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TOM SWIFT AND HIS AERIAL WARSHIP or The Naval Terror of the Seas

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the case. The Secret Service has several agents in the field.

"We are convinced in Washington," went on Lieutenant Marbury,
when he, Tom and Ned were seated in the private office, "that
foreign spies are at work against you and against our

"Why against me?" asked Tom, in wonder.

"Because of the inventions you have perfected and turned over
to Uncle Sam--notably the giant cannon, which rivals anything
foreign European powers have, and the great searchlight, which
proved so effective against the border smugglers. The success of
those two alone, to say nothing of your submarine, has not only
made foreign nations jealous, but they fear you--and us," the
officer went on.

"Well, if they only take it out in fear--"

"But they won't!" interrupted the officer--"They are seeking to
destroy those inventions. More than once, of late, we have nipped
a plot just in time."

"Have they really tried to damage the big gun?" asked Tom,
referring to one he had built and set up at Panama.

"They have. And now this fire proves that they are taking other
measures--they are working directly against you."

"Why, I wonder?"

"Either to prevent you from making further inventions, or to
stop you from completing your latest--the aerial warship."

"But I didn't know the foreign governments knew about that,"
Tom exclaimed. "It was a secret."

"Few secrets are safe from foreign Spies," declared Lieutenant
Marbury. "They have a great ferreting-out system on the other
side. We are just beginning to appreciate it. But our own men
have not been idle."

"Have they really learned anything?" Tom asked.
"Nothing definite enough to warrant us in acting," was the
answer of the government man. "But we know enough to let us see
that the plot is far-reaching."

"Are the French in it?" asked Ned impulsively.

"The French! Why do you ask that?"

"Tell him about Eradicate, and the man who wanted to buy the
mule, Tom," suggested Ned,

Thereupon the young inventor mentioned the story told by
Eradicate. He also brought out the fire-bomb, and explained his
theory as to how it had operated to set the red shed ablaze.

"I think you are right," said Lieutenant Marbury. "And, as
regards the French, I might say they are not the only nation
banded to obtain our secrets--yours and the government's!"

"But I thought the French and the English were friendly toward
us!" Ned exclaimed.

"So they are, in a certain measure," the officer went on. "And
Russia is, too. But, in all foreign countries there are two
parties, the war party, as it might be called, and the peace

"But I might add that it is neither France, England, nor Russia
that we must fear. It is a certain other great nation, which at
present I will not name."

"And you think spies set this fire?"

"I certainly do."

"But what measures shall I adopt against this plot?" Tom asked.

"We will talk that over," said Lieutenant Marbury. "But, before
I go into details, I want to give you another warning. You must
be very careful about--"

A sudden knock on the door interrupted the speaker.


"Who is that?" asked Ned Newton, with a quick glance at his chum.

"I don't know," Tom answered. "I left orders we weren't to be
disturbed unless it was something important."

"May be something has happened," suggested the navy officer,
"another fire, perhaps, or a--"

"It isn't a fire," Tom answered. "The automatic alarm would be
ringing before this in that case."

The knock was repeated. Tom went softly to the door and opened
it quickly, to disclose, standing in the corridor, one of the
messengers employed about the shops.

"Well, what is it?" asked Tom a bit sharply.

"Oh, if you please, Mn Swift," said the boy, a man has applied
for work at the main office, and you know you left orders there
that if any machinists came along, we were to--"

"Oh, so I did," Tom exclaimed. "I had forgotten about that,"
he went on to Lieutenant Marbury and Ned. "I am in need of
helpers to rush through the finishing touches on my aerial
warship, and I left word, if any applied, as they often do,
coming here from other cities, that I wanted to see them. How
many are there?" Tom asked of the messenger.

"Two, this time. They both say they're good mechanics."

"That's what they all say," interposed Tom, with a smile. "But,
though they may be good mechanics in their own line, they need to
have special qualifications to work on airships. Tell them to
wait, Rodney," Tom went on to the lad, "and I'll see them

As the boy went away, and Tom closed the door, he turned to
Lieutenant Marbury.

"You were about to give me another warning when that
interruption came. You might complete it now."

"Yes, it was another warning," spoke the officer, "and one I
hope you will heed. It concerns yourself, personally."

"Do you mean he is in danger?" asked Ned quickly.

"That's exactly what I do mean," was the prompt reply. "In
danger of personal injury, if not something worse."

Tom did not seem as alarmed as he might reasonably have been
under the circumstances.

"Danger, eh?" he repeated coolly. "On the part of whom?"

"That's just where I can't warn you," the officer replied. "I
can only give you that hint, and beg of you to be careful."

"Do you mean you are not allowed to tell?" asked Ned

"No, indeed; it isn't that!" the lieutenant hastened to assure
the young man. "I would gladly tell, if I knew. But this plot,
like the other one, directed against the inventions themselves,
is so shrouded in mystery that I cannot get to the bottom of it.

"Our Secret Service men have been working on it for some time,
not only in order to protect you, because of what you have done
for the government, but because Uncle Sam wishes to protect his
own property, especially the searchlight and the big cannon. But,
though our agents have worked hard, they have not been able to
get any clues that would put them on the right trail.

"So we can only warn you to be careful, and this I do in all
earnestness. That was part of my errand in coming here, though,
of course, I am anxious to inspect the new aerial warship you
have constructed. So watch out for two things--your inventions,
and, more than all, your life!"

"Do you really think they would do me bodily harm?" Tom asked,
a trifle skeptical.

"I certainly do. These foreign spies are desperate. If they
cannot secure the use of these inventions to their own country,
they are determined not to let this country have the benefit of

"Well, I'll be careful," Tom promised. "I'm no more anxious
than anyone else to run my head into danger, and I certainly
don't want any of my shops or inventions destroyed. The fire in
the red shed was as close as I want anything to come."

"That's right!" agreed Ned. "And, if there's anything I can do,
Tom, don't hesitate to call on me."

"All right, old man. I won't forget. And now, perhaps, you
would like to see the Mars," he said to the lieutenant.

"I certainly would," was the ready answer. "But hadn't you
better see those men who are waiting to find out about positions

"There's no hurry about them," Tom said. "We have applicants
every day, and it's earlier than the hour when I usually see
them. They can wait. Now I want your opinion on my new craft.
But, you must remember that it is not yet completed, and only
recently did I begin to solve the problem of mounting the guns.
So be a little easy with your criticisms."

Followed by Ned and Lieutenant Marbury, Tom led the way into
the big airship shed. There, Swaying about at its moorings, was
the immense aerial warship. To Ned's eyes it looked complete
enough, but, when Tom pointed out the various parts, and
explained to the government officer how it was going to work, Ned
understood that considerable yet remained to be done on it.

Tom showed his official guest how a new system of elevation and
depressing rudders had ben adopted, how a new type of propeller
was to be used and indicated several other improvements. The
lower, or cabin, part of the aircraft could be entered by
mounting a short ladder from the ground, and Tom took Ned and
Lieutenant Marbury through the engine-room and other compartments
of the Mars.

"It certainly is most complete," the officer observed. "And
when you get the guns mounted I shall be glad to make an official
test. You understand," he went on, to Tom, "that we are vitally
interested in the guns, since we now have many aircraft that can
be used purely for scouting purposes. What we want is something
for offense, a veritable naval terror of the seas."

"I understand," Tom answered. "And I am going to begin work on
mounting the guns at once. I am going to use the Newton recoil
check," he added. "Ned, here, is responsible for that."

"Is that so?" asked the lieutenant, as Tom clapped his chum on
the back.

"Yes, that's his invention."

"Oh, it isn't anything of the sort," Ned objected. "I just--"

"Yes, he just happened to solve the problem for me!"
interrupted Tom, as he told the story of the door-spring.

"A good idea!" commented Lieutenant Marbury.

Tom then briefly described the principle on which his aerial
warship would work, explaining how the lifting gas would raise
it, with its load of crew, guns and explosives, high into the
air; how it could then be sent ahead, backward, to either side,
or around in a circle, by means of the propellers and the
rudders, and how it could be raised or lowered, either by rudders
or by forcing more gas into the lifting bags, or by letting some
of the vapor out.

And, while this was being done by the pilot or captain in
charge, the crew could be manning the guns with which hostile
airships would be attacked, and bombs dropped on the forts or
battleships of the enemy.

"It seems very complete," observed the lieutenant. "I shall be
glad when I can give it an official test."

"Which ought to be in about a week," Tom said. "Meanwhile I
shall be glad if you will be my guest here."

And so that was arranged.

Leaving Ned and the lieutenant to entertain each other, Tom
went to see the mechanics who had applied for places. He found
them satisfactory and engaged them. One of them had worked for
him before. The other was a stranger, but he had been employed in
a large aeroplane factory, and brought good recommendations.

There followed busy days at the Swift plant, and work was
pushed on the aerial warship. The hardest task was the mounting
of the guns, and equipping them with the recoil check, without
which it would be impossible to fire them with the craft sailing
through the air.

But finally one of the big guns, and two of the smaller ones
were in place, with the apparatus designed to reduce the recoil
shock, and then Tom decided to have a test of the Mars.

"Up in the air, do you mean?" asked Ned, who was spending all
his spare time with his chum.

"Well, a little way up in the air, at least," Tom answered.
"I'll make a sort of captive balloon of my craft, and see how she
behaves. I don't want to take too many chances with that new
recoil check, though it seems to work perfectly in theory."

The day came when, for the first time, the Mars was to come out
of the big shed where she had been constructed. The craft was not
completed for a flight as yet, but could be made so in a few
days, with rush work. The roof of the great shed slid back, and
the big envelope containing the buoyant gas rose slowly upward.
There was a cry of surprise from the many workmen in the yard, as
they saw, most of them for the first time, the wonderful new
craft. It did not go up very high, being held in place with
anchor ropes.

The sun glistened on the bright brass and nickel parts, and
glinted from the gleaming barrels of the quick-firing guns.

"That's enough!" Tom called to the men below, who were paying
out the ropes from the windlasses. "Hold her there."

Tom, Ned, Lieutenant Marbury and Mr. Damon were aboard the
captive Mars.

Looking about, to see that all was in readiness, Tom gave
orders to load the guns, blank charges being used, of course.

The recoil apparatus was in place, and it now remained to see
if it would do the work for which it was designed.

"All ready?" asked the young inventor.

"Bless my accident insurance policy!" exclaimed Mr. Damon. "I'm
as ready as ever I shall be, Tom. Let 'em go!"

"Hold fast!" cried Tom, as he prepared to press the electrical
switch which would set off the guns. Ned and Lieutenant Marbury
stood near the indicators to notice how much of the recoil would
be neutralized by the check apparatus.

"Here we go!" cried the young inventor, and, at the same
moment, from down below on the ground, came a warning cry:

"Don't shoot, Massa Tom. Don't shoot! Mah mule, Boomerang--"

But Eradicate had spoken too late. Tom pressed the switch;
there was a deafening crash, a spurt of flame, and then followed
wild cries and confused shouts, while the echoes of the reports
rolled about the hills surrounding Shopton.


"What was the matter down there?"

"Was anyone hurt?"

"Don't forget to look at those pressure gauges!"

"Bless my ham sandwich!"

Thus came the cries from those aboard the captive Mars. Ned,
Lieutenant Marbury and Tom had called out in the order named.
And, of course, I do not need to tell you what remark Mr. Damon
made. Tom glanced toward where Ned and the government man stood,
and saw that they had made notes of the pressure recorded on the
recoil checks directly after the guns were fired. Mr. Damon,
blessing innumerable objects under his breath, was looking over
the side of the rail to discover the cause of the commotion and
cries of warning from below.

"I don't believe it was anything serious, Tom," said the odd
man. "No one seems to be hurt." "Look at Eradicate!" suddenly
exclaimed Ned.

"And his mule! I guess that's what the trouble was, Tom!"

They looked to where the young bank employee pointed, and saw
the old colored man, seated on the seat of his ramshackle wagon,
doing his best to pull down to a walk the big galloping mule,
which was dragging the vehicle around in a circle.

"Whoa, dere!" Eradicate was shouting, as he pulled on the
lines. "Whoa, dere! Dat's jest laik yo', Boomerang, t' run when
dere ain't no call fo' it, nohow! Ef I done wanted yo' t' git a
move on, yo'd lay down 'side de road an' go to sleep. Whoa, now!"

But the noise of the shots had evidently frightened the long-
eared animal, and he was in no mood for stopping, now that he had
once started. It was not until some of the workmen ran out from
the group where they had gathered to watch Tom's test, and got in
front of Boomerang, that they succeeded in bringing him to a

Eradicate climbed slowly down from the seat, and limped around
until he stood in front of his pet.

"Yo'--yo're a nice one, ain't yo'?" he demanded in sarcastic
tones. "Yo' done enough runnin' in a few minutes fo' a week ob
Sundays, an' now I won't be able t' git a move out ob ye! I'se
ashamed ob yo', dat's what I is! Puffickly ashamed ob yo'. Go
'long, now, an' yo' won't git no oats dish yeah day! No sah!"
and, highly indignant, Eradicate led the now slowly-ambling mule
off to the stable.

"I won't shoot again until you have him shut up, Rad!" laughed
Tom. "I didn't know you were so close when I set off those guns."

"Dat's all right, Mass a Tom," was the reply. "I done called t'
you t' wait, but yo' didn't heah me, I 'spects. But it doan't
mattah, now. Shoot all yo' laik, Boomerang won't run any mo' dis
week. He done runned his laigs off now. Shoot away!"

But Tom was not quite ready to do this. He wanted to see what
effect the first shots had had on his aerial warship, and to
learn whether or not the newly devised recoil check had done what
was expected of it.

"No more shooting right away," called the young inventor. "I
want to see how we made out with the first round. How did she
check up, Ned?"

"Fine, as far as I can tell."

"Yes, indeed," added Lieutenant Marbury. "The recoil was hardly
noticeable, though, of course, with the full battery of guns in
use, it might be more so."

"I hope not," answered Tom. "I haven't used the full strength
of the recoil check yet. I can tune it up more, and when I do,
and when I have it attached to all the guns, big and little, I
think we'll do the trick. But now for a harder test."

The rest of that day was spent in trying out the guns, firing
them with practice and service charges, though none of the shells
used contained projectiles. It would not have been possible to
shoot these, with the Mars held in place in the midst of Tom's
factory buildings.

"Well, is she a success, Tom?" asked Ned, when the
experimenting was over for the time being.

"I think I can say so--yes," was the answer, with a questioning
look at the officer.

"Indeed it is--a great success! We must give the Newton shock
absorber due credit."

Ned blushed with pleasure.

"It was only my suggestion," he said. "Tom worked it all out."

"But I needed the Suggestion to start with," the young inventor

"Of course something may develop when you take your craft high
in the air, and discharge the guns there," said the lieutenant.
"In a rarefied atmosphere the recoil check may not be as
effective as at the earth's surface. But, in such case doubtless,
you can increase the strength of the springs and the hydrostatic

"Yes, I counted on that," Tom explained. "I shall have to work
out that formula, though, and be ready for it. But, on the whole,
I am pretty well satisfied."

"And indeed you may well feel that way," commented the
government official.

The Mars was hauled back into the shed, and the roof slid shut
over the craft. Much yet remained to do on it, but now that Tom
was sure the important item of armament was taken care of, he
could devote his entire time to the finishing touches.

As his plant was working on several other pieces of machinery,
some of it for the United States Government, and some designed
for his own use, Tom found himself obliged to hire several new
hands. An advertisement in a New York newspaper brought a large
number of replies, and for a day or two Tom was kept busy sifting
out the least desirable, and arranging to see those whose answers
showed they knew something of the business requirements.

Meanwhile Lieutenant Marbury remained as Tom's guest, and was
helpful in making suggestions that would enable the young
inventor to meet the government's requirements.

"I'd like, also, to get on the track of those spies who, I am
sure, wish to do you harm," said the lieutenant, "but clues seem
to be scarce around here."

"They are, indeed," agreed Tom. "I guess the way in which we
handled that fire in the red shed sort of discouraged them."

Lieutenant Marbury shook his head.

"They're not so easily discouraged as that," he remarked. "And,
with the situation in Europe growing more acute every day, I am
afraid some of those foreigners will take desperate measures to
gain their ends."

"What particular ends do you mean?"

"Well, I think they will either try to so injure you that you
will not be able to finish this aerial warship, or they will
damage the craft itself, steal your plans, or damage some of your
other inventions."

"But what object would they have in doing such a thing?" Tom
wanted to know. "How would that help France, Germany or Russia,
to do me an injury?"

"They are seeking to strike at the United States through you,"
was the answer. "They don't want Uncle Sam to have such
formidable weapons as your great searchlight, the giant cannon,
or this new warship of the clouds."

"But why not, as long as the United States does not intend to
go to war with any of the foreign nations?" Tom inquired.

"No, it is true we do not intend to go to war with any of the
conflicting European nations," admitted Lieutenant Marbury, "but
you have no idea how jealous each of those foreign nations is of
all the others. Each one fears that the United States will cease
to be neutral, and will aid one or the other."

"Oh, so that's' it?" exclaimed Tom.

"Yes, each nation, which may, at a moments notice, be drawn
into a war with one or more rival nations, fears that we may
throw in our lot with its enemies."

"And, to prevent that, they want to destroy some of my
inventions?" asked Tom.

"That's the way I believe it will work out. So you must be
careful, especially since you have taken on so many new men.

"That's so," agreed the young inventor. "I have had to engage
more strangers than ever before, for I am anxious to get the
Mars finished and give it a good test. And, now that you have
mentioned it, there are some of those men of whom I am a bit

"Have they done anything to make you feel that way?" asked the

"Well, not exactly; it is more their bearing, and the manner in
which they go about the works. I must keep my eye on them, for it
takes only a few discontented men to spoil a whole shop full. I
will be on my guard."

"And not only about your new airship and other inventions,"
said the officer, "but about yourself, personally. Will you do

"Yes, though I don't imagine anything like that will happen."

"Well, be on your guard, at all events," warned Lieutenant

As Tom had said, he had been obliged to hire a number of new
men. Some of these were machinists who had worked for him, or his
father, on previous occasions, and, when tasks were few, had been
dismissed, to go to other shops. These men, Tom felt sure, could
be relied upon.

But there were a number of others, from New York, and other
large cities, of whom Tom was not so sure.

"You have more foreigners than I ever knew you to hire before,
Tom," his father said to him one day, coming back from a tour of
the shops.

"Yes, I have quite a number," Tom admitted. "But they are all
good workmen. They stood the test."

"Yes, some of them are too good," observed the older inventor.
"I saw one of them making up a small motor the other day, and he
was winding the armature a new way. I spoke to him about it, and
he tried to prove that his way was an improvement on yours. Why,
he'd have had it short-circuited in no time if I hadn't stopped

"Is that so?" asked Tom. "That is news to me. I must look into

"Are any of the new men employed on the Mars?" Mr. Swift asked.

"No, not yet, but I shall have to shift some there from other
work I think, in order to get finished on time."

"Well, they will bear watching I think," his father said.

"Why, have you seen anything--do you--" began the young man,
for Mr. Swift had not been told of the suspicions of the

"Oh, it isn't anything special," the older inventor went on.
"Only I wouldn't let a man I didn't know much about get too much
knowledge of my latest invention."

"I won't, Dad. Thanks for telling me. This latest craft is sure
going to be a beauty."

"Then you think it will work, Tom?"

"I'm sure of it, Dad!"

Mr. Swift shook his head in doubt


Tom Swift pondered long and intently over what his father had
said to him. He sat for several minutes in his private office,
after the aged inventor had passed out, reviewing in his mind the
talk just finished.

"I wonder," said Tom slowly, "if any of the new men could have
obtained work here for the purpose of furthering that plot the
lieutenant suspects? I wonder if that could be true?"

And the more Tom thought of it, the more he was convinced that
such a thing was at least possible.

"I must make a close inspection, and weed out any suspicious
characters," he decided, "though I need every man I have working
now, to get the Mars finished in time. Yes, I must look into

Tom had reached a point in his work where he could leave much
to his helpers. He had several good foremen, and, with his father
to take general supervision over more important details, the
young inventor had more time to himself. Of course he did not lay
too many burdens on his father's shoulders since Mr. Swift's
health was not of the best.

But Tom's latest idea, the aerial warship, was so well on toward
completion that his presence was not needed in that shop more
than two or three times a day.

"When I'm not there I'll go about in the other shops, and sort
of size up the situation," he decided. "I may be able to get a
line on some of those plotters, if there are any here."

Lieutenant Marbury had departed for a time, to look after some
personal matters, but he was to return inside of a week, when it
was hoped to give the aerial warship its first real test in
flight, and under some of the conditions that it would meet with
in actual warfare.

As Tom was about to leave his office, to put into effect his
new resolution to make a casual inspection of the other shops, he
met Koku, the giant, coming in. Koku's hands and face were black
with oil and machine filings.

"Well, what have you been doing?" Tom wanted to know. "Did you
have an accident?" For Koku had no knowledge of machinery, and
could not even be trusted to tighten up a simple nut by himself.
But if some one stood near him, and directed him how to apply his
enormous strength, Koku could do more than several machines.

"No accident, Master," he replied. "I help man lift that
hammer-hammer thing that pounds so. It get stuck!"

"What, the hammer of the drop forger?" cried Tom. "Was that out
of order again?"

"Him stuck," explained Koku simply.

There was an automatic trip-hammer in one of the shops, used
for pounding out drop forgings, and this hammer seemed to take
especial delight in getting out of order. Very often it jammed,
or "stuck," as Koku described it, and if the hammer could not be
forced back on the channel or upright guide-plates, it meant that
it must be taken apart, and valuable time lost. Once Koku had
been near when the hammer got out of order, and while the workmen
were preparing to dismantle it, the giant seized the big block of
steel, and with a heave of his mighty shoulders forced it back on
the guides.

"And is that what you did this time?" asked Tom.

"Yes, Master. Me fix hammer," Koku answered. "I get dirty, I no
care. Man say I no can fix. I show him I can!"

"What man said that?"

"Man who run hammer. Ha! I lift him by one finger! He say he no
like to work on hammer. He want to work on airship. I tell him I
tell you, maybe you give him job--he baby! Koku can work hammer.
Me fix it when it get stuck."

"Well, maybe you know what you're talking about, but I don't,"
said Tom, with a pleasant smile at his big helper. "Come on,
Koku, we'll go see what it all means."

"Koku work hammer, maybe?" asked the giant hope fully.

"Well, I'll see," half promised Tom. "If it's going to get out
of gear all the while it might pay me to keep you at it so you
could get it back in place whenever it kicked up a fuss, and so
save time. I'll see about it."

Koku led the way to the shop where the triphammer was
installed. It was working perfectly now, as Tom could tell by
the thundering blows it struck. The man operating it looked up
as Tom approached, and, at a gesture from the young inventor,
shut off the power.

"Been having trouble here?" asked Tom, noting that the workman
was one of the new hands he had hired.

"Yes, sir, a little," was the respectful answer. "This hammer
goes on a strike every now and then, and gets jammed. Your giant
there forced it back into place, which is more than I could do
with a big bar for a lever. He sure has some muscle."

"Yes," agreed Tom, "he's pretty strong. But what's this you
said about wanting to give up this job, and go on the airship

The man turned red under his coat of grime.

"I didn't intend him to repeat that to you, Mr. Swift," he
said. "I was a little put out at the way this hammer worked. I
lose so much time at it that I said I'd like to be transferred to
the airship department. I've worked in one before But I'm not
making a kick," he added quickly. "Work is too scarce for that."

"I understand," said Tom. "I have been thinking of making a
change. Koku seems to like this hammer, and knows how to get it
in order once it gets off the guides. You say you have had
experience in airship construction?"

"Yes, sir. I've worked on the engines, and on the planes."

"Know anything about dirigible balloons?"

"Yes, I've worked on them, too, but the engineering part is my
specialty. I'm a little out of my element on a trip-hammer."

"I see. Well, perhaps I'll give you a trial. Meanwhile you
might break Koku in on operating this machine. If I transfer you
I'll put him on this hammer."

"Thank you, Mr. Swift! I'll show him all I know about it. Oh,
there goes the hammer again!" he exclaimed, for, as he started it
up, as Tom turned away, the big piece of steel once more jammed
on the channel-plates.

"Me fix!" exclaimed the giant eagerly, anxious
for a chance to exhibit his great strength.

"Wait a minute!" exclaimed Tom. "I want to get a look at that

He inspected it carefully before he signaled for Koku to force
the hammer back into place. But, if Tom saw anything suspicious,
he said nothing. There was, however, a queer look on his face as
he turned aside, and he murmured to himself, as he walked away:

"So you want to be transferred to the airship department, do
you? Well, we'll see about that We'll see."

Tom had more problems to solve than those of making an aerial
warship that would be acceptable to the United States Government.

Ned Newton called on his chum that evening. The two talked of
many things, gradually veering around to the subject uppermost in
Tom's mind--his new aircraft.

"You're thinking too much of that." Ned warned him. "You're as
bad as the time you went for your first flight."

"I suppose I am," admitted Tom. "But the success of the Mars
means a whole lot to me. And that's something I nearly forgot.
I've got to go out to the shop now. Want to come along, Ned?"

"Sure, though I tell you that you're working too hard--burning
the electric light at both ends."

"This is just something simple," Tom said. "It won't take

He went out, followed by his chum.

"But this isn't the way to the airship shed," objected the
young bank clerk, as he noted in which direction Tom was leading

"I know it isn't," Tom replied. "But I want to look at one of
the trip-hammers in the forge shop when none of the men is
around. I've been having a little trouble there."

"Trouble!" exclaimed his chum. "Has that plot Lieutenant
Marbury spoke of developed?"

"Not exactly. This is something else," and Tom told of the
trouble with the big hammer.

"I had an idea," the young inventor said, "that the man at the
machine let it get out of order purposely, so I'd change him. I
want to see if my suspicions are correct."

Tom carefully inspected the hammer by the light of a powerful
portable electric lamp Ned held.

"Ha! There it is!" Tom suddenly exclaimed.

"Something wrong?" Ned inquired.

"Yes. This is what's been throwing the hammer off the guides
all the while," and Tom pulled out a small steel bolt that had
been slipped into an oil hole. A certain amount of vibration, he
explained to Ned, would rattle the bolt out so that it would
force the hammer to one side, throwing it off the channel-plates,
and rendering it useless for the time being.

"A foxy trick," commented Tom. "No wonder the machine got out
of kilter so easily."

"Do you think it was done purposely?"

"Well, I'm not going to say. But I'm going to watch that man.
He wants to be transferred to the airship department. He put this
in the hammer, perhaps, to have an excuse for a change. Well,
I'll give it to him."

"You don't mean that you'd take a fellow like that and put him
to work on your new aerial warship, do you, Tom?"

"Yes, I think I will, Ned. You see, I look at it this way: I
haven't any real proof against him now. He could only laugh at me
if I accused him. But you've heard the proverb about giving a
calf rope enough and he'll hang himself, haven't you?"

"I think I have."

"Well, I'm going to give this fellow a little rope. I'll
transfer him, as he asks, and I'll keep a close watch on him."

"But won't it be risky?"

"Perhaps, but no more so than leaving him in here to work
mischief. If he is hatching a plot, the sooner it's over with the
better I shall like it. I don't like a shot to hang fire. I'm
warned now, and I'll be ready for him. I have a line on whom to
suspect. This is the first clue," and Tom held up the
incriminating bolt.

"I think you're taking too big a risk, Tom," his chum said.
"Why not discharge the man?"

"Because that might only smooth things over for a time. If this
plot is being laid the sooner it comes to a head, and breaks, the
better. Have it done, short, sharp and quick, is my motto. Yes,
I'll shift him in the morning. Oh, but I wish it was all over,
and the Mars was accepted by Uncle Sam!" and Tom put his hand to
his head with a tired gesture.

"Say, old man!" exclaimed Ned, "what you want is a day off, and
I'm going to see that you get it. You need a little vacation."

"Perhaps I do," assented Tom wearily.

"Then you'll have it!" cried Ned. "There's going to be a little
picnic to-morrow. Why can't you go with Mary Nestor? She'd like
you to take her, I'm sure. Her cousin, Helen Randall, is on from
New York, and she wants to go, also."

"How do you know?" asked Tom quickly.

"Because she said so," laughed Ned. "I was over to the house to
call. I have met Helen before, and I suggested that you and I
would take the two girls, and have a day off. You'll come, won't

"Well, I don't know," spoke Tom slowly. "I ought to--"

"Nonsense! Give up work for one day!" urged Ned. "Come along.
It'll do you good--get the cobwebs out of your head."

"All right, I'll go," assented Tom, after a moment's thought.

The next day, having instructed his father and the foremen to
look well to the various shops, and having seen that the work on
the new aerial warship was progressing favorably, Tom left for a
day's outing with his chum and the two girls.

The picnic was held in a grove that surrounded a small lake,
and after luncheon the four friends went for a ride in a launch
Tom hired. They went to the upper end of the lake, in rather a
pretty but lonesome locality.

"Tom, you look tired," said Mary. "I'm sure you've been working
too hard!"

"Why, I'm not working any harder than usual," Tom insisted.

"Yes, he is, too!" declared Ned, "and he's running more
chances, too."

"Chances?" repeated Mary.

"Oh, that's all bosh!" laughed Tom. "Come on, let's go ashore
and walk."

"That suits me," spoke Ned. Helen and Mary assented, and soon
the four young persons were strolling through the shady wood.

After a bit the couples became separated, and Tom found himself
walking beside Mary in a woodland path. The girl glanced at her
companion's face, and ventured:

"A penny for your thoughts, Tom."

"They're worth more than that," he replied gallantly. "I was
thinking of--you."

"Oh, how nicely you say it!" she laughed. "But I know better!
You're puzzling over some problem. Tell me, what did Ned mean
when he hinted at danger? Is there any, Tom?"

"None at all," he assured her. "It's just a soft of notion--"

Mary made a sudden gesture of silence.

"Hark!" she whispered to Tom, "I heard someone mention your
name then. Listen!"


Mary Nestor spoke with such earnestness, and her action in
catching hold of Tom's arm to enjoin silence was so pronounced
that, though he had at first regarded the matter in the light of
a joke, he soon thought otherwise. He glanced from the girl's
face to the dense underbrush on either side of the woodland path.

"What is it, Mary?" he asked in a whisper.

"I don't just know. I heard whispering, and thought it was the
rustling of the leaves of the trees. Then someone spoke your name
quite loudly. Didn't you hear it?"

Tom shook his head in negation.

"It may be Ned and his friend," he whispered, his lips close to
Mary's ear.

"I think not," was her answer. "Listen; there it is again."

Distinctly then, Tom heard, from some opening in the screen of
bushes, his own name spoken. "Did you hear it?" asked Mary,
barely forming the words with her lips. But Tom could read their

"Yes," he nodded. Then, motioning to Mary to remain where she
was, he stepped forward, taking care to tread only on grassy
places where there were no little twigs or branches to break and
betray his presence. He was working his way toward the sound of
the unseen voice.

There was a sudden movement in the bushes, just beyond the spot
Tom was making for. He halted quickly and peered ahead. Mary,
too, was looking on anxiously.

Tom saw the forms of two men, partially concealed by bushes,
walking away from him. The men took no pains to conceal their
movements, so Tom was emboldened to advance with less caution. He
hurried to where he could get a good view, and, at the sight of
one of the men, he uttered an exclamation.

"What is it?" asked Mary, who was now at his side. She had seen
that Tom had thrown aside caution, and she had come up to join

"That man--I know him!" the young inventor exclaimed. "It is
Feldman--the one who wanted to be changed from the trip-hammer to
the airship department. But who is that with him?"

As Tom spoke the other turned, and at the sight of his face
Mary Nestor said:

"He looks like a Frenchman, with that little mustache and

"So he is!" exclaimed Tom, in a hoarse whisper. "He must be the
Frenchman that Eradicate spoke about. I wonder what this can
mean? I didn't know Feldman had left the shop."

"You may know what you're talking about, but I don't, Tom,"
said Mary, with a smile at her companion. "Are they friends of

"Hardly," spoke the young inventor dryly. "That one, Feldman,
is one of my workmen. He had charge of a drop-forge press and
trip-hammer that--"

"Spare me the details, Tom!" interrupted Mary. "You know I
don't understand a thing about machinery. The wireless you
erected on Earthquake Island was as much as I could comprehend."

"Well, a trip-hammer isn't as complicated as that," spoke Tom,
with a laugh, as he noticed that the two men were far enough away
so they could not hear him. "What I was going to say was, that
one of those men works in our shops. The other I don't know, but
I agree with you that he does look like a Frenchman, and old
Eradicate had a meeting with a man whom he described as being of
that nationality."

"And you say they are not friends of yours?"

"I have no reason to believe they are."

"Then they must be enemies!" exclaimed Mary with quick
intuition. "Oh, Tom, you will be careful, won't you?"

"Of course I will, little girl," he said, a note of fondness
creeping into his voice, as he covered the small hand with his
own large one. "But there is no danger."

"Then why were these men discussing you?"

"I don't know that they were, Mary."

"They mentioned your name."

"Well, that may be. Probably one of them, Feldman, who works
for me, was speaking to his companion about the chance for a
position. My father and I employ a number of men, you know."

"Well, I suppose it is all right, Tom, and I surely hope it is.
But you will be careful, won't you? And you look more worried
than you used to. Has anything gone wrong?"

"Not a thing, little girl. Everything is going fine. My new
aerial warship will soon make a trial flight, and I'd be pleased
to have you as a passenger."

"Would you really, Tom?"

"Of course. Consider that you have the first invitation."

"That's awfully nice of you. But you do look worried, Tom. Has
anything troubled you?"

"No, not much. Everything is going all right now. We did have a
little trouble at a fire in one of my buildings--"

"A fire! Oh, Tom! You never told me!"

"Well, it didn't amount to much--the only suspicious fact about
it was that it seemed to have been of incendiary origin."

Mary seemed much alarmed, and again begged Tom to be on his
guard, which he promised to do. Had Mary known the warnings
uttered by Lieutenant Marbury she might have had more occasion
for worry.

"Do you suppose that hammer man of yours came to these woods to
meet that Frenchman and talk about you, Tom?" asked his
companion, when the two men had strolled out of sight, and the
young people were on their way back to the launch.

"Well, it's possible. I have been warned that foreign spies are
trying to get hold of some of my patents, and also to hamper the
government in the use of some others I have sold. But they'll
have their own troubles to get away with anything. The works are
pretty well guarded, and you forget I have the giant, Koku, who
is almost a personal bodyguard."

"Yes, but he can't be everywhere at once. Oh, you will be
careful, won't you, Tom?"

"Yes, Mary, I will," promised the young inventor. "But don't
say anything to Ned about what we just saw and heard."

"Why not?"

"Because he's been at me to hire a couple of detectives to
watch over me, and this would give him another excuse. Just don't
say anything, and I'll adopt all the precautions I think are

"I will on condition that you do that."

"And I promise I will."

With that Mary had to be content. A little later they joined
Ned and his friend, and soon they were moving swiftly down the
lake in the launch.

"Well, hasn't it done you good to take a day off?" Ned demanded
of his chum, when they were on their homeward way.

"Yes, I think it has," agreed Tom.

"You swung your thoughts into a new channel, didn't you?"

"Oh, yes, I found something new to think about," admitted the
young inventor, with a quick look at Mary.

But, though Tom thus passed off lightly the little incident of
the day, he gave it serious thought when he was alone.

"Those fellows were certainly talking about me," he reasoned.
"I wonder what for? And Feldman left the shop without my
knowledge. I'll have to look into that. I wonder if that Frenchy
looking chap I saw was the one who tried to pump Eradicate?
Another point to settle."

The last was easily disposed of, for, on reaching his shops
that afternoon, Tom cross-questioned the colored man, and
obtained a most accurate description of the odd foreigner. It
tallied in every detail with the man Tom had seen in the woods.

"And now about Feldman," mused Tom, as he went to the foreman
of the shop where the suspected man had been employed.

"Yes, Feldman asked for a day off," the foreman said in
response to Tom's question. "He claimed his mother was sick, and
he wanted to go to see her. I knew you wouldn't object, as we
were not rushed in his department."

"Oh, that's all right," said Tom quickly. "Did he say where his
mother lived?"

"Over Lafayette way."

"Humph!" murmured Tom. To himself he added: "Queer that he
should be near Lake Loraine, in an opposite direction from
Lafayette. This will bear an investigation."

The next day Tom made it his business to pass near the hammer
that was so frequently out of order. He found Feldman busy
instructing Koku in its operation. Tom resolved on a little

"How is it working, Feldman?" he asked.

"Very well, Mr. Swift. There doesn't seem to be any trouble at
all, but it may happen any minute. Koku seems to take to it like
a duck to water."

"Well, when he is ready to assume charge let me know."

"And then am I to go into the aeroplane shop?"

"I'll see. By the way, how is your mother?" he asked quickly,
looking Feldman full in the face.

"She is much better. I took a day off yesterday to go to see
her," the man replied quietly enough, and without sign of

"That's good. Let me see, she lives over near Lake Loraine,
doesn't she?"

This time Feldman could not repress a start. But he covered it
admirably by stooping over to pick up a tool that fell to the

"No, my mother is in Lafayette," he said. "I don't know where
Lake Loraine is."

"Oh," said Tom, as he turned aside to hide a smile. He was sure
now he knew at least one of the plotters

But Tom was not yet ready to show his hand. He wanted better
evidence than any he yet possessed. It would take a little more

Work on the aerial warship was rushed, and it seemed likely
that a trial flight could be made before the date set. Lieutenant
Marbury sent word that he would be on hand when needed, and in
some of the shops, where fittings for the Mars were being made,
night and day shifts were working.

"Well, if everything goes well, we'll take her for a trial
flight to-morrow," said Tom, coming in from the shops one

"Guns and all?" asked Ned, who had come over to pay his chum a
visit. Mr. Damon was also on hand, invoking occasional blessings.

"Guns and all," replied Tom.

Ned had a little vacation from the bank, and was to stay all
night, as was Mr. Damon.

What time it was, save that it must be near midnight, Tom could
not tell, but he was suddenly awakened by hearing yells from

"Massa Tom! Massa Tom!" yelled the excited colored man. "Git
up! Git up! Suffin' turrible am happenin' in de balloon shop.
Hurry! An' yo' stan' still, Boomerang, or I'll twist yo' tail,
dat's what I will! Hurry, Massa Tom!"

Tom leaped out of bed.


Tom Swift was something like a fireman. He had lived so long in
an atmosphere of constant alarms and danger, that he was always
ready for almost any emergency. His room was equipped with the
end in view that he could act promptly and effectively.

So, when he heard Eradicate's alarm, though he wondered what
the old colored man was doing out of bed at that hour, Tom did
not stop to reason out that puzzle. He acted quickly.

His first care was to throw on the main switch, connected with
a big storage battery, and to which were attached the wires of
the lighting system. This at once illuminated every shop in the
plant, and also the grounds themselves. Tom wanted to see what
was going on. The use of a storage battery eliminated the running
of the dynamo all night.

And once he had done this, Tom began pulling on some clothes
and a pair of shoes. At the same time he reached out with one
hand and pressed a button that sounded an alarm in the sleeping
quarters of Koku, the giant, and in the rooms of some of the
older and most trusted men.

All this while Eradicate was shouting away, down in the yard.

"Massa Tom! Massa Tom!" he called. "Hurry! Hurry! Dey is
killin' Koku!"

"Killing Koku!" exclaimed Tom, as he finished his hasty
dressing. "Then my giant must already be in the fracas. I wonder
what it's all about, anyhow."

"What's up, Tom?" came Ned's voice from the adjoining room. "I
thought I heard a noise."

"Your thoughts do you credit, Ned!" Tom answered. "If you
listen right close, you'll hear several noises."

"By Jove! You're right, old man!"

Tom could hear his chum bound out of bed to the floor, and, at
the same time, from the big shed where Tom was building his
aerial warship came a series of yells and shouts.

"That's Koku's voice!" Tom exclaimed, as he recognized the
tones of the giant.

"I'm coming, Tom!" Ned informed his chum. "Wait a minute."

"No time to wait," Tom replied, buttoning his coat as he sped
down the hall.

"Oh, Tom, what is it?" asked Mrs. Baggert, the housekeeper,
looking from her room.

"I don't know. But don't let dad get excited, no matter what
happens. Just put him off until I come back. I think it isn't
anything serious."

Mr. Damon, who roomed next to Ned, came out of his own
apartment partially dressed.

"Bless my suspenders!" he cried to Tom, those articles just
then dangling over his hips. "What is it? What has happened?
Bless my steam gauge, don't tell me it's a fire!"

"I think it isn't that," Tom answered. "No alarm has rung. Koku
seems to be in trouble."

"Well, he's big enough to look after himself, that's one
consolation," chuckled Mr. Damon. "I'll be right with you."

By this time Ned had run out into the hall, and, together, he
and Tom sped down the corridor. They could not hear the shouts of
Eradicate so plainly now, as he was on the other side of the

But when the two young men reached the front porch, they could
hear the yells given with redoubled vigor. And, in the glare of
the electric lights, Tom saw Eradicate leading along Boomerang,
the old mule.

"What is it, Rad? What is it?" demanded the young inventor

"Trouble, Massa Tom! Dat's what it am! Trouble!"

"I know that--but what kind?"

"De worstest kind, I 'spects, Massa Tom. Listen to it!"

From the interior of the big shed, not far from the house, Tom
and Ned heard a confused jumble of shouts, cries and pleadings,
mingled with the rattle of pieces of metal, and the banging of
bits of wood. And, above all that, like the bellowing of a bull,
was noted the rumbling voice of Koku, the giant.

"Come on, Ned!" Tom cried.

"It's suah trouble, all right," went on Eradicate. "Mah mule,
Boomerang, had a touch ob de colic, an' I got up t' gib him some
hot drops an' walk him around, when I heard de mostest terrific
racket-sound, and den I 'spected trouble was comm."

"It isn't coming--it's here!" called Tom, as he sped toward the
big shop. Ned was but a step behind him. The big workshop where
the aerial warship was being built was, like the other buildings,
brilliantly illuminated by the lights Tom had switched on. The
young inventor also saw several of his employees speeding toward
the same point.

Torn was the first to reach the small door of the shed. This
was built in one of the two large main doors, which could be
swung open when it was desired to slide the Mars in from the
ground, and not admit it through the roof.

"Look!" cried Tom, pointing.

Ned looked over his chum's shoulder and saw the giant, Koku,
struggling with four men--powerful men they were, too, and they
seemed bent on mischief.

For they came at Koku from four sides, seeking to hold his
hands and feet so that he could not fight them back. On the floor
near where the struggle was taking place was a coil of rope, and
it was evident that it had been the intention of the men to
overcome Koku and truss him up, so that he would not interfere
with what they intended to do. But Koku was a match for even the
four men, powerful as they were.

"We're here, Koku!" cried Tom. "Watch for an opening, Ned!" he
called to his chum.

The sound of Tom's voice disconcerted at least two of the
attackers, for they looked around quickly, and this was fatal to
their chances.

Though such a big man, Koku was exceptionally quick, and no
sooner did he see his advantage, as two of the men turned their
gaze away from him, than he seized it.

Suddenly tearing loose his hands from the grip of the two men
who had looked around, Koku shot out his right and left fists,
and secured good hold on the necks of two of his enemies. The
other two, at his back, were endeavoring to pull him over, but
the giant's sturdy legs still held.

So big was Koku's hands that they almost encircled the necks of
his antagonists. Then happened a curious thing.

With a shout that might have done credit to some ancient cave-
dweller of the stone age, Koku spread out his mighty arms, and
held apart the two men he had grasped. In vain they struggled to
free themselves from that terrible grip. Their faces turned
purple, and their eyes bulged out.

"He's choking them to death!" shouted Ned.

But Koku was not needlessly cruel.

A moment later, with a quick and sudden motion he bent his
arms, bringing toward each other the two men he held as captives.
Their heads came together with a dull thud, and a second later
Koku allowed two limp bodies to slip from his grip to the floor.

"He's done for them!" Tom cried. "Knocked them unconscious.
Good for you, Koku!"

The giant grunted, and then, with a quick motion, slung himself
around, hoping to bring the enemies at his back within reach of
his powerful arms. But there was no need of this.

As soon as the other two ruffians had seen their companions
fall to the floor of the shop they turned and fled, leaping from
an open window.

"There they go!" cried Ned.

"Some of the other men can chase them," said the young
inventor. "We'll tie up the two Koku has captured."

As he approached nearer to the unconscious captives Tom uttered
a cry of surprise, for he recognized them as two of the new men
he had employed.

"What can this mean?" he asked wonderingly.

He glanced toward the window through which the two men had
jumped to escape, and he was just in time to see one of them run
past the open door. The face of this one was under a powerful
electric light, and Tom at once recognized the man as Feldman,
the worker who had had so much trouble with the trip-hammer.

"This sure is a puzzle," marveled Tom. "My own men in the plot!
But why did they attack Koku?"

The giant, bending over the men he had knocked unconscious by
beating their heads together, seemed little worse for the attack.

"We tie 'em up," he said grimly, as he brought over the rope
that had been intended for himself.


Little time was lost in securing the two men who bad been so
effectively rendered helpless by Koku's ready, if rough,
measures. One of them was showing signs of returning
consciousness now, and Tom, not willing to inflict needless pain,
even on an enemy, told one of his men, summoned by the alarm, to
bring water. Soon the two men opened their eyes, and looked about
them in dazed fashion.

"Did--did anything hit me?" asked one meekly.

"It must have been a thunderbolt," spoke the other dreamily.
"But it didn't look like a storm."

"Oh, dere was a storm, all right," chuckled Eradicate, who,
having left his mule, Boomerang outside, came into the shed. "It
was a giant storm all right."

The men put their hands to their heads, and seemed to
comprehend. They looked at the rope that bound their feet. Their
forearms had been loosened to allow them to take a drink of

"What does this mean--Ransom--Kurdy?" asked Tom sternly, when
the men seemed able to talk. "Did you attack Koku?"

"It looks as though he had the best of us, whether we did or
not," said the man Tom knew as Kurdy. "Whew, how my head aches!"

"Me sorry," said Koku simply.

"Not half as sorry as we are," returned Ransom ruefully.

"What does it mean?" asked Tom sternly. "There were four of
you. Feldman and one other got away."

"Oh, trust Feldman for getting away," sneered Kurdy. "He always
leaves his friends in the lurch."

"Was this a conspiracy?" demanded Tom.

The two captives looked at one another, sitting bound on the
floor of the shop, their backs against some boxes.

"I guess it's all up, and we might as well make a clean breast
of it," admitted Kurdy.

"Perhaps it would be better," said Tom
quietly. "Eradicate," he went on, to the colored man, "go to the
house and tell Mrs. Baggert that everything is all right and no
one hurt."

"No one hurt, Massa Tom? What about dem dere fellers?" and the
colored man pointed to the captives.

"Well, they're not hurt much," and Tom permitted himself a
little smile. "I don't want my father to worry. Tell him
everything is all right."

"All right, Massa Tom. I'se gwine right off. I'se got t' look
after mah mule, Boomerang, too. I'se gwine," and he shuffled

"Who else besides Feldman got away?" asked Tom, looking
alternately at the prisoners.

They hesitated a moment about answering.

"We might as well give up, I tell you," spoke Kurdy to Ransom.

"All right, go ahead, we'll have to take our medicine. I might
have known it would turn out this way--going in for this sort of
thing. It's the first bit of crooked business I ever tried," the
man said earnestly, "and it will be the last--believe me!"

"Who was the fourth man?" Tom repeated.

"Harrison," answered Kurdy, naming one of the most efficient of
the new machinists Tom had hired during the rush.

"Harrison, who has been working on the motor?" cried the young

"Yes," said Ransom.

"I'm sorry to learn that," Tom went on in a low voice. "He was
an expert in his line. But what was your object, anyhow, in
attacking Koku?"

"We didn't intend to attack him," explained Ransom, "but he
came in when we were at work, and as he went for us we tried to
stand him off. Then your colored man heard the racket, and--well,
I guess you know the rest."

"But I don't understand why you came into this shed at night,"
went on Tom. "No one is allowed in here. You had no right, and
Koku knew that. What did you want?"

"Look here!" exclaimed Kurdy, "I said we'd make a clean breast
of it, and we will. We're only a couple of tools, and we were
foolish ever to go in with those fellows; or rather, in with that
Frenchman, who promised us big money if we succeeded."

"Succeeded in what?" demanded the young inventor.

"In damaging your new aerial warship, or in getting certain
parts of it so he could take them away with him."

Tom gave a surprised whistle.

"A frenchman!" he exclaimed. "Is he one of the--?"

"Yes, he's one of the foreign spies," interrupted Ransom.
"You'd find it out, anyhow, if we didn't tell you. They are after
you, Tom Swift, and after your machines. They had vowed to get
them by fair means or foul, for some of the European governments
are desperate."

"But we were only tools in their hands. So were Feldman and
Harrison, but they knew more about the details. We were only
helping them."

"Then we must try to capture them," decided Tom. "Ned, see if
the chase had any results. I'll look after these chaps--Koku and

"Oh, we give in," admitted Kurdy. "We know when we've had
enough," and he rubbed his head gently where the giant had banged
it against that of his fellow-conspirator.

"Do you mean that you four came into this shop, at midnight, to
damage the Mars?" asked Tom.

"That's about it, Mr. Swift," replied Kurdy rather
shamefacedly. "We were to damage it beyond repair, set fire to
the whole place, if need be, and, at the same time, take away
certain vital parts

"Harrison, Feldman, Ransom and I came in, thinking the coast
was clear. But Koku must have seen us enter, or he suspected we
were here, for he came in after us, and the fight began. We
couldn't stop him, and he did for us. I'm rather glad of it, too,
for I never liked the work. It was only that they tempted me with
a promise of big money."

"Who tempted you?" demanded Tom.

"That Frenchman--La Foy, he calls himself, and some other
foreigners in your shops."

"Are there foreigners here?" cried Tom.

"Bless my chest protector!" cried Mn Damon, who had come in and
had been a silent listener to this. "Can it be possible?"

"That's the case," went on Kurdy. "A lot of the new men you
took on are foreign spies from different European nations. They
are trying to learn all they can about your plans, Mr. Swift!"

"Are they friendly among themselves?" asked Tom.

"No; each one is trying to get ahead of the other. So far the
Frenchman seems to have had the best of it. But to-night his plan

"Tell me more about it," urged Tom.

"That's about all we know," spoke Ransom. "We were only hired
to do the rough work. Those higher up didn't appear. Feldman was
only a step above us."

"Then my suspicions of him were justified," thought Tom. "He
evidently met La Foy in the woods to make plans. But Koku and
Eradicate spoiled them."

The two captives seemed willing enough to make a confession,
but they did not know much. As they said, they were merely tools,
acting for others. And events had happened just as they had said.

The four conspirators had managed, by means of a false key, and
by disconnecting the burglar alarm, to enter the airship shed.
They were about to proceed with their work of destruction when
Koku came on the scene.

The giant's appearance was due to accident. He acted as a sort
of night watchman, making a tour of the buildings, but he entered
the shed where the Mars was because, that day, he had left his
knife in there, and wanted to get it. Only for that he would not
have gone in. When he entered he surprised the four men.

Of course he attacked them at once, and they sprang at him.
Then ensued a terrific fight. Eradicate, arising to doctor his
mule, as he had said, heard the noise, and saw what was going on.
He gave the alarm.

"Well, Ned, any luck?" asked Tom, as his chum came in.

"No, they got away, Tom. I had a lot of your men out helping me
search the grounds, but it wasn't of much use."

"Particularly if you depended on some of my men," said Tom

"What do you mean?"

"I mean that the place is filled with spies, Ned! But we will
sift them out in the morning. This has been a lucky night for me.
It was touch and go. Now, then, Koku, take these fellows and lock
them up somewhere until morning. Ned, you and I will remain on
guard here the rest of the night."

"I'm with you, Tom."

"Will you be a bit easy on us, considering what we told you?"
asked Kurdy.

"I'll do the best I can," said Tom, gently, making no promises.

The two captives were put in secure quarters, and the rest of
the night passed quietly. During the fight in the airship shed
some machinery and tools had been broken, but no great amount of
damage was done. Tom and Ned passed the remaining hours of
darkness there.

A further search was made in the morning for the two
conspirators who had escaped, but no trace of them was found. Tom
then realized why Feldman was so anxious to be placed in the
aeroplane department--it was in order that he might have easier
access to the Mars.

A technical charge was made against the two prisoners,
sufficient to hold them for some time. Then Tom devoted a day to
weeding out the suspected foreigners in his place. All the new
men were discharged, though some protested against this action.

"Probably I am hitting some of the innocent in punishing those
who, if they had the chance, would become guilty," Tom said to
his chum, "but it cannot be helped--I can't afford to take any

The Mars was being put in shape for her first flight. The guns,
fitted with the recoil shock absorbers, were mounted, and
Lieutenant Marbury had returned to go aloft in the big aerial
warship. He congratulated Tom on discovering at least one plot in

"But there may be more," he warned the young inventor. "You are
not done with them yet."

The Mars was floated out of her hangar, and made ready for an
ascent. Tom, Ned, Lieutenant Marbury, Mr. Damon, and several
workmen were to be the first passengers. Tom was busy going over
the various parts to see that nothing had been forgotten.

"Well, I guess we re ready," he finally announced. "All

"Bless my insurance policy!" exclaimed Mr. Damon. "Now that the
time comes I almost wish I wasn't going."

"Nonsense!" exclaimed Tom. "You're not going to back out at the
last minute. All aboard! Cast off the ropes!" he cried to the

A moment later the Mars, the biggest airship Tom Swift had ever
constructed, arose from the earth like some great bird, and
soared aloft.


"Well, Tom, we're moving!" cried Ned Newton, clapping his chum
on the back, as he stood near him in the pilot-house. "We're
going up, old sport!"

"Of course we are," replied Tom. "You didn't think it wouldn't
go up, did you?"

"Well, I wasn't quite sure," Ned confessed. "You know you were
so worried about--"

"Not about the ship sailing," interrupted Tom. "It was only the
effect the firing of the guns might have. But I think we have
that taken care of."

"Bless my pin cushion!" cried Mr. Damon, as he looked over the
rail at the earth below. "We're moving fast, Tom."

"Yes, we can make a quicker ascent in this than in most
aeroplanes," Tom said, "for they have to go up in a slanting
direction. But we can't quite equal their lateral speed."

"Just how fast do you think you can travel when you are in
first-class shape?" asked Lieu tenant Marbury, as he noted how
the Mars was behaving on this, the first trip.

"Well, I set a limit of seventy-five miles an hour," the young
inventor replied, as he shifted various levers and handles, to
change the speed of the mechanism. "But I'm afraid we won't quite
equal that with all our guns on board. But I'm safe in saying
sixty, I think."

"That will more than satisfy the government requirements," the
officer said. "But, of course, your craft will have to come up to
expectations and requirements in the matter of armament."

"I'll give you every test you want," declared Tom, with a
smile. "And now we'll see what the Mars can do when put to it."

Up and up went the big dirigible aerial warship. Had you been
fortunate enough to have seen her you would have observed a craft
not unlike, in shape, the German Zeppelins. But it differed from
those war balloons in several important particulars.

Tom's craft was about six hundred feet long, and the diameter
of the gas bag, amidships, was sixty feet, slightly larger than
the largest Zeppelin. Below the bag, which, as I have explained,
was made up of a number of gas-tight compartments, hung from wire
cables three cabins. The forward one was a sort of pilot-house,
containing various instruments for navigating the ship of the
air, observation rooms, gauges for calculating firing ranges, and
the steering apparatus.

Amidships, suspended below the great bag, were the living and
sleeping quarters, where food was cooked and served and where
those who operated the craft could spend their leisure time.
Extra supplies were also stored there.

At the stern of the big bag was the motor-room, where gas was
generated to fill the balloon compartments when necessary, where
the gasoline and electrical apparatus were installed, and where
the real motive power of the craft was located. Here, also, was
carried the large quantity of gasoline and oil needed for a long
voyage. The Mars could carry sufficient fuel to last for over a
week, provided no accidents occurred.

There was also an arrangement in the motor compartment, so that
the ship could be steered and operated from there. This was in
case the forward pilot-house should be shot away by an enemy.
And, also, in the motor compartment were the sleeping quarters
for the crew.

All three suspended cabins were connected by a long covered
runway, so that one could pass from the pilot-house to the motor-
room and back again through the amidship cabin

At the extreme end of the big bag were the various rudders and
planes, designed to keep the craft on a level keel,
automatically, and to enable it to make headway against a strong
wind. The motive power consisted of three double-bladed wooden
propellers, which could be operated together or independently. A
powerful gasoline engine was the chief motive power, though there
was an auxiliary storage battery, which would operate an
electrical motor and send the ship along for more than twenty-
four hours in case of accident to the gasoline engine.

There were many other pieces of apparatus aboard, some not
completely installed, the uses of which I shall mention from time
to time, as the story progresses. The gas-generating machine was
of importance, for there would be a leakage and shrinking of the
vapor from the big bag, and some means must be provided for
replenishing it.

"You don't seem to have forgotten anything, Tom," said Ned
admiringly, as they soared upward.

"We can tell better after we've flown about a bit," observed
the young inventor, with a smile. "I expect we shall have to make
quite a number of changes."

"Are you going far?" asked Mr. Damon.

"Why, you're not frightened, are you?" inquired Tom. "You have
been up in airships with me before."

"Oh, no, I'm not frightened!" exclaimed the odd man. "Bless my
suspenders, no! But I promised my wife I'd be back this evening,

"We'll sail over toward Waterford," broke in Tom, "and I'll
drop you down in your front yard."

"No, don't do that! Don't! I beg of you!" cried Mr. Damon. "You
see--er--Tom, my wife doesn't like me to make these trips. Of
course, I understand there is no danger, and I like them. But
it's just as well not to make her worry-you understand!"

"Oh, all right," replied Tom, with a laugh. "Well, we're not
going far on this trip. What I want to do, most of all, is to
test the guns, and see if the recoil check will work as well when
we are aloft as it did down on the ground. You know a balloon
isn't a very stable base for a gun, even one of light caliber."

"No, it certainly is not," agreed Lieutenant Marbury, "and I am
interested in seeing how you will overcome the recoil."

"We'll have a test soon," announced Tom.

Meanwhile the Mars, having reached a considerable height, being
up so far, in fact, that the village of Shopton could scarcely be
distinguished, Tom set the signal that told the engine-room force
to start the propellers. This would send them ahead.

Some of Tom's most trusted workmen formed the operating crew,
the young inventor taking charge of the pilot-house himself.

"Well she seems to run all right," observed Lieutenant Marbury,
as the big craft surged ahead just below a stratum of white,
fleecy clouds.

"Yes, but not as fast as I'd like to see her go, Tom replied.
"Of course the machinery is new, and it will take some little
time for it to wear down smooth. I'll speed her up a little now."

They had been running for perhaps ten minutes when Tom shoved
over the hand of an indicator that communicated with the engine-
room from the pilot-house. At once the Mars increased her speed.

"She can do it!" cried Ned.

"Bless my-hat! I should say so!" cried Mr. Damon, for he was
standing outside the pilot-house just then, on the "bridge," and
the sudden increase of speed lifted his hat from his head.

"There you are--caught on the fly!" cried Ned, as he put up his
hand just in time to catch the article in question.

"Thanks! Guess I'd better tie it fast," remarked the odd man,
putting his hat on tightly.

The aerial warship was put through several evolutions to test
her stability, and to each one she responded well, earning the
praise of the government officer. Up and down, to one side and
the other, around in big circles, and even reversing, Tom sent
his craft with a true hand and eye. In a speed test fifty-five
miles was registered against a slight wind, and the young
inventor said he knew he could do better than that as soon as
some of the machinery was running more smoothly.

"And now suppose we get ready for the gun tests," suggested
Tom, when they had been running for about an hour.

"That's what I'm mostly interested in," said Lieutenant
Marbury. "It's easy enough to get several good types of dirigible
balloons, but few of them will stand having a gun fired from
them, to say nothing of several guns."

"Well, I'm not making any rash promises," Tom went on, "but I
think we can turn the trick."

The armament of the Mars was located around the center cabin.
There were two large guns, fore and aft, throwing a four-inch
projectile, and two smaller calibered quick-firers on either
beam. The guns were mounted on pedestals that enabled the weapons
to fire in almost any direction, save straight up, and of course
the balloon bag being above them prevented this. However, there
was an arrangement whereby a small automatic quick-firer could be
sent up to a platform built on top of the gas envelope itself,
and a man stationed there could shoot at a rival airship directly

But the main deck guns could be elevated to an angle of nearly
forty-five degrees, so they could take care of nearly any hostile
aircraft that approached.

"But where are the bombs I heard you speaking of?" asked Ned,
as they finished looking at the guns.

"Here they are," spoke Tom, as he pointed to a space in the
middle of the main cabin floor. He lifted a brass plate, and
disclosed three holes, covered with a strong wire netting that
could be removed. "The bombs will be dropped through those
holes," explained the young inventor, "being released by a
magnetic control when the operator thinks he has reached a spot
over the enemy's city or fortification where the most damage will
be done. I'll show you how they work a little later. Now we'll
have a test of some of the guns."

Tom called for some of his men to take charge of the steering
and running of the Mars while he and Lieutenant Marbury prepared
to fire the two larger weapons. This was to be one of the most
important tests.

Service charges had been put in, though, of course, no
projectiles would be used, since they were then flying over a
large city not far from Shopton.

"We'll have to wait until we get out over the ocean to give a
complete test, with a bursting shell," Tom said.

He and Lieutenant Marbury were beside a gun, and were about to
fire it, when suddenly, from the stern of the ship, came a
ripping, tearing sound, and, at the same time, confused shouts
came from the crew's quarters.

"What is it?" cried Tom.

"One of the propellers!" was the answer. "It's split, and has
torn a big hole in the gas bag!"

"Bless my overshoes!" cried Mr. Damon. "We're going down!"

All on board the Mars became aware of a sudden sinking


"Steady, all!" came in even tones from Tom Swift. Not for an instant
had he lost his composure. For it was an accident, that much was certain,
and one that might endanger the lives of all on board.

Above the noise of the machinery in the motor room could be
heard the thrashing and banging of the broken or loose propeller-
blade. Just what its condition was, could not be told, as a bulge
of the gas bag hid it from the view of those gathered about the
gun, which was about to be fired when the alarm was given.

"We're sinking!" cried Mr. Damon. "We're going down, Tom!"

"That's nothing," was the cool answer. "It is only for a
moment. Only a few of the gas compartments can be torn. There
will soon enough additional gas in the others to lift us again."

And so it proved. The moment the pressure of the lifting gas in
the big oiled silk and aluminum container was lowered, it started
the generating machine, and enough extra gas was pumped into the
uninjured compartments to compensate for the loss.

"We're not falling so fast now," observed Ned.

"No, and we'll soon stop falling altogether," calmly declared
Tom. "Too bad this accident had to happen, though."

"It might have been much worse, my boy!" exclaimed the
lieutenant. "That's a great arrangement of yours--the automatic
gas machine."

"It's on the same principle as the air brakes of a trolley
car," explained Tom, when a look at the indicators showed that
the Mars had ceased falling and remained stationary in the air.
Tom had also sent a signal to the engine-room to shut off the
power, so that the two undamaged propellers, as well as the
broken one, ceased revolving.

"In a trolley car, you see," Tom went on, when the excitement
had calmed down, "as soon as the air pressure in the tanks gets
below a certain point, caused by using the air for a number of
applications of the brakes, it lets a magnetized bar fall, and
this establishes an electrical connection, starting the air pump.
The pump forces more air into the tanks until the pressure is
enough to throw the pump switch out of connection, when the pump
stops. I use the same thing here."

"And very clever it is," said Mr. Damon. "Do you suppose the
danger is all over, Tom?"

"For the time being, yes. But we must unship that damaged
propeller, and go on with the two."

The necessary orders were given, and several men from the
engine-room at once began the removal of the damaged blades.

As several spare ones were carried aboard one could be put on
in place of the broken one, had this been desired. But Tom
thought the accident a good chance to see how his craft would act
with only two-thirds of her motive force available, so he did not
order the damaged propeller replaced. When it was lowered to the
deck it was carefully examined.

"What made it break?" Ned wanted to know.

"That's a question I can't answer," Tom replied. "There may
have been a defect in the wood, but I had it all carefully
examined before I used it."

The propeller was one of the "built-up" type, with alternate
layers of ash and mahogany, but some powerful force had torn and
twisted the blades. The wood was splintered and split, and some
jagged pieces, flying off at a tangent, so great was the
centrifugal force, had torn holes in the strong gas bag.

"Did something hit it; or did it hit something?" asked Ned as
he saw Tom carefully examining the broken blades.

"Hard to say. I'll have a good look at this when we get back.
Just now I want to finish that gun test we didn't get a chance to

"You don't mean to say you're going to keep on, and with the
balloon damaged; are you?" cried Mr. Damon, in surprise.

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