was not content with merely riding the repaired

motorcycle. He made improvements on it.

Tom lived with his father in the town of Shopton, their home being

looked after, since the death of Mrs. Swift, by Mrs. Baggert. Mr.

Wakefield Damon lived in the neighboring town of Waterfield, and spent

much time at Tom's home, often going on trips with him in various

vehicles of the land, sea or air.

As related in the various volumes of this series, Tom was not content

to remain on earth. He built a speedy motor boat, and then secured an

airship, following that with a submarine. He also made an electric

runabout that was the speediest car on the road. Sending wireless

messages, having thrilling experiences among the diamond makers,

journeying to the caves of ice, and making perilous trips in his sky

racer took up part of the young inventor's time.

With his electric rifle he did some wonderful shooting, and in the

"City of Gold" made some strange discoveries, part of the fortune he

secured enabling him to build his sky racer. It was in a land of giants

that Tom was made captive, but he succeeded in escaping, and brought

two giants, of whom Koku was one, away with him.

Following this achievement Tom invented a wizard camera and a great

searchlight, which, with his giant cannon, was purchased by the United

States Government. Work on his photo-telephone and his aerial warship,

the problem of digging a big tunnel, and then traveling to the land of

wonders, kept Tom Swift very busy, and he had just completed a

wonderful piece of work when the present story opens.

This last achievement was the perfecting of a machine to aid in the

great World War and you will find the details set down in the volume

which immediately precedes this. "Tom Swift and His War Tank," it is

called, and in that is related how he not only invented a marvelous

machine, but succeeded in keeping its secret from the plotters who

tried to take it from him. In this Tom was helped by the inspiration of

Mary Nestor, whom he hoped some day to marry, and by Ned Newton, a

chum, who, though no inventor himself, could admire one.

Ned and Tom had been chums a long while, but Ned inclined more to

financial and office matters than to machinery. At times he had managed

affairs for Tom, and helped him finance projects. Ned was now an

important bank official, and since the United States had entered the

war had had charge of some Red Cross work, as well as Liberty Bond

campaigns.

Somehow, as she sat there in the craft which seemed disabled, Mary

Nestor could not help thinking of Tom's many activities, in some of

which she had shared.

"Oh, if he falls now, and is killed!" she thought. "Oh, what will

happen to us?"

"It's all right, Mary! Don't worry! It's all right!" cried Tom, through

the speaking tube.

"What's that? I can't hear you very well!" she called back.

"No wonder, with the racket this motor is making," he answered. "Why

can't something be done so you can talk in an aeroplane as well as in a

balloon? That's an idea! If I could tell you what was the matter now

you wouldn't be a bit frightened, for it isn't anything. But, as it

is--"

"What are you saying, Tom? I can't hear you!" cried Mary, still much

frightened.

"I say it's all right--don't get scared. And don't jump!" Tom shouted

until his ears buzzed. "It's all nonsense--having a motor making so

much noise one can't talk!" he went on, irritatedly.

A strange idea had come to the young inventor, but there was no time to

think of it now. Mentally he registered a vow to take up this idea and

work on it as soon as possible. But, just now, the aeroplane needed all

his attention.

As he had told Mary, there was really nothing approaching any great

danger. But it was rather an anxious moment. If Tom had been alone he

would have thought little of it, but with Mary along he felt a double

responsibility.

What had happened was that the craft had suddenly gone into an "air

pocket" or partial vacuum, and there had been a sudden fall and a slide

slip. In trying to stop this too quickly Tom had broken one of his

controls, and he was busily engaged in putting an auxiliary one in

place and trying to reassure Mary at the same time.

"But it's mighty hard trying to do that through a speaking tube with a

motor making a noise like a boiler factory," mused the young inventor.

Tom worked quickly and to good purpose. In a few moments, though to

Mary they seemed like hours, the machine was again gliding along on a

level keel, and Tom breathed more easily.

"And now for my great idea!" he told himself.

But it was some time before he could give his attention to that.

CHAPTER III

THE BIG OFFER

Working with all the skill he possessed, Tom had got the aeroplane in

proper working order again. As has been said, the accident was a

trivial one, and had he been alone, or with an experienced aviator, he

would have thought little of it. Then, very likely, he would have

volplaned to earth and made the repairs there. But he did not want to

frighten Mary Nestor, so he fixed the control while gliding along, and

made light of it. Thus his passenger was reassured.

"Are we all right?" asked Mary through the tube, as they sailed along.

"Right as a fiddle," answered Tom, shouting through the same means of

communication.

"What's that about a riddle?" asked Mary, in surprise at his seeming

flippancy at such a time.

"I didn't say anything about a riddle--I said we are as fit as a

fiddle!" cried Tom. "Never mind. No use trying to talk with the racket

this motor makes, and it isn't the noisiest of its kind, either. I'll

tell you when we get down. Do you like it?"

"Yes, I like it better than I did at first," answered Mary, for she had

managed to understand the last of Tom's questions. Then he sailed a

little higher, circled about, and, a little later, not to get Mary too

tired and anxious, he headed for his landing field.

"I'll take you home in the auto," he cried to his passenger. "We could

go up to your house this way--in style--if there was a field near by

large enough to land in. But there isn't. So it will have to be a

plain, every-day auto."

"That's good enough for me," said Mary. "Though this trip is

wonderful--glorious! I'll go again any time you ask me."

"Well, I'll ask you," said Tom. "And when I do maybe it won't be so

hard to hold a conversation. It will be more like this," and he shut

off the motor and began to glide gently down. The quiet succeeding the

terrific noise of the motor exhaust was almost startling, and Tom and

Mary could converse easily without using the tube.

Then followed the landing on the soft, springy turf, a little glide

over the ground, and the machine came to a halt, while mechanics ran

out of the hangar to take charge of it.

"I'll just go in and change these togs," said Mary, as she alighted and

looked at her leather costume.

"No, don't," advised Tom. "You look swell in em. Keep 'em on. They're

yours, and you'll need 'em when we go up again. Here comes the auto.

I'll take you right home in it. Keep the aviation suit on.

"I wonder what Mr. Damon could have wanted," remarked Tom, as he drove

Mary along the country road.

"He seemed very much excited," she replied.

"Oh, he almost always is that way--blessing everything he can think of.

You know that. But this time it was different, I'll admit. I hope

nothing is the matter. I might have stopped and spoken to him, but I

was afraid if I did you'd back out and wouldn't come for a sky ride."

"Well, I might have. But now that I've had one, even with an accident

thrown in, I'll go any time you ask me, Tom," and Mary smiled at the

young inventor.

"Shucks, that wasn't a real accident!" he laughed. "But I do wonder

what Mr. Damon wanted."

"Better go back and find out, Tom," advised Mary, as they stopped in

front of her house.

"Oh, I want to come in and talk to you. Haven't had a chance for a good

talk today, that motor made such a racket."

"No, go along now, but come back and see me this afternoon if you like."

"I do like, all right! And I suppose Mr. Damon will be fussing until he

sees me. Well, glad you liked your first ride in the air, Mary--that

is, the first one of any account," for Mary had been in an aeroplane

before, though only up a little way--a sort of "grass-cutting stunt,"

Tom called it.

Waving farewell to the pretty girl, the young aviator turned the auto

about and speeded for his home and the shops adjoining it. His father

had not been well, of late, and Tom was a bit anxious about him.

"Mr. Damon may bother him, though he wouldn't mean to," thought Tom.

"He seemed to have his mind filled with some new idea. I wonder if it

is anything like mine? No, it couldn't be. Well, I'll soon find out,"

and, putting his foot on the accelerator, Tom sent the machine along at

a pace that soon brought him within sight of his home.

"Is father all right?" he asked Mrs. Baggert, who was out on the front

porch, as though waiting for him.

"Oh, yes, Tom, he's all right," the housekeeper answered.

"Is Mr. Damon with him?"

"No."

"He hasn't gone home, has he?"

"No, he's around somewhere. But some one else is with your father. Some

visitors."

"Any relations?"

"No; strangers. They came to see you, and they're rather impatient. I

came out to see if you were in sight. Your father sent me."

"Are they bothering him--talking business that I ought to attend to

when he's ill? That mustn't be."

"Well, I suppose it is business that the strangers are talking over

with your father, Tom," said Mrs. Baggert, "for I heard sums of money

spoken of. But your father seems to be all right, only a trifle anxious

that you should come."

"Well, I'm here now and I'll attend to things. Where are the strangers,

and who are they?"

"I don't know," answered the housekeeper. "I never saw them before, but

they're in the library with your father. Do you think they'll stay to

dinner? If you do, I'll have Eradicate or Koku catch and kill a

chicken."

"If you let one do it don't tell the other about it," said Tom with a

laugh, "or you'll have a chicken race around the yard that will make

the visitors sit up and take notice."

There was great rivalry between Eradicate Sampson, the aged colored

man, and Koku, the giant, and they were continually disputing. Each one

loved and served Tom in his own way, and there was jealousy between

them. Koku, the giant Tom had brought with him from the land where the

young inventor had been made captive, was a big, powerful man, and

could do things the aged colored servant could not attempt. But "Rad,"

as he was often called, and his mule "Boomerang" had long been fixtures

on the Swift homestead. But old age crept on apace with Eradicate,

though he hated to admit it, and Koku did many things the colored man

had formerly attended to, and Rad was always on the lookout not to be

supplanted. Hence Tom's warning to Mrs. Baggert about letting the two

be entrusted with the same mission of catching a chicken for the pot.

"Better get the fowl yourself and say nothing to either of them about

it," Tom advised the housekeeper. "Mr. Damon will stay to dinner, as he

always does when he comes, and as it's near twelve now, and as I may be

delayed talking business to these strangers, you'd better get up a

bigger meal than usual."

"I will, Tom," promised Mrs. Baggert. And then the young inventor,

having seen that one of the men took the automobile to the garage, went

into the house.

"Oh, here you are!" was his father's greeting, as he came out into the

hall from the library. "I've been waiting anxiously for you, my boy. I

couldn't think what was keeping you."

"Oh, I had a little trouble with the air machine--nothing serious."

A moment later Tom was standing before two well-dressed,

prosperous-looking business men, who smiled pleasantly at him.

"Mr. Thomas Swift?" interrogated one, the elder, as he held out his

hand.

"That's my name," answered Tom, pleasantly.

"I'm Peton Gale, and this gentleman is Boland Ware," went on the man

who had taken Tom's hand. "I'm president and he's treasurer of the

Universal Flying Machine Company, of New York."

"Oh, yes," said Tom, as he shook hands with Mr. Ware. "I have heard of

your concern. You are doing a lot of government work, are you not?"

"Yes; war orders. And we're up to our neck in them. This war is going

to be almost as much fought in the air as on the ground, Mr. Swift."

"I can well believe that," agreed Tom. "Won't you have a chair?"

"Well, we didn't come to stay long," said Mr. Gale with a laugh, which,

somehow or other, grated on Tom and seemed to him insincere. "Our

business is such a rushing one that we don't spend much time anywhere.

To get down to brass tacks, we have come to see you to put a certain

proposition before you, Mr. Swift. You are open to a business

proposition, aren't you?"

"Oh, yes," answered Tom. "That's what I'm here for."

"I thought so. Well, now I'll tell you, in brief, what we want, and

then Mr. Ware, our treasurer, can elaborate on it, and give you facts

and figures about which I never bother myself. I attend to the

executive end and leave the details to others," and again came that

laugh which Tom did not like.

"You came here to make me an offer?" asked the young inventor,

wondering to which of his many machines the visitors had reference.

"Yes," went on Mr. Gale, "we came here to make you a big offer. In

short, Mr. Swift, we want you to work for our company, and we are

willing to pay you ten thousand dollars a year for the benefit of your

advice and your inventive abilities. Ten thousand dollars a year! Do

you accept?"

CHAPTER IV

MR. DAMON'S WHIZZER

Characteristic it was of Tom Swift that he did not seem at all

surprised at what most young men would call a liberal offer. Certainly

not many youths of Tom's age would be sought out by a big manufacturing

concern, and offered ten thousand dollars a year "right off the reel,"

as Ned Newton expressed it later. But Tom only smiled and shook his

head in negation.

"What!" cried Mr. Gale, "you mean you won't accept our offer?"

"I can't," answered Tom.

"You can't!" exclaimed the treasurer, Mr. Ware. "Oh, I see. Mr. Gale, a

word with you. Excuse us a moment," he added to Tom and his father.

The two men consulted in a corner of the library for a moment, and

then, with smiles on their faces, once more turned toward the young

inventor.

"Well, perhaps you are right, Tom Swift," said Mr. Gale. "Of course, we

recognize your talents and ability, but you cannot blame us for trying

to get talent, as well as material for our airships, in the cheapest

market. But we are not hide-bound, nor sticklers for any set sum. We'll

make that offer fifteen thousand dollars a year, if you will sign a

five-year contract and agree that we shall have first claim on anything

and everything you may patent or invent in that time. Now, how does

that strike you? Fifteen thousand dollars a year--paid weekly if you

wish, and our Mr. Ware, here, has a form of contract which can be fixed

up and signed within ten minutes, if you agree."

"Well, I don't like to be disagreeable," said Tom with a smile; "but,

really, as I said before, I can't accept your very kind offer. I may

say liberal offer. I appreciate that."

"You can't accept!" cried Mr. Gale.

"Are you sure you don't mean 'won't'?" asked Mr. Ware, in a half growl.

"You may call it that if you like," replied Tom, a bit coolly, for he

did not like the other's tone, "Only, as I say, I cannot accept. I have

other plans."

"Oh, you--" began the brusk treasurer, but Mr. Gale, the president of

the Universal Flying Machine Company, stopped his associate with a

warning look.

"Just a moment, Mr. Swift," begged the president. "Don't be hasty. We

are prepared to make you a last and final offer, and I do not believe

you can refuse it."

"Well, I certainly will not refuse it without hearing it," said Tom,

with a smile he meant to make good-natured. Yet, truth to tell, he did

not at all like the two visitors. There was something about them that

aroused his antagonism, and he said later that even if they had offered

him a sum which he felt he ought not, in justice to himself and his

father, refuse, he would have felt a distaste in working for a company

represented by the twain.

"This is our offer," said Mr. Gale, and he spoke in a pompous manner

which seemed to say: "If you don't take it, why, it will be the worse

for you." He looked at his treasurer for a confirmatory nod and,

receiving it, went on. "We are prepared to offer and pay you, and will

enter into such a contract, with the stipulation about the inventions

that I mentioned before--we are prepared to pay you--twenty thousand

dollars a year! Now what do you say to that, Tom Swift?

"Twenty-thousand-dollars-a-year!" repeated Mr. Gale unctuously, rolling

the words off his tongue. "Twen-ty-thou-sand-dol-lars-a-year! Think of

it!"

"I am thinking of it," said Tom Swift gently, "and I thank you for your

offer. It is, indeed, very generous. But I must give you the same

answer. I cannot accept."

"Tom!" exclaimed his aged father.

"Mr. Swift!" exclaimed the two visitors.

Tom smiled and shook his head.

"Oh, I know very well what I am saying, and what I am turning down," he

said. "But I simply cannot accept. I have other plans. I am sorry you

have had your trip for nothing," he added to the visitors, "but,

really, I must refuse."

"Is that your final answer?" asked Mr. Gale.

"Yes."

"Don't you want to take a day or two to think it over?" asked the

treasurer. "Don't be hasty. Remember that very few young men can

command that salary, and I may say you will find us liberal in other

ways. You would have some time to yourself."

"That is what I most need," returned Tom. "Time to myself. No, thank

you, gentlemen, I cannot accept."

"Be careful!" warned Mr. Gale, and it sounded as though there might be

a threat in his voice. "This is our last offer, and your last chance.

We will not renew this. If you do not accept our twenty thousand

dollars now, you will never get it again."

"I realize that," said Tom, "and I am prepared to take the consequences.

"Very well, then," said Mr. Gale. "There seems nothing for us to do,

Mr. Ware, but to go back to New York. I bid you good-day," and he bowed

stiffly to Tom. "I hope you will not regret your refusal of our offer."

"I hope so myself," said Tom, lightly.

When the visitors had gone Mr. Swift turned toward his son, and,

shaking his head, remarked:

"Of course, you know your own business best, Tom. Yet I cannot but feel

you have made a mistake."

"How?" asked Tom. "By not taking that money? I can easily make that in

a year, with an idea I have in mind for an improvement on an airship.

And your new electric motor will soon be ready for the market. Besides,

we don't really need the money."

"No, not now, Tom, but there is no telling when we may," said Mr.

Swift, slowly. "This big war has made many changes, and things that

brought us in a good income before, hardly sell at all, now."

"Oh, don't worry, Dad! We still have a few shots left in the locker--in

other words, the bank. I'm expecting Ned Newton over any moment now, to

give us the annual statement of our account, and then we'll know where

we stand. I'm not afraid from the money end. Our business has done

well, and it is going to do better. I have a new idea."

"That's all very well, Tom," said Mr. Swift, who seemed oppressed by

something. "As you say, money isn't everything, and I know we shall

always have enough to live on. But there is something about those two

men I do not like. They were very angry at your refusal of their offer.

I could see that. Tom, I don't want to be a croaker, but I think you'll

have to watch out for those men. They're going to be your enemies--your

rivals in the airship field," and Mr. Swift shook his head dolefully.

"Well, rivalry, when it's clean and above board, is the spice of trade

and invention," returned Tom, lightly. "I'm not afraid of that."

"No, but it may be unfair and underhand," said Mr. Swift. "I think it

would have been better, Tom, to have accepted their offer. Twenty

thousand a year, clear money, is a good sum."

"Yes, but I may make twice that with something that occurred to me only

a little while ago. Forget about those men, Dad, and I'll tell you my

new idea. But wait, I want Mr. Damon to hear it, too. Where is he?"

"He was here a little while ago. He went out when those two men came

and--"

At that moment, from the garden at the side of the library, the sound

of voices in dispute could be heard.

"Now yo' all g'wan 'way from yeah!" exclaimed some one who could be

none other than Eradicate Sampson. "Whut fo' yo' all want to clutter up

dish yeah place fo'? Massa Tom said I was to do de garden wuk, an' I'se

gwine to do it! G'wan 'way, Giant!"

"Ho! You want me to get out, s'pose you put me, black face!" cried a

big voice, that of Koku, the giant.

"There they go! At it again!" cried Tom with a smile. "Might have known

if I told Rad to do anything that Koku would be jealous. Well, I'll

have to go out now and give that giant something to do that will tax

his strength."

But as Tom was about to leave the room another voice was heard in the

garden.

"Now, boys, be nice," said some one soothingly. "The garden is large

enough for you both to work in. Rad, you begin at the lower end and

spade toward the middle. Koku, you begin at the upper end and work

down. Whoever gets to the middle first will win."

"Ha! Den I'll show dat giant some spade wuk as is spade wuk!" cried the

colored man. "Garden wuk is mah middle name."

"Be careful, Rad!" laughed Mr. Damon, for he it was who was trying to

act as peacemaker. "Remember that Koku is very strong."

"Yas, sah! He may be strong, but he's clumsy!" chuckled Eradicate. "You

watch me beat him!"

"Ho! Black man get stuck in mud!" challenged Koku. "I show him!"

Then there was silence, and Tom and his father, looking out, saw the

two disputants beginning to spade the soil while Mr. Damon, satisfied

that he had, for the time being, stopped a quarrel, turned toward the

house.

"I was just coming to look for you," said Tom. "Sorry I had to go off

in such a hurry and leave you, but I had promised to take Mary for a

ride, and as it was her first one, for a distance, I didn't want her to

back out."

"That's all right, Tom, that's all right!" said Mr. Damon genially.

"Ladies first every time. But I do want to see you, and it's about

something important."

"No trouble, I hope?" queried Tom, for the manner of the eccentric man

was rather grave.

"Trouble? Oh, no! Bless my frying pan, no trouble, Tom! In fact, it may

be the other way about. Tom, I have an idea, and there may be millions

in it! That's it--millions!"

"Good!" cried the young inventor. "Might as well bite off a big lump

while you're at it. So you have a new idea! Well, I have myself, but

I'll listen to yours first. What is it, Mr. Damon?"

"It's a new kind of airship, Tom. I haven't got it all worked out yet,

but I can give you a rough outline. On my way over I got to thinking

about balloons, aeroplanes and the like, and it occurred to me that the

present principles are all wrong."

"So I evolved a new type of machine. I'm going to call it the Damon

Whizzer. Maybe Demon Whizzer would be more appropriate, but we won't

decide on that now. Anyhow, it's going to be a whizzer, and I want to

talk to you about it. There is an entirely new principle of elevation

and propulsion involved in my Whizzer, and I--"

At that moment there came a crash and clatter of steel and wood from

the garden, out of sight of which Tom and Mr. Damon had walked while

talking. Then followed a jangle of words.

"They're at it again!" cried Tom, as he ran toward the side of the

house. "I guess it's a fight this time!"

CHAPTER V

TOM'S PROJECT

Curious was the sight that met the gaze of Tom Swift and Mr. Wakefield

Damon as they rounded the corner of the house and looked into the newly

spaded garden. There stood the giant, Koku, holding aloft in the air,

by one hand, the form of the struggling colored man, Eradicate Sampson.

And Eradicate was vainly trying to get at his enemy and rival, but was

prevented by the long-distance hold the giant had on him.

"Yo' let me go, now! Yo' let me go, big man," cried Eradicate. "Ef yo'

don't I'll bust yo' wide open, dat's whut I'll do! An' 'sides, I'll

tell Massa Tom on yo', dat's whut I'll do!"

"Ho! You tell--I let you fall!" threatened Koku.

His threat was dire enough, for such was his size and strength that he

held the colored man nearly nine feet from the ground, and a fall from

that distance would seriously jar Eradicate, if it did nothing else.

The colored man's eyes opened wide as he heard what Koku said, and then

he cried:

"Let me down! Let me down, an' I won't say nuffin!"

"An' you let me scatter dirt?" asked Koku, for such was the giant's

idea of working in the garden.

"Yes, yo' kin scatter de dirt seben ways from Sunday fo' all I keers!"

conceded Eradicate. Then, as he was lowered to the ground, he and the

giant turned and saw Mr. Damon and Tom approaching.

"What's wrong?" asked the young inventor.

"'Scuse me, Massa Tom," began Eradicate, "but didn't yo' tell me to

spade de garden?"

"I guess I did," admitted Tom Swift.

"An' you tell me help--yes?" questioned Koku.

"Well, I thought it would be a little too much for you, Rad," said Tom,

gently. "I thought perhaps you'd like help."

"Hu! Not him, anyhow!" declared the colored man in great disgust. "When

I git so old dat I cain't spade a garden, den me an' Boomerang, we-all

gwine to die, dat's all I got to say. I was a-spadin' my part ob de

garden, Massa Tom, same laik Mr. Damon done tole me to, an' dish yeah

big mess ob bones steps on my side ob de middle an--"

"Him too slow. Koku scatter dirt twice times so fast!" declared the

giant, whose English was not much better than Eradicate's.

"Yes, I see," said Tom. "You are so strong, Koku, that you finished

your part before Eradicate did. Well, it was good of you to want to

help him."

At this the giant grinned at his rival.

"At the same time," went on Tom, winking an eye at Mr. Damon,

"Eradicate knows a little more about garden work, on account of having

done it so many years."

"Ha! Whut I tell yo', Giant!" boasted the colored man. It was his turn

to smile.

"And so," went on Tom, judicially, "I guess I'll let Rad finish spading

the garden, and you, Koku, can come and help me lift some heavy engine

parts. Mr. Damon wants to explain something to me."

"Ha! Nothing what so heavy Koku not lift!" boasted the giant.

"Go on! Lift yo'se'f 'way from heah!" muttered Eradicate as he picked

up his dropped spade. And then, with a smile of satisfaction, he fell

to work in the mellow soil while Tom led Koku to one of the shops where

he set him to lifting heavy motor parts about in order to get at a

certain machine that was stored away in the back of one of the rooms.

"That will keep him busy," said the young inventor. "And now, Mr.

Damon, I can listen to you. Do you really think you have a new idea in

airships?"

"I really think so, Tom. My Whizzer is bound to revolutionize travel in

the air. Let me tell you what I mean. Now cast your mind back. How many

ways are now used to propel an airship or a dirigible balloon through

the air? How many ways?"

"Two, as far as I know," said Tom. "At least there are only two that

have proved to be practical."

"Exactly," said Mr. Damon. "One with the propeller, or propellers, in

front, and that is the tractor type. The other has the propeller in the

rear, and that is the pusher type. Both good as far as they go, but I

have something better."

"What?" asked Tom with a smile.

"It's a Whizzer," said the eccentric man. "Bless my gold tooth! but

that is the best name I can think of for it. And, really, the propeller

I'm thinking of inventing does whiz around."

"But are you going to use a tractor or pusher type?" Tom wanted to know.

"It's a combination of both," answered Mr. Damon. "As it is now, Tom,

you have to get an aeroplane in pretty speedy motion before it will

rise from the ground, don't you?"

"Yes, of course. That's the principle on which an aeroplane rises and

keeps aloft, by its speed in the air. As soon as that speed stops it

begins to fall, or volplane, as we call it."

"Exactly. Now, instead of having to depend on the speed of the

aeroplane for this, why not depend on the speed of the propeller--in

other words, the whizzer?"

"Well, we do," said Tom, a bit puzzled as to what his friend was trying

to get at. "If the propeller didn't move the airship wouldn't

rise--that is, unless it's of the balloon type."

"What I mean," said Mr. Damon, "is to have an aeroplane that will move

in the air the same as a boat moves in the water. You don't have to get

the propeller of a boat racing around at the rate of a million

revolutions a minute, more or less, before your boat will travel, do

you? If the engine turns the screw, or propeller, just over say fifty

times a minute you would get some motion of the boat, wouldn't you?"

"Why, yes, some," admitted Tom.

"And what causes it?" asked Mr. Damon, anticipating a triumph.

"The resistance of the water to the blades of the screw, or propeller,"

answered Tom.

"Exactly! And it's the resistance of the air to the blades of an

airship propeller that sends the craft along, isn't it?"

"Yes. And because of the difference in density between air and water it

becomes necessary to revolve an aeroplane propeller many times faster

than a boat propeller. It's the density that makes the difference, Mr.

Damon. If air were as dense as water we could have comparatively

slow-moving motors and propellers and--"

"Ha! There you have it, Tom! And there is where my Whizzer--Wakefield

Damon's Whizzer--is going to revolutionize air travel!" cried the

eccentric man. "The difference in density! If air were as dense as

water the problem would be solved. And I have solved it! I'm going to

turn the trick, Tom! One more question. How can air be made as dense as

water, Tom Swift?"

"Why, by condensation or compression, I suppose," was the rather slow

answer. "You know they have condensed, or compressed, air until it is

liquid. I've done it myself, as an experiment."

"That's it, Tom! That's it!" cried Mr. Damon in delight. "Compressed

air will do the trick! Not compressed to a liquid, exactly, but almost

so. I'm going to revolve the propellers of my new airship in compressed

air, so dense that they will not have to have a speed of more than

seven hundred revolutions a minute. What's that compared to the three

to ten thousand revolutions of the propellers now used? The propellers

of Damon's Whizzer will be of the pusher type, and will revolve in

dense, compressed air, almost like water, and that will do away with

high speed motors, with all their complications, and make traveling in

the clouds as simple as taking out a little one-cylinder motor boat.

How's that, Tom Swift? How's that for an idea?"

To Mr. Damon's disappointment, Tom was not enthusiastic. The young

inventor gazed at his eccentric friend, and then said slowly:

"Well, that's all right in theory, but how is it going to work out in

practice?"

"That's what I came to see you about, Tom," was the reply. "Bless my

tall hat! but that's just why I hurried over here. I wanted to tell you

when I saw you going off on a trip with Miss Nestor. That's my big

idea--Damon's Whizzer--propellers revolving in compressed air like

water. Isn't that great?"

"I'm sorry to shatter your air castle," said Tom; "but for the life of

me I can't see how it will work. Of course, in theory, if you could

revolve a big-bladed propeller in very dense, or in liquid, air, there

would be more resistance than in the rarefied atmosphere of the upper

regions. And, if this could be done, I grant you that you could use

slower motors and smaller propeller blades--more like those of a motor

boat. But how are you going to get the condensed air?"

"Make it!" said Mr. Damon promptly. "Air pumps are cheap. Just carry

one or two on board the aeroplane, and condense the air as you go

along. That's a small detail that can easily be worked out. I leave

that to you."

"I'd rather you wouldn't," said Tom. "That's the whole

difficulty--compressing your air. Wait! I'll explain it to you."

Then the young inventor went into details. He told of the ponderous

machinery needed to condense air to a form approximating water, and

spoke of the terrible pressure exerted by the liquid atmosphere.

"Anything that you would gain by having a slow-speed motor and smaller

propeller blades, would be lost by the ponderous air-condensing

machinery you would need," Tom told Mr. Damon. "Besides, if you could

surround your propellers with a strata of condensed air, it would

create such terrible cold as to freeze the propeller blades and make

them as brittle as glass.

"Why, I have taken a heavy piece of metal, dipped it into liquid air,

and I could shatter the steel with a hammer as easily as a sheet of

ice. The cold of liquid air is beyond belief.

"Attempts have been made to make motors run with liquid air, but they

have not succeeded. To condense air and to carry it about so that

propellers might revolve in it, would be out of the question."

"You think so, Tom?" asked Mr. Damon.

"I'm sure of it!"

"Oh, dear! That's too bad. Bless my overshoes, but I thought I had a

new idea. Well, you ought to know. So Damon's Whizzer goes on the scrap

heap before ever it's built. Well, we'll say no more about it. You

ought to know best, Tom. I wasn't thinking of it so much for myself as

for you. I thought you'd like some new idea to work on."

"Much obliged, Mr. Damon, but I have a new idea," said Tom.

"You have? What is it? Tell me--that is, if it isn't a secret," went on

the eccentric man, as much delighted over Tom's new plan as he had been

over his own Whizzer, doomed to failure so soon.

"It isn't a secret from you," said Tom. "I got the idea while I was

riding with Mary. I wanted to talk to her--to tell her not to jump out

when we had a little accident--but I had trouble making myself

understood because of the noise of the motor."

"They do make a great racket," conceded Mr. Damon. "But I don't suppose

anything can be done about it."

"I don't see why there can't!" exclaimed Tom. "And that's my new

idea--to make a silent aircraft motor--perhaps silent propeller blades,

though it's the motor that makes the most noise. And that's what I'm

going to do--invent a silent aeroplane. Not because I want so much to

talk when I take passengers up in the air, but I believe such a motor

would be valuable, especially for scouting planes in war work. To go

over the enemy's lines and not be heard would be valuable many times.

"And that's what I'm going to do--work on a silent motor for Uncle Sam.

I've got the germ of an idea and now--"

"Excuse me," said a voice behind Mr. Damon and Tom, and, turning, the

young inventor beheld the form of Mr. Peton Gale, president of the

Universal Flying Machine Company.

CHAPTER VI

MAKING PLANS

Tom Swift had drawn pencil and paper from his pocket, and, as he and

Mr. Damon were sitting on the steps of one of the shops, the young

inventor was about to demonstrate by a drawing part of his new project,

when the interruption came in the shape of one of the men who had, an

hour before, made a business offer to Tom.

"Excuse me," went on Mr. Peton Gale, "but Mr. Ware and I got to talking

it over on our way to the station--the matter of having you in our

company, Mr. Swift--and we concluded that it was worth twenty-five

thousand dollars a year for us to have you. So I came back--"

"It isn't of the slightest use, Mr. Gale, I assure you," said Tom, a

bit heatedly, for he did not like the persistency of this man, nor did

he like his coming on the factory grounds unannounced and in this

secret manner. "I told you I could not accept your offer. It is not

altogether a matter of money. My word was final."

"Oh very well, if you put it that way," said Mr. Gale stiffly, "of

course there is nothing more to say. But I thought perhaps you did not

consider we had offered you enough and--"

"Your offer is fair enough from a financial standpoint," said Tom; "but

I simply cannot accept it. I have other plans. Jackson!" he called to

one of his mechanics who was passing, "kindly see Mr. Gale to the gate,

and then let me know how it was any one came in here without a permit."

"Yes, sir," said the mechanic, as he stood significantly waiting.

"There was no one at the gate when I came in," said Mr. Gale, and his

manner was antagonizing. "I wanted to speak to you--to ask you to

reconsider your offer--so I came back."

"It is against the rules to admit strangers to the shop grounds," said

Tom. "Good-day!"

The president of the Universal Flying Machine Company did not respond,

but there was a look on his face as he turned away that, had Tom seen

it, might have caused him some uneasiness. But he did not see. Instead,

he resumed his talk with Mr. Damon.

"Tom, your idea is most interesting," declared the eccentric man. "I

hope you will be able to work it out!"

"I'm going to try," said the young inventor. "I hope that man--Mr.

Gale--didn't hear anything of what I was saying. He sneaked up on us

before I was aware any one was near but ourselves."

"I don't imagine he heard very much, Tom," said Mr. Damon. "He may have

heard you mention a silent motor--"

"That's just what I wish he hadn't heard," broke in Tom. "That's the

germ of the idea, and once it becomes known that I am working on that--

Well, there's no use crying over spilled milk," and he smiled at the

homely proverb. "I'll have to work in secret, once I've started."

"Do you think the government would use it, Tom?" asked his friend.

"I should think it would be glad to. Consider what a wonderful part

airships are playing in the present war. It really is a struggle to see

which will be the master of the sky--the Allies or the Germans--and, up

to recently, the Huns had the advantage. Then the Allies, recognizing

how vital it was, began to forge ahead, and now Uncle Sam with his

troops under General Pershing is leading everything, or will lead

shortly. We have been a bit slow with our aircraft production, but now

we are booming along. Uncle Sam will soon have the mastery of the sky."

"I hope so," sighed Mr. Damon. "We must beat the Germans!"

Briefly, Tom spoke of what Pershing's men were doing with their

aeroplanes in France, and mention was made of what the French and

British had done prior to the entrance of the United States into the

World War.

"While we were yet neutral, Americans had made gallant names for

themselves flying for France, and with my silent motor they ought to do

better," declared Tom.

"Is silence its chief recommendation?" asked Mr. Damon.

"Yes," replied Tom. "Or rather, it will be when I have it perfected.

Aeroplane motors now are about as compact and speedy as they can be

made. It is only the terrific noise that is a handicap. It is a

handicap to the pilots and observers in the craft, as they cannot

communicate except through a special speaking tube, and this is not

always satisfactory or sure. Then, too, the noise of an airship

proclaims its approach to the enemy, sometimes long before it can be

seen.

"With a silent motor all this would be done away with. With my new

craft, in case I can perfect it, the enemy's lines can be approached as

silently as the Indians used to approach the log cabins of the white

settlers. That will be its great advantage--not that conversation can

be more easily carried on, for that is, after all, an unimportant

detail. But to approach the enemy's lines in the silence of the night

would be a distinct gain."

"I believe it would, Tom!" exclaimed Mr. Damon. "And I should think,

too, that Uncle Sam would be glad to get such a motor," he added.

"Well, he'll have one to take if he wants it, if I can make my plans a

success," declared Tom. "That is, unless those other fellows get ahead

of me."

"What other fellows?" asked Mr. Damon.

"Gale, Ware and their crowd," was the answer. "I fancy they are

provoked because I wouldn't agree to work for them, and now, that Gale

overheard--as he must have--what I propose working on, they may try

that game themselves."

"You mean try to turn out a silent motor?"

"Yes. It would be a big feather in their cap for their company, so far,

hasn't been very successful on government orders. That's why they came

to me, I guess."

"I shouldn't be surprised, Tom," conceded Mr. Damon. "Since the

government accepted your giant cannon and your great searchlight, you

have come into greater prominence than ever before. And those two

things are a wonderful success."

"Yes," admitted Tom, modestly enough, "the big electric light seems to

have been of some benefit on the European battle front, and though they

haven't been able to make and transport as many of my giant cannons as

I'd like to see over there, it is progressing, I understand."

And this is true. For the details of these two inventions of Tom

Swift's I refer my readers to the books bearing those titles.

Sufficient to state here that the government was using these two

inventions, and there had been no necessity for commandeering them

either, since Tom had freely offered them at the declaration of war

with Germany.

"Well, since I can't help you with my 'Whizzer,'" said Mr. Damon, with

a smile, "let me do what I can toward your silent motor, Tom. What are

you going to call it?"

"Oh, I don't know--hadn't thought of a name. I guess 'Air Scout' would

be as good as any. That's what it will be--a machine for silently

scouting in the air. And now to get down to brass tacks, as the poet

says, I believe I will--"

"Gentleman to see you, Mr. Swift," interrupted Jackson.

"Bless my penwiper!" cried Mr. Damon. "More visitors! I hope it isn't

Gale or Ware come back to see what they can spy on!"

CHAPTER VII

A PROBLEM IN SOUND

Tom Swift looked up with a distinct appearance of being annoyed that

was unusual with him, for he was, nearly always, good-natured. But the

frown that had replaced the pleasant look on his face while he was

talking to Mr. Damon about the projected new air scout was at once

wiped away as he looked at the card Jackson held out to him.

"Bring him in right away!" he ordered. "He needn't have stood on that

ceremony."

"Well, he said it was a business call," returned the mechanician with a

cheerful grin, "and he said he wanted it done according to form. So he

gave me his card to bring you."

"Who is it?" asked Mr. Damon, with the privilege of an old friend.

"It's Ned Newton," Tom answered; "though why he's putting on all this

formality I can't fathom."

Jackson went back to the main gate and told the man on guard there to

admit Ned, who had so formally sent in his card.

"Ah, Mr. Swift, I believe?" began the bank employee with that suave,

formal air which usually precedes a business meeting.

"That is my name," said Tom, with a suppressed grin, and he spoke as

stiffly as though to a perfect stranger.

"Mr. Tom Swift, the great inventor?" went on Ned.

"Yes."

"Ah, then I am at the right place. Just sign here, please, on the

dotted line," and he held out a blank form, and a fountain pen to Tom,

who took them half mechanically.

"Huh? What's the big idea, Ned?" asked the young inventor, unable

longer to carry on the joke. "Is this a warrant for my arrest, or

merely a testimonial to you. If it's the latter, and concerns your

nerve, I'll gladly sign it."

"Well, it's something like that!" laughed Ned. "That's your application

for another block of Liberty Bonds, Tom, and I want you, as a personal

favor to me, as a business favor to the bank, and as your plain duty to

Uncle Sam, to double your last subscription."

Tom looked at the sum Ned had filled in on the blank form, and uttered

a slight whistle of surprise.

"That's all right now," said Ned, with the air of a professional

salesman. "You can stand that and more, too. I'm letting you off easy.

Why, I got Mary's father--Mr. Nestor--for twice what he took last time,

and Mary herself--hard as she's working for the Red Cross--gave me a

nice application. So it's up to you to--"

"Nuff said!" exclaimed Tom, sententiously, as he signed his name. "I

may have to reconsider my recent refusal of the offer of the Universal

Flying Machine Company, though, if I haven't money enough to meet this

subscription, Ned."

"Oh, you'll meet it all right! Much obliged," and Ned folded the

Liberty Bond subscription paper and put it in his pocket. "But did you

turn down the offer from those people?"

"I did," answered Tom. "But how did you know about it, Ned?"

"First let me say that I'm glad you decided to have nothing to do with

them. They're a rich firm, and have lots of money, but I wouldn't trust

'em, even if they have some government contracts. The way I happened

to know they were likely to make you an offer is this," continued Ned

Newton.

"They do business with one of the New York banks with which my

bank--notice the accent on the my, Tom--is connected. The other day I

happened to see some correspondence about you. These flying machine

people asked our bank to find out certain things about you, and, as a

matter of business, we had to give the information. Sort of a

commercial agency report, you know, nothing unusual, and it isn't the

first time it's been done since your business got so large. But that's

how I happened to know these fellows contemplated dickering with you."

"Do you know Gale or Ware?" Tom asked.

"Not personally. But in a business way, Tom, I'd warn you to look out

for them, as they're sharp dealers. They put one over on the government

all right, and there may be some unpleasant publicity to it later. But

they're putting up a big bluff, and pretending they can turn out a lot

of flying machines for use in Europe. Why don't you get busy on that

end of the game, Tom?"

"I know you've more than done your bit, with Liberty Bonds,

subscriptions to the Y. M. C. A. and other war work, besides your war

tank and other inventions. But you're such a shark on flying machines I

should think you'd offer your factory to the government for the

production of aeroplanes."

"I would in a minute, Ned, and you know it; but the fact of the matter

is my shops aren't equipped for the production of anything in large

numbers. We do mostly an experimenting business here, making only one

or two of a certain machine. I have told the government officials they

can have anything I've got, and you know they wouldn't let me enlist

when I was working on the war tank."

"Yes, I remember that," said Ned. "You're no slacker! I wanted to

shoulder a rifle, too, but they keep me at this Liberty Loan work.

Well, Uncle Sam ought to know."

"That's what I say," agreed Tom, "and that's why I haven't gone to the

front myself. And now, as it happens, I've got something else in mind

that may help Uncle Sam."

"What is it?"

"A silent flying machine for scout work on the battle front," Tom told

his friend, and then he gave a few details, such as those he had been

telling Mr. Damon.

"Then I don't wonder you turned down the offer of the Universal

people," remarked Ned, at the conclusion of the recital. "This will be

a heap more help to the government, Tom, than working for those people,

even at twenty-five thousand dollars a year. And if you get short, and

can't meet your newest Liberty Bond payments, why, I guess the bank

will stretch your credit a little."

"Thanks!" laughed Tom, "but I'll try not to ask them."

The friends talked together a little longer, and then Ned had to take

his departure to solicit more subscriptions, while Mr. Damon went with

him, the eccentric man saying he would go home to Waterfield.

"But, bless my overshoes, Tom!" he exclaimed, as he departed, "don't

forget to let me know when you have your silent motor working. I want

to see it."

"I'll let you know," was the promise given by the young inventor.

"And watch out for those Universal people," warned Ned. "I'm not

telling you this as a bank official, for I'm not supposed to, but it's

personal."

"I'll be on the watch," said Tom. And, as he went into his private

workshop, he wondered why it was his father and Ned had both warned him

not to trust Gale and Ware.

The next few days were busy ones for Tom Swift. Once he had made up his

mind to go to work seriously on a silent motor, all else was put aside.

He sent a note to Mary Nestor, telling her what he was going to do,

and, asking her to say nothing about it, which, of course, Mary agreed

to.

"Come and see me when you can," she sent back word, "but I know you

won't have much chance when you're experimenting with your invention.

And I shall be working so hard for the Red Cross that I sha'n't get

much chance to entertain you. But the war can't last forever."

"No," agreed Tom with a sigh, as he put away her letter, "and thank

goodness that it can't!"

The young inventor threw himself into the perplexing work of inventing

a silent motor with all the fervor he had given to the production of

his war tank, his giant cannon, his wonderful searchlight and other

machines.

"And," mused Tom, as he sat at his work table with pencil and paper

before him, "since this is a problem in acoustics, I had best begin I

suppose by going back to first principles, and after determining what

makes an aeroplane engine noisy, try to figure out how to make it

quiet. Now as to the first, the principle causes of noise are--"

And at that instant there broke on Tom's ears a succession of

discordant sounds which seemed to be a combination of an Indian's war

whoop and a college student's yells at a football game.

"Now I wonder what that is!" mused the young inventor as he hastily

arose. "Better solve that problem before I tackle the aeroplane motor."

CHAPTER VIII

THROUGH THE ROOF

Tom rushed from his private office, and when he reached the outer door

he heard with more distinctness the sounds that had alarmed him. They

seemed to come from a small building given over to electrical

apparatus, and which, at the time, was not supposed to be in use. It

had been Tom's workroom, so to speak, when he was developing his

electric runabout and rifle, but of late he had not spent much time in

it.

"Somebody's in there!" reflected the young inventor, as he heard yells

coming from the open door of the place. "And if it isn't Koku and

Eradicate I miss my guess! Wonder what they can be doing there."

He crossed the yard between his private office and the electrical shop

in a few rapid strides, and, as he entered the latter place, he was

greeted with a series of wild yells.

"Good volume of sound here, at all events," mused Tom. "Almost as much

as my motor made when I was trying to talk to Mary. Hello there! What's

going on? Is any one hurt? What's the matter?" he cried, for, at first,

he could see no one in the dim light of the place. The interior was a

maze of electrical apparatus.

"Who's here?" demanded Tom, as he advanced.

"Oh, Master! Come quick! Koku 'most dead an' no can let go!" was the

cry.

"Yo' jest bet yo' cain't let go!" chimed in the voice of Eradicate. "I

done knowed yo would git into trouble ef yo' come heah, an' I'se glad

ob it! So I is!"

"What is it, Rad? What has happened to Koku?" cried Tom, running

forward, for though no very powerful current could be turned on in the

electrical shop at this period of unuse, there was enough to be very

painful. "What is it, Rad?"

"Oh, dat big foolish giant, Koku, done got his se'f into trouble!"

chuckled the colored man. "He done got holt ob one ob dem air

contraptions, Massa Tom, an' he cain't let go! Ha! Ha! Golly! Look at

him squirm!" and Rad laughed shrilly, which accounted for some of the

sounds Tom had heard.

Then came yells of rage and pain from the giant, and they were so loud

and vigorous, mingling with Eradicate's as they did, that it was no

wonder Tom was startled. The sounds were heard in the other shops, and

men came running out. But before then Tom had put an end to the trouble.

One look showed him what had happened. Just how or why Koku and

Eradicate had entered the electrical shop Tom did not then stop to

inquire. But he saw that the giant had grasped the handles of one of

the electric machines, designed for charging Leyden jars used in Tom's

experiments, and the powerful, though not dangerous, current had so

paralyzed, temporarily, the muscles of the giant's hands and arms that

he could not let go, and there he was, squirming, and not knowing how

to turn off the current, and unable to ease himself, while Eradicate

stood and laughed at him, fairly howling with delight.

"Ha! Guess yo' won't do no mo' spadin' in' Massa Tom's garden right

away, big man!" taunted Eradicate.

"Be quiet, Rad!" ordered Tom, as he reached up and pulled out the

switch, thus shutting off the current. "This isn't anything to laugh

at."

"But he done look so funny, Massa Tom!" pleaded the colored man. "He

done squirm laik--"

But Eradicate did not finish what he intended to say. Once free from

the powerful current, the giant looked at his numb hands, and then,

seeming to think that Eradicate was the cause of it all, he sprang at

the colored man with a yell. But Eradicate did not stay to see what

would happen. With a howl of terror, he raced out of the door, and, old

and rheumatic as he was, he managed to gain the stable of his mule,

Boomerang, over which he had his humble but comfortable quarters.

"Well, I guess he's safe for a while!" laughed Tom, as he saw the giant

turn away, shaking his fist at the closed door, for Koku, big as he

was, stood in mortal terror of the mule's heels.

Tom locked the door of the electrical shop and went back to his

interrupted problem. From Jackson he learned that Koku and Eradicate

had merely happened to stroll into the forbidden place, which had been

left open by accident. There, it appeared, Koku had handled some of the

machinery, ending by switching on the current of the machine the

handles of which he later unsuspectingly picked up. Then he received a

shock he long remembered, and for many days he believed Eradicate had

been responsible for it, and there was more than the usual hostile

feeling between the two. But Eradicate was innocent of that trick, at

all events.

"Though," said Tom, telling his father about it later, "Rad would have

turned on the current if he had known he could make trouble for Koku by

it. I never saw their like for having disagreements!"

"Yes, but they are both devoted to you, Tom," said the aged inventor.

"But what is this you hinted at--a silent motor you called it, I

believe? Are you really serious in trying to invent one?"

"Yes, Dad, I am. I think there's a big field for an aeroplane that

could travel along over the enemy's lines--particularly at night--and

not be heard from below. Think of the scout work that could be done.

"Well, yes, it could be done if you could get a silent motor, or

propellers that made no noise, Tom. But I don't believe it can be done."

"Well, maybe not, Dad. But I'm going to try!" and Tom, after a further

talk with his father, began work in earnest on the big problem. That it

was a big one Tom was not disposed to deny, and that it would be a

valuable invention even his somewhat skeptical father admitted.

"How are you going to start, Tom?" asked Mr. Swift, several days after

the big idea had come to the young man.

"I'm going to experiment a bit, at first. I've got a lot of old motors,

that weren't speedy enough for any of my flying machines, and I'm going

to make them over. If I spoil them the loss won't amount to anything,

and if I succeed--well, maybe I can help out Uncle Sam a bit more."

As Tom had said he would do, he began at the very foundation, and

studied the fundamental principles of sound.

"Sound," the young inventor told Ned Newton, in speaking about the

problem, "is a sensation which is peculiar to the ear, though the

vibrations caused by sound waves may be felt in many parts of the body.

But the ear is the great receiver of sound."

"You aren't going to invent a sort of muffler for the ears, are you,

Tom?" asked Ned. "That would be an easy way of solving the problem, but

I doubt if you could get the Germans to wear your ear-tabs so they

wouldn't hear the sound of the Allied aeroplanes."

"No, I'm not figuring on doing the trick that way," said Tom with a

laugh. "I've really got to cut down the sound of the motor and the

propeller blades, so a person, listening with all his ears, won't hear

any noise, unless he's within a few feet of the plane."

"Well, I can tell you, right off the reel, how to do it," said the bank

employee.

"How?" asked Tom eagerly.

"Run your engine and propellers in a vacuum," was the prompt reply.

"Hum!" said Tom, musingly. "Yes, that would be a simple way out, and

I'll do it, if you'll tell me how to breathe in a vacuum."

"Oh, I didn't agree to do that," laughed Ned.

But he had spoken the truth, as those who have studied physics well

know. There must be an atmosphere for the transmission of sound, which

is the reason all is cold and silent and still at the moon. There is no

atmosphere there. Sound implies vibration. Something, such as liquid,

gas, or solid, must be set in motion to produce sound, and for the

purpose of science the air we breathe may be considered a gas, being

composed of two.

Not only must the object, either solid, liquid, or gaseous, be in

motion to produce sound, but the air surrounding the vibrating body

must also be moving in unison with it. And lastly there must be some

medium of receiving the sound waves--the ear or some part of the body.

Totally deaf persons may be made aware of sound through the vibrations

received through their hands or feet. They receive, of course, only the

more intense, or largest, sound waves, and can not hear notes of music

nor spoken words, though they may feel the vibration when a piano is

played. And, as Ned has said, no sound is produced in a vacuum.

"But," said Tom, "since I can't run my aeroplane in a vacuum, or even

have the propellers revolve in one, it's up to me to solve the problem

some other way. The propellers don't really make noise enough to worry

about when they're high in the air. It's the exhaust from the motor,

and to get rid of that will be my first attempt."

"Can it be done?" asked Ned.

"I don't know," was Tom's frank answer.

"They do it on an automobile to a great extent," went on Ned. "Some of

'em you cant hardly hear."

"Yes, but an aeroplane engine runs many, many times faster than the

motor of an auto," said Tom, "and there are more explosions to muffle.

I doubt if the muffler of an auto would cut down the sound of an aero

engine to any appreciable extent. But, of course, I'll try along those

lines."

"They have mufflers or silencers for guns and rifles," went on Ned.

"Couldn't you make a big one of those contraptions and put it on an

aeroplane?"

"I doubt it," said Tom, shaking his head. "Of course it's the same

principle as that in an auto muffler, or on a motor boat--a series of

baffle plates arranged within a hollow cylinder. But all such devices

cut down power, and I don't want to do that. However, I'm going to

solve the problem or--bust!"

And Tom came near "busting," Ned remarked later, when he and his friend

talked over the progress of the invention.

Two weeks had passed since the start of his evolution of his new idea,

and following the visiting of the representatives of the Universal

Flying Machine Company. Since then neither Gale nor Ware had

communicated with Tom.

"But I must be on the watch against them," thought the young inventor.

"I'm pretty sure Gale heard me mention what I was going to try to

invent, and he may get ahead of me, and put a silent motor on the

market first. Not that I'm afraid of being done out of any profits, but

I simply don't want to be beaten."

The details of Tom's invention cannot be gone into, but, roughly, it

was based on the principle of not only a muffler but also of producing

less noise when the charges of gasoline exploded in the cylinders. It

is, of course, the explosion of gasoline mixed with air that causes an

internal combustion engine to operate. And it is the expulsion of the

burned gases that causes the exhaust and makes the noise that is heard.

Tom was working along the well-known line of the rate of travel of

sound, which progresses at the rate of about 1090 feet a second when

air is at the freezing point. And, roughly, with every degree increase

in the atmosphere's temperature the velocity of sound increases by one

foot. Thus at a temperature of 100 degrees Fahrenheit, or 68 degrees

above freezing, there would be added to the 1090 feet the 68 feet,

making sound travel at 100 degrees Fahrenheit about 1158 feet a second.

Tom had set up in his shop a powerful, but not very speedy, old

aeroplane engine, and had attached to it the device he hoped would help

him toward solving his problem of cutting down the noise. He had had

some success with it, and, after days and nights of labor, he invited

his father and Ned, as well as Mr. Damon, over to see what he hoped

would be a final experiment.

His visitors had assembled in the shop, and Eradicate was setting out

some refreshments which Tom had provided, the colored man being in his

element now.

"What's all this figuring, Tom?" asked Mr. Damon, as he saw a series of

calculations on some sheets of paper lying on Tom's desk.

"That's where I worked out how much faster sound traveled in hydrogen

gas than in the ordinary atmosphere," was the answer. "It goes about

four times as fast, or nearly four thousand two hundred feet a second.

You remember the rule, I suppose. 'The speed of sonorous vibrations

through gases varies inversely as the squares of the weights of equal

volumes of the gases,' or, in other words--"

"Give it to us chiefly in 'other words,' if you please, Tom!" pleaded

Ned, with a laugh. "Let that go and do some tricks. Start the engine

and let's see if we can hear it."

"Oh, you can hear it all right," said Tom, as he approached the motor,

which was mounted on a testing block. "The thing isn't perfected yet,

but I hope to have it soon. Rad! Where is that black rascal? Oh, there

you are! Come here, Rad!"

"Yaas sah, Massa Tom! Is I gwine to help yo' all in dish yeah job?"

"Yes. Just take hold of this lever, and when I say so pull it as hard

as you can."

"Dat's whut I will, Massa Tom. Golly! ef dat no 'count giant was heah

now he'd see he ain't de only one whut's got muscle. I'll pull good

an' hard, Massa Tom."

"Yes, that's what I want you to. Now I guess we're all ready. Can you

see, Dad--and Ned and Mr. Damon?"

"Yes," they answered. They stood near the side wall of the shop, while

Tom and Eradicate were at the testing block, on which the motor, with

the noise-eliminating devices attached, had been temporarily mounted.

"All ready," called the young inventor, as he turned on the gas and

threw over the electrical switch. "All ready! Pull the starting lever,

Rad, and when it's been running a little I'll throw on the silencer and

you can see the difference."

The motor began to hum, and there was a deafening roar, just as there

always is when the engine of an aeroplane starts. It was as though half

a dozen automobile engines were being run with the mufflers cut out.

"Now I'll show you the difference!" yelled Tom, though such was the

noise that not a word could be heard. "This shows you what my silencer

will do."

Tom pulled another lever. There was at once a cessation of the

deafening racket, though it was not altogether ended. Then, after a

moment or two, there suddenly came a roar as though a blast had been

let off in the shop.

Tom and Eradicate were tossed backward, head over heels, as though by

the giant hands of Koku himself, and Mr. Damon, Ned, and Tom's father

saw the motor fly from the testing block and shoot through the roof of

the building with a rending, crashing, and splintering sound that could

be heard for a mile.

CHAPTER IX

AFTER A SPY

Curious as it may seem, Eradicate, the oldest and certainly not the

most energetic of the party assembled in the experiment room, was the

first to recover himself and arise. Tottering to his feet he gave one

look at the testing block, whence the motor had torn itself. Then he

looked at the prostrate figures around him, none of them hurt, but all

stunned and very much startled. Then the gaze of Eradicate traveled to

the hole in the roof. It was a gaping, ragged hole, for the motor was

heavy and the roof of flimsy material. And then the colored man

exclaimed:

"Good land ob massy! Did I do dat?"

His tone was one of such startled contrition, and so tragic, that Tom

Swift, rueful as he felt over the failure of his experiment and the

danger they had all been in, could not help laughing.

"I take it, hearing that from you, Tom, that we're all right," said Ned

Newton, as he recovered himself and brushed some dirt off his coat. Ned

was a natty dresser.

"Yes, we seem to be all right," replied Tom slowly. "I can't say what

damage the flying motor has done outside, but--"

"Bless my insurance policy! but what happened?" asked Mr. Damon. "I saw

Eradicate pull on that lever as you told him to, Tom, and then things

all went topsy-turvy! Did he pull the wrong handle?"

"No, it wasn't Rad's fault at all," said Tom. "The trouble was, as I

guess I'll find when I investigate, that I put too much power into the

motor, and the muffler didn't give any chance for the accumulated

exhaust gases to expand and escape. I didn't allow for that, and they

simply backed up, compressed and exploded. I guess that's the whole

explanation."

"I'm inclined to agree with you, Son," said Mr. Swift dryly. "Don't

try to get rid of all the noise at once. Eliminate it by degrees and it

will be safer."

"I guess so," agreed Tom.

By this time a score of workmen from the other shops had congregated

around the one though the roof of which the motor had been blown. Tom

opened the door to assure Jackson and the others that no one was hurt,

and then the young inventor saw the exploded motor had buried in the

dirt a short distance away from the experiment building.

"Lucky none of us were standing over it when it went up," said Tom, as

he made an inspection of the broken machine. "We'd have gone through

the roof with it."

"She certainly went sailing!" commented Ned. "Must have been a lot of

power there, Tom."

And this was evidenced by the bent and twisted rods that had held the

motor to the testing block, and by the cylinders, some of which were

torn apart as though made of paper instead of heavy steel. But for the

fact that all the force of the explosion was directly upward, instead

of at the sides, none might have been left alive in the shop. All had

escaped most fortunately, and they realized this.

"Well," queried Ned, as Tom gave orders to have the damaged machine

removed and the roof repaired, "does this end the wonderful silent

motor, Tom?"

"End it! What do you mean--"

"I mean are you going to experiment any further?"

"Why, of course! Just because I've had one failure doesn't mean that

I'm going to give up. Especially when I know what the matter was--not

leaving any vent for the escaping gases. Why this isn't anything. When

I was perfecting my giant cannon I was nearly blown up more than once,

and you remember how we got stuck in the submarine."

"I should say I did!" exclaimed Ned with a shudder. "I don't want any

more of that. But as between being blown through a roof and held at the

bottom of the sea, I don't know that there's much choice."

"Well, perhaps not," agreed Tom. "But as for ending my experiments, I

wouldn't dream of such a thing! Why, I've only just begun! I'll have a

silent motor yet!"

"And a non-explosive one, I hope," added Mr. Damon dryly. "Bless my

shoe buttons, Tom, but if my wife knew what danger I'd been in she'd

never let me come over to see you any more."

"Well, the next time I invite you to a test I'll be more careful,"

promised the young inventor.

"There isn't going to be any next time as far as I'm concerned!"

laughed Ned. "I think it's safer to sell Liberty Bonds."

And, though they joked about it, they all realized the narrow escape

they had had. As for Eradicate, once he knew he had not been the one

who caused the damage, he felt rather proud of the part he had taken in

the mishap, and for many days he boasted about it to Koku.

True to his determination, Tom Swift did not give up his experimental

work on the silent motor. The machine that had been blown through the

roof was useless now, and it was sent to the scrap heap, after as much

of it as possible had been salvaged. Then Tom got another piece of

apparatus out of his store room and began all over again.

He worked along the same lines as at first--providing a chamber for the

escaping gases of the exhaust to expend their noise and energy in, at

the same time laboring to cut down the concussion of the explosions in

the cylinder without reducing their force any. And that it was no easy

problem to do either of these, Tom had to admit as he progressed. All

previous types of mufflers or silencers had to be discarded and a new

one evolved.

"Jackson, I need some one to help me," said Tom to his chief

mechanician one day. "Haven't you a good man who is used to

experimental work that you can let me take from the works?"

"Why, yes," was the answer. "Let me see. Roberts is busy on the new

bomb you got up, but I could take him off that--"

"No, don't!" interposed Tom. "I want that work to go on. Isn't there

some one else you can let me have?"

"Well, there's a new man who came to me well recommended. I took him on

last week, and he's a wonderful mechanic. Knows a lot about gas

engines. I could let you have him--Bower his name is. The only thing

about it, though, is that I don't like to give you a man of whom I am

not dead certain, when you're working on a new device."

"Oh, that will be all right," said Tom. "There won't be any secrets he

can get, if you mean you think he might be up to spy work."

"That's what I did mean, Tom. You never can tell, you know, and you

have some bitter enemies."

"Yes, but I'll take care this man doesn't see the plans, or any of my

drawings. I only want some one to do the heavy assembling work on the

experimental muffler I'm getting up. We can let him think it's for a

new kind of automobile."

"Oh, then I guess it will be all right. I'll send Bower to you."

Tom rather liked the new workman, who seemed quiet and efficient. He

did not ask questions, either, about the machine on which he was

engaged, but did as he was told. As Tom had said, he kept his plans and

drawing under lock and key--in a safe to be exact--and he did not think

they were in any danger from his new helper.

But Tom Swift held into altogether too slight regard the powers of

those who were opposed to him. He did not appreciate the depths to

which they would stoop to gain their ends.

He had been working hard on his new device, and had reached a point

further along than when the other motor had exploded. He began to see

success ahead of him, and he was jubilant. Whether this made him

careless does not matter, but the fact was that he left Bower more to

himself, and alone in the experimental shop several times.

And it was on one of these occasions, when Tom had been for some time

in one of the other shops, where he and Jackson were in consultation

over a new machine, that as he came back to the test room unexpectedly,

he saw Bower move hastily away from in front of the safe. Moreover, Tom

was almost certain he had heard the steel door clang shut as he

approached the building.

And then, before he could ask his helper a question, Tom looked from a

window and saw a stranger running hastily along the side of the

building where his trial motor was being set up.

"Who's that? Who is that man? Did he come in here? Was he tampering

with my safe?" cried Tom. He saw Bower hesitate and change color, and

Tom knew it was time to act.

The window was open, and with one bound the young inventor was out and

running after the stranger he had seen departing in such a hurry. The

man was but a short distance ahead of him, and Tom saw he was stuffing

some papers into his pocket.

"Here! Come back! Stop!" ordered Tom, but the man ran on the faster.

"That's a spy as sure as guns!" reflected Tom Swift. "And Bower is in

with him!" he added. "I've got to catch that fellow!" and he speeded

his pace as he ran after the fellow.

CHAPTER X

A BIG SPLASH

There was no question in the mind of Tom Swift but that the man he was

running after was guilty of some wrong-doing. In the first place he was

a stranger, and had no right inside the big fence that surrounded the

Swift machine plant. Then, too, the very fact that he ran away was

suspicious.

And this, coupled with the confusion on the part of Bower, and his

proximity to the safe, made Tom fear that some of his plans had been

stolen. These he was very anxious to recover if this strange man had

them, and so he raced after him with all speed.

"Stop! Stop!" called Tom, but the on-racing stranger did not heed.

The cries of the young inventor soon attracted the attention of his

men, and Jackson and some of the others came running from their various

shops to give whatever aid was needed. But they were all too far away

to give effective chase.

"Bower might have come with me if he had wanted to help," thought Tom.

But a backward glance over his shoulder did not show that the new

helper was engaging in the pursuit, and he could have started almost on

the same terms as Tom himself.

The runaway, looking back to see how near the young inventor was to

him, suddenly changed his course, and, noting this, Tom Swift thought:

"I've got him now! He'll be bogged if he runs that way," for the way

led to a piece of swampy land that, after the recent rains, was a

veritable bog which was dangerous for cattle at least; and more than

one man had been caught there.

"He can't run across the swamp, that's sure," reflected Tom with some

satisfaction. "I'll get him all right!"

But he wanted to capture the man, if possible, before he reached the

bog, and, to this end, Tom increased his speed to such good end that

presently, on the firm ground that bordered the swamp, Tom was almost

within reaching distance of the stranger.

But the latter kept up running, and dodged and turned so that Tom could

not lay hands on him. Suddenly, turning around a clump of trees the

fleeing man headed straight for a veritable mud hole that lay directly

in his path. It was part of the swamp--the most liquid part of the bog

and a home of frogs and lizards.

Too late, the man, who was evidently unaware of the proximity of the

swamp, saw his danger. His further flight was cut off by the mud hole,

but it was too late to turn back. Tom Swift was at his heels now, and

seeing that it was impossible to grab the man, Tom did the next best

thing. He stuck out his foot and tripped him, and tripped him right on

the edge of the mud hole, so that the man fell in with a big splash,

the muddy water flying all around, some even over the young inventor.

For a moment the man disappeared completely beneath the surface, for

the mud hole was rather deep just where Tom had thrown him. Then there

was another violent agitation of the surface, and a very woebegone and

muddy face was raised from the slough, followed by the rest of the

figure of the man. Slowly he got to his feet, mud and water dripping

from him. He cleared his face by rubbing his hands over it, not that it

made his countenance clean, but it removed masses of mud from his eyes,

nose, and mouth, so that he could see and speak, though his first

operation was to gasp for breath.

"What--what are you doin'?" he demanded of Tom, and as the man opened

his mouth to speak Tom was aware of a glitter, which disclosed the

'fact that the man had a large front tooth of gold.

"What am I doing?" repeated Tom. "I think it's up to you to answer that

question, not me. What are you doing?"

"You--you tripped me into this mud hole!" declared the man.

"I did, yes; because you were trespassing on my property, and ran away

instead of stopping when I told you to," went on Tom. "Who are you and

what are you doing? What were you doing with Bower at my shop?"

"Nothin'! I wasn't doin' nothin'!"

"Well, we'll inquire into that. I want to see what you have in your

pockets before I believe you. Come on out!"

"You haven't any right to go through my pockets!" blustered the

stranger.

"Oh, haven't I? Well, I'm going to take the right. Jackson--Koku--just

see that he doesn't get away. We'll take him back and search him," and

Tom motioned to his chief machinist and the giant, who had reached the

scene, to take charge of the man. But Koku was sufficient for this

purpose, and the mud-bespattered stranger seemed to shrink as he saw

the big creature approach him. There was no question of running away

after that.

"Bring him along," ordered Tom, and Koku, taking a tight grip on the

man by the slack of his garments behind, walked him along toward the

office, the mud and water splashing and oozing from his shoes at every

step.

"Now you look here!" the gold-toothed man cried, as he was forced

along, "you ain't got any right to detain me. I ain't done nothin'!"

And each time he spoke the bright tooth in his mouth glittered in the

sun.

"I don't know whether you've done anything or not," said Tom. "I'm

going to take you back and see what you and Bower have to say. He may

know something about this."

"If he does I don't believe he'll tell," said Jackson.

"Why not?" asked Tom, quickly.

"Because he's gone."

"Gone! Bower gone?"

"Yes," answered Jackson. "I saw him running out of the experiment shop

as we raced along to help you. I didn't think, at the time, that he was

doing more than go for aid, perhaps. But I see the game now."

"Oh, you mean--him?" and Tom pointed to the dripping figure.

"Yes," said Jackson in a low voice, as Koku went on ahead with his

prisoner. "If, as you say, this man was in league with Bower, the

latter has smelled a rat and skipped. He has run away, and I only hope

he hasn't done any damage or got hold of any of your plans."

"We'll soon know about that," said Tom. "I wonder who is at the bottom

of this?"

"Maybe those men you wouldn't work for," suggested the machinist.

"You mean Gale and Ware of the Universal Flying Machine Company?"

"Yes."

"Oh, I don't believe they'd stoop to any such measures as this--sending

spies around," replied Tom. "But I can't be too careful. We'll

investigate."

The first result of the investigation was to disclose the fact that

Bower was gone. He had taken his few possessions and left the Swift

plant while Tom was racing after the stranger. A hasty examination of

the safe did not reveal anything missing, as Tom's plans and papers

were intact. But they showed evidences of having been looked over, for

they were out of the regular order in which the young inventor kept

them.

"I begin to see it," said Tom, musingly. "Bower must have managed to

open the safe while I was gone, and he must have made a hasty copy of

some of the drawings of the silent motor, and passed them out of the

window to this gold-tooth man, who tried to make off with them. Did you

find anything on him?" he asked, as one of the men who had been

instructed to search the stranger came into the office just then.

"Not a thing, Mr. Swift! Not a thing!" was the answer. "We took off

every bit of his clothes and wrapped him in a blanket. He's in the

engine room getting dry now. But there isn't a thing in any of his

pockets."

"But I saw him stuffing some papers in as he ran away from me," said

Tom. "We must be sure about this. And don't let the fellow get away

until I question him."

"Oh, he's safe enough," answered the man. "Koku is guarding him. He

won't get away."

"Then I'll have a look at his clothes," decided Tom. "He may have a

secret pocket."

But nothing like this was disclosed, and the most careful search did

not reveal anything incriminating in the man's garments.

"He might have thrown away any papers Bower gave him," said Tom. "Maybe

they're at the bottom of the mud hole! If they're there they're safe

enough. But have a search made of the ground where this man ran."

This was done, but without result. Some of the workmen even dragged the

mud hole without finding anything. Then Tom and his father had a talk

with the stranger, who refused to give his name. The man was sullen and

angry. He talked loudly about his innocence and of "having the law on"

Tom for having tripped him into the mud.

"All right, if you want to make a complaint, go ahead," said the young

inventor. "I'll make one against you for trespass. Why did you come on

my grounds?"

"I was going to ask for work. I'm a good machinist and I wanted a job."

"How did you get in? Who admitted you at the gate?"

"I--I jest walked in," said the man, but Tom knew this could not be

true, as no strangers were admitted without a permit and none had been

issued. The man denied knowing anything about Bower, but the latter's

flight was evidence enough that something was wrong.

Not wishing to go to the trouble of having the man arrested merely as a

trespasser, Tom let him go after his clothes had been dried on a boiler

in one of the shops.

"Take him to the gate, and tell him if he comes back he'll get another

dose of the same kind of medicine," ordered Tom to one of the guards at

the plant, and when the latter had reported that this had been done, he

added in an earnest tone:

"He went off talking to himself and saying he'd get even with you, Mr.

Swift."

"All right," said Tom easily. "I'll be on the watch."

The young inventor made a thorough examination of his experiment shop

and the test motor. No damage seemed to have been done, and Tom began

to think he had been too quick for the conspirators, if such they were.

His plans and drawings were intact, and though Bower might have given a

copy to the stranger with the gold tooth, the latter did not take any

away with him. That he had some papers he wished to conceal and escape

with, seemed certain, but the splash into the mud hole had ended this.

No trace was found of Bower, and an effort Tom made to ascertain if the

man was a spy in the employ of Gale and Ware came to naught. The

machinist had come well recommended, and the firm where he was last

employed had nothing but good to say of him.

"Well, it's a mystery," decided Tom. "However, I got out of it pretty

well. Only if that gold-tooth individual shows up again he won't get

off so easily."

CHAPTER XI

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?

CHAPTER XII

THE CRY FOR HELP

"All ready, Mr. Damon?" asked Tom, as he looked to see that all the

levers, wheels, valves, and other controls were in working order on his

Air Scout.

"As ready as I ever shall be, Tom," was the answer. "I don't know why

it is, but somehow I feel that something is going to happen on this

trip."

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

"I suppose so. Don't think I'm going to back out, or anything like

that, but I wish it were successfully over with, Tom Swift, I most

certainly do."

"It will be in a little while," returned Tom, as he settled himself

comfortably in his seat and pulled the safety strap tight. "You've gone

up in this same plane before, when it didn't have the silent motor

aboard."

"Yes, I know I have. Oh, I dare say it will be all right, Tom. And

yet, somehow, I can't help feeling--"

But Tom Swift felt that the best way to set Mr. Damon's premonitions to

rest was to start the motor, and this he gave orders to have done,

Jackson and some others of the men from the shops congregating about

the craft to see the beginning of the night flight. Mr. Swift was there

also, and Eradicate. Mary Nestor had been invited, but her Red Cross

work engaged her that evening, she said. Ned Newton was away from town

on Liberty Bond business, and he could not be present at the test.

However, as Tom expected to have other trials when his motor was in

even better shape, he was not exactly sorry for the absence of his

friends.

"Contact!" called the young inventor, when Jackson had stepped back,

indicating it was time to throw over the switch.

"Let her go!" cried Tom, and the next moment the motor was in

operation, but so silently that his voice and that of Mr. Damon's could

easily be heard above the machinery.

"Good, Tom! That's good!" cried Mr. Swift, and Tom easily heard his

father's voice, though under other, and ordinary, circumstances this

would have been impossible.

True, the hearing of Tom and Mr. Damon was muffled to a certain extent

by the heavy leather and fur-lined caps they wore. But Tom had several

small eyelet holes set into the flaps just over the opening of the

ears, and these holes were sufficient to admit sounds, while keeping

out most of the cold that obtains in the upper regions.

The aeroplane moved swiftly along the level starting ground, and away

from the lighted hangars. Faster and faster it swung along as Tom

headed it into the wind, and then, as the speed of the motor increased,

the Air Scout suddenly left the earth and went soaring aloft as she had

done before.

But there was this difference. She moved almost as silently as a great

owl which swoops down out of the darkness--a bit of the velvety

blackness itself. Up and up, and onward and onward, went the Air Scout.

Tom Swift's improved, silent motor urged it onward, and as the young

inventor listened to catch the noise of the machinery, his heart gave a

bound of hope. For he could detect only very slight sounds.

"She's a success!" exulted Tom to himself. "She's a success, but she

isn't perfect yet," he added. "I've got to make the muffler bigger and

put in more baffle-plates. Then I think I can turn the trick."

He swung the machine out over the open country, and then, when they

were up at a height and sailing along easily, he called back to Mr.

Damon in the seat behind him:

"How do you like it?"

"Great!" exclaimed the eccentric man. "Bless my postage stamp, but it's

great! Why, there's hardly a sound, Tom, and I can hear you quite

easily."

"And I can hear you," added Tom. "I don't believe, down below there,"

and he nodded toward the earth, though Mr. Damon could not see this, as

the airship, save for a tiny light over the instrument board, was in

darkness, "they know that we're flying over their heads."

"I agree with you," was the answer. "Tom, my boy, I believe you've

solved the trick! You have produced a silent aeroplane, and now it's up

to the government to make use of it."

"I'm not quite ready for that yet," replied the young inventor. "I

have several improvements to make. But, when they are finished, I'll

let Uncle Sam know what I have. Then it's up to him."

"And you must be careful, Tom, that some of your rivals don't hear of

your success and get it away from you," warned Mr. Damon, as Tom guided

the Air Scout along the aerial way--an unlighted and limitless path in

the silent darkness.

"Oh, they'll have to get up pretty early in the morning to do that!"

boasted Tom, and afterward he was to recall those words with a bit of

chagrin.

On and on they sailed, and as Tom increased the speed of the motor, and

noted how silently it ran, he began to have high hopes that he had

builded better than he knew. For even with the motor running at almost

full speed there was not noise enough to hinder talk between himself

and Mr. Damon.

Of course there was some little sound. Even the most perfect electric

motor has a sort of hum which can be detected when one is close to it.

But at a little distance a great dynamo in operation appears to be

silence itself.

"I can go this one better, though," said Tom as he sailed along in the

night. "I see where I've made a few mistakes in the baffle plate of the

silencer. I'll correct that and--"

As he spoke the machine gave a lurch, and the motor, instead of

remaining silent, began to cough and splutter as in the former days.

"Bless my rubber boots, Tom! what's the matter?" cried Mr. Damon.

"Something's gone wrong," Tom answered, barely able to hear and make

himself heard above the sudden noise. "I'll have to shut off the power

and glide down. We can make a landing in this big field," for just then

the moon came out from behind a cloud, and Tom saw, below them, a great

meadow, not far from the home of Mary Nestor. He had often landed in

this same place.

"Something has broken in the muffler, I think, letting out some of the

exhaust," he said to Mr. Damon, for, now that the motor was shut off,

Tom could speak in his ordinary tones. "I'll soon have it fixed, or, if

I can't, we can go back in the old style--with the machine making as

much racket as it pleases."

So Tom guided the machine down. It went silently now, of course,

making, with the motor shut off, no more sound than a falling leaf.

Down to the soft, springy turf in the green meadow Tom guided the

machine. As it came to a stop, and he and Mr. Damon got out, there was

borne to their ears a wild cry:

"Help! Help!"

CHAPTER XIII

SOMETHING QUEER

"Did you hear that?" asked Tom Swift of his companion.

"Hear it? Bless my ear drums, I should say I did hear it! Some one is

in trouble, Tom. Caught in a bog, most likely, the same as that spy

chap who was at your place. That's it--caught in a bog!"

"There isn't any bog or swamp around here, Mr. Damon. If there was I

shouldn't have tried a landing. No, it's something else besides that.

Hark!"

Again the cry sounded, seeming to come from a point behind the landing

place of the silent airship. It was clear and distinct:

"Help! Help! They are--"

The voice seemed to die away in a gurgle, as though the person's mouth

had been covered quickly.

"He's sinking, Tom! He's sinking!" cried Mr. Damon. "I once heard a man

who almost drowned cry out, and it sounded exactly like that!"

"But there isn't any water around here for any one to drown in,"

declared Tom. "It's a big, dry meadow. I know where we are."

"Then what is it?"

"I don't know, but we're going to find out. Some one attacked by some

one else--or something, I should say," ventured the young inventor.

"Something! do you mean a wild beast, Tom?"

"No, for there aren't any of those here any more than there is water.

Though it may be that some farmer's bull or a savage dog has got loose

and has attacked some traveler. But, in that case I think we would hear

bellows or barks, and all I heard was a cry for help."

"The same with me, Tom. Let's investigate;"

"That's what I intend doing. Come on. The airship will be all right

until we come back."

"Better take a light--hadn't you? It's dark, even if the moon does show

now and then," suggested Mr. Damon.

"Guess you are right," agreed Tom. Aboard his airship there were

several small but powerful portable electric lights, and after securing

one of these Tom and Mr. Damon started for the spot whence the call for

help had come. As they walked along, their feet making no noise on the

soft turf, they listened intently for a repetition of the call for aid.

"I don't hear anything," said Tom, after a bit.

"Nor I," added Mr. Damon. "We don't know exactly which way to go, Tom."

"That's right. Guess we'd better give him a hail; whoever it is."

Tom came to a halt, and raising his voice to a shout called:

"Hello there! What's the matter? We'll help you if you can tell us

which way to come!"

They both listened intently, but no voice answered them. At the same

time, however, they were aware of a sound as of hurrying feet, and

there seemed to be muttered imprecations not far away. Tom and Mr.

Damon looked in the direction of the sound, and the young inventor

flashed his light. But there was a clump of bushes and trees at that

point and the electrical rays did not penetrate very far.

"Some one's over there!" exclaimed Tom in a whisper. "We'd better go

and see what it is."

"All right," agreed Mr. Damon, and he, too, spoke in a low voice.

Why they did this when their previous talk had been in ordinary tones,

and when Tom had shouted so loudly, they did not stop to reason about

or explain just then. But later they both admitted that they whispered

because they thought there was something wrong on foot--because they

feared a crime was being committed and they wanted to surprise the

perpetrators if they could.

And it was this fact of their whispering that enabled the two to hear

something that, otherwise, they might not have heard. And this was the

sound of some vehicle hurrying away--an automobile, if Tom was any

judge. The cries for help had been succeeded by stifled vocal sounds,

and these, in turn, by the noise of wheels on the ground.

"What does it all mean?" asked Mr. Damon in a whisper.

"I don't know," answered Tom, resolutely, "but we've got to find out.

Come on."

They advanced toward the dark clump of trees and low bushes. There was

no need to be especially cautious in regard to being silent, as their

feet made little, if any, sound on the deep grass. And, as Tom walked

in advance, now and then flashing his light, Mr. Damon suddenly caught

him by the coat.

"What is it?" asked the young inventor.

"Look! Just over the top of that hill, where the moon shines. Don't

you see an automobile outlined?"

Tom looked quickly.

"I do," he answered. "There's a road from here, just the other side of

those trees, to that hill. The auto must have gone that way. Well,

there's no use in trying to follow it now. Whoever it was has gotten

away."

"But they may have left some one behind, Tom. We'd better look in and

around those trees."

"I suppose we had, but I don't believe we'll find anything. I can

pretty nearly guess, now, what it was."

"What?" asked Mr. Damon.

"Well, some chauffeur was out for a ride in his employer's car without

permission. He got here, had an accident--maybe some friends he took

for a ride were hurt and they called for help. The chauffeur knew if

there was any publicity he'd be blamed, and so he got away as quickly

as he could. Guess the accident--if that's what it was--didn't amount

to much, or they couldn't have run the car off. We've had our trouble

for our pains."

"Well, maybe you're right, Tom Swift, but all the same, I'd like to

have a look among those trees," said Mr. Damon.

"Oh. we'll look, all right," assented Tom, "but I doubt if we find

anything."

And he was right. They walked in and about the little grove, flashing

the light at intervals, but beyond marks of auto wheels in the dust of

the road, which was near the clump of maples, there was nothing to

indicate what had happened.

"Though there was some sort of fracas," declared Tom. "Look where the

dust is trampled down. There were several men here, perhaps skylarking,

or perhaps it was a fight."

"Some one must have been hurt, or they wouldn't have cried for help,"

said Mr. Damon.

"Well, that's so. But perhaps it was some one not used to riding in

autos, and he may have imagined the accident was worse than it was, and

called for help involuntarily. There is no evidence of any serious

accident having happened--no spots of blood, at any rate," and Tom

laughed at his own grimness. "It was a new car, too, or at least one

with new tires on."

"How do you know?" asked Mr. Damon.

"Tell by the plain marks of the rubber tread in the dust," was the

answer. "Look," and Tom pointed to the wheel marks in the focus of his

electric lamp. "It's a new tire, too, with square protuberances on the

tread instead of the usual diamond or round ones. A new kind of tire,

all right."

He and Mr. Damon remained for a few minutes looking about the place

whence had come the calls for help, and then the eccentric man remarked:

"Well, as long as we can't do anything here, Tom, we might as well

travel on; what do you say?"

"I agree with you. There isn't any use in staying. We'll get the Air

Scout fixed up and travel back home. But this was something queer,"

mused Tom. "I hope it doesn't turn out later that a crime has been

committed, and we didn't show enough gumption to prevent it."

"We couldn't prevent it. We heard the cries as soon as we landed."

"Yes, but if we had rushed over at once we might have caught the

fellows. But I guess it was only a slight accident, and some one was

more frightened than hurt. We'll have to let it go at that."

But the more he thought about it the more Tom Swift thought there was

something queer in that weird cry for help on the lonely meadow in the

darkness of the night.

CHAPTER XIV

THE TELEPHONE CALL

The defect in the motor which had caused Tom Swift to shut off the

power and drift down to earth was soon remedied, once the young

inventor began an examination of the craft. One of the oil feeds had

become choked and this automatically cut down the gasoline supply,

causing one or more cylinders to miss. It was a safety device Tom had

installed to prevent the motor running dry, and so being damaged.

Once the clogged oil feed was cleared the motor ran as before, and just

as silently, though, as Tom had said, he was not entirely satisfied

with the quietness, but intended to do further work toward perfecting

it.

"I'll start the propellers now, Mr. Damon," said Tom, when the trouble

had been remedied. "You know how to throw the switch, don't you?"

"I guess so," was the answer. Mr. Damon and Tom had traveled so often

together in gasoline craft that the young inventor had taught his

friend certain fundamentals about them, and in an emergency the

eccentric man could help start an aeroplane. This he now did, taking

charge of the controls which could be operated from his seat as well as

from Tom's. Tom whirled the propellers, and soon the motor was in

motion.

Mr. Damon, once the big wooden blades were revolving, slowed down the

apparatus until Tom could jump aboard, after which the latter took

charge and soon speeded up the machine, sending it aloft.

As the green meadow, dimly seen in the light of the moon, seemed to

drop away below them, and the clump of trees vanished from sight, both

Tom and Mr. Damon wondered who it was that had called for help, and if

the matter were at all serious. They were inclined to think it was not,

but Tom could not rid himself of a faint suspicion that there might

have been trouble.

However, thoughts of his new silent Air Scout soon drove everything

else from his mind, and as he guided the comparatively silent machine

on its quiet way toward his own home he was thinking how he could best

improve the muffler.

"Well, here we are again, safe and sound," remarked Tom, as he brought

the craft to a stop in front of the hangar, and Jackson and his

helpers, who were awaiting the return, hurried out to take charge.

"Yes, everything seems to point to success, Tom," agreed Mr. Damon.

"That is, unless the slight accident we had means trouble."

"Oh, no, that had nothing to do with the operation of the silencer. But

I'm going to do better yet. Some day I'll take you for a ride in a

silent machine which will make so little noise that you can hear a pin

drop."

"Well," remarked Mr. Damon' with a laugh, "I don't know that listening

to falling pins will give me any great amount of pleasure, Tom, but I

appreciate your meaning."

"Everything all right?" asked Mr. Swift, as he came out to hear the

details from his son. "Do you think you have solved the problem?"

"Not completely, but I'll soon be able to write Q. E. D. after it. Some

refinements are all that are needed, Dad."

"Glad to hear it. I was a bit anxious."

Mr. Swift questioned his son about the technical details of the trip,

asking how the motor had acted under the pressure caused by so

completely muffling the exhaust, and for some minutes the two

inventors, young and old, indulged in talk which was not at all

interesting to Mr. Damon. They went into the house, and Tom asked to

have a little lunch, which Mrs. Baggert set out for him.

"It's rather late to eat," said the young inventor, "but I always feel

hungry after I test a new machine and find that it works pretty well.

Will you join me in a sandwich or two, Mr. Damon?"

"Why, bless my ketchup bottle, I believe I will."

And so they ate and talked. Tom was on the point of telling his father

something of the queer cry for help they had heard on the lonely meadow

when Mrs. Baggert produced a letter which she said had come for Tom

that afternoon, but had been mislaid by a new maid who had been engaged

to help with the housework.

"She took it to the shop after you had left, and only now told me about

it," explained Mrs. Baggert. "So I sent Eradicate for it."

"How long ago was that?" asked Tom, as he took the missive.

"Oh, an hour ago," answered Mrs. Baggert, with a smile. "But don't

blame poor Rad for that. He wanted to deliver the letter to you

personally, and so did Koku. The result was your giant kept after Rad,

trying to get the letter from him, and Rad kept hiding and slinking

about for a chance to see you himself until I saw what was going on, a

little while ago, and took the letter myself. Else you might never have

gotten it, so jealous are those two," and Mrs. Baggert laughed.

"Guess it isn't of much importance," Tom said, as he tore open the

envelope. "It's from the Universal Flying Machine Company, of New York,

and I imagine they're trying to get me to reconsider my refusal to link

up with them."

"Yes," he went on, as he read the missive, "that's it. They've raised

the amount to thirty thousand a year now, Dad, and they say they feel

sure I shall regret it if I do not accept.

"This is a bit queer, though," went on the young inventor. "This

letter was written three days ago, but it reached Shopton only to-day.

And it says that unless they hear from me at once they will have to

take steps that will cause me great inconvenience. They have nerve, at

any rate, and impudence, too! I won't even bother to answer. But I

wonder what they mean, and why this letter was delayed?"

"The mails are all late on account of the transportation congestion

caused by moving troops to the camps," said Mr. Damon. "Some of my

letters are delayed a week. But, as you say, Tom, these fellows are

very impudent to threaten that way."

"It's all bluff," declared Tom. "I'm not worrying. And now, Dad, since

I've almost reached the top of the hill with my Air Scout, I may be

able to help you on that new electric motor you're puzzling over."

"I wish you would, Tom. I am trying to invent a new system of

interchangeable brush contacts, but so far I've been unable to make

them work. However, there is no great hurry about that. If you are

going to offer your silent machine to the government finish that first.

We need all the aircraft we can get. The battles on the other side seem

to be all in favor of the Germans, so far."

"We haven't got into our stride yet," declared Mr. Damon. "Once Uncle

Sam gets the boys over there in force, there'll be a different story to

tell. I only wish--"

At that moment the telephone set up an insistent ringing, breaking in

on Mr. Damon's remarks.

"I'll answer," said Tom, as Mrs. Baggert moved toward the instrument,

which was an extension from the main one.

"Hello!" called the young inventor into the transmitter, and as he

received an answer a look of pleasure came over his face.

"Yes, Mary, this is Tom," he said. He remained silent a moment, while

it was evident he was listening to the voice at the other end of the

wire. Then he suddenly exclaimed:

"What's that? Tell him to come home? Why, he isn't here. I just came in

and--what--wait a minute!"

With a rather strange look on his face Tom covered the mouth-piece of

the instrument with his hand, and, turning to his father, asked:

"Is Mr. Nestor here?"

"No," replied Mr. Swift slowly, "He was here, though. He came a little

while after you and Mr. Damon started off in the Air Scout. But he

didn't stay. Said he wanted to see you about something and would call

again."

"Oh," remarked the young man. "I didn't know he had been there."

"I meant to tell you," said Mrs. Baggert; "but getting the lunch made

me forget it, I guess."

Tom uncovered the transmitter of the telephone again, and spoke to Mary

Nestor.

"Hello," he said. "I was wrong, Mary. Your father was here, but he left

when he found I wasn't at home. How long ago? Wait a minute and I'll

inquire.

"How long ago did Mr. Nestor leave?" asked the young inventor of the

housekeeper. "Nearly an hour," he said into the instrument, after he

had received the answer. Then, after listening a moment, he added:

"Yes, I guess he'll be home soon now. Probably stopped down town to see

some of his friends. Yes, Mr. Damon and I tried out the Air Scout. Yes,

she worked pretty well, for a starter, but there is something yet to be

done. Oh, yes, now I'll have time to come over to see you, and take you

for a ride too. We won't have to talk through a speaking tube, either.

Tell your father I am sorry I was out when he called. I'll come to see

him to-morrow, if he wants me to. Yes--yes. I guess so!" and Tom

laughed, it being evident that his remarks at the end of the

conversation had to do with personal matters.

"A telegram has come for Mr. Nestor and they were anxious that he

should get it," Tom explained to his little audience as he hung up the

receiver and put aside the telephone. "I wonder what he wanted to see

me about?"

"He didn't say," replied Mrs. Baggert.

Mr. Damon, Tom, and his father remained in conversation a little while

longer, and the eccentric man was thinking that it was about time for

him to return home, when the telephone rang again.

"Hello," answered Tom, as he was nearest the instrument. "Oh, yes,

Mary, this is he. What's that? Your father hasn't reached home yet? And

your mother is worried? Oh tell her there is no cause for alarm. As I

said, he probably stopped on his way to see some friends."

Tom listened for perhaps half a minute to a talk that was inaudible to

the others in the room, and they noticed a grave look come over his

face. Then he said:

"I'll be right over, Mary. Yes, I'll come at once. And tell your mother

not to worry. I'm sure nothing could have happened. I'll be with you

in a jiffy!"

As Tom Swift hung up the receiver he said:

"Mr. Nestor hasn't reached home yet, and as he promised to return at

once in case he didn't find me, his wife is much worried. I'll go over

and see what I can do."

"I'll come along!" volunteered Mr. Damon. "It isn't late yet."

"Yes, do come," urged Tom. "But I suppose when we get there we'll find

our friend has arrived safely. We'll go over in the electric runabout."

CHAPTER XV

A VAIN SEARCH

Tom Swift's speedy little electric car was soon at the door in

readiness to take him and Mr. Damon to the Nestor home. The electric

runabout was a machine Tom had evolved in his early inventive days, and

though he had other automobiles, none was quite so fast or so simple to

run as this, which well merited the name of the most rapid machine on

the road. In it Tom had once won a great race, as has been related in

the book bearing the title, "Tom Swift and His Electric Runabout."

"Mary didn't telephone again, did she?" Tom asked his father, as he

stopped at the house to get Mr. Damon, having gone out to see about

getting the electric runabout in readiness.

"No," was the answer. "The telephone hasn't rung since."

"Then, I guess, Mr. Nestor can't have arrived home," said Tom. "It's a

bit queer, his delay, but I'm sure it will be explained naturally. Only

Mary and her mother are alone and, very likely, they're nervous. I'll

telephone to let you know everything is all right as soon as I get

there," Tom promised his father and Mrs. Baggert as he drove off down

the road, partly illuminated by the new moon.

Rapidly and almost as silently as his Air Scout Tom Swift drove the

speedy car down the highway. It was about three miles from his home to

that of Mary Nestor, and though the distance was quickly covered, to

Tom, at least, the space seemed interminable. But at length he drove

up to the door. There were lights in most of the rooms, which was

unusual at this time of night.

The sound of the wheels had not ceased echoing on the gravel of the

drive before Mary was out on the porch, which she illuminated by an

overhead light.

"Oh, Tom," she cried, "he hasn't come yet, and we are so worried! Did

you see anything of father as you came along?"

"No," was Tom's answer. "But we didn't look for him along the road, as

we came by the turnpike, and he wouldn't travel that way. But he will

be along at any moment now. You must remember it's quite a walk from my

house, and--"

"But he was on his bicycle," said Mary. "We wanted him to go in the

auto, but he said he wanted some exercise after supper, and he went

over on his wheel. He said he'd be right back, but he hasn't come yet."

"Oh, he will!" said Tom reassuringly. "He may have had a puncture, or

something like that. Bicyclists are just as liable to them as

autoists," he added with a laugh.

"Well, I'm sure I hope it will be all right," sighed Mary. "I wish you

could convince mother to that effect. She's as nervous as a cat. Come

in and tell us what to do."

"Oh, he'll be all right," declared Mr. Damon, adding his assurances to

Tom's.

They found Mrs. Nestor verging on an attack of hysteria. Though Mr.

Nestor often went out during the evening, he seldom stayed late.

"And he said he'd be right back if he found you weren't at home, Tom,"

said Mrs. Nestor. "I'm sure I don't know what can be keeping him!"

"It's too soon to get worried yet," replied the young inventor

cheerfully. "I'll wait a little while, and then, if he doesn't come,

Mr. Damon and I will go back over the road and look carefully. He may

have had a slight fall--sprained his ankle or something like that--and

not be able to ride. We came by the turnpike, a road he probably

wouldn't take on his wheel. He's all right, you may be sure of that."

Tom tried to speak reassuringly, but somehow, he did not believe

himself. He was beginning to think more and more how strange it was

that Mr. Nestor did not return home.

"We'll wait just a bit longer before setting out on a search," he told

Mary and her mother. "But I'm sure he will be along any minute now."

They went into the library, Mary and her mother, Tom and Mr. Damon. And

there they sat waiting. Tom tried to entertain Mary and Mrs. Nestor

with an account of his trial trip in the Air Scout, but the two women

scarcely heard what he said.

All sat watching the clock, and looking from that to the telephone,

which they tried to hope would ring momentarily and transmit to them

good news. Then they would listen for the sound of footsteps or bicycle

wheels on the gravel walk. But they heard nothing, and as the seconds

were ticked off on the clock the nervousness of Mrs. Nestor increased,

until she exclaimed:

"I can stand it no longer! We must notify the police--or do something!"

"I wouldn't notify the police just yet," counseled Tom. "Mr. Damon and

I will start out and look along the road. If it should happen, as will

probably turn out to be the case, that Mr. Nestor has met with only a

simple accident, he would not like the notoriety, or publicity, of

having the police notified."

"No, I am sure he would not," agreed Mary. "Tom's way is best, Mother."

"All right, just as you say, only find my husband," and Mrs. Nestor

sighed, and turned her head away.

"Even if Mr. Nestor had had a fall," reasoned Tom, "he could call for

help, and get some one to telephone, unless--"

And as he reasoned thus Tom Swift gave a mental start at his own use of

the word "help."

That weird cry on the lonely meadow came back to him with startling

distinctness.

"Come on, Mr. Damon!" cried Tom, in a voice he tried to make cheerful.

"We'll find that Mr. Nestor is probably walking along, carrying his

disabled bicycle instead of having it carry him. We'll soon have him

safe back to you," he called to the two women.

"I wish I could go with you, and help search," observed Mary.

"Oh, I couldn't bear to be left alone!" exclaimed her mother.

"We'll telephone as soon as we find him," called Tom to Mrs. Nestor, as

he and Mr. Damon again got into the runabout and started away from the

place.

"What do you think of it, Tom?" asked the eccentric man, when they were

once more on the road.

"Why, nothing much--as yet," Tom said. "That is, I think nothing more

than a simple accident has happened, if, indeed, it is anything more

than that he has delayed to talk to some friends."

"Would he delay this long?"

"I don't know."

"And then, Tom--bless my spectacles! what of that cry we heard? Could

that have been Mr. Nestor?"

There! It was out! The suspicion that Tom had been trying to keep his

mind away from came to the fore. Well, he might as well race the issue

now as later.

"I've been thinking of that," he told Mr. Damon. "It might have been

Mary's father calling for help."

"But we looked, Tom, near the trees, and couldn't discover anything. If

he had been calling for help--"

Mr. Damon did not finish.

"He may have fallen from his wheel and been hurt," said Tom, as he

turned the electric runabout into the highway that Mr. Nestor would,

most likely, have taken on his way from Shopton. "Then he may have

called for help, and some autoists, passing, may have heard and taken

him away."

"Yes, but where, Tom? Whoever called for help was taken away, that's

sure. But where?"

"To some hospital, I suppose."

"Then hadn't we better inquire there? There are only two hospitals of

any account around here. The one in Shopton and the one in Waterfield.

My wife is on the board of Lady Managers there. We could call that

hospital up and--"

"We'll look along the road first," said Tom. "If we begin to make

inquiries at the hospitals there will be a lot of questions asked, and

a general alarm may be sent out. Mr. Nestor wouldn't like that, if he

isn't in any danger. And it may turn out that he has met an old friend,

and has been talking with him all this while, forgetting all about the

passage of time."

They were now driving along the highway that led from the little suburb

where Mr. Nestor lived, to the main part of Shopton, just beyond which

was Tom's home. This section was country-like, with very few houses and

those placed at rather infrequent intervals. The road was a good one,

though not the main-traveled one, and Mr. Nestor, as was known,

frequently used it when he rode his bicycle, an exercise of which he

was very fond.

As Tom and Mr. Damon drove along, they scanned, as best they could in

the light from the young moon and the powerful lamps on the runabout,

every part of the highway. They were looking for some dark blot which

might indicate where a man had fallen from his wheel and was lying in

some huddled heap on the road. But they saw nothing like this, much to

their relief.

"Do you know, Tom," said Mr. Damon, when they were nearing the town,

and their search, thus far, had been in vain, "I think we're going at

this the wrong way."

"Why, so?"

"Because Mr. Nestor may have fallen, and been hurt, and have been

carried into any one of a dozen houses along the road. In that case we

wouldn't see him. We've passed over the most lonely part of the journey

and haven't seen him. If the accident occurred near the houses his

cries would have brought some one out to help him. He is well known

around here, and, even if he were unconscious and couldn't tell who he

was, he could be identified by papers in his pockets. Then his family

would be notified by telephone."

"Perhaps you are right, Mr. Damon. We may be wasting time this way.

What do you suggest?" asked Tom.

"That we don't delay any longer, but call up the hospitals at once. If

he isn't in either of those he must be in some house, and in such

condition that his identity cannot be established. In that event it is

a case for the police. We haven't found him, and I think we had better

give the alarm."

Tom Swift thought it over for a moment. Then he came to a sudden

decision.

"You're right!" he told Mr. Damon. "We mustn't waste any more time. He

isn't along the road he ought to have traveled in coming from my house

to his home--that's sure. But before I call up the hospitals I want to

try out one more idea."

"What's that, Tom?"

"I want to go to the place where we heard that cry for help."

"Do you think that could have been Mr. Nestor?"

"It may have been. We'll go and take another look around there. Some

man was evidently hurt there, and was taken away. We may get a clew.

The lights on the runabout will give us a better chance to look around

than we had by the little pocket lamp. We'll try there, and, if we

don't find anything, then I'll call up the hospitals."

CHAPTER XVI

THE LONG NIGHT

With the speedy runabout it did not take Tom Swift and Mr. Damon long

to reach the place where the Air Scout had been grounded a few hours

before, and where they had heard the cry for help. All was as dark and

as silent as when they had been there before.

But, as Tom had said, the lights from his electric runabout would give

a brilliant illumination, and these he now directed toward the clump of

trees whence the cry for help had seemed to come.

"Doesn't appear to have been visited by any one since we were here,"

remarked Tom, as he observed the marks of the new automobile tire in

the dust. "Now we'll look about more carefully."

This they did, but they were about to give up in despair and start for

the nearest telephone to call up the hospitals, when Mr. Damon gave an

exclamation.

"What is it?" asked Tom.

"Something bright and shining!" said his companion. "I saw it gleam in

the light of the lamps. You nearly put your foot on it, Tom. Just step

back a moment."

Tom did so, and the eccentric man, with another exclamation, this time

of satisfaction, reached down and picked something up from the dusty

road.

"It's a watch!" he exclaimed. "A gold watch! And it's been stepped on,

evidently, or run over by an auto. Not much damaged, but the case is a

bit bent and scratched. It's stopped, too!" he added as he held it to

his ear.

"What time does it show?" asked Tom.

"Eight forty-seven," answered Mr. Damon, as he consulted the dial.

"Why, Tom, that was just about when we heard the cries for help!"

"Yes, it must have been. Let me see that watch."

No sooner had the young inventor taken the timepiece into his hands

than he, too, uttered a cry of amazement.

"Do you recognize it?" asked Mr. Damon, in great excitement.

"It's Mr. Nestor's watch!" cried Tom. "He must have fallen here, and

been hurt. It was Mr. Nestor who cried for help, and who was taken away

by the autoists. They've probably taken him to some hospital. There's

been an accident all right."

Tom and Mr. Damon were of one mind now in thinking that Mr. Nestor had

met with some mishap on the road--an automobile accident most

likely--and that he was the person who had called for help.

"If they had only answered when we hallooed at them," said Tom, "we

wouldn't be in all this stew now. We could have told the strangers who

came to his aid who he was, and we might even have taken him to the

hospital in the airship."

"Well, it's too late to think of that now," returned Mr. Damon. "We

had better get into communication with him as soon as we can, and then

send word to his wife and daughter. I hope he isn't badly hurt."

Tom hoped so, too, with all his heart.

There was nothing to do but to get back in the runabout and make all

speed for the nearest telephone, and Tom Swift lost little time in

doing this. They found a drug store which was open a little later than

usual, and at once Tom went into the booth and called up the Shopton

hospital. He was well known there, as he and his father were liberal

supporters of the institution, which was a private affair. Many of

Tom's men were treated at the dispensary, and, as accidents were of

more or less frequent occurrence at the works, the young inventor had

frequent occasions to call up the place.

"Mr. Nestor would ask to be taken there, as it's nearest his home--that

is, if he was able to speak," Tom said to Mr. Damon, who agreed with

him. There was a little delay in getting the hospital on the wire, but

when Tom had it, and was talking to the superintendent, he was rather

surprised, to tell the truth, to be told that Mr. Nestor had not been

brought in.

"We haven't had any accident cases all day, nor to-night, Mr. Swift,"

the superintendent reported. "Was this some one special you were

inquiring about?"

For Tom, determining not to give Mr. Nestor's name, except as a last

resort, had merely inquired whether any recent accident cases had been

brought in.

"I'll let you know later, Mr. Millard," he told the superintendent, not

exactly answering the question. He hung up the receiver, and, opening

the door of the booth, said to Mr. Damon: "He isn't there."

"Then try Waterfield," was the suggestion; and Tom did so, though he

could not imagine why an injured man, such as Mr. Nestor might prove to

be, should be taken as far as Waterfield, when the hospital at Shopton

was nearer.

"Unless," he told Mr. Damon, "the people which ran down Mary's father

didn't know about our hospital."

The reply from the institution in Mr. Damon's home town was just as

discouraging as had been the answer from Shopton. At first, when Tom

inquired, the head nurse had said there was an accident case at that

moment being brought in. Tom was all excitement until she went to

inquire the name and circumstances, and then he learned that it was the

case of a little boy who had fallen downstairs at his home and broken a

leg. There was no record of any one answering the description of Mr.

Nestor having been brought in that evening.

"Hum! This is getting to be mysterious," mused Tom, as he came out of

the booth. "What shall we do--go back and tell Mrs. Nestor and Mary, or

communicate with the police?"

"Why not try the Alexian Hospital?" asked Mr. Damon. "That's away over

in Centerford, to be sure, but it's more likely to be known to

passing tourists than either of our institutions around here,

especially if the autoists were strangers."

"That's so," agreed Tom. The Alexian Hospital was operated under the

direction of the Brothers of that faith, and was well known in that

part of the state. Often cases of persons who had been injured by

passing automobiles had been taken there for treatment, for, as Mr.

Damon had said, it was well known, and Centerford was the nearest large

city.

"I can just about see how it happened," said Tom. "They ran Mr. Nestor

down, and stopped to pick him up after they heard his cries for help.

And the Alexian Hospital was the first one they thought of. We should

have called that up first."

But once more disappointment awaited the young inventor and his friend.

Word came back over the wire that no accident case, which bore any

resemblance to Mary's father, had been brought in.

"Well, I'm stumped!" exclaimed Tom. "What shall we do now, Mr. Damon?"

"Much as I dislike it," said the eccentric man who was too much

worried, now, to do any "blessing," which was his favorite expression,

"I think we ought to communicate with Mrs. Nestor. She will be very

anxious."

"I guess we'll have to," said Tom. "But wait! I'll call up my house

first, and see if he has gone back there."

But Mr. Nestor had not done this, and Mrs. Baggert, who answered the

telephone, said Mary had been calling frantically for Tom, as her

mother was now on the verge of complete collapse.

"No help for it," said Tom, ruefully. "We've got to tell 'em we have no

news, and can't find him."

And, hearing this, Mrs. Nestor did collapse, and a doctor was called in.

Thereupon Tom, who with Mr. Damon had gone back to the Nestor home,

took charge of matters, sending for Mrs. Nestor's sister to come and

stay with her and take charge of the house.

"You'll need some one to stay with you," he told Mary.

"Yes, I shall," she admitted, trying bravely not to give way to her

emotion. "Oh, Tom, I wish you could stay, too. I'm sure something

dreadful must have happened to poor father. Please stay and help us

find him!"

"I will," Tom promised. "As soon as your aunt comes I'll take Mr. Damon

home, and then I'll give the rest of my time to you."

And this Tom did, sending word home that he would remain at the

Nestor's all night and part of the next day.

Tom got but little sleep that night. He communicated with the police

and saw to it that a general alarm was sent out. He called up all

hospitals within a radius of fifty miles, but could get no trace of any

injured man whose description resembled that of Mr. Nestor.

"What can have happened?" asked Mary tearfully.

"Well, the way I figure it out is this," said Tom. "Your father left my

house soon after Mr. Damon and I did in the Air Scout. Mr. Nestor was

riding his bicycle, and he must have been run into by an automobile.

That is how his watch was damaged and that was when Mr. Damon and I

heard the cries for help."

"Oh, do you think he was badly hurt?" asked Mary.

"No, I don't," and Tom answered truthfully. "The voice sounded as

though he was in pain, certainly, but it was strong and vigorous, and

not at all as though he was dangerously hurt."

"And what do you think happened to him after he was hurt?" asked Mary.

"The autoists took him away," decided Tom. "In fact, we heard the

machine go, but of course we never connected the call for help and what

followed with your father. The autoists took him away."

"Where?"

"I should say to some hospital. Perhaps a private one of which we know

nothing, and which may be near here. I'll get a full list from the

Board of Health to-morrow. Or it may be that the autoists, seeing the

damage they had done, took your father to the home of one of

themselves, and summoned a doctor there."

"Why would they do that?"

"Well, they may have been so frightened they didn't realize what they

were doing, or they may have thought he would get better treatment in a

private house, if he were not badly injured, than if he should be taken

to a hospital. It may have been that one of the persons in the auto was

a physician, and wished to try his own skill on the man he had hurt."

"You make me feel more comfortable, Tom," said Mary. "But, even

supposing all this, why couldn't they telephone to us that my father

was all right? He always carries an identification card with him, and

if he were unconscious it could be ascertained who he was."

"That's what I can't understand," said Tom frankly. "It puzzles me. But

we'll find him--never fear!"

And so he kept on with his telephone inquiries, while a physician and

her sister ministered to Mrs. Nestor. The night was very, very long,

and no good news came in.

CHAPTER XVII

SILENT SAM

Slowly the dawn broke through the mists of darkness, and made the earth

light. The sun came straggling in through cracks in the shutters in the

home of Mr. Nestor, the gradually increasing gleam paling the electric

lights, in the glare of which Tom Swift, Mary, and her aunt sat,

waiting for some word of the missing man. But none came.

"What shall we do now?" asked Mary, as she looked at Tom.

"Oh, there's lots to do," he said, trying to make his voice sound

cheerful. "We'll be busy all day. I sent word to have one of my touring

cars ready to hurry to any part of the country the moment we should get

word from your father."

"And do you think we shall get word, Tom?" the girl went on wistfully.

"Of course we shall!" he cried. "Word may come in at any time. Now get

ready, eat a good breakfast, and then you can go with me as soon as we

hear anything definite. Come, we'll have breakfast!"

"I can't eat a thing!" protested Mary.

"Oh, yes you can," said her aunt, who was a cheerful sort of person.

"I'll see about getting something for you and Mr. Swift, and see that

your mother is all right."

She left the room to give orders to the servant about the meal, and

returned to say that Mrs. Nestor was sleeping quietly. She had been

given a sedative. Mary managed to eat a little, and she gave Tom the

address of several friends who were called up in the vain hope that,

somehow, Mr. Nestor might have gone to see them.

"Tom, what do you really think has happened?" asked Mary again, as they

sat facing one another in the library, during a respite from the

telephone.

Tom Swift repeated, to the girl his theory of what had happened with an

assumption of confidence he did not altogether feel.

His prediction of a speedy end to the suspense did not come true that

day, nor for many days. No news was heard of Mr. Nestor. After the

first day, when there was no information and when no reports came of

any one of his description having been hurt in an automobile accident

or having been taken to any hospital, the police started an energetic

search.

The authorities in all near-by cities were notified, and all thought of

keeping from the public what had happened was given over. Tom's story,

of how he and Mr. Damon had heard the cry for help on the lonely

meadow, was printed in the papers, though the young inventor did not

say that he had been out trying his new aeroplane. That was a detail

not needed in the finding of Mr. Nestor.

But Mary's father was not found. The mystery regarding his

disappearance deepened, and there was no trace of him after he had left

Tom's house that eventful evening. Persons living along the roads he

might have taken in riding his bicycle were questioned, but they had

seen nothing of him, nor were they aware of any accident. Tom's

testimony and that of Mr. Damon was all the clew there was.

"I don't believe he's dead!" stoutly declared the young inventor, when

this dire possibility had been hinted at. "I believe the persons who

were responsible for the accident are afraid to reveal his whereabouts

until he recovers from possible injuries. You'll see! Mr. Nestor will

come back safe!"

And, somehow, though her mother was skeptical, Mary believed what Tom

said.

The search was kept up, but without result, and Tom aided all he could.

But there was not much he could do. The police and other authorities

were at a total loss.

In the intervals of visiting Mary and her mother, and doing what he

could for them, Tom worked on his new motor. He knew that he was on the

right track and that all that was needed now was to make certain

refinements and adjustments in the apparatus he had already

constructed, so that it would operate more quietly.

"Absorbing the vibrations from the exhaust, caused by the exploded

gases in the cylinders, does the trick," Tom told his father.

"But there is enormous pressure to overcome, Tom. You must be sure your

muffler will stand the strain. Otherwise she is going to blow out a

gasket some day, when you least expect it. Then the sudden resumption

of pressure outside the cylinders is going to cause a change in the

equilibrium, and you may turn turtle in the air."

"I've thought of that," said Tom. "At worst it can't be any more than

looping the loop. But I'll make the muffler doubly strong."

"Better provide an auxiliary chamber to take care of part of the

exhaust in case your main apparatus breaks," advised the older

inventor, and Tom said he would. He did, too, for he valued his

father's expert advice.

Meanwhile he was busy fitting one of his latest aeroplanes with the new

motor. The motor he and Mr. Damon had used in their flight was one

patched up from an old one. But now Tom was working on a complete new

one, made after his revised model, and in which the silencer was an

integral part, instead of being built on.

While giving Mary and her mother all the assistance in his power, Tom

still found time to work on his new, pet scheme. He had matters now

where he did not fear any tampering with his plans, for he had filed

away his papers in a safe place, and was making his new machine from

memory.

"But if some one got in and had a look at the inside of your silencer

he could see how it is constructed, couldn't he?" asked Ned Newton.

"Yes," assented Tom, "But they're not going to get in very easily. Koku

sleeps in the experiment shop now, and my machine is there."

"Oh, well that explains your confidence. I feel sorry for the burglar

who makes the attempt, once Koku wakes up. Heard anything more from

those Universal people?"

"No, not directly. I understand they are working hard on some new type

of plane for army use, but I haven't bothered my head about them. I'm

too much occupied with my own affairs and trying to help Mary."

"Very strange about Mr. Nestor, isn't it?"

"Worse than strange," said Tom. "If this keeps on, and he isn't heard

from, it will be tragic pretty soon."

"He must be held a prisoner somewhere," declared Ned.

"It begins to look that way," assented Tom. "Though who would have an

object in that I can't understand. He had no enemies, as far as is

known, and his business affairs were in excellent shape. Unless, as I

said, the persons who ran him down are, through fear, keeping him

hidden until he recovers, I can't imagine what has become of him."

"Well, it certainly is a puzzle," said Ned. And Tom agreed with his

chum.

It was about a week after the disappearance of Mr. Nestor that Mr.

Damon came over to see Tom.

"Bless my shoe laces, Tom!" exclaimed the eccentric man, "but you are

as busy as ever." For he found the young inventor in the experiment

shop, surrounded by a mass of papers and all sorts of mechanical

devices.

"Yes, I'm working a little," said Tom. "But you are just in time. Come

on out, I want to introduce you to Silent Sam."

"'Silent Sam!'" exclaimed Mr. Damon. "Have you been taking a new trip

to the Land of Wonders? Have you brought back some new kind of servant?"

"Not exactly a servant," said Tom with a laugh, "though I hope Silent

Sam will serve me well."

"'Silent Sam?' What does it mean? Is that a joke?" asked the puzzled

Mr. Damon.

"I hope it doesn't turn out a joke," replied Tom. "But come on, I'll

introduce you to him, Mr. Damon."

He led the way to one of the big hangars where his various machines of

the air were housed. On the way Mr. Damon asked about news of Mr.

Nestor, but was told there was none.

Tom Swift opened the big, swinging doors and pulled aside an enveloping

canvas curtain. There stood revealed a big aeroplane, of somewhat new

pattern, the wings gleaming like silver from the varnish that had been

applied. In shape it was not unlike the machines already in use, except

that the propellers were of somewhat different design.

The engine was mounted in front, and even with his slight knowledge of

mechanics Mr. Damon could tell that it was exceedingly powerful. But it

was certain devices attached to the engine that attracted his

attention, for they were totally different from any on any other

aeroplane, though they bore some resemblance to apparatus on the plane

in which Tom and the eccentric man had made the night flight.

"Is this your new machine, Tom?" asked Mr. Damon.

"Yes."

"Well, I don't see anything of that fellow you spoke of--Silent Sam."

"This is Silent Sam," returned Tom, with a laugh. "I've named my new

noiseless aeroplane--my Air Scout--I've named that Silent Sam. Wait

until you hear it, or rather, don't hear it, and I think you'll agree

with me. Silent Sam for Uncle Sam!"

"Good!" cried Mr. Damon. "Bless my dictionary, but that's a good name!

Does it sail silently, Tom?"

"I'll let you judge presently. Silent Sam is all ready for his first

trial, and I'll be glad to have you with me. Now, I'll just--"

Tom suddenly ceased speaking and held up a hand to enjoin silence.

Then, while Mr. Damon watched, the young inventor began moving

noiselessly toward the rear of the big shed, inside which was his new

machine.

CHAPTER XVIII

SUSPICIONS

"Who's there?" suddenly called Tom, and in such a sharp voice that Mr.

Damon started, ready as he was for something unusual.

There was no answer and Tom suddenly switched on all the lights in the

shed. Up to then there had been only a few glowing--just enough for him

to show the new Air Scout to his friend.

"Who's there?" asked Tom again, sharply.

"Bless my opera glasses, Tom!" cried Mr. Damon, "but are you seeing

things?"

"No; but I'm hearing them," answered Tom with a short laugh. "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 right."

"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 hide."

"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 Tom, after a further search of the premises. "Now, Mr.

Damon, if all goes as I hope you will see what my new machine can do.

Strain your ears for a sound, and let me know how much you hear."

His men helping him, Tom started the new motor which was tried for the

first time attached to the new craft. No flight was to be made yet, the

motor being tested as though on the block, though, in reality, the

craft was ready for instant flight if need be.

Slowly the great propellers began to revolve, and then Tom, taking his

place in the cockpit, turned on more power. The new craft--Silent

Sam--was made fast so it could not progress even though the propellers

revolved at high speed.

"I'm not sending her to the limit," said Tom to his friend, as the

young inventor throttled down the motor. "If I did I'd tear her loose

from the holding blocks."

"Her!" cried Mr. Damon. "Bless my typewriter, Tom! but I thought Silent

Sam was a gentleman aeroplane.

"So he is!" laughed the young man, frankly. "I forgot about 'Silent

Sam.' Guess I'll have to say 'him' instead of 'her,' though the latter

sounds more natural. Anyhow what do you think?"

"I think it's wonderful!" exclaimed Mr. Damon. "There the motor is,

going at almost full speed, and I can hardly hear a thing. You can the

easier believe that when I say that I can hear you talk perfectly well.

And I guess you hear me, don't you?"

"Yes," replied Tom. "And we don't have to shout, either. This is the

best test ever! I think everything is a success."

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

"Yes, now that I'm 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. I--er--I--"

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

CHAPTER XIX

ANOTHER FLIGHT

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 office."

"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 secrets."

"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 done.

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 heard 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.

CHAPTER XX

QUEER MARKS

"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 it."

"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 circumstances.

"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 workshop.

"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 through--leaving 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 metal.

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

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 before."

CHAPTER XXI

THE DESERTED CABIN

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, Tom."

"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 enemies."

"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 marks.

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 down.

"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 does."

"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."

"How?"

"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 tread."

"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 marks.

"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 on."

"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.

CHAPTER XXII

CLEWS AT LAST

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."

"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 door.

"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 rooms.

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 lately--"

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.

CHAPTER XXIII

THE GOVERNMENT TEST

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's 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 exclaim:

"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 files."

"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.

CHAPTER XXIV

IN THE MOONLIGHT

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 Swift.

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 motor."

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 it."

"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.

"Fine!"

"Wonderful!"

"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. Terrill.

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 Swift!"

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 had 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?"

CHAPTER XXV

THE GOLD TOOTH

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 whispered:

"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. "We 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 everything!"

"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 right?"

"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 cried:

"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 it."

"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 then after I couldn't imagine. Only, from what I

later 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 burst.

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 States?"

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.

THE END

----------------------------------------------------------------

THE TOM SWIFT SERIES

By VICTOR APPLETON

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.

TOM SWIFT AND HIS MOTOR CYCLE

TOM SWIFT AND HIS MOTOR BOAT

TOM SWIFT AND HIS AIRSHIP

TOM SWIFT AND HIS SUBMARINE BOAT

TOM SWIFT AND HIS ELECTRIC RUNABOUT

TOM SWIFT AND HIS WIRELESS MESSAGE

TOM SWIFT AMONG THE DIAMOND MAKERS

TOM SWIFT IN THE CAVES OF ICE

TOM SWIFT AND HIS SKY RACER

TOM SWIFT AND HIS ELECTRIC RIFLE

TOM SWIFT IN THE CITY OF GOLD

TOM SWIFT AND HIS AIR GLIDER

TOM SWIFT IN CAPTIVITY

TOM SWIFT AND HIS WIZARD CAMERA

TOM SWIFT AND HIS GREAT SEARCHLIGHT

TOM SWIFT AND HIS GIANT CANNON

TOM SWIFT AND HIS PHOTO TELEPHONE

TOM SWIFT AND HIS AERIAL WARSHIP

TOM SWIFT AND HIS BIG TUNNEL

TOM SWIFT IN THE LAND OF WONDERS

TOM SWIFT AND HIS WAR TANK

TOM SWIFT AND HIS AIR SCOUT

TOM SWIFT AND HIS UNDERSEA SEARCH

TOM SWIFT AMONG THE FIRE FIGHTERS

TOM SWIFT AND HIS ELECTRIC LOCOMOTIVE

SIX LITTLE BUNKERS SERIES

By LAURA LEE HOPE

Author of "The Bobbsey Twins Books,"

"The Bunny Brown Series,"

"The Make-Believe Series," Etc.

Delightful stories for little boys and girls which sprung into

immediate popularity. To know the six little Bunkers is to take them at

once to your heart, they are so intensely human, so full of fun and

cute sayings. Each story has a little plot of its own--one that can be

easily followed--and all are written in Miss Hope's most entertaining

manner. Clean, wholesome volumes which ought to be on the bookshelf of

every child in the land.

SIX LITTLE BUNKERS AT GRANDMA BELL'S

SIX LITTLE BUNKERS AT AUNT JO'S

SIX LITTLE BUNKERS AT COUSIN TOM'S

SIX LITTLE BUNKERS AT GRANDPA FORDS

SIX LITTLE BUNKERS AT UNCLE FRED'S

SIX LITTLE BUNKERS AT CAPTAIN BEN'S

SIX LITTLE BUNKERS AT COWBOY JACK'S

THE MOVING PICTURE BOYS SERIES

THE MOVING PICTURE BOYS

THE MOVING PICTURE BOYS IN THE WEST

THE MOVING PICTURE BOYS ON THE COAST

THE MOVING PICTURE BOYS IN THE JUNGLE

THE MOVING PICTURE BOYS IN EARTHQUAKE LAND

THE MOVING PICTURE BOYS AND THE FLOOD

THE MOVING PICTURE BOYS AT PANAMA

THE MOVING PICTURE BOYS UNDER THE SEA

THE MOVING PICTURE BOYS ON THE WAR FRONT

THE MOTION PICTURE CHUMS SERIES

THE MOTION PICTURE CHUMS' FIRST VENTURE

THE MOTION PICTURE CHUMS AT SEASIDE PARK

THE MOTION PICTURE CHUMS ON BROADWAY

THE MOTION PICTURE CHUMS' OUTDOOR EXHIBITION

THE MOTION PICTURE CHUMS' NEW IDEA

THE MOTION PICTURE CHUMS AT THE FAIR

THE MOTION PICTURE CHUMS' WAR SPECTACLE

End of 's Tom Swift and his Air Scout, by Victor Appleton