Five Thousand Miles Underground; Or, the Mystery of the Centre of the Earth

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Title: Five Thousand Miles Underground; Or, the Mystery of the Centre of the Earth
Author: Rockwood, Roy
Language: English
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*** Start of this LibraryBlog Digital Book "Five Thousand Miles Underground; Or, the Mystery of the Centre of the Earth" ***

[Illustration: THE FLYING MERMAID SANK LOWER AND LOWER TOWARD THE
MYSTERIOUS HOLE.]

------------------------------------------------------------------------

Five Thousand Miles Underground

The Mystery of the Centre of the Earth

ROY ROCKWOOD

Author of “Through the Air to the North Pole,” “Under
the Ocean to the South Pole,” “The Rival
Ocean Divers,” Etc.

ILLUSTRATED

NEW YORK
CUPPLES & LEON COMPANY

------------------------------------------------------------------------

GOOD BOOKS FOR BOYS

By Roy Rockwood

THE GREAT MARVEL SERIES

THROUGH THE AIR TO THE NORTH POLE

UNDER THE OCEAN TO THE SOUTH POLE

FIVE THOUSAND MILES UNDERGROUND

Cloth. Illustrated
Price per volume, 60 cents

------------------------------------------------------------------------

Five Thousand Miles Underground

------------------------------------------------------------------------

CONTENTS

I WASHINGTON BACKS OUT
II THE FLYING MERMAID
III WASHINGTON DECIDES
IV WHAT DID MARK SEE?
V ATTACKED BY A WHALE
VI THE CYCLONE
VII A QUEER SAIL
VIII THE FLYING MERMAID DISABLED
IX THE MUTINY
X FOOLING THEIR ENEMIES
XI MYSTERIOUS HAPPENINGS
XII THE BIG HOLE
XIII DOWN INTO THE EARTH
XIV MANY MILES BELOW
XV IN THE STRANGE DRAUGHT
XVI THE NEW LAND
XVII A STRANGE COUNTRY
XVIII CAUGHT BY A STRANGE PLANT
XIX THE BIG PEACH
XX OVERHAULING THE SHIP
XXI THE FISH THAT WALKED
XXII THE SNAKE-TREE
XXIII THE DESERTED VILLAGE
XXIV THE GIANTS
XXV HELD BY THE ENEMY
XXVII A FRIEND INDEED
XXVII A GREAT JOURNEY
XXVIII THE TEMPLE OF TREASURE
XXIX BACK HOME—CONCLUSION

------------------------------------------------------------------------

FIVE THOUSAND MILES UNDERGROUND

CHAPTER I

WASHINGTON BACKS OUT

“Washington! I say Washington!”

Throughout a big shed, filled for the most part with huge pieces of
machinery, echoed the voice of Professor Amos Henderson. He did not look
up from a small engine over which he was bending.

“Washington! Where are you? Why don’t you answer me?”

From somewhere underneath an immense pile of iron, steel and aluminum
came the voice of a colored man.

“Yas sir, Perfesser, I’se goin’ t’ saggasiate my bodily presence in yo’
contiguous proximity an’ attend t’ yo’ immediate conglomerated
prescriptions at th’ predistined period. Yas, sir!”

“Well, Washington, if you had started when you began that long speech
you would have been at least half way here by this time. Hurry up! Never
mind tightning those bolts now. Find the boys. I need them to help me
with this engine. They must be around somewhere.”

“I seen ’em goin’ fishin’ down by th’ brook a little while ago,”
answered the negro, crawling out from under what seemed to be a combined
airship and watercraft. “Jack says as how yo’ gived him permission t’
occupy his indisputatious period of levity in endeavorin’ t’ extract
from th’ liquid element some specimens of swimmin’ creatures.”

“If you mean I said he and Mark could go fishing in the brook, you’re
right, Washington,” replied the professor with a smile. “But you waste a
lot of time and breath trying to say it. Why don’t you give up using big
words?”

“I reckon I was brought up t’ it,” replied the colored man grinning from
ear to ear. He did not always use big words but when he did they were
generally the wrong ones. Sometimes, he spoke quite correctly.

“Well, I suppose you can’t help it,” resumed Mr. Henderson. “However,
never mind that. Find the boys and send them to me.”

“With th’ least appreciatableness amount of postponement,” answered the
messenger, and he went out.

Washington White, who in color was just the opposite to his name, a
general helper and companion to Professor Henderson, found Mark Sampson
and Jack Darrow about a quarter of a mile from the big shed, which was
in the center of a wooded island off the coast of Maine. The lads were
seated on the bank of a small brook, fishing.

“Perfesser wants yo’ immediate,” said Washington.

“But we haven’t caught a single fish,” objected Mark.

“Them’s the orders from headquarters,” replied the colored man. “Yo’
both got t’ project yo’selves in th’ vicinity of th’ machine shop. I
reckon th’ new fangled contraption that th’ perfesser is goin’ t’
navigate th’ air an’ sail th’ angry seas in, am about done. He want’s t’
try th’ engine.”

“Come on then,” said Jack. “We probably would not catch any fish,
anyhow, Mark.”

Accompanied by Washington, the youths, each of whom was about eighteen
years old, started toward the big shed.

While they are on their way opportunity may be taken to tell a little
about them, as well as about Washington and the professor, and the
curious craft on which the scientist was working.

A few years before this story opens Mr. Henderson had invented a
wonderful electric airship. He had it about completed when, one day, he
and the two boys became unexpectedly acquainted, and, as it developed,
friends.

Mark and Jack were orphans. After having rather a hard time knocking
about the world trying to make a living, they chanced to meet, and
resolved to cast their lots together. They boarded a freight train, and,
as told in the first volume of this series, entitled, “Through the Air
to the North Pole; or the Wonderful Cruise of the Electric Monarch,” the
cars were wrecked near where Professor Henderson was building his
strange craft.

The boys were cared for by the scientist, and, after their recovery from
hurts received in the collision, they accepted his invitation to make
the trip through the upper regions in the airship, to search for the
north pole. With them went Andy Sudds, an old hunter, and Tom Smith and
Bill Jones, two farmers, but who were hired as helpers on the voyage.
The party had many adventures on the trip, having battles with savage
animals and more savage Esquimaux, and were tossed about in terrible
storms. After making some scientific observations, which the professor
was much interested in, they started back home.

Having found he could successfully sail in the air, Mr. Henderson
resolved to try what it might be like under water.

He moved his machine shop to a lonely spot on the Maine coast, and
there, with the help of the boys, Washington, Andy and two machinists
constructed a submarine boat, called the _Porpoise_.

In this the professor resolved to seek the south pole, he having a
theory that it was surrounded by an open sea. After much hard work the
_Porpoise_ was made ready for the voyage.

What occurred on this great trip is described in the second book of this
series, called “Under the Ocean to the South Pole, or the Strange Cruise
of the Submarine Wonder.” In that is told how once more Tom and Bill,
with Andy, the boys and Washington, accompanying Professor Henderson,
had many thrilling experiences.

They were caught in the grip of the grass of the terrible Sargasso Sea.
Monstrous suckers grasped the boat in their powerful arms, and had to be
fought off. They were caught in a sea of boiling water and imprisoned
between big fields of ice.

By means of strong diving suits they were able to leave the ship and
walk about on the bottom of the sea. They visited a graveyard of sunken
ships, saw many strange monsters as well as many beautiful fish in the
great depths to which they sunk. Many times they were in dire peril but
the resources of the professor, the bravery and daring of the boys, no
less than the help Washington and Andy Sudds, the hunter, rendered at
times, brought them through.

Those of you who read of their adventures will recall the strange island
which they came upon in the Atlantic Ocean, far from the coast of South
America.

When they first drew near this island they were almost sucked into the
depths of a great whirlpool, caused by water pouring down a big hole
that seemed to lead far into the earth. They reversed their ship just in
time.

But, on going to another side of the island they were able to approach
safely, as at this point the great hole was farther from the shore. Then
they landed and investigated.

They found the island was almost circular, and the hole was also round,
but not in the center of the land. It was an immense cavity, so wide
they could not see across, and as for the depth they could only guess at
it. Looking down they could only see rolling masses of vapor and clouds
caused by the water which poured down from the ocean with the force of a
Niagara.

Gazing down into the big hole Mark suggested it might lead to the centre
of the earth, which some scientists claim is hollow. The professor
admitted that the cavity looked as though it led to China.

They had no means of investigating further the mystery of the opening
and returned to their submarine, completing the voyage to the south
pole.

It was now about two years since they had come back from that eventful
trip. One of the first things the professor did, after docking the
_Porpoise_, was to shut himself up in his study and begin to draw plans.
To the questions of the boys he returned no answer for several days.
Then he announced he was working on a craft which could both sail on top
of the water and navigate the air.

In time the plans were done, and, in order to keep the work secret, the
shop was moved to an island which the professor owned.

Parts of the _Monarch_ and the _Porpoise_ were used in constructing the
new craft, so there was no need to get other help than that which the
boys, Washington and Bill and Tom could give, since the two latter
accepted an offer of the professor to remain and work for him. The boys,
of course, would not leave their friend.

The professor realized that he had a more difficult task in his new
venture than he had set himself on other occasions. For a ship to be
light enough to rise in the air, and, at another time, and with no
change, to be strong enough to navigate the ocean, was indeed something
to tax Mr. Henderson’s ingenuity.

However, in the course of a little over a year the larger part of the
work was done. Inside the big shed was the huge affair which, it was
hoped, would enable its owner to be master of both air and water.

“Did the professor say anything special?” asked Mark of Washington.

“Nope. I reckon he were too busy problamatin’ the exact altitude
projected in an inverse direction by th’ square root of th’ new engine
when operated at a million times inside of a few seconds, but he didn’t
say nothin’ t’ me. I were busy underneath th’ ship, fixin’ bolts when he
tole me t’ find yo’. I wouldn’t be s’prised if he had th’ thing goin’
soon.”

“Do you think he’ll be generating the new gas to-day?” asked Jack
eagerly. “That’s the most troublesome part; to get that gas right.”

“He didn’t say nothin’ t’ me 'bout it,” Washington stated, as he walked
along beside the two boys. “He jest seemed anxious like.”

“We’d better hurry,” advised Mark. “He may be at an important part in
his experiments and probably needs us. I hope it will work. He has spent
many days on it, and we all have worked hard. It ought to be a success.”

“Perfesser allers makes things work,” declared Washington stoutly.

“That’s a good way to feel about it, anyway,” observed Mark. “Well,
we’ll soon know.”

The three hurried to the shed which they could see as they rounded a
turn of the path through the wood. They noticed an elderly man
approaching with a gun on his shoulder. On one arm he carried a game
bag.

“Guess Andy got something for dinner,” remarked Jack.

“I hopes so, honey,” put in Washington. “I’se got a sort of gone feelin’
in my stomach!”

“Any luck, Andy?” called Mark, when he came within hailing distance.

“Fine,” replied Andy Sudds. “Rabbits and quail. We’ll have a good dinner
to-morrow.”

While Andy entered the living part of the big shed to put away his gun
and game, the boys and Washington kept on to the engine room. They found
the professor, with Bill and Tom, busy fitting pipes to the small engine
which was set up at one side of the structure.

“Come, boys, I need your aid,” remarked Mr. Henderson as they entered.
“Take off your coats and pitch in. Tighten up these bolts, Jack. Mark,
you mix up those chemicals the way I taught you, and see that the dynamo
is in working order for Washington to attend to.”

In a little while the shop was a veritable hive of industry, and it
resounded to the sound of hammers, wrenches and machinery. In the
background was the big ship, which seemed like two immense cigars, one
above the other, the lower one the larger.

“Where was you calalatin’ t’ take this here ship when it gits done,
Perfesser?” asked Washington, during a lull in the operations.

“Do you remember that big hole in the island we visited on our trip to
the south pole?”

“I suah does,” answered the colored man.

“We are going to explore that,” went on the scientist. “We are going to
make a voyage to the interior of the earth in our _Flying Mermaid_.”

“Go down into th’ earth!” exclaimed Washington, his eyes big with
fright.

“Certainly; why not?”

“Not for mine!” cried the colored man, dropping the wrench he was
holding. “No sir! I’m not goin’ t’ project myself int’ a grave while
I’se alive. Time enough when I kicks th’ bucket. No sir! If yo’ an’ the
boys wants t’ risk yo’ se’ves goin’ down int’ th’ interior of th’ earth,
where th’ Bible says there’s fiery furnaces, yo’ kin go, but Washington
White stays on terra cotta! That’s where he stays; He ain’t ready t’ be
buried, not jest yet!” and the frightened colored man started to leave
the shed.

CHAPTER II

THE FLYING MERMAID

“Here! Stop him!” cried Professor Henderson. “Don’t let him get away. We
still need his help to get the ship in shape. He needn’t be frightened.
We’re not going to start at once.”

Mark and Jack ran after Washington, whose progress was somewhat impeded
because he kept looking back as if he feared the new ship was chasing
him.

“Come on back!” said Mark. “There’s no danger, and if there was we’re
not going to start to-day.”

“Ain’t yo’ foolin’ me?” asked Washington, pausing and looking doubtfully
at the boys.

“Of course not,” answered Mark. “You know Professor Henderson would not
make you do anything you didn’t want to do, Wash. He wishes you to stay
and help him get ready, that’s all.”

“Well, Washington,” observed the aged scientist. “I didn’t think you’d
go back on me.”

“I’d do mos’ anything fer yo’, Perfesser,” said the colored man, “but I
got t’ beg off this time,” and he looked at the _Flying Mermaid_ as if
he thought the metal sides would open and devour him.

“Then help me get things in shape to generate the gas,” the scientist
said. “I want to give the new vapor the first real test in lifting power
to-day. On the success of it depends the future of the ship.”

Seeing there was no immediate danger of being carried to the centre of
the earth, Washington resumed his labors. The professor, the boys, Bill
and Tom were also hurrying matters to enable a test to be made before
night.

As will readily be seen, even by those not familiar with the
construction of airships and submarines, the chief problem was to find
some agent strong enough to lift from the earth a weight heavier than
had ever before been put into an apparatus that was destined to traverse
the clouds. For the _Flying Mermaid_ was not only an airship but an
ocean voyager as well. It had to be made light enough to be lifted far
above the earth, yet the very nature of it, necessitating it being made
heavy enough to stand the buffeting of the waves and the pressure of
water, was against its flying abilities.

Professor Henderson realized this and knew that the chief concern would
be to discover a gas or vapor with five times the lifting power of
hydrogen, one of the lightest gases known, and one sometimes used to
inflate balloons.

After long study he had been partially successful, but he knew from
experiments made that the gas he had so far been able to manufacture
would not answer. What he wanted was some element that could be mixed
with the gas, to neutralize the attraction of gravitation, or downward
pull of the earth.

While he was seeking this, and experimenting on many lines, the
construction of the air-water ship went on. In general the outward
construction was two cigar shaped hulls, one above the other. Aluminum,
being the lightest and strongest metal that could be used for the
purpose, formed the main part of both bodies.

The upper hull was one hundred feet long and twenty feet in diameter at
the widest part. It tapered to points at either end. It was attached to
the lower hull by strong braces, at either end, while from the center
there extended a pipe which connected with the lower section. This pipe
was intended to convey the lifting gas to the part which corresponded to
the bag of the balloon, save that it was of metal instead of silk, or
rubber as is usual.

There were two reasons for this. One was that it would not be liable to
puncture, particularly in the proposed underground trip, and the other
was that it did not have to be so large as a cloth bag would have had to
be. It was also a permanent part of the ship, and on a voyage where part
of the time the travelers would be in the air and part on the water, and
when the change from one to the other would have to be made quickly,
this was necessary. It would have taken too long to raise the ship in
the air had a cloth bag been used to contain the gas.

The lower hull or main part of the craft was one hundred and fifty feet
long, and forty feet through at the largest part, in the centre.

It was divided into four sections. The forward one contained the
sleeping quarters of Professor Henderson and his crew. There was a small
stateroom for each one. Above was a conning or observation tower,
reached by a small flight of steps. From this tower the ship could be
steered, stopped and started, as could also be done from the engine
room, which was in the after part of the hull.

As in the _Porpoise_ and _Monarch_, electricity formed the motive power
and was also used for many other purposes on board. Engines operated by
gas produced the current which heated, lighted and moved the ship, as
well as played a part in producing the wonderful gas.

The ship moved forward or backward by means of a novel arrangement. This
was by the power of compressed air. From either end of the lower hull
there projected a short pipe working in a ball and socket joint, so it
could be turned in any direction. By means of strong pumps a current of
compressed air could be sent out from either pipe. Thus when floating
above the earth the ship was forced forward by the blast of air rushing
from the pipe at the stern. It was the same principle as that on which a
sky rocket is shot heavenward, save that gases produced by the burning
of powder in the pasteboard rocket form its moving impulse.

In the case of the _Flying Mermaid_, it could be made to move backward
by sending the air out of the forward tube. Thus, when in the water, the
compressed air rushing from the pipe struck the fluid and forced the
ship forward or backward as was desired. It floated on the surface, the
deck being about three feet out of water, while the aluminum gas bag was
overhead.

The engine room was a marvel of machine construction. It contained pumps
for air and water, motors, dynamos, gas engines, and a maze of wheels
and levers. Yet everything was very compact and no room was wasted.

The use of the air method of propulsion did away with the necessity of a
large propellor such as most airships have to use, a propellor which
must of necessity be very light and which is easily broken.

Next to the engine room was the kitchen. It contained an electric range
and all necessary appliances and utensils for preparing meals. There
were lockers and a large reserve storeroom which when the time came
would be well stocked with food. Forward of the kitchen was the living
and dining room. It contained comfortable seats, folding tables and a
small library. Here, also were many instruments designed to show how the
various machines were working. There were gages, pointers and dials,
which told the direction the ship was traveling, the speed and the
distance above the earth or below the surface. Similar indicators were
in the conning tower, which had a powerful search light.

The ship was lighted throughout by incandescent lamps, and there was
even a small automatic piano worked by the electric current, on which
popular airs could be played.

If the gas and the gravity neutralizer worked as Professor Henderson
hoped they would, as soon as the ship was completed, all that would be
necessary to start on the voyage would be to fill the aluminum bag and
set the air compressor in motion.

The gas was made from common air, chemically treated and with a secret
material added which by means of a complicated machine in a measure did
away with the downward pull of the earth. Thus all that was necessary to
carry on a long voyage was a quantity of gasolene to operate the engine
which worked the electric machines, and some of this secret compound.

The professor and his helpers had been working to good advantage. At
last all was in readiness for the gas test.

It was proposed to try it on an experimental scale. Some of the fluid
was to be generated and forced into an aluminum cylinder under the same
pressure it would be used in the air ship. To this cylinder were
attached weights in proportion to the weight of the _Flying Mermaid_
with its load of human freight, engines and equipment.

“This cylinder is just one one-hundredth the size of the cylinder of the
ship,” said the professor. “I am going to fasten to it a hundred pound
weight. If it lifts that our latest contrivance will be a success.”

“You mean if the little cylinder pulls a hundred pounds up the big ship
will take us and the machinery up?” asked Mark.

“Certainly,” answered the professor. “If this cylinder lifts a hundred
pounds, one a hundred times as big (as that of the _Mermaid_ is), will
lift a hundred times as much, or ten thousand pounds. That is five tons,
or more than a ton over what I figure to be the weight of our ship and
contents. The latest war balloon can lift one ton with ease, and if my
machine can not do five times as well I shall be disappointed.”

The last adjustments were made, pipes were run from the gas generator to
the cylinder, and the hundred pound weight was attached.

“Everybody look out now,” said Mr. Henderson. “I am going to start the
machine and let the gas enter the cylinder. It is a very powerful gas
and may break the cylinder. If it does you must all duck.”

The scientist gave a last look at everything. The boys got behind some
boards whence they could see without being in danger. Washington, who
had little fear so long as there was no danger of going under ground,
took his place at the dynamo. Andy Sudds, with Bill and Tom, stationed
themselves in safe places.

“All ready!” called the professor.

He pulled a lever toward him, turned a wheel and signalled to Washington
to start the dynamo. There was a sound of buzzing machinery, which was
followed by a hiss as the gas began to enter the cylinder under
pressure. Would it stand the strain? That question was uppermost in
every one’s mind save the professor’s. He only cared to see the cylinder
leave the ground, carrying the weight with it. That would prove his long
labors were crowned with success.

Faster and faster whirred the dynamo. The gas was being generated from
the air. The secret chemical made a hissing which could be heard for
some distance. The gage registered a heavy pressure. Anxiously the
professor watched the cylinder.

“There!” he exclaimed at length. “It has all the gas it can hold. Now to
see if it works!”

He disconnected the pipe leading from the generator. This left the
cylinder free. It seemed to tremble slightly. There appeared to be a
movement to the hundred pound weight which rested on the ground. It was
as if it was tugging to get loose.

“There it goes! There it goes!” cried Mark, joyfully.

“Hurrah!” shouted Jack. “There she rises!”

“It suttinly am projectin’ itself skyward!” yelled Washington, coming
from the dynamo.

Sure enough the cylinder was slowly rising in the air, bearing the
weight with it. It had lifted it clear from the ground and was
approaching the roof of the big shed.

“It will work! It will work!” exclaimed the professor, strangely
excited.

The next instant the cylinder, carrying the weight, sailed right out of
an open skylight, and began drifting outside the shop, and across the
fields.

“Quick! We must get it back!” cried Mr. Henderson. “If it gets away my
secret may be discovered and I will lose all! We must secure it!”

But the cylinder was now two hundred feet in the air and being blown to
the east, the weight dangling below it, making it look like a miniature
airship.

“We can never catch that!” cried Mark.

CHAPTER III

WASHINGTON DECIDES

“We must catch that cylinder!” the professor exclaimed. “Some one may
find it when it comes down and analyze the gas. Then he would discover
how to make it. The cylinder must come down!”

“Don’t see how we can proximate ourselves inter th’ vicinity of it
lessen we delegate th’ imperial functions of ornithological specimens t’
some member of this here party,” observed Washington.

“If you mean we can’t catch that there contraption unless we turn into
birds I’ll show you that you’re mistaken!” cried Andy Sudds. “I guess I
have a trick or two up my sleeve,” and the old hunter quickly threw open
the breech of his gun and inserted a couple of cartridges.

He raised the piece to his shoulder and took quick aim. There was a
sliver of flame, a puff of smoke and a sharp report. The professor and
the boys who were watching the cylinder saw it vibrate up in the air.
Then there came a whistling sound. An instant later the metal body began
to descend, and it and the weight fell to the earth.

“I’m sorry I had to put a bullet through it, Professor,” said old Andy
with a queer smile, “but it was the only way I saw of bringing it down.
Hope it isn’t damaged much.”

“It doesn’t matter if it is,” the scientist answered. “I can make more
cylinders, but I don’t want that secret of the gas to become known. Your
bullet served a good turn, Andy, for it let the compressed vapor out
just in time.”

“Then we may consider the experiment a success,” said Mark, as
Washington went to where the cylinder had fallen, to detach it from the
weight and bring both to the shed.

“It seems so,” Mr. Henderson answered. “True, it was only an experiment.
We have yet to test the ship itself.”

“When can we do that?” asked Jack.

“I hope by Monday,” the scientist answered.

“Will you try it in the water or air first?” asked Mark.

“I’m almost certain it will float in the water,” the aged inventor said.
“It does not require much work to make a ship which will do that. But
the air proposition is another matter. However, since the cylinder rose,
I am pretty sure the _Flying Mermaid_ will.

“But we have done enough work to-day. Let’s rest and have something to
eat. Then, with Sunday to sit around and talk matters over, we will be
ready for Monday’s test.”

Some of the game Andy had killed was soon on the table, for Washington,
in addition to his other accomplishments, was an expert cook. During the
evening the boys and their friends sat in the living room of the big
shed and talked over the events of the day.

Sunday was spent in discussing what adventures might lie before them
should they be able to descend into the big hole. Washington did not say
much, but it was easy to see he had no notion of going. He even began to
pack his few belongings in readiness to leave the service of Mr.
Henderson, for whom he had worked a good many years.

No one remained long abed Monday morning. Even Washington was up early
in spite of the interest he had lost in the professor’s voyage.

“I jest wants t’ see yo’ start fer that place where they buries live
folks,” he said.

In order to properly test the _Flying Mermaid_ it was necessary to move
the craft from the shed from which place it had never been taken since
it’s construction was started. It had been built on big rollers in
anticipation of this need, so that all which was now necessary was to
open the doors at the end, and roll the craft out.

This was accomplished with no small amount of labor, and it was nearly
noon before the big ship was moved into the open. It was shoved along to
a little clearing in front of the shed, where no trees would interfere
with its possible upward movement.

Everyone was bustling about. The professor was busiest of all. He went
from one machine to another; from this apparatus to that, testing here,
turning wheels there, adjusting valves and seeing that all was in
readiness for the generating of the powerful gas.

As the airship was half round on the bottom and as it rested in a sort
of semi-circular cradle; it brought the entrance some distance above the
ground. To make it easier to get in and out while preparations for the
trial were going on, Bill and Tom had made an improvised pair of steps,
which were tied to the side of the ship with ropes.

Up and down these the professor, the boys and Andy went, taking in tools
and materials, and removing considerable refuse which had accumulated
during the building of the craft.

Finally all was in readiness for starting the making of the gas. The
ship was not wholly complete and no supplies or provisions for the long
voyage had been taken aboard. The _Flying Mermaid_ was about a ton
lighter than it would be when fully fitted out, but to make up for this
the professor had left in the ship a lot of tools and surplus machinery
so that the craft held as much weight as it would under normal
conditions. If the gas lifted it now it would at any other time.

“Start the generator,” said Mr. Henderson, to Mark. “We’ll soon see
whether we are going to succeed or fail.”

The boy turned a number of levers and wheels. The machine which made the
powerful vapor was soon in operation. The professor had already added
enough of the secret compound to the tank containing the other
ingredients, and the big pump was sucking in air to be transformed into
the lifting gas.

The boys and the professor were in the engine room. Andy Sudds, with
Bill and Tom, had taken their places in the living room, to more evenly
balance the ship, since the things in it were not yet all in their
proper places. As for Washington he was busy running from the shed to
the ship with various tools and bits of machinery the professor desired.

The gas was being generated rapidly. Throughout the ship there resounded
a hissing noise that told it was being forced through the pipe into the
aluminum shell above the ship proper.

“I wonder how soon it will begin to lift us,” said Mark.

“It will take about half an hour,” replied Mr. Henderson. “You see we
have first to fill the holder completely, since there is no gas in it.
After this we will keep some on hand, so that it will only need the
addition of a small quantity to enable the ship to rise.”

He was busy watching the pointer on a dial which indicated the pressure
of the gas, and the lifting force. The boys were kept busy making
adjustments to the machinery and oiling bearings.

Suddenly, throughout the length of the craft there was felt a curious
trembling. It was as though the screw of a powerful steamer was
revolving in the water.

“What is it?” asked Jack.

“I hope it is the lifting power of the gas making itself felt,” the
professor answered. “Perhaps the _Flying Mermaid_ is getting ready to
try her wings.”

The trembling became more pronounced. The gas was being generated faster
than ever. The whole ship was trembling. Tom and Bill came from the
room, where they were stationed, to inquire the meaning, but were
reassured by the professor.

“Don’t be alarmed if you find yourselves up in the air pretty soon,” he
remarked with a smile. “Remember the _Electric Monarch_, and the flights
she took. We may not go as high as we did in her, but it will answer the
same purpose.”

The gas was hissing through the big tube as it rushed into the overhead
holder. The gage indicated a heavy pressure. The ship began to tremble
more violently and to sway slightly from side to side.

“I think we shall rise presently,” said Mr. Henderson. His voice showed
the pride he felt at the seeming success with which his invention was
about to meet.

Suddenly, with a little jerk, as though some one with a giant hand had
plucked the _Flying Mermaid_ from the earth, the ship gave a little
bound into the air, and was floating free.

“Here we go!” cried Mr. Henderson. “The ship is a success. Now we’re off
for the hole in the earth!”

The _Flying Mermaid_ was indeed rising in the air. True it did not go up
so swiftly as had the _Monarch_, but then it was a much heavier and
stronger vessel, and flying was only one of its accomplishments.

“It’s a success! It’s a success!” shouted Mark, capering about in his
excitement.

“Now we’ll see what the centre of the earth looks like,” went on Jack.
“I can hardly wait for the time to come when we are to start on the
voyage.”

At that instant, when the ship was but a few feet from the ground, but
slowly rising, the boys and the professor heard a shouting below them.

“What’s that?” asked the scientist. “Is any one hurt?”

Mark ran to a small window, something like a port hole in an ocean
steamer, and looked out.

“Quick!” he shouted. “Stop the ship! Washington will be killed!”

In fact from the agonized yells which proceeded from somewhere under the
craft it seemed that the accident was in process of happening.

“Save me! Save me!” cried the colored man. “I’m goin’ to fall! Catch me,
some one!”

“What is it?” asked the professor, making ready to shut off the power
and let the ship settle back to earth, from which it had moved about
fifty feet.

“It’s Washington,” explained Mark. “He evidently tried to walk up the
steps just as the boat mounted skyward. He rolled down and managed to
grab the end of the rope which was left over after the steps were tied.
Now he’s swinging down there.”

“Are you going to lower the ship?” asked Jack.

“Of course!” exclaimed the professor. “I only hope he hangs on until his
feet touch the earth.”

“Keep a tight hold!” shouted Mark, from out of the small window.

“That’s th’ truest thing yo’ ever said!” exclaimed Washington. “You bet
I’m goin’ to hold on, and I’m comin’ up too,” which he proceeded to do,
hand over hand, like a sailor.

The boys and the professor watched the colored man’s upward progress.
The ship had hardly begun to settle as, in the excitement, not enough
gas had been let out. Closer and closer came Washington, until he was
able to grasp the edge of the opening, to which the steps were fastened.

“I thought you weren’t coming with us,” observed the professor, when he
saw that his helper was safe.

“I changed my mind,” said the colored man. “It’s jest luck. Seems like
th’ ship done wanted me t’ go 'long, an’ I’m goin’. I’ll take my chances
on bein’ buried alive. I ain’t never seen th’ centre of th’ earth, an’ I
want’s to 'fore I die. I’m goin’ 'long, Perfessor!”

CHAPTER IV

WHAT DID MARK SEE?

“Well, I’m glad you’ve decided at last,” the professor remarked. “Now
come inside and we’ll see how the ship works.”

Once over his fright, Washington made himself at home on the craft he
had helped build. He went from one room to another and observed the
engine.

“She certainly am workin’” he observed with pride. “Are we still goin’
up, Perfessor?”

“Still mounting,” replied Mr. Henderson. “We are now three hundred feet
above the earth,” he added as he glanced at a registering gage.

The great air pump was set going and soon from the after tube, a big
stream of the compressed vapor rushed. It acted on the ship instantly
and sent the craft ahead at a rapid rate. By elevating or depressing the
tube the craft could be sent obliquely up or down. Then, by forcing the
air from the forward tube, the _Mermaid_ was reversed and scudded
backward.

But it was more with the ship’s ability to rise and descend that
Professor Henderson was concerned, since on that depended their safety.
So various tests were made, in generating the gas and using the negative
gravity apparatus.

All worked to perfection. Obeying the slightest turn of the wheels and
levers the _Mermaid_ rose or fell. She stood still, suspended herself in
the air, or rushed backward and forward.

Of course the machinery was new and did not operate as smoothly as it
would later, but the professor and his friends were very well satisfied.

“Now we’ll try something new,” said the scientist to the two boys as
they stood beside him in the tower. “I only hope this part succeeds, and
we shall soon be off on our voyage.”

He turned several levers. There was a hissing sound as the gas rushed
from the container, and the ship began to settle down.

“What’s th’ matter? Are we goin’ t’ hit th’ earth?” yelled Washington,
rushing from the engine room.

“Keep quiet,” ordered the professor. “We are only going down, that’s
all.”

“But good land! Perfesser!” exclaimed the colored man. “The ocean’s
right under us! You forgot you sailed away from the island! We’ll be
drowned suah!”

“Leave it to me,” said Mr. Henderson. “The _Flying Mermaid_ is going to
take a bath!”

“As long as it swims it will be all right,” observed Mark in a low tone
to Jack. “I’m glad I can take care of myself in the water.”

Before Jack could reply the _Mermaid_ seemed to take a sudden dive
through the air. The next instant she struck the water with a splash
that sent the waves rolling all about. The craft rocked violently to and
fro on the surface of the sea. For a while there were anxious hearts
aboard, for there was no certainty but that the ship might not sink to
the bottom.

But the old professor had not calculated and builded in vain. After
rocking about like a vessel newly launched, the strange craft rode
safely and upright on the water. It set down far enough to bring the
propelling tubes well under, but not so far but that the conning tower
was well out and there was a small deck available.

“Now to see if we can conquer the water as we did the air!” cried the
professor. “Mark, start the air pump. Jack, you steer, for I want to
watch the machinery under the additional strain.”

From the rear tube rushed such a volume of air that the ocean near it
bubbled and foamed. The ship trembled from stem to stern, and then,
after hanging for an instant as if undecided what to do, it began to
move forward as easily as though it had never sailed any other element
than the sea.

“She fits her name!” the professor cried. “She is indeed the _Flying
Mermaid_, for she sails the ocean as easily as she navigates in the
clouds!”

For a mile or two the craft was sent ahead over the waves. Then it was
reversed and run backwards. Satisfied that his long months of work had
not gone for naught, the professor after trying several experiments,
decided to try and raise the ship while in motion.

With Jack and Mark to look after the air pumps, while Washington, Tom
and Bill busied themselves in the engine room, Mr. Henderson began to
generate the gas and start the negative gravity apparatus. All the while
the craft was forging ahead.

There was again the hissing sound that told of the aluminum holder being
filled. For a few minutes there seemed to be no change, the _Mermaid_
plowing forward.

Then like a bird rising from the waves, or like a flying fish leaping
from the sea to escape some pursuing monster of the deep, the new ship
shot up diagonally from the surface and winged its way into the upper
regions of the air.

“Success! Success!” cried the professor. “This proves all I wanted to
know. Now we are ready for our great trip!”

Great were the rejoicings in the camp that night. It was like living
over again the days when they were aboard the diving _Porpoise_ or the
flying _Monarch_. To the recollections were added the anticipations of
what was before them in the trip to the interior of the earth.

Busy days followed, for there was still much to be done to the _Flying
Mermaid_. The machinery, which was only partly completed, had to be
finished. Besides this the professor was working on some apparatus, the
use of which he did not disclose to any one. It was stored aboard the
ship at the last minute.

Plenty of provisions had to be taken aboard, and many supplies needed to
work the _Mermaid_ and insure that it would go to the end of the voyage.
The materials for generating the gas and negative gravity, spare parts,
records for the automatic piano and other things were stored away.

Some guns and ammunition were taken along as were a few revolvers, since
old Andy had said it was best to prepare for any thing in the shape of
enemies or wild beasts that might be met with in the interior regions.

It was decided to make the start by sailing along the surface of the sea
for several days, as in the event of any weakness in the machinery being
discovered there would be less danger. If, at the end of four days, no
trouble developed, the professor said he would send the _Mermaid_ into
the air and make the rest of the voyage through the sky.

The night before the start was to be made the professor, with the boys,
Washington and the other helpers, went about through the various shops
and buildings, locking them up securely. For they could not tell how
long they would be away, and they had to leave behind much valuable
material.

As there were several things that needed attention they divided the work
up. Mark had finished his share and was walking back toward the living
cabin where they were all quartered, when, down at the shore, near where
the boat was moored, he fancied he saw, in the gathering darkness, a
moving figure.

“I wonder who that can be,” he thought. “All the others are near the
machine shop, for I just left them there. Perhaps it’s some one trying
to spy out how the _Mermaid_ is built.”

Knowing the professor wanted his secret well guarded, Mark walked softly
toward the little dock that served as a place whence the _Mermaid_ could
be easily boarded. As he approached he saw the figure moving. Something
struck the boy as peculiar.

Though the object had some of the characteristics of a man it did not
walk like a human being, but shuffled along more like a huge ape or
monkey. It seemed bent over, as if it stooped toward the ground.

“Who are you?” called Mark suddenly.

For an instant the figure halted and then hurried on faster than before,
with a curious, shuffling walk. It was approaching the ship.

Somehow it struck Mark as if it was an uncanny being; an inhabitant of
some other world. Then he laughed at his half-fear, and started on a run
toward the dock.

“If it’s some tramp trying to find a place to sleep he’d better not go
aboard the ship, he might do some damage,” the boy thought.

He could hardly see the figure now as it had passed into the shadow cast
by the boat. He was about to summon the professor to make an
investigation, when Washington started going the search light which was
placed just over the door of the living cabin. It was kept there as a
sort of beacon light, as, near the island was a dangerous ledge of
rocks.

Then, in the blinding white glare from the big lantern as Washington
accidentally swung it toward the _Mermaid_, Mark beheld a strange sight.

The figure he had been watching stood out in bold relief. Though it was
shaped like a human being it was not like any person the boy had ever
seen. It seemed covered with a skin twice too large for it; a skin,
which, in spite of the clothes that concealed it, hung in folds about
the arms and legs, dropping pendent like from the neck like a big
garment, and flapping in the wind.

For an instant Mark was so startled he cried out, and the professor and
the others ran to see what was the matter.

“There—by the ship! A horrible creature!” exclaimed Mark.

Shouting to Washington to keep the light steady in the direction of the
dock, Mr. Henderson ran toward the moored _Mermaid_. Jack, Andy, Bill
and Tom, with Mark in the rear followed him.

“Nothing here,” said the scientist, after a careful search about. “Are
you sure you saw something, Mark?”

“Positively,” replied the lad with a shudder. He described the vision of
the darkness.

“I guess it was a big otter, or maybe an enormous turtle,” the professor
said.

CHAPTER V

ATTACKED BY A WHALE

But Mark was certain it was nothing like that, though a careful search
failed to reveal anything or any person near the ship. It was too dark
to examine for footprints, and even Mark, after taking a look all about,
felt he might have been deceived by shadows. Still he was a little
nervous, and could hardly sleep for imagining what the thing he saw
could have been.

The next day every one was so busy that no one, not even Mark, recalled
the little excitement of the night before. Shortly after noon, final
preparations having been made, they all got aboard the _Mermaid_ and
started off.

It was a bright sunshiny day, and the craft, speeding away from the
island where it had been constructed, over the dancing blue waves, must
have presented a strange sight had there been any spectators. For surely
no such ship had ever before sailed those waters.

However, there was no other vessel in sight, and the island, as far as
the professor and his friends knew, had never been inhabited.

“We will not try for any great speed,” Mr. Henderson remarked as he,
with Mark and Jack, stood in the conning tower managing the _Mermaid_.
“We don’t want to strain any joints at the start or heat any engine
bearings. There will be time enough for speed later.”

“Yes, and we may need it more when we get into the centre of the earth
than we do now,” observed Mark.

“Why so?” asked Jack.

“No telling what we may run up against underneath the ground,” went on
Mark. “We may have to fight strange animals and stranger beings.
Besides, the atmosphere and water there can’t be the same as up here; do
you think so, Professor?”

For a few minutes the scientist was silent. He seemed to be thinking
deeply.

“I will tell you what I believe,” he said at length. “I have never
spoken of it before, but now that we are fairly started and may
eventually have a chance to prove my theory, I will say that I think the
centre of this earth on which we live is hollow. Inside of it, forming a
core, so to speak, I believe there is another earth, similar to ours in
some respects which revolves inside this larger sphere.”

They were well out to sea now, as they could observe when they emerged
on the little deck. Above their heads was the aluminum gas holder, which
served as a sort of protection from the sun that was quite warm. The
_Mermaid_ rode with an easy motion, being submerged just enough to make
her steady, yet not deep enough to encounter much resistance from the
water. In fact it could not have been arranged better for speed or
comfort.

“I think we will sail well to the eastward before making our course
south,” Mr. Henderson said. “I do not care to meet too many ships, as
those aboard will be very curious and I do not want too much news of
this venture to get out. We will take an unfrequented route and avoid
delays by being hailed by every passing vessel whose captain will wonder
what queer craft he had met with.”

The boys enjoyed the sail, for the weather could not have been better.
Even old Andy, who seldom said much, seemed delighted with the prospect
of having strange adventures. He had his rifle with him, and, indeed, he
seldom went anywhere that he did not carry it.

“For there’s no telling when you may see something you want to shoot or
that ought to be shot,” he used to say, “and it’s always the man without
a gun who needs it most. So I’m taking no chances.”

They sailed all that afternoon without meeting with a craft of any kind.
Straight to the east they went, and when night began to settle down
Washington got supper. It was decided to run slowly after dark until all
hands were more familiar with the ship.

Morning found the _Mermaid_ about a hundred miles from the island where
she had been launched. The night had been uneventful, except that Mark
told Jack he heard some strange noise near his bunk several times. He
was nearest the storeroom where spare parts, and the curious cylinder
the professor had brought aboard, were kept.

“I guess it was rats,” said Jack. “They are always in ships.”

“Old wooden ships, yes,” admitted Mark. “But I’ll bet there’s not a rat
aboard the _Mermaid_.”

“Then you were dreaming,” said Jack, as if that settled it.

Mark did not speak further of the noise, but he did considerable
thinking. However, the next night there was no further disturbance.

The fourth day out, when everything had passed off well, the engines
doing their best, the professor decided to speed them up a bit, since he
was satisfied they had “found” themselves as mechanics term it.

“We’ll see how fast we can go through the water,” said Mr. Henderson,
“and then I think we can safely turn our course south. We are well
beyond the ordinary lines of travel now.”

Having oiled the bearings well, and seen that everything was in place
and properly adjusted, the professor and the boys took their places in
the conning tower, while Washington, Tom and Bill remained in the engine
room. Andy stayed on deck with his gun.

“I might see a big fish, and we could vary our bill of fare,” he said
with a laugh.

“Here we go!” exclaimed the professor as he shifted the levers and
turned some wheels and valves. “Now we’ll see how fast we can travel.”

As he spoke the _Mermaid_ responded to the added impulse of the
compressed air and shot through the water at a terrific speed. The
sudden increase in momentum almost threw the boys from their feet, and
they would have fallen had they not grasped some projecting levers.

“I guess that will do,” said the scientist. “I think we have speed
enough for almost any emergency. I’ll let her run at this rate for a
while, and then we’ll slack up.”

Looking ahead, the boys could see the green waters parting in front of
the bow of the _Mermaid_, as if to make room for her. Two huge waves
were thrown upon either side.

Suddenly, dead ahead, there loomed up a big black object.

“Look out you’ll hit the rock!” cried Mark to the professor, who was
steering.

With a turn of his wrist Mr. Henderson moved the wheel which controlled
the tube. It was deflected and sent the boat to larboard.

At that instant from the rock two small fountains of water rose in the
air, falling back in a shower of spray through which the sun gleamed.

“That’s not a rock! It’s a big whale!” cried Jack. “And we’re going to
hit him!”

The professor had miscalculated the speed of the craft, or else had not
thrown her far enough to larboard, for, a second later, the _Mermaid_
was almost upon the big leviathan.

With a desperate twirling of the steering wheel the professor veered the
craft as far as possible. But all he could do did not suffice, for the
craft hit the whale a glancing blow on the side, and the ship careened
as if she would turn turtle.

At the same time there rang out from upon deck the sound of a rifle
shot. Old Andy had taken a chance at the enormous creature of the deep.

“Hurrah!” the boys heard him shout. “I give him one plumb in the eye! A
fine shot! And we hit him besides with the boat. I guess he’s a goner!”

“I’m afraid not,” muttered the professor. “That was a bad blow we struck
him, but I think it will only ruffle his temper. We’ll have to look
sharp now, boys.”

By this time the ship had rushed past the whale, but the boys, looking
through a window in the rear of the tower could see the huge body. Now
the fountains of water which the whale spouted were tinged with red.

“He’s bleeding!” exclaimed the professor. “I guess Andy hit him in a
vital spot.”

“But not vital enough!” cried Mark. “See! He’s coming after us!”

And so it proved. The whale, angered, and, probably half crazed by the
pain of the bullet and the blow, was coursing after the ship, coming on
with the speed of an express train. Straight at the _Mermaid_ he lunged
his huge bulk.

“We must escape him!” cried Mr. Henderson. “If he hits us he’ll send us
to the bottom!”

He had made ready to slow up the _Mermaid_ to see if it had sustained
any damage from the impact with the whale, but when he saw the monster
coming after the boat he knew the only safety lay in flight.

“Let us go up into the air and so escape him!” cried Jack, with sudden
inspiration.

For an instant neither Mark nor the professor grasped what Jack meant.
Then, with an exclamation, the professor pulled forward the lever that
generated the gas and set working the gravity neutralizer, which would
enable the ship to rise.

Faster through the water went the _Mermaid_, and faster after her came
the whale. Above the hum of the engines was heard the hiss of the
powerful gas. The ship trembled more violently.

“We are rising!” exclaimed the professor, as he looked at a gage.

The boys could feel the craft lifting from the waves which clung to her
as if they hated to lose her. The boys knew the gas was beginning to
operate.

“If it is not too late!” whispered Mark, half to himself.

For the monster of the seas was coming on, lashing the water to foam
with his terrible flukes, and sending aloft a bloody spray. His speed
was awful.

Now he was but ten feet away from the fleeing craft—now but eight—now
five! Ten seconds more and the big head, like the blunt stern of a
battle ship, forced forward by the tons of blubber, flesh, bone and fat
behind it would strike the _Mermaid_ and crush it like an egg shell.

Now if ever was the need for the _Flying Mermaid_ to prove herself
worthy of the name. Now, if ever, was the time for her to leave the
watery element and take to the lighter one.

And she did. With a last tremble, as if to free herself from the hold of
the waves, the gallant craft soared up into the air, leaving the water,
which dripped from her keel like a fountain’s spray, and shooting aloft
like a bird, escaped her terrible enemy which passed under her, so close
that the lower part of the _Flying Mermaid_ scraped the whale’s back.

“Saved!” exclaimed the professor.

[Illustration: THE LOWER PART OF THE FLYING MERMAID SCRAPED THE WHALE’S
BACK.]

CHAPTER VI

THE CYCLONE

It was only in the nick of time, for a second later and the big mammal
of the ocean would have struck the ship and split it from stem to stern.

Higher and higher into the air mounted the _Flying Mermaid_, while in
the water below, the whale, incensed by missing his prey, was lashing
the waves to foam.

“Well, that was a narrow squeak; as close as I ever care to come to it!”
exclaimed Andy as he let go of the steel rail to which he was clinging
and entered the conning tower. “I had no idea of hitting the big fish.”

“I guess he would have taken after us whether you had fired at him or
not,” said Mr. Henderson. “He was probably looking for trouble, and took
the first thing that came in his way, which happened to be us. Some
whales are like that, so I have read; big bull creatures, exiled from
the school to which they once belonged, they get like mad creatures and
know neither friend nor foe. Something like rogue elephants, I imagine.”

Now, having thus unexpectedly risen into the air, the professor decided
to continue travel in that style for a while at least. It would require
less force to propel the ship, and the going would be more comfortable,
since in the upper regions the _Mermaid_ rode on an even keel, while in
the water there was more or less rolling, due to the action of the
waves.

Once recovered from their fright caused by the whale, and having lost
sight of the enormous creature, for they were now far above the ocean,
the adventurers began to think of something to eat.

Washington lost little time in preparing a meal, and it was eaten with a
relish. The electric cooking stove worked to perfection, for the colored
man had learned how to use that aboard the _Porpoise_ and _Monarch_, and
could be depended on to turn out appetizing dishes.

“What do you say to traveling through the air at night?” asked Mr.
Henderson, as he arose from the table.

“Suits me,” replied Mark. “There’s less danger than in the water, I
think.”

Bill, Tom and Washington arranged to stand the night watch, and, when
the professor had examined the engines and given orders about keeping
the ship on her course through the air, he retired to his bunk. Jack and
Mark soon followed.

It must have been about midnight when Mark was awakened by a movement
that seemed to come from the storeroom next to where his sleeping place
was located. At first he thought he had been dreaming, but, as he found
he was wide awake, he knew it was no imagination that had affected him.

“I certainly heard something,” he said to himself. “It sounded just as
it did the other night. I wonder if I ought to investigate.”

He thought over the matter carefully as he sat upright in his bunk in
the darkness. True the noise might be a natural one, due to the
vibration of the engine, or to some echo from the machinery. As Mark
listened he heard it again.

This time he realized it was the slow movement of some heavy body. He
felt a cold shiver run over him and his hair evinced an uncomfortable
tendency to stand upright. But he conquered his feelings and resolved to
keep cool and see if he could discover what had awakened him.

He got up and moved softly about the little room that contained his
bunk. He could hear better now, and knew it was no echo or vibration
that had come to his ears.

Once again he heard the strange sound. It was exactly the same as
before; as if some big creature was pulling itself over the floor.

“Maybe it’s a snake; a water snake!” thought Mark. “It may have crawled
aboard when we did not notice it.”

Then he remembered that the ship had not been open in any way that would
enable a serpent to come on it, since it had been started on its ocean
trip. Before that, he was sure no snake had entered the _Flying
Mermaid_. Still it sounded more like a snake than anything else.

“I’m going to make a search,” decided the boy.

He took a small portable electric light, run by a storage battery, and,
slipping on a pair of shoes and a bath robe, he left his stateroom.

He had decided that the noise came from the storage compartment and so
made for that. The door he knew was not locked, since he had seen Mr.
Henderson go in late that afternoon, and the professor had used no key.

Moving softly, Mark left his room and soon found himself in a corridor,
on either side of which were located the sleeping quarters of the
others. He did not want to awaken them, and, perhaps, be laughed at for
his curiosity.

To get to the storeroom Mark had to go first from the corridor into the
dining room. He soon reached the door that guarded what he thought might
be a strange secret. Trying the knob softly he found it giving under his
fingers.

“I wonder if I had better go in,” he thought. “Perhaps, after all, it
was only rats, as Jack said.”

But, even as he listened he again heard the odd sound coming from the
room. This determined him. He would solve the mystery if possible.

Cautiously he turned the knob. The door was slowly swinging open when
Mark was startled by a noise from behind him. He turned suddenly to see
Professor Henderson confronting him.

“What is it, Mark? Is the ship on fire? What’s the matter? Is any one
hurt?”

“I was just going in this room to——” began Mark.

“Don’t do it! Don’t do it!” exclaimed the professor in an excited
whisper. “No one must go in that room. I forgot to tell you and Jack
about it. No one must enter. It contains a secret!”

“I heard a strange noise and——” Mark began again.

“It could make no noise! It would be impossible for it to make a noise!”
the professor exclaimed.

“I heard something,” the boy insisted.

“You were dreaming!” said the professor. “Now go back to bed, Mark, and
don’t let this happen again. Remember, no one must enter that room
unless I give permission!”

Somewhat crestfallen at the outcome of his investigations, but realizing
that the professor could do what he wanted to aboard his own ship, Mark
went back to bed. But he could not sleep. All the rest of the night he
was wondering whether Mr. Henderson had some strange creature hidden
aboard the _Mermaid_. He feared lest the old scientist’s mind might be
affected and, in his wildness he had made some infernal machine that
would, in time, blow the whole ship apart.

But tired nature asserted itself at last, and, weary with vain
imaginings, Mark fell into a slumber. The next morning he awoke with a
start from a dream that he was being devoured by an immense water snake.

He said nothing to the others about his night’s adventure, for, as it
transpired, no one else had been awakened by his investigations. The
professor did not refer to his conversation with Mark.

“There’s something queer going on aboard the ship this trip,” said Mark
to himself. “But I guess it’s none of my business. Professor Henderson
seems to know what he is doing and I guess I can trust him.”

He resolved to think no more of the strange noises and movements, and,
for several nights thereafter he was not disturbed by them.

The weather, which, up to this time had been fair, took a sudden turn
for the worse about the fourth day after Mark’s little night expedition.
One evening the sun sank in a mass of dull lead-colored clouds and a
sharp wind sprang up.

“We’re going to have a storm,” said Mr. Henderson. “It’s liable to be a
bad one, too, from the way the barometer is falling.”

He looked at the glass, and scanned the various instruments that told
how high up the _Mermaid_ was and how fast she was traveling.

“We’re pretty high up in the air,” he said, “and scooting along at about
fifty miles an hour. We are going against the wind, too, but fortunately
it is not blowing hard.”

At that moment there sounded from without a peculiar howling sound, as
if a siren whistle was being blown.

“'Pears like there’s goin’ t’ be a tumultuous demonstration of
sub-maxiliary contortions in th’ empherial regions contiguous t’ th’
upper atmosphere!” exclaimed Washington, entering from the engine room
into the conning tower.

“What’s the trouble?” asked Mr. Henderson.

“Terrible big black cloud chasin’ us from behind!” exclaimed the colored
man.

Noting the alarm in Washington’s voice the professor glanced from the
rear window. What he saw caused him to exclaim:

“It’s a cyclone! We must drop down to avoid it!”

He sprang to a lever controlling the gas and yanked it toward him. There
was a shrill hissing sound, and a second later the _Mermaid_ began to
sink. The boys watching the gages on the wall of the tower, saw that the
craft was falling rapidly.

But, with a rush and roar, the terrible wind was upon them. It caught
the craft in its fearful grip and heeled it over as a ship careens to
the ocean blast.

“It’s a storm in the upper regions! We’ll find it calm below!” cried the
professor above the howling of the gale. He opened the gas outlet wider
and the ship fell more rapidly.

“Are you sure we’re over the ocean?” asked Mark.

“Positive!” the professor called back. “We have been traveling straight
south over the Atlantic for the last week. We will land in the midst of
the waters and float safely.”

Lower and lower went the _Mermaid_. The wind was now blowing with the
force of a tornado, and, as the craft had to slant in order to descend,
it felt the power of the gale more than if it had scudded before it.
But, by skilful use of the directing tube, the professor was able to
keep the boat from turning over. As they came further down toward the
earth the force of the wind was felt less and less, until, as they came
within two hundred feet of the water which they saw below them in the
gathering dusk, it died out altogether.

“Now we are free from it,” said the professor as the _Mermaid_ came down
on the waves like an immense swan.

“Are you going ahead or going to stop here?” asked Mark.

“We’ll keep right on,” Mr. Henderson answered. “No telling when the
storm may strike down here. We’ll go as far as we can to-night.”

CHAPTER VII

A QUEER SAIL

Now that the fear and worriment was over they all began to feel hungry,
and, while Mark and Jack took charge of the conning tower Washington got
breakfast. The professor seemed preoccupied during the meal, and several
times, when Mark spoke to him, he did not reply.

“I wonder if he is worried about something, or is thinking of something
which seems to be concealed in the storeroom,” the boy thought.

But, after a while, the professor seemed to be more like himself. He was
busy over several maps and charts, and then announced the ship would try
air-sailing again for a while.

“We can make better time above than we can on the water,” he said, “and
I am anxious to get to the mysterious island and learn what is in store
for us.”

Perhaps if the professor had been able to look ahead, and see what was
soon going to happen, he would not have been so anxious for it to occur.

It was shortly after dinner when, the gas container having been filled,
the ship rose in the air, and began sailing over the ocean, about a mile
up. The day was a fine one, and, as they were moving south, it was
constantly growing warmer. Down on the water, in fact, it was quite hot,
but in the air it was just right.

Like some immense bird the _Mermaid_ went flying through the air. The
boys and the professor sat upon the deck in easy chairs. It was like
being on the top of some tall “sky-scraper” building which, by some
strange power, was being moved forward. Below them the ocean tumbled in
long, lazy swells.

Suddenly Mark, who was looking through a telescope at the expanse of
water stretched out under them, gave a cry.

“There’s a ship! She’s on fire!”

“Where?” asked the professor, stretching out his hand for the glass.

“Just to the port of the forward tube. See the smoke!” exclaimed Mark.

Mr. Henderson looked. Through the lens he saw a column of black vapor
rising skyward. Mingled with it were red flames.

“Lower the _Mermaid_!” he cried. “We must save those on board if we
can!”

Mark ran to the conning tower, where Washington was, to give the order.
The colored man, who was looking ahead, intent on guiding the ship, did
not at first hear what Mark called.

“Lower us! Send the _Mermaid_ down!” Mark cried again.

The sudden shout and the excited voice of Mark so startled Washington,
that, fearing some accident had happened, he pulled the lever,
controlling the gas supply, with more force than necessary.

There was a loud explosion, followed by a crackling sound, a flash of
light, and the _Mermaid_ came to a sudden stop.

“What’s the matter?” cried Mark, feeling that something was wrong.

“I don’t know!” Washington replied, as he dashed toward the engine room.

The _Mermaid_, her forward flight checked, hung in the air, suspended,
neither rising or falling.

“Why don’t we go on down?” the professor asked, hurrying to the tower.

“There has been an explosion—an accident!” exclaimed Mark. “I guess we
can’t go down!”

“But we must!” Mr. Henderson insisted, seizing the lever which should
have produced a downward motion. The handle swung to and fro. It was
disconnected from the apparatus it operated.

The ship was now stationary in the air, moving neither forward nor
backward, neither rising nor falling. Washington had stopped the air
pumps as soon as he learned something was wrong.

When Mr. Henderson saw the useless lever, which had controlled the
outlet of gas from the holder, he ran out on deck. One glance told him
what had happened. One of the electric wires had become
short-circuited,—that is, the insulation had worn off and allowed the
current to escape. This had produced a spark, which had exploded the gas
which was in the pipe leading from the generator up into the aluminum
holder. Fortunately there was an automatic cut-off for the supply of
vapor, or the whole tank would have gone up.

As it was, only a small quantity had blown up, but this was enough to
break the machinery at the point where the lever in the conning tower
joined the pipe. If it had not been for the automatic cut-off all the
gas in the holder would have poured out in a great volume, and the ship
would have fallen like a shot.

“Can we do nothing to save those on the burning vessel?” asked Mark,
pointing to where a cloud of smoke hung over the ocean.

“I fear not, now,” answered the professor. “We are in a bad plight
ourselves.”

“Are we in any danger?” asked Jack.

“Not specially,” Mr. Henderson replied. “But we must find a means of
lowering ourselves gradually.”

“Then it will be too late to save any of those on the ship,” observed
Mark.

“I’m afraid so,” the scientist made reply.

The _Mermaid_ rested some distance above the surface of the waters. She
moved slightly to and fro with the wind, and rocked gently. The
professor was examining the broken machinery.

“I have a plan!” suddenly cried Mark.

“What is it?” asked Mr. Henderson.

“Can’t we bore a hole in the tank, insert a small faucet or tap, and let
the gas out that way gradually?” asked the boy. “When we get down we can
rescue those in danger of fire, and, later, can repair the break.”

“The very thing!” exclaimed Mr. Henderson. “I never thought of that!
Here, Washington! Bring me a drill, and a small stop-cock!”

The drill was obtained from the engine room. Working rapidly Mr.
Henderson bored a hole in the lower part of the holder. As soon as the
metal was penetrated the gas, which was under considerable pressure,
rushed from the tank with a hissing sound. At once the _Mermaid_ began
to settle rapidly.

But the professor was prepared for this. He thrust the end of the
stop-cock into the hole. It was screwed fast and the valve turned. This
stopped the flow of gas and checked the descent of the ship. Then, by
opening the tap the vapor was allowed to escape gradually, bringing the
_Flying Mermaid_ gently to the water.

As the adventurers approached they could see that the vessel was now a
mass of flames. The wind was driving the fire toward the forecastle, and
the crew had sought refuge aft. But this expedient could not last long,
for, already the tongues of fire were licking the sides of the craft and
coming nearer and nearer the seemingly doomed men. The vessel was a
large one, and heavily laden.

As those in peril caught sight of the _Mermaid_ settling down into the
water, apparently from the clouds, their fears gave place to
astonishment. So great was this that they ceased their cries of terror.
Then, as they saw that the strange craft navigated the ocean, for the
engines were started aboard the _Mermaid_, they began to call for help.

CHAPTER VIII

THE FLYING MERMAID DISABLED

“We’ll save you!” shouted Mr. Henderson, who was on the deck, while Mark
was steering the craft. “Hold on a few minutes longer and we’ll be
alongside!”

“They’re real! They’re real!” some of those aboard the burning ship
could be heard to shout. Evidently more than one of them had taken the
_Mermaid_ for a delusion of their fear-crazed brain.

“They are real persons!” they called again and again. “They are coming
to save us!”

Mr. Henderson ran his ship as near the burning craft as he dared. Then
he called to the crew to leap into the water and swim to him. He, with
Washington, Jack, Bill and Tom, stood ready to haul aboard any who were
too weak to help themselves.

In a few minutes all of those left alive on the sailing vessel—fourteen
in all—had come safely aboard the _Mermaid_. The ship was now
completely enveloped in flames.

“Are there any more left on her?” asked Mr. Henderson of one who
appeared to be a mate of the burning craft.

“Not a soul!” was the answer. “The captain and ten men perished in the
flames. The fire broke out a week ago in the lower hold. We fought it as
well as we could but it got the best of us. Then it suddenly broke
through the decks, almost like an explosion, a little while ago, and the
captain and others were lost, and so were our small boats. We managed to
get aft but were about to give up when you appeared.”

“What ship is it and where are you from?”

“The _Good Hope_, laden with logwood, hides, jute and other materials
from South America,” the mate answered. “We were bound for New York.”

“It is more like the _Last Hope_ instead of the _Good Hope_,” observed
Mr. Henderson in a quiet voice, as he saw the flames mount higher and
higher over the ship. A few seconds later the craft seemed rent by an
internal explosion. It appeared to break in two parts, and, amid a
shower of sparks and a cloud of black smoke, the vessel sank under the
water and was seen no more.

The rescued men turned to behold the final end of their ship. They
betrayed no particular emotion, and some of them even laughed, which the
professor thought, at the time, was rather strange. But there was little
opportunity for speculation. The men were in a sad plight. Few of them
had more than the clothes they stood in, though each one wore about his
waist a belt, and all of them seemed to guard the leather circlets
jealously.

The professor and his crew were soon busy supplying remedies for burns,
since several of the men were seared by the flames. Then, as it was
learned they had eaten nothing for many hours, it having been impossible
to use the galley, a meal was prepared and the survivors of the wreck
were well fed.

The hunger of the newcomers having been appeased, they showed much
curiosity over the strange craft that had so opportunely come to their
rescue. Most of the sailors were ignorant men, and the professor had
little fear of them learning anything concerning his secrets. He
explained briefly about the _Mermaid_, but said nothing of whither she
was bound.

The addition of fourteen men to the rather small accommodations of the
_Mermaid_ was a serious matter to consider. The ship was able to hold
them all, and even to sail through the air with them, since Mr.
Henderson had provided an excess of power. But it was going to be a
problem to feed so many, and still save enough provisions for the long
voyage which lay ahead.

However, Mr. Henderson felt his first duty to be toward his fellowmen,
even if his voyage must be delayed, or given up for a time, while he got
more provisions. There would be no sleeping quarters for the sailors,
but when this was explained to them they cheerfully said they would
sleep on deck if necessary. In fact some of them had to, but as the
weather was warm and clear this was no hardship. A few found quarters in
the engine room and other apartments of the _Mermaid_.

Finding, after an examination, that his ship was in good order save for
the broken gas apparatus, Mr. Henderson gave orders to proceed along the
surface of the ocean. The sailors wanted to see how it felt to mount
into the air, but Mr. Henderson, refused to attempt a flight until he
had made complete repairs, and this would take a day or more.

At this there appeared to be some discontent among the survivors, and
they muttered to each other as they stood in a group on deck. But the
professor and his assistants were too busy with their preparations for
fixing the break to notice this.

While the men were gathered in a knot near the after part of the small
deck, the mate separated from them, and, coming close to where Mark was
standing, unscrewing some of the broken parts of the pipe said, in a low
voice.

“Tell the captain to watch out.”

“What do you mean?” asked Mark quickly.

“Hush! Not so loud!” the mate exclaimed. “If the men hear me talking to
you, or see me, they may kill me. Tell the captain to look out; that’s
all. Be on guard, and watch the engine room carefully.”

“But why—?” Mark began, when, turning suddenly, the mate left him. It
was well he did so, for, at that instant, one of the sailors, who had
observed the two conversing, strolled in their direction.

Much alarmed, Mark sought Mr. Henderson and told him what he had heard.

“I suppose the fire may have turned the poor man’s head,” the scientist
said. “I wonder if he thinks the men I rescued would mutiny and take
possession of my ship? If they did they would not know how to work it,
so what good would it do?”

“Hadn’t we better look out?” asked Mark.

“I’m not afraid,” replied the professor. “I will be too busy the next
few days, repairing the break, to think of anything else. Besides, what
would they want to harm us for? Didn’t we save their lives?”

Seeing the scientist placed no faith in what the mate had said, Mark
went back to his task.

It soon became too dark to work, and it was decided, after supper, to
halt the ship until morning as it would be less risky.

Mark did not sleep well, his dreams being disturbed by visions of
pirates and black flags. But morning came and nothing had developed. The
men seemed to recover their spirits with daybreak, and most of the crew,
after breakfast, greeted Mr. Henderson pleasantly, and asked to be
allowed to help fix the ship.

It took the skilled labor of the professor, Washington and the boys to
mend the break, and, even at that, it was four days in the repairing.
But at last the final bolt was in place, and the _Mermaid_ was able to
resume her trips through the air.

“We will rise the first thing in the morning,” said the professor to
Mark and Jack that night. “I am anxious to see how the ship behaves with
a big load aboard.”

CHAPTER IX

THE MUTINY

Mark was awakened that night by feeling some one trying to turn him
over. At first he thought it was Jack, and sleepily muttered that he
wanted to be let alone.

“Sorry I can’t oblige ye, my hearty!” exclaimed a rough voice in his
ear, “but I got particular orders t’ tie you up!”

At that Mark tried to sit up, but he found he could not. He discovered
that he was closely bound with many turns of a rope, while in front of
his bunk stood one of the rescued sailors.

“There,” said the man, with a final tightening of the ropes. “I guess
you’re safe.”

“What’s the matter? What does it all mean?” asked Mark, much bewildered.

“It means that we have possession of the ship,” the sailor answered,
“and, if you’re wise you’ll not make a fuss. It wouldn’t do any good,
anyhow, as all your friends are in the same condition.”

Then, picking Mark up, as if he was a baby, the man slung him over his
shoulder and carried him to the living room. There Mark saw Jack, the
professor, Washington, and the others similarly bound.

“Do you realize what you are doing?” asked the professor angrily of his
captors. “You are mutinying, and are liable to severe punishment.”

“If they ever get us,” added one of the men. “We’ve got the ship now,
and we mean to keep her. You’ll have to run her or show us how.”

“Never!” cried the professor.

“I guess he will when he feels this,” said one of the men, as he dragged
from a recess two wires. “I happen to know something of electricity, and
when he feels these perhaps he’ll change his mind. I’ll start the
dynamo.”

The sailor showed that he was acquainted with machinery, for soon the
hum of the electric apparatus was heard.

“Now to make him tell!” the man with the wires exclaimed, advancing
toward the professor, who turned pale.

“Stop! You must not torture the old man!” cried a voice, and the mate of
the _Good Hope_ stepped in front of the sailor with the electrified
wires.

“Who’s going to stop me?” asked the man.

“I will. It’s not necessary,” the mate went on quickly. “If we make him
weak we may kill him, and he can not tell us what we want to know. One
of the boys can tell us how to run the ship.”

The mate came quickly over to where Mark lay, and whispered:

“Consent to tell. It is the only way of saving his life. Tell ’em how to
raise the craft. Then leave all to me. I will save you all and the ship,
too, if I can. But consent.”

Mark nodded his head, and the mate cried:

“I knew I could fetch ’em. I have hypnotic power. This boy will raise
the ship for us. Loosen his bonds, some of you.”

Satisfied that they were now on the way to experiencing a new sensation,
the sailors took the ropes off Mark’s arms and legs, and he was allowed
to rise. With a reassuring nod toward the professor he led the way to
the engine room, followed by half the men. He resolved to start the gas
machine slowly, so as to make the upward trip last longer, thinking
before it had gone far, some way of escape from the mutineers might be
found.

While a crowd of the sailors stood near him, Mark operated the machinery
in the engine room that started the gas generating, and set the negative
gravity apparatus working.

“You’d better not try any tricks on us,” said one of the men in an ugly
tone of voice.

“I’m not going to,” replied Mark. “If you go out on deck you will soon
see the ship leaving the water and mounting into the air.”

“Some of you go,” ordered a man with a big bushy red beard. “See if the
ship rises. When she begins to go up sing out. I’m going to stay here
and see how the young cub does it so I can work it myself.”

Obeying the red-bearded man, who seemed to be a leader, several of the
sailors went out on the deck. It was quite dark, but there was a
phosphorous glow to the water which made the rolling waves visible.

The gas was being generated, as could be told by the hissing sound. Mark
watched the machinery anxiously, for he knew much depended on him, and
the professor was not at hand to guide and instruct him. He watched the
dial of the gage which registered the gas pressure and saw it slowly
moving. In a little while it would be at the point at which the ship
ought to rise.

Presently a quiver seemed to run through the _Mermaid_. Now a shout came
from the watchers on deck.

“She’s going up!”

The ship was indeed rising. The red-bearded man, who was addressed as
Tony, ran from the engine room to the deck. He saw that the ship was now
ten feet above the water. Back he came to where Mark stood by the gas
machine.

“Lucky for you that you didn’t fool us, lad,” he said with a leer. “See
that you mind me hereafter. Now show me how the shebang works.”

When the ship had risen as far as Tony desired he made Mark send it
straight ahead. The boy adjusted the air tube to carry the craft toward
the south, but Tony, seeing by a compass in which direction they were
headed, ordered Mark to steer due east.

“Fix things so they will stay so, too,” added Tony. “I don’t want to
stop until I get a thousand miles away. Then we’ll come down, sail to
some sunny island, and enjoy life.”

Mark locked the steering apparatus so as to keep the _Mermaid_ headed
due east.

“Now you can go back to your friends,” Tony said. “When I want you I’ll
send for you.”

With a heavy heart Mark rejoined the professor and others. He found them
with their bonds removed. But to guard against their escape several men
were on watch outside the door.

“What are they doing?” asked the professor eagerly as Mark entered, and
the boy told him what had taken place.

“They will ruin my ship and spoil the whole trip,” cried the old
scientist. “Oh, why did I ever go to the rescue of the scoundrels?”

“Never mind,” said Jack. “Perhaps we may yet outwit them.”

Morning came at last. The ship was still shooting forward at fast speed,
in an easterly direction. The sailors had learned, in their short stay
aboard, where the food and stores were kept, and they lost little time
in getting breakfast. They sent some in to their captives, including a
big pot of hot coffee, and, after partaking of this the professor and
his friends felt better.

The mate of the _Good Hope_ came in to help clear away the dishes. As he
passed Mark he slipped into the boy’s hand a note.

“Don’t read it until you are alone,” he said in a low voice, as he
hurried from the room.

As soon as the other sailors had left, Mark glanced at the slip of
paper. It bore these words:

“Open when you hear three raps, then two, then three, and keep silent.”

“What is it?” asked Mr. Henderson.

Mark showed him the paper.

“I wonder what it means,” the boy said.

“Do you think he is a friend of ours?” the professor asked.

Mark told him of the mate’s conversation the night previous.

“I think we can trust him,” the scientist went on. “He must intend to
pay us a visit when the others are asleep. When we hear the knocks as he
specifies we must open the door and let him in.”

All that day the captives were kept in the living room. Once or twice
Mark was sent for to make some adjustment to the machinery, but the
apparatus, for the most part, was automatic, and needed little
attention. The professor, as well as the others, were all impatience for
the promised visit of the mate. Still they felt he would not come until
night.

In fact it was long past midnight before Mark, Jack and the professor,
who were anxiously listening, heard the three raps, then two, then three
more. Mark quickly opened the door, and the mate stepped inside, holding
his finger to his lips as a sign of caution. Old Andy, Washington, Bill
and Tom had fallen asleep.

“I have only time for a few words,” the mate said. “I am closely
watched. Tony mistrusts me. I will save you if I can.”

“Why have they repaid my kindness with such actions?” asked Mr.
Henderson.

“Because they are desperate men,” replied the mate. “They are nothing
more than pirates. They mutinied on the other ship, killed the captain
and those of the crew who would not join them, and started off to seek
their fortunes. I pretended to join them to save my life, but I have
only been watching for a chance to escape.

“Because of lax discipline the ship was sent on fire. We tried to put it
out but could not. The rest you know.

“I heard them plan to capture this airship, but could do nothing to stop
them. Then I resolved to pretend to act with them. They fear pursuit for
their other mutiny, and are anxious to get as far away as possible.”

“Do you think they will abandon the ship in a little while?” asked the
professor hopefully.

“I’m afraid not,” answered the mate. “I think they want to get rid of
all of you, so they can sail about as they please. Tony is a smart man.
He could soon learn to run this ship, he thinks.”

“I doubt it,” Mr. Henderson answered. “But how are you going to help
us?”

“I have not fully made up my plans,” the mate answered. “However I
wanted you to know I would do my best to save you. Now I must go. Be on
the watch and when I can I will let you know what I have decided on. I
will hand Mark a note when I bring your meals, just as I did to-day. I
think——”

“Hark! What was that?” asked the professor.

There was a noise outside the door, as if some one was listening.

“Put out the lights!” whispered the mate, and Jack switched off the
electric incandescents.

A knock sounded on the door and the voice of Tony called:

“Mark! Come here! I want you to look at the gas machine. It has stopped
working, and we are falling!”

CHAPTER X

FOOLING THEIR ENEMIES

Mark hurried into the corridor, taking care to close the door after him,
so Tony could get no glimpse of the mate who had risked so much to save
his friends. But he need not have been alarmed for the leader of the
mutineers was too excited over the stopping of the gas apparatus to give
any heed to who was in with the captives.

“Do you think you can fix it?” he asked the boy.

“I guess so,” Mark replied confidently. “If I can’t there is no danger,
for we will fall gradually and land in the water.”

“But I don’t want to do that,” Tony objected. “I want to keep on through
the air.”

Mark did not reply. By this time he was at the gas machine. He soon saw
nothing was the matter save that new material must be placed in the
retort where the vapor was generated. He refilled it, the gas was
manufactured once more, and the ship began to rise.

“I will know how to do it next time,” Tony said with a grin. Mark
realized that every time he showed the leader of the mutineers something
about the ship it was putting the professor and his friends more and
more into the power of the scoundrels. But there was no help for it.

The ship was still plunging ahead, and kept about a mile above the
earth. As there was no further need of Mark, he was told he could go
back to his friends. When he reached the room where they were held
prisoners, he found the mate had gone away, promising again to do all he
could for them.

The next night, which it seemed would never come, for the day, locked as
the captives were in their room, seemed endless, finally closed in.
Mark, Jack and the professor were anxious to know whether the mate would
pay them another visit. As for Andy, Tom and Bill, while they were
interested in the ship, and wanted to be free from the power of the
mutineers, they did not lose any sleep over it.

Shortly after midnight, there came again the peculiar knock, and the
mate entered the room. He seemed much excited over something, and, as
soon as the portal was securely closed he said to Professor Henderson:

“Is there an island any where near here where men could live for a
time?”

“What do you mean?” asked the scientist. “Do you want us to desert the
ship and leave these scoundrels in charge?”

“Nothing of the sort,” replied the mate, who, had said his name was Jack
Rodgers. “But first answer my question. A great deal may depend on it.”

Seeing Rodgers was in earnest, the professor looked over some maps and
charts, and announced that they were within a few hundred miles of a
group of islands.

“When would we reach them?” was Rodgers’ next question.

Mr. Henderson made a few rapid calculations on a piece of paper.

“At the present rate of sailing,” he said, “we should be there about ten
o’clock to-morrow. That is, provided the ship does not slacken speed or
increase it.”

“There is no danger of either of those two things happening,” said the
mate. “Tony is too afraid of the machinery to do anything to it. So you
may safely figure that our speed will continue the same.”

“Then I can guarantee, with all reasonable certainty,” the professor
said, “that about ten o’clock to-morrow we will be less than a mile from
the islands. They are a group where friendly natives live, and where
many tropical fruits abound. One could scarcely select a better place to
be shipwrecked. But I hope the plans of Tony and his friends do not
include landing us there.”

“No, nothing like that,” the mate answered. “Quite the contrary. But I
had better be going. I will try and see Mark some time to-morrow. Tony
does not mind when I speak to him.”

With this Rodgers left the captives, as he heard some of the sailors
moving about and did not want to be discovered. The professor and the
boys wondered what the mate’s plan might be, but they had to be content
to wait and see.

The night passed without incident. About nine o’clock the next morning
the mate came to the door of the room where the professor and his
friends were prisoners. He made no secret of his approach, but knocked
boldly.

“Tell Mark I want to see him,” he said, as the professor answered. “All
of you keep quiet,” he added in a whisper. “There may be good news
soon.”

Mark slipped from the room. He followed the mate to the upper deck
which, at that time was deserted as all the sailors were in the dining
room eating, which practice they indulged in as often as they could.

“I have a plan to get rid of these rough men,” the mate said to Mark.
“It may work, and, again it may not. At any rate it is worth trying. It
all depends on you with what help I can give you.”

“I’m willing to do my share,” Mark said, and for the next ten minutes
the boy and the mate were in earnest conversation.

It was about thirty-five minutes later when there arose a sudden
commotion in the ship. Mark had returned to his friends and the mate had
disappeared. The confusion seemed to come from the engine room where
Tony had posted some of his men.

“We’re falling down! We’ll all be killed!” shouted the men. “The ship is
falling into the sea!”

“What is the trouble?” asked the professor as he heard the commotion.

“It is part of the mate’s plan,” said Mark. “He told me to tell you to
do nothing. If Tony or any of the other men come to you just refer them
to me.”

Two minutes later Tony came rushing into the apartment where the
captives were held prisoners.

“Here! Come quickly, Mark!” he exclaimed. “Something has gone wrong with
the gas machine again, and you must come and fix it before we are all
dashed to pieces!”

With every appearance of haste Mark rushed from the apartment, following
Tony. The latter led the way to the engine room.

“Can anything be done?” he asked.

Mark took a survey of the machinery.

“It is too late,” he said as though much excited. “The ship is falling
down toward the sea with terrific force.”

It needed but a glance at the height gage to show this. The pointer was
revolving rapidly about the face of the dial.

“Will the ship stand the blow?” asked Tony.

“Not at the rate it is falling,” replied Mark. “She will go all to
pieces when she strikes the water, and she may explode!”

“What are we to do then?” asked the leader of the mutineers.

“We must save ourselves!” cried the mate, running in at this juncture.
“Let our prisoners shift for themselves as best they can. Let’s all leap
into the sea. There we at least have a chance for our lives. But if we
stay on this ship we will all be drowned like cats in a bag.”

“What do you propose?” asked Tony, his face white with fear.

“When the ship comes near enough the surface of the water to make it
safe we should all drop overboard!” the mate exclaimed. “We are near
some islands, I understand, and we can thus save our lives by swimming
ashore.”

This plan seemed to meet with instant favor, and a little later there
was a rush for the deck, as each one wished to be the first to escape
from the boat they believed to be doomed.

Lower and lower fell the _Mermaid_. She was like a wounded bird which
the shot of the hunter has crippled. Down and down she fluttered.

By this time all the sailors, save the mate were on deck. He and Mark
remained in the engine room.

“Don’t let her get too low,” the mate whispered.

“I’ll watch out,” Mark replied. “I want to give them a good scare while
I’m at it.”

The ship was now within fifty feet of the water. There was a cry of
terror from the sailors. Some of them leaped over the rail and started
to swim ashore, as the ship was by this time close to a group of
islands.

Suddenly, from the engine room the mate rushed.

“Jump! Jump for your lives!” he exclaimed. “The ship is about to blow
up!”

CHAPTER XI

MYSTERIOUS HAPPENINGS

The voice of the mate echoed through the _Mermaid_. Those on deck heard
it, as did Tony in the engine room, where he was vainly trying to
understand the complicated machinery.

An instant later there sounded from beneath the ship a series of
splashes. More sailors were leaping from the deck of the craft to the
ocean. The distance was not great, particularly as they all landed in
water.

“Quick!” cried the mate to a group of sailors that hesitated before
taking the jump. “The ship may blow up any minute now.”

The men needed no second urging. As soon as they struck the water they
began to swim ashore, as it was not far away. One after another they
jumped over the rail. Tony was the last to go. He urged the captives to
follow him, but they all refused.

A minute later the only one of the pirate crew left on the ship was the
mate. The others were all struggling in the sea. Eventually they all
reached shore in safety.

The airship was now within about twenty feet of the water. It was still
falling but not so rapidly.

“Better send her up, now,” said the mate to Mark, and the boy turned the
necessary levers to accomplish this.

Dipping into the water as a sea gull does when searching for food on the
wing, for she had come quite low, the _Mermaid_ mounted once more into
the air, and was soon sailing along over the heads of Tony and his gang.

“What’s it all about?” asked Mr. Henderson, who seemed in a sort of
stupor. “I thought the ship was broken. How, then, can it rise?”

“It was only a trick of mine,” Rodgers said. “The gas machine is not
broken. I had Mark fix it so that only a little vapor would be
generated. When the supply in the holder was not enough, and no more was
being made, the ship had to sink. Mark and I pretended it was worse than
it really was just to scare the scoundrels.”

“And you evidently succeeded,” observed Mr. Henderson. “They have all
left us. I am glad you stayed.”

“So am I,” said Rodgers. “I was just waiting for a chance to escape from
that crowd. This was the plan I thought of that night. I wanted to see
the men put on some island where they could manage to live, and which
was not too far away.”

The _Mermaid_ was now mounting upward rapidly, as Mark had adjusted the
machinery properly. The craft was well rid of the pirate crew, and was
able to proceed on its way, and enable Mr. Henderson to carry out his
plans.

When the _Mermaid_ had reached a certain height her prow was turned the
other way, and she was sent back racing over the ground she had just
covered. But now the ship was in the hands of friends. Fortunately no
great damage had been done by the sailors, and the professor was soon
able to get things in ship-shape. The engines had not been molested and
were working better than ever.

“Now to make another attempt to reach the big hole in the earth,” the
professor cried. “We will be careful next time, who we rescue from ships
at sea.”

The island was soon left behind, becoming a mere speck on the ocean.
Those aboard the _Mermaid_ knew no harm could befall the sailors, as
there were no savage tribes on the little spot of land. Eventually the
sailors were picked up by a passing vessel and taken to their homes. The
story of their first mutiny leaked out and they were properly punished.

It required several days travel before the airship regained the distance
she had lost because of the plans of the pirates. Also, there were a
number of minor repairs to make, and the professor and his friends were
kept busy.

“How much longer before we come to the big hole?” asked Jack, one day.

“I think we ought to be near it in about two weeks,” the professor
replied. “I only hope we shall not be disappointed, and will be able to
explore it.”

“'Tain’t goin’ t’ be no fun t’ be decimated an’ expurgitated inter a
conglomerous aggregation of elements constituting th’ exterior portion
of human anatomy,” said Washington in dubious tones.

“You mean you’re afraid of being boiled in the steam from the big hole?”
asked Mark.

“Jest so,” replied the colored man.

“You don’t need to worry about that,” put in the professor. “I will not
take the ship down if there is any danger, though of course there will
be some risk.”

The ship, having been fully repaired, was now able to be speeded up, and
was sent scudding along toward her destination. Rodgers proved a
valuable acquisition toward the crew, for he had sailed many years in
the waters over which they were flying, and was able to give the
professor many valuable hints. He had heard vague stories of the island
with the big hole, but had never been near it. He did not make the trip
however, as, at his request, he was put off at an inhabited island one
night.

It was about a week after the sailors were frightened from the ship,
that a curious experience befell Mark. Washington was on duty in the
conning tower, attending to the apparatus as the ship flew through the
air, and all the others had gone to bed. Mark had remained up, later
than the others as he was interested in reading a book on science.

About ten o’clock he became hungry, and going to the pantry got some
bread and cold meat. He set these on a table, and then, remembering he
would need some water to drink, started after some in the cooler, which
was in a little room near the tower.

Washington heard the boy as he turned the faucet to draw the liquid, and
spoke to him, as the colored man was rather lonesome at his post. Mark
did not linger more than a minute or two, but when he returned to where
he had left the food he was much surprised.

There was not a trace of it to be seen. The dishes were on the table,
but every vestige of bread and meat had disappeared.

“I wonder if a cat or dog has been here,” was Mark’s first thought. Then
he remembered that no such animals were aboard the _Mermaid_.

Something on the floor caught his eye. He stooped and picked it up. It
was a slice of bread, but in such shape that the boy stared at it,
puzzled as to how it could have become so.

It was flattened out quite thin, but the strangest part of it was that
it bore what seemed to be the marks of thumb and fingers from a very
large hand. So big, in fact, was the print, that Mark’s hand scarce
covered half of it, and, where the bread had been squeezed into a putty
like mass (for it was quite fresh) the peculiar markings on the skin of
the tips of the fingers were visible.

“It looks as if a giant grabbed this slice of bread,” Mark observed.
“There are strange happenings aboard this ship. I wish I knew what they
meant.”

He looked all around for the food, thinking perhaps a rat had dragged it
off, but there was no trace of it.

Suddenly the boy thought he heard a sound from the big storeroom. He was
almost sure he heard something moving in there. He started toward the
door when he was stopped by hearing the professor’s voice call:

“Don’t open that door, Mark. Have I not told you that place must not be
entered?”

“I thought I heard some one in there,” Mark replied.

“There is nothing in there but some apparatus of mine,” Mr. Henderson
said. “I want no one to see it. What is the matter?”

Mark explained matters to the scientist, who had, as he said later,
arisen on hearing the boy moving about.

“Oh, it was a rat that took your stuff,” Mr. Henderson said. “I guess
there are some pretty big ones on the ship. Get some more food and go to
sleep.”

Mark felt it best to obey, though he was by no means satisfied with the
professor’s explanation. He listened intently to see if any more noises
came from the storeroom, but none did, and he went to bed.

Several times after that Mark tried the experiment of leaving food
about. On each occasion it was taken.

“It looks as if the ship was haunted,” he said. “Of course I know it
isn’t, but it’s very queer. They must be strange rats that can get food
from shelves when there is only the smooth side of the ship to climb
up,” for on some occasions Mark had tried the experiment of putting the
food as nearly out of reach as possible.

It took several nights to learn all this, and, as he did not want to
take any one into his confidence, he had to work in secret. But, with
all his efforts he learned nothing, save that there was something odd
about the ship that he could not fathom.

At first he believed the professor had some strange animal concealed in
the storeroom, but he dismissed this idea almost as soon as he thought
of it. For what could the scientist want with an animal when they were
going to the interior of the earth? That some beast had slipped aboard
was out of the question. Mark was much puzzled, but finally, deciding
the matter did not concern him a great deal, gave up trying to solve the
mystery, at least for a time.

The ship was now in the neighborhood of the equator and the climate had
become much warmer. So hot indeed were some nights that they slept out
on deck, with the _Mermaid_ flying through the air at a moderate pace,
for it was deemed best not to go at any great speed after dark.

One night the professor, after consulting various charts and maps, and
making calculations which covered several sheets of paper announced:

“We should sight the mysterious island to-morrow.”

“That’s good news!” exclaimed Jack. “I’m anxious to see what’s below
inside of that big hole.”

“Everybody git ready for their funerals!” exclaimed Washington in a deep
voice. “I ain’t got many——”

“Cheer up,” interrupted Jack, poking Washington in the ribs. The colored
man was very ticklish, and he began to laugh heartily, though, perhaps,
he did not feel like it.

Suddenly, above the sound of his shouts, there came a crashing, grinding
noise from the engine room.

CHAPTER XII

THE BIG HOLE

“Something has gone wrong!” exclaimed the professor as he jumped up. He
reached the engine room ahead of any one else, and when the two boys got
there they found him busy twisting wheels and shifting levers.

“Anything serious?” asked Jack.

“It’s the gas machine again,” Mr. Henderson replied. “It broke where we
fixed it. However it doesn’t matter. I was going to lower the ship
anyhow, as I want to approach the island from the water. We will go down
a little sooner than I counted on.”

The disabling of the gas machine caused the vapor to escape slowly from
the tank, and this made the ship sink gradually. By means of the
emergency stop-cock the descent could be controlled almost as well as
though the machinery was in working order. Half an hour later the
_Mermaid_ rested on the water.

It was a little rough, as there was quite a swell on, and not so
pleasant as floating in the air on an even keel, but they made the best
of it.

On account of the little accident, and not being certain of its extent,
it was deemed best not to send the ship ahead. So they laid to until
morning.

For the better part of two days all those on board the _Mermaid_ had
their hands full mending the break and making other repairs found
necessary. In that time they lay to, floating idly with the currents, or
blown by the wind, for the professor would not start any of the engines
or apparatus until the ship was in good condition.

In this time Mark had several times recalled the curious happenings in
regard to the disappearing food, and the mystery of the storeroom. But
there were no further manifestations, and no other signs that there
might be a strange visitor aboard.

“I couldn’t have imagined it all,” said Mark, “but I guess what did
happen may have been caused by natural means, only I can’t discover
them.”

It was about two days after this, the ship having sailed scores of miles
on the surface of the water, that Mark, who was in the conning tower
exclaimed:

“That looks like a waterspout ahead of us.”

“That’s what it is!” Jack agreed. “What shall we do?”

“Call the professor!” said Mark. “He’ll know.”

When Mr. Henderson came, he looked for a long time at a cloud of black
vapor which hung low in the east.

“It may be a waterspout,” he said. “We’ll rise in the air and see if we
can avoid it.”

The ship was sent up into the air. As it rose higher and higher, the
professor, making frequent observations from his conning tower, cried
out:

“That is no waterspout!”

“What is it?” asked Mark.

“It is the steam and vapor rising from the big hole in the earth! Boys,
we are almost there!”

“Are you sure that’s it?” asked Mark.

“Almost positive,” Mr. Henderson replied. “You can see how much warmer
it has become of late, as we approached the equator. We are almost due
at the island, and I have no doubt we have reached it.”

As the ship flew forward the mass of dark vapor became more pronounced.
Through the glasses it could be noticed to consist of rolling masses of
clouds. What lay beneath them no one knew. The adventurers were going to
try to find out.

Now that they had arrived at the beginning of the main part of their
journey, the travelers felt their spirits sink a little. It was one
thing to plan to go down into the depths of the earth, but it was quite
another to make the actual attempt. Still, they were not going to give
up the project. The professor had confidence in his ship and believed it
could safely make the trip. Still it was with no little apprehension
that Mr. Henderson watched the nearer approach of the craft to that
strange island.

“Perfesser, are yo’ really an’ truly goin’ t’ depress this elongated
spheroid an’ its human consignment int’ that conglomerous convoluted
mass of gaseous vapor regardless of th’ consequences?” asked Washington,
as he gazed with wide opened eyes at the sight before him.

“If you mean am I going to let the _Mermaid_ go down into that hole you
are perfectly correct,” the scientist answered, “though you could have
said it in fewer words, Washington.”

“I—I guess I’ll get out an’ walk,” the colored man made reply.

“This isn’t any trolley car,” observed Mark. “Don’t lose your nerve,
Wash. Stay with us, and we’ll discover a gold or diamond mine, maybe.”

“Is there diamonds down there?” asked the colored man, his fright
seeming to leave him.

“There are all sorts of things inside the earth,” the professor
answered.

“Then I’m goin’ along!” Washington declared. “I always did want a
diamond ring, an’ I knows a little colored gal that wants one, too. I’m
goin’ all right! This suttenly am th’ most kloslosterous conjunctivity
of combativeness that I ever sagaciated!” and he began to do a sort of
impromptu cake-walk.

CHAPTER XIII

DOWN INTO THE EARTH

It was now noon, but the adventurers did not think of dinner in the
excitement of approaching the mysterious island. The speed of the ship
was increased that they might the more quickly come to it. As they
approached they could see the masses of vapor more plainly, and it
appeared that some great commotion must be going on inside the big hole,
since clouds of steam arose.

“I only hope it doesn’t prove too hot for us,” observed the professor.
“However, I provided a water jacket for the ship, and we may need it, as
well as the vacuum chambers to keep the heat from us.”

It was about three o’clock when the flying ship reached the edge of the
island. From there it was about a mile to the rim of the big hole, over
one side of which the waters of the ocean poured with a roar that could
be heard over half a mile off.

“I think we had better halt and see that everything is in good shape
before proceeding,” said Mr. Henderson. “Jack, you and Mark make a
thorough inspection of the engine room, and see that all the apparatus
is in working order.”

The two boys prepared to do as they were told. Mark, who was walking a
little ahead of Jack, entered the apartment from which the storeroom
opened. As he did so he saw, or thought he saw, the door of the place
where the extra supplies were kept, close. Without saying anything to
Jack he hurried forward, and tried the knob. It would not turn.

“That’s funny,” said Mark to himself. “I could almost swear I saw some
one go into that room. Yet I know the professor did not enter, for I
just left him. And none of the others would dare to. I wonder if I will
ever solve the mystery.”

But he had too much to do to allow him to dwell on that matter. Several
of the dynamos needed adjusting and for two hours he and Jack had all
they could do.

In the meanwhile the professor had gone over the other parts of the
ship, and gotten everything in readiness for the descent. The _Mermaid_
was lowered to within a few hundred feet of the sea, and, through a hose
that was let down, the compartments, provided for this emergency were
filled with water. These compartments were between the outer and inner
hulls of the lower part of the craft, and were designed to prevent the
interior becoming heated in case the travelers found they had to pass
close to fire. There were also vacuum chambers, and from these the air
was exhausted, as of course every schoolboy knows a vacuum is a
non-conductor of either heat or cold.

“Now I think we are ready,” the professor announced at length.

“Everything’s all right in the engine room,” announced Jack.

“Yes, an’ everything’s all right in th’ kitchen,” put in Washington.
“I’ve got a good meal ready as soon as any one wants to eat.”

“It will have to wait a while,” Mr. Henderson remarked. “We are going to
start to make the descent before we dine.”

The hose was reeled up, and the ship was sent a few hundred feet higher
into the air, as Mr. Henderson wanted to take a last good observation
before he went down into the hole.

But having risen some distance above the masses of rolling vapors he
found he was at no advantage, since the strongest telescope he could
bring to bear could not pierce the cloud masses.

“We’ll just have to trust to luck,” the scientist said. “I judge we’re
about over the centre of the opening. Lower away Mark!”

The boy, who, under the watchful eye of the professor, was manipulating
the levers and wheels in the conning tower, shifted some handles. The
gas was expelled from the holder, the negative gravity apparatus ceased
to work, and the _Flying Mermaid_ sank lower and lower, toward the
mysterious hole that yawned beneath her.

The hearts of all beat strangely, if not with fear, at least with
apprehension, for they did not know what they might encounter. Perhaps
death in some terrible form awaited them. But the desire to discover
something new and strange had gripped all of them, and not one would
have voted to turn back.

Even old Andy, who seldom got excited, was in unusual spirits. He took
down his gun and remarked:

“Maybe I can kill some new kind of animal, and write a book about its
habits, for surely we will see strange beasts in the under-world.”

Lower and lower sank the ship. Now it was amid the first thin masses of
vapors, those that floated highest and were more like a light fog, than
anything else. By means of a window in the bottom of the craft, which
window was closed by a thick piece of plate glass, Professor Henderson
could look down and see what was beneath them.

“The clouds seem to be getting thicker,” he said, as he peered through
the small casement. “If they would only clear away we could see
something.”

But instead of doing this the vapors accumulated more thickly about the
ship. It was so dark inside the _Mermaid_ now that the electric lights
had to be switched on. In the room with the floor-window the lights were
not used, as had they shone one could not have seen down below.

The professor maintained his position. The descent was a perilous one,
and he wanted to be on the watch to check it at once if the _Mermaid_
was liable to dash upon some pointed rock or fall into some fiery pit.
His hand was on the signal levers.

Suddenly he looked up and glanced at a gage on the wall. The hand of it
was slowly revolving.

“We are at the earth’s surface,” the scientist said. “Now we are below
it. Now we are fairly within the big hole! Boys, we may be on the verge
of a great discovery!”

An instant later it seemed as if a hot wave had struck the _Mermaid_, or
as if the craft had been plunged into boiling water.

“It’s going to be hot!” cried the professor. “Lucky I provided the water
jackets!”

Then the lights in the interior of the ship went out, leaving the whole
craft in darkness.

“What has happened?” cried Mark.

CHAPTER XIV

MANY MILES BELOW

“Don’t be alarmed,” spoke the calm voice of the professor. “I have only
turned off the electrics. I want to switch on the search lights, to see
if we can learn anything about our position.”

As he spoke he turned a switch, and, the gloom below the ship, as the
boys could see by glimpses from the floor-window, was pierced by a
dazzling glare. In the bottom of the _Mermaid_ were set a number of
powerful electric arc lights with reflectors, constructed to throw the
beams downward. The professor had built them in for just this emergency,
as he thought that at some time they might want to illuminate what was
below the craft.

Not that it was of much avail on this occasion, for, though the lights
were powerful, they could not pierce the miles of gloom that lay below
them. The beams only served to accentuate the darkness.

“I guess we’ll have to trust to luck,” the professor said, after a vain
attempt, by means of powerful glasses, to distinguish something. “There
is too much fog and vapor.”

“What makes it so warm?” asked Mark, removing his coat.

“Well, you must remember you are approaching the interior of the earth,”
the professor answered. “It has been calculated that the heat increases
one degree for every fifty-five feet you descend. We have come down
several hundred feet and of course it is getting warmer.”

“Then if we go down very far it will get so hot we will not be able to
stand it,” Jack put in.

“I do not believe we will suffer any great inconvenience,” Mr. Henderson
went on. “I believe that after we pass a certain point it will become
cooler. I think the inner fires of the earth are more or less heated gas
in a sort of inner chamber between two shells. If we can pass the second
shell, we will be all right.”

“But aren’t we liable to hit something, going down into the dark this
way?” asked Mark.

“We will guard ourselves as far as possible,” the scientist answered.

The _Mermaid_ seemed to be going down on a side of the immense shaft a
good way distant from the strange waterfall. When they had first dropped
into the hole the travelers could hear the rush of waters, but now the
noise was not audible.

“I think the hole must widen out the farther down we go,” the professor
said. “We are probably many miles from the fall now.”

“I’m sure I hope so,” put in Jack. “It would be no fun to have to take a
shower bath in this place.”

After a meal, the boys and the professor took some more observations,
but with all their efforts nothing could be seen below the ship but a
vast black void, into which they were steadily descending.

“I wonder when we’re going to stop,” asked Mark. “It’s like playing the
game ‘Going to Jerusalem,’ you keep wondering when the music will cease
and you will have a chance to grab a chair. I only hope we have a chair
or something else to sit on, in case we go to smash.”

“We’re not liable to have any accidents with the professor in charge,”
Jack answered. “Didn’t he bring us safe out of some pretty tight holes
when we went to the north pole in the airship, and again when we found
the south pole in the submarine?”

“Yes, but this is different,” objected Mark.

“Well, I’m not worrying,” Jack went on. “It doesn’t do any good, and
only makes you lie awake nights. By the way, I wonder what time it is
getting to be.”

He looked at his watch and found it was close on to eight o’clock in the
evening. So late had dinner been served, and so varied were the
happenings of the last few hours, that time had passed quickly.

“Why it’s almost bed-time,” said Jack. “I wonder if we are to go on
dropping into the depths of nowhere all night.”

At that moment the professor entered the room where the boys were. He
seemed quite pleased over something, and was smiling.

“Everything is going along famously,” he said. “I have just tested the
air and find it is rich in oxygen. We shall suffer nothing on that
score. The heat too, seems to have decreased. On the whole, everything
favors us.”

“Are we going on down?” asked Mark.

“As far as we can,” Mr. Henderson answered. “Let me see how far we are
below now.”

He went to the gage that indicated the vertical position of the ship.
Because of the changed conditions, the craft now sinking below the
surface of the earth instead of rising above it, as was its wont, some
calculations were necessary. These the scientist made as quickly as he
could.

“We are now ten miles underground!” he exclaimed. “That is doing very
well. My theories are working out. I think we shall land somewhere
before long.”

“I hopes so!” exclaimed Washington coming in at this point. “I’m mighty
skeered shootin’ down int’ this dark hole, and no time-table t’ show
when we’s due t’ arrive.”

“We ought to land in a couple of days more,” the professor answered.
“Never mind about worrying Washington, I’ll take care of you.”

“I hopes so, Perfesser,” the colored man said. “I got a little girl
waitin’ for me back in Georgia, an’ I’d like t’ see her 'fore I git
burned up.”

Accompanied by the professor, the boys made a tour of the ship to see
that all the machinery and apparatus were in working order. Owing to the
changed conditions the negative gravity engine had to be worked at
faster speed than usual, since the downward pull of the earth was
greater the farther they descended into the interior and they did not
want to fall too swiftly. But this was easily provided for, since the
professor had made the apparatus capable of standing a great strain.

The ten miles had become fourteen when the professor, finding that
everything was in good shape, proposed that the boys go to bed. They did
not want to, though they were sleepy, and they feared to miss some
strange sights.

But when the professor had promised to call them in case anything
unusual developed, they consented to turn in, and Bill and Tom assumed
their duties, which were light enough, now that the ship was merely
falling into the immense shaft.

When Mark turned into his bunk he could not go to sleep at once. It may
have been the excitement over their new position, or because he had
eaten too hearty a supper, but the fact was he remained awake for some
time.

While thus tossing restlessly on his bed, wondering what ailed him, he
thought he heard a noise in the main apartment out of which the
storeroom opened. He crawled softly from his bed, and looked from his
stateroom door.

In the light of a shaded electric Mark saw the figure of some one glide
across the floor and take refuge in the room, which Professor Henderson
always was so particular about.

“I wonder what or who that was,” reasoned Mark. “There is some mystery
in this. Can the professor have concealed some one on this ship whose
presence he does not want to admit? It certainly looks so.”

Not wanting to awaken the ship’s crew, and remembering what Mr.
Henderson had said about any one entering the storeroom, Mark went back
to bed, to fall into an uneasy slumber.

“Breakfast!” called Washington breaking in on a fine dream Jack was
having about being captain of a company of automobile soldiers. “Last
call for breakfast!”

“Hello! Is it morning?” asked Jack.

“Not so’s you could notice it,” Washington went on. “It’s as dark as a
stack of black cats and another one throwed in. But breakfast is ready
jest the same.”

The boys were soon at the table, and learned that nothing of importance
had occurred during the night. The _Mermaid_ had been kept going slowly
down, and about seven o’clock registered more than fifty miles below the
earth’s surface.

Still there was no change in the outward surroundings. It remained as
black as the interior of Egypt when that country was at its darkest. The
powerful electrics could not pierce the gloom. The ship was working
well, and the travelers were very comfortable.

Down, down, down, went the _Mermaid_. The temperature, which had risen
to about ninety went back to sixty-nine, and there seemed to be no more
danger from the inner fires.

They were now a hundred miles under the surface. But still the professor
kept the _Mermaid_ sinking. Every now and again he would take an
observation, but only found the impenetrable darkness surrounded them.

“We must arrive somewhere, soon,” he muttered.

It was about six o’clock that night that the alarm bell set up a sudden
ringing. The professor who was making some calculations on a piece of
paper jumped to his feet, and so did a number of the others.

“We are nearing the bottom!” he cried. “The bell has given us warning!”

CHAPTER XV

IN THE STRANGE DRAUGHT

The boys ran to attend to the engines and apparatus to which they had
been assigned in view of this emergency. The professor, Washington,
Bill, Tom and Andy, who had kept to themselves since the descent, came
running out of the small cabin where they usually sat, and wanted to
know what it was all about.

“We may hit something, in spite of all precautions,” Mr. Henderson
remarked. “Slow down the ship.”

The _Mermaid_ was, accordingly checked in her downward flight, by a
liberal use of the gas and the negative gravity machine.

The bell continued to ring, and the dials pointed to the mark that
indicated the ship was more than one hundred and fifty miles down.

Mark, who had run to the engine room to check the descent, came back.

“Why didn’t you slow her down?” asked the professor.

“I did,” replied the boy. “The negative gravity and the gas machines are
working at full speed.”

“Then why are we still descending?” asked the scientist. “For a while
our speed was checked, but now we are falling faster than before.”

“I attended to the apparatus,” Mark insisted.

Just then, from without the ship, came a terrible roaring sound, as
though there was a great cyclone in progress. At the same time, those
aboard the craft could feel themselves being pulled downward with
terrific force.

“We are caught in a draught!” Mr. Henderson cried. “We are being sucked
down into the depths of the earth!”

He ran to the engine room. With the help of the boys he set in motion an
auxiliary gravity machine, designed to exert a most powerful influence
against the downward pull of the earth. As they watched the great wheels
spin around, and heard the hum and whirr of the dynamos, the boys
watched the pointer which indicated how low they were getting.

And, as they watched, they saw that the needle of the dial kept moving,
moving, moving.

“Our efforts are useless! We can’t stop!” the professor cried.

Grave indeed was the plight of the adventurers. In their ship they were
being sucked down into unknown regions and all their efforts did not
avail to save them. It was an emergency they could not guard against,
and which could not have been foreseen.

“What are to do?” asked Mark.

“We can only wait,” Mr. Henderson replied. “The terrible suction may
cease, or it may carry us to some place of safety. Let us hope for the
best.”

Seeing there was no further use in running the engines in an effort to
check the downward rush the machines were stopped. Then they waited for
whatever might happen.

Now that they seemed in imminent peril Washington was as cool as any
one. He went about putting his kitchen in order and getting ready for
the next meal as if they were sailing comfortably along on the surface
of the ocean. As for old Andy he was nervous and frightened, and plainly
showed it. With his gun in readiness he paced back and forth as if on
the lookout for strange beasts or birds.

Bill and Tom were so alarmed that they were of little use in doing
anything, and they were not disturbed in their staterooms where they
went when it became known that the ship was unmanageable.

The boys and the professor, while greatly frightened at the unexpected
turn of events, decided there was no use in giving way to foolish alarm.
They realized they could do nothing but await developments.

At the same time they took every precaution. They piled all the bedding
on the floor of the living room, so that the pillows and mattresses
might form a sort of pad in case the ship was dashed down on the bottom
of the big hole.

“Not that it would save us much,” Jack observed with a grim smile, “but
somehow it sort of makes your mind easier.”

All this while the ship was being sucked down at a swift pace. The
pointer of the gage, indicating the depth, kept moving around and soon
they were several hundreds of miles below the surface of the earth.

The professor tried, by means of several instruments, to discover in
which direction they were headed, and whether they were going straight
down or at an angle. But some strange influence seemed to affect the
gages and other pieces of apparatus, for the pointers and hands would
swing in all directions, at one time indicating that they were going
down, and, again, upward.

“There must be a strong current of electricity here,” Mr. Henderson
said, “or else there is, as many suspect, a powerful magnet at the
center of the earth, which we are nearing.”

“What will you do if the ship is pulled apart, or falls and is smashed?”
asked Mark with much anxiety.

“You take a cheerful view of things,” said Jack.

“Well, it’s a good thing to prepare for emergencies,” Mark added.

“If the ship was to be separated by the magnetic pull, or if it fell on
sharp rocks and was split in twain, I am afraid none of us could do
anything to save ourselves,” the professor answered. “Still, if we were
given a little warning of the disaster, I have means at hand whereby we
might escape with our lives. But it would be a perilous way of——”

“I reckon yo’ all better come out an’ have supper,” broke in Washington.
“Leastways we’ll call it supper, though I don’t rightly know whether
it’s night or mornin’. Anyhow I’ve got a meal ready.”

“I don’t suppose any of us feel much like eating,” observed Mr.
Henderson, “but there is no telling when we will have the chance again,
so, perhaps, we had better take advantage of it.”

For a while they ate in silence, finding that they had better appetites
than they at first thought. Old Andy in particular did full justice to
the food Washington had prepared.

“I always found it a good plan to eat as much and as often as you can,”
the hunter remarked. “This is a mighty uncertain world.”

“You started to tell us a little while ago, Professor,” said Mark,
“about a plan you had for saving out lives if worst came to worst, and
there was a chance to put it into operation. What is it?”

“I will tell you,” the aged inventor said. “It is something about which
I have kept silent, as I did not want to frighten any of you. It was my
latest invention, and I had only perfected it when we started off on
this voyage. Consequently I had no chance to try it. The machine works
in theory, but whether it does in practice is another question. That is
why I say there is a risk. But we may have to take this risk. I have
placed aboard this ship a——”

The professor was interrupted in what he was about to say by a curious
tremor that made the whole ship shiver as though it had struck some
obstruction. Yet there was no sudden jolt or jar such as would have been
occasioned by that.

At the same time Washington, who was out in the kitchen, came running
into the dining room, crying:

“We’re droppin’ into a ragin’ fire, Perfesser!”

“What do you mean?” asked Mr. Henderson.

“I jest took a look down through th’ hole in th’ bottom of the ship!”
cried Washington. “It’s all flames an’ smoke below us!”

“I wonder if it is the end,” the professor muttered in a low voice.

Followed by the boys, the inventor hastened to the floor-window. The
lights were turned off to enable a better view to be had of what was
below them.

Leaning over the glass protected aperture the boys and the professor
saw, far, far down, a bright light shining. It was as if they were miles
above a whole town of blast furnaces, the stacks of which were belching
forth flames and smoke. The rolling clouds of vapor were illuminated by
a peculiar greenish light, which, at times, turned to red, blue, purple
and yellowish hues.

The effect was weird and beautiful though it was full of terror for the
travelers. It seemed as if they were falling into some terrible pit of
fire, for the reflection of what they feared were flames, could plainly
be seen.

“I wish I’d never come on this terrible voyage!” wailed Washington. “I’d
rather freeze to death than be burned up.”

“Washington, be quiet!” commanded the professor sternly. “This is no
time for foolishness. We must work hard to save our lives, for we are in
dire peril.

“Mark, you and Washington, with Jack, start the engines. Turn on every
bit of power you can. Fill the gas holder as full as it will hold, and
use extra heavy pressure. I will see if I can not work the negative
gravity apparatus to better advantage than we did before. We must escape
if possible!”

The boys, as was also Washington, were only too glad to have something
to do to take their mind off their troubles. All three were much
frightened, but Mark and Jack tried not to show it. As for Washington he
was almost crying.

Soon the whirr and hum of the machinery in the _Mermaid_ was heard. The
craft, which was rushing in some direction, either downward, ahead or
backwards within the unknown depths, shivered from the speed of the
dynamos and other apparatus. Soon the boys could hear the professor
starting the negative gravity engine, and then began a struggle between
the forces of nature and those of mankind.

Once more the adventurers anxiously watched the gages and indicators.
For a while the ship seemed to be holding out against the terrible
influence that was sucking her down. She appeared to hesitate. Then, as
the downward force triumphed over the mechanical energy in the craft,
she began to settle again, and soon was descending, if that was the
direction, as fast as before.

“It is of no use,” said the professor with a groan. “I must try our last
resort!”

He started from the engine room where Mark and Jack had gone. As he did
so, he glanced at a thermometer hanging on the wall near the door.

“Has any one turned on the heat?” he asked.

“It’s shut off,” replied Mark, looking at the electric stove.

“Then what makes it so hot?” asked the scientist.

He pointed to the little silvery column in the tiny tube of the
instrument. It registered close to one hundred degrees, though a few
minutes before it had been but sixty. And the starting of the machinery
could not account for the rise in temperature, since most of the
apparatus was run by electricity and developed little heat save in the
immediate proximity. The thermometer was fully ten feet away from any
machine.

“It’s the fiery furnace that’s doing it!” cried Washington. “We’re
falling into th’ terrible pit an’ we’re goin’ t’ be roasted alive!”

“It certainly is getting warmer,” observed Mark, as he took off his
coat. Soon he had to shed his vest, and Jack and the professor followed
his example. The others too, also found all superfluous garments a
burden, and, in a little while they were going about in scanty attire.

Still the heat increased, until it was almost torture to remain in the
engine room. Nor was it much cooler elsewhere. In vain did the professor
set a score of big electric fans to whirring. He even placed cakes of
ice, from the small ice machine that was carried, in front of the
revolving blades, to cool off the air. But the ice was melted almost as
soon as it was taken from the apparatus.

“Them flames is gittin worser!” Washington cried a little later. “We’s
comin’ nearer!”

From the bottom window the professor and the boys looked down. True
enough the curious, changing, vari-colored lights seemed brighter. They
could almost see the tongues of flame shooting upward in anticipation of
what they were soon to devour.

The heat was increasing every minute. The sides of the ship were hot.
The heads of the travelers were getting dizzy. They could hardly talk or
move about.

“I must save our lives! I must trust to the——” The professor, who was
muttering to himself started toward the storeroom. As in a dream Mark
watched him. He remembered afterward that he had speculated on what
might be the outcome of the mystery the professor threw about the place.
“I will have to use it,” he heard the scientist say softly.

Just as Mr. Henderson was about to open the door there came a fiercer
blast of heat than any that had preceded. At the same instant the
conditions in the _Mermaid_ became so fearful that each of the travelers
felt himself fainting away.

“Go to—storeroom—get cylinder—get in——” the professor murmured, and
then he fell forward in a faint.

CHAPTER XVI

THE NEW LAND

“What is it? Tell us!” exclaimed Jack, almost in his last breath, for, a
few seconds later he too toppled over senseless. Then Washington went
down, while Andy, Bill and Tom succumbed to the terrible heat.

Mark felt his head swimming. His eyes were almost bulging from their
sockets. He dimly remembered trying to force himself to go to the
storeroom and see what was there. He started toward it with that
intention, but fell half way to it.

As he did so he saw something which impressed itself on his mind, half
unconscious as he was.

The door of the storeroom suddenly opened, and from it came a giant
shape, that seemed to expand until it filled the whole of the apartment
where the stricken ones lay. It was like the form of some monster, half
human, half beast. Mark shuddered, and then, closing his eyes, he felt
himself sinking down into some terrible deep and black pit. A second
later the whole ship was jarred as though it had hit something.

How long he and the others remained unconscious Mark did not know. He
was the first to revive, and his first sensation was one as though he
had slept hard and long, and did not want to get up. He felt very
comfortable, although he was lying flat on the floor, with his head
jammed against the side of a locker. It was so dark that he could not
distinguish his hand held close to his face.

“I wonder if I’m dead, and if all the others are dead too,” he thought
to himself. “What has happened? Let’s see, the last I remember was some
horrible shape rushing from the storeroom. I wonder what it could have
been? Surely that was not the secret the professor referred to.”

Mark shuddered as he recalled the monster that seemed to have grown more
terrible as each second passed. Then the boy raised himself up from his
prostrate position.

“Well, at any rate, some one has turned off the heat,” he murmured.
“It’s very comfortable in here now. I wish I could strike a light.”

He listened intently, to learn if any of the others were moving about.
He could hear them breathing, but so faintly as to indicate they were
insensible. Mark stretched out his hand and felt that some one was lying
close to him, but who of the adventurers it was he could not determine.

“If only the dynamo was working we could have light,” he said. “But it
seems to have stopped,” and, indeed there was a lacking of the familiar
purr and hum of the electrical machine. In fact none of the apparatus in
the ship was working.

“The storage battery!” exclaimed Mark. “That would give light for a
while, if I can only find the switch in the dark.”

He began crawling about on his hands and knees. It was so intensely
black that he ran into many things and received severe bruises. At last
he came to a doorway, and as he did so his hand came in contact with an
easy chair. It was the only one aboard, and by that he knew he had
passed into the sitting room. He had his general direction now, and knew
if he kept straight on he would come to the engine room. There he was
familiar enough with the apparatus and levers to be able to turn the
electric switch.

Crawling slowly and cautiously, he reached the room where all the
engines were. Then he had to feel around the sides to locate the switch.
At length he found it. There was a click, a little flash of greenish
fire, and the copper conductors came together, and the ship was flooded
with the glow from the incandescents.

Mark hurried back to where the others were lying. They were still
unconscious, but an uneasy movement on the part of Jack told that he was
coming out of the stupor. Mark got some ammonia and held it beneath his
comrade’s nose. The strong fumes completed the work that nature had
started and Jack opened his eyes.

“Where am I? What has happened? Are any of them dead?” he asked quickly.

“I hope no one is dead,” Mark replied. “As to the other question, I
can’t answer. I don’t know whether we are a thousand miles underground,
or floating on the ocean, though I’m more inclined to the former theory.
But never mind that now. Help me to bring the others back to their
senses. I’ll work on the professor and you can begin on Bill or Tom.
Washington seems to be all right,” for at that moment the colored man
opened his eyes, stared about him and then got up.

“I thought I was dead for suah!” he exclaimed.

“Some of the others may be if we don’t hurry,” said Mark. “Get to work,
Wash!”

With the colored man to help them the two boys, by the use of the
ammonia, succeeded in reviving Bill, Tom and old Andy. But the
professor, probably on account of his advanced age, did not respond so
readily to the treatment. The boys were getting quite alarmed, as even
some of the diluted ammonia, forced between his lips, did not cause him
to open his eyes, or increase his heart action.

“If he should die, and leave us all alone with the ship in this terrible
place, what would we do?” asked Jack.

“He’s not going to die!” exclaimed Mark. “Here I have another plan.
Washington bring that medical electrical battery from the engine room.”
This was a small machine the professor had brought along for
experimental purposes.

Quickly adjusting it, Mark placed the handles in the nerveless fingers
of Mr. Henderson. Then he started the current. In about a minute the
eyelids of the aged inventor began to quiver, and, in less than five
minutes he had been revived sufficiently to enable him to sit up. He
passed his hand across his forehead.

“What has happened?” he asked in a faint voice.

“I don’t know; none of us knows,” Mark answered. “We all lost our senses
when it got so hot, and there seemed to be some peculiar vapor in the
air. The last I remember was seeing some horrible shape rush from the
storeroom, soon after the ship struck. Then I fainted away. When I woke
up I managed to turn the lights on, and then I came back here.”

“I wonder where we are,” the old man murmured. “I must find out. We must
take every precaution. Washington, go and look at the gage indicating
our depth.”

The colored man was gone but a few seconds. When he returned his eyes
were bulging in terror.

“What is it?” asked Mr. Henderson, who, thanks to the battery, had
almost completely recovered.

“It ain’t possible!” gasped Washington. “I’ll never believe it!”

“What is it?” asked Mr. Henderson, while the others waited in anxiety
for the answer.

“We’re five hundred miles down!” declared Washington.

“Five hundred miles!” muttered the inventor. “It does not seem possible,
but it must be so. We fell very rapidly and the terrible draught sucked
us down with incredible rapidity. But come, we must see what our
situation is, and where we are. We are stationary, and are evidently on
some solid substance.”

They all felt much recovered now, and, as the terrible fright of being
consumed in a fiery furnace had passed, they all were in better spirits.

At the suggestion of the professor, the boys and Washington made a tour
of the ship. They found, for some unaccountable reason, that nearly all
the engines and apparatuses were out of gear. In some the parts had
broken, and others were merely stopped, from the failure of some other
machine, on which they were dependent.

“I’m afraid this is the end of the _Mermaid,”_ said Mark, in a sorrowful
tone.

“Nonsense!” replied Jack, who was of a more cheerful nature. “Things are
not so bad as they look. The professor can fix everything.”

“I’m sure I hope so,” Mark went on, not much encouraged, however, by
Jack’s philosophy. “It would be no joke to have to stay five hundred
miles underground the rest of our lives.”

“You don’t know,” retorted Jack. “Don’t judge of a country you’ve never
seen. This may be as fine a place as it is on the surface of the earth.
I want a chance to see it,” and Jack began to whistle a cheerful tune.

They completed the tour of the ship, and found, that, aside from the
damage to the machinery, the _Mermaid_ had not sustained any harm. The
hull was in good order, though of course they could not tell about the
gas holder. It was not possible to see this except by going into the
conning tower or out on the small deck, and this they did not venture to
do. The connections between the holder and the main ship seemed to be
all right, and there was still a small quantity of gas in the big tank,
as Mark found on opening a stop-cock.

They went back to the professor and told him what they had observed. He
seemed somewhat alarmed, the more so as the experience he had just
passed through had weakened him considerably.

“I hope I shall be able to make the repairs,” he said. “It is our only
hope.”

As he spoke he looked up at the electric lights that shone overhead from
wall brackets.

“Who is shutting down the power?” he asked.

“There is no power on, Professor,” replied Mark. “I am running the
lights from the storage battery. But something is the matter, for they
are growing dim.”

The filaments were now mere dull red wires, and the ship was being
shrouded in gloom again.

“The battery is failing!” exclaimed Mr. Henderson. “We shall be left in
darkness, and there is no other way to produce light. I ought to have
brought some lamps or candles along in case of emergency.”

The next instant the _Mermaid_ became as black as Egypt is popularly
supposed to be, and something like an exclamation of terror came from
the professor.

For several minutes they all sat there in the blackness and gloom,
waiting for they knew not what. Then, suddenly, there sounded throughout
the ship, a creaking as of metal sliding along metal. Some big lever
creaked, and, a second later the whole place was flooded with light.

“What has happened?” cried the professor, starting to his feet in alarm.

“We are going to be burned up!” exclaimed old Andy.

“It’s all right! It’s all right!” yelled Washington from the engine room
where the boys had left him. “Don’t git skeered! I done it! I opened the
port holes, by yanking on the lever. Golly, but we’s arrived at the new
land! Look out, everybody!”

CHAPTER XVII

A STRANGE COUNTRY

They all ran to the port holes, which were openings in the side of the
ship. They were fitted with thick, double glass, and covered on the
outside with steel shutters. These shutters were worked by a single
lever from the engine room, so that one person could open or close them
in a second or two. Washington, by accident, it appeared later, had slid
back the protecting pieces of steel, and the rest followed.

As the adventurers looked from the glass ports they saw that the light
which had flooded the ship came from without. They were in the midst of
a beautiful glow, which seemed to be diffused about them like rays from
a sun.

Only, in place of being a yellow or white light, such as the sun gives
off at varying times, the glow was of violet hue. And, as they watched,
they saw the light change color, becoming a beautiful red, then blue,
and again green.

“Well, this is certainly remarkable!” the professor said. “I wonder what
causes that.”

“We’ve arrived! We’re here, anyhow!” Washington cried, coming into the
room. “See the country!”

Then, for the first time, the travelers, taking their attention from the
curious light that was all around them, saw that they had indeed
arrived. They were on a vast plain, one, seemingly, boundless in extent,
though off to the left there was a range of lofty mountains, while to
the right there was the glimmer of what might be a big lake or inland
sea.

“See, we are resting on the ground!” exclaimed Jack. He pointed out of
the window, and the others, looking close at hand, noted that the
_Mermaid_ had settled down in the midst of what seemed to be a field of
flowers. Big red and yellow blossoms were all in front, and some grew so
tall as to almost be up to the edge of the port.

“I wonder if we can be seeing aright,” the professor muttered. “Is this
really the interior of the earth; such a beautiful place as this?”

There could be little doubt of it. The ship had descended through the
big shaft, had been sucked down by the terrible air current, and had
really landed in a strange country.

Of its size, shape and general conditions the adventurers, as yet, could
but guess. They could see it was a pleasant place, and one where there
might be the means to sustain life. For, as the professor said
afterward, he felt that where there were flowers there would be fruits,
and where both of these provisions of nature were to be found there
would likely be animal life, and even, perhaps, human beings.

But, for the time, they were content to look from the port on the
beautiful scene that lay stretched out before them. The ship rested on
an even keel and had landed so softly that none of the plates were
strained.

“We have plenty of air, at all events,” said the professor as he took a
deep breath. “I was afraid of that, but it seems there was no need. The
air appears to be as good and fresh as that on the surface of the earth,
only there is a curious property to it. It makes one feel larger. I
imagine it must be thinner than the air of the earth, which is a rather
strange thing, since the higher one goes the more rarefied the air
becomes, and the lower, the more dense. Still we can not apply natural
philosophy to conditions under the earth. All the usual theories may be
upset. However, we should be content to take things as we find them, and
be glad we were not dashed to pieces when the ship was caught in the
terrible current.”

“What do you suppose caused the awful heat, and then made it go away
again?” asked Jack.

“I can only make a guess at it,” Mr. Henderson answered. “There are many
strange things we will come across if we stay here long, I believe. As
for the fire I think we must have passed a sort of interior volcano.”

“But what sort of a place do you think we have come to, Professor?”
asked Mark.

“It is hard to say,” the scientist replied. “We are certainly somewhere
within the earth. Our gage tells us it is five hundred miles. That may
or may not be correct, but I believe we are several hundred miles under
the crust, at all events. As to what sort of a place it is, you can see
for yourselves.”

“But how is it we can breathe here, and things can grow?” asked Bill,
who was beginning to lose his fright at the thought of being practically
buried alive.

“I do not know what makes such things possible,” Mr. Henderson replied,
“but that there is air here is a certainty. I can hardly believe it is
drawn from the surface of the earth, down the big hole, and I am
inclined to think this place of the under-world has an atmosphere of its
own, and one which produces different effects than does our own.”

“They certainly have larger flowers than we have,” said Mark. “See how
big they grow, and what strong colors they have.”

He pointed to the port, against which some of the blooms were nodding in
the wind that had sprung up, for, in spite of the many differences, the
under-world was in some respects like the upper one.

“Probably the difference in the atmosphere accounts for that,” the
professor said. “It enables things to grow larger. And, by the way,
Mark, that reminds me of something you said about seeing some horrible
monster fleeing from the ship. Did you dream that?”

“I did see something horrible, Professor,” he answered. “I’m not
positive what it was, but I’ll tell you as nearly as I can what it was
like.”

Thereupon Mark detailed what he had seen.

“But how could anything, least of all some big monster, be concealed in
the storeroom, and we not know anything about it?” asked Mr. Henderson.

“I thought you did know something of it,” replied Mark.

“Who, me? My dear boy, you must be dreaming again. Why should I want to
conceal any being in the storeroom? Come, there is something back of
this. Tell me all you know of it. I can’t imagine why you think I was
hiding something in the apartment.”

“I thought so because you were always so anxious not to have me go near
it,” answered the boy. “Don’t you remember when you saw me going toward
it, several times, you warned me away?”

“So I did!” exclaimed Mr. Henderson, a light breaking over his face.
“But, Mark, it was not because I had hidden some human being or animal
there. I can’t tell you what it is yet, save that I can say it is merely
a machine of mine that I have invented. For reasons of my own I don’t
want any one to see it yet. Perhaps it may never be seen. I thought, not
long ago, that we might have to undertake a terrible risk in escaping
from this place. I directed you to go to the storeroom—but there, I
can’t say any more, my friends. Sufficient that I had nothing in the
animal line concealed there.”

“But I am certain there was some beast or human being in there,”
insisted Mark. “I heard curious noises in there. Besides, how do you
account for the food disappearing and the door being open at times?”

“It might have been rats,” said Jack.

“I don’t believe there are rats in the ship,” put in the professor.
“More likely it was one of us who got up hungry and took the victuals.”

“I’m sorry I can’t agree with you,” Mark added respectfully. “I am sure
some strange being was on board this ship, and I believe it has now
escaped. Who or what it was I can’t say, but you’ll find I’m right, some
day.”

“All right,” spoke Mr. Henderson with a laugh. “I like to see any one
brave enough to stick up for his opinion, but, at the same time, I can’t
very well imagine any person or thing being concealed in that storeroom
ever since we started. How could it get in?”

Mark did not answer, but there came to him the recollection of that
night, previous to the sailing of the _Flying Mermaid_, when he had
observed some strange shadow that seemed to glide aboard the craft.

“Now let’s forget all about such things,” the professor went on. “We are
in a strange country, and there are many things to see and do. Let’s
explore a little. Then we must see what we can do with the ship. We are
dependent on it, and it will not do to allow it to remain in a damaged
state. We expect to travel many miles in the interior of the earth if it
is possible, and we have only our craft to go in.”

“I reckon we’d all better assimilate into our interior progression some
molecules and atoms of partly disentegrated matter in order to supply
combustion for the carbonaceous elements and assist in the manufacture
of red corpuscles,” said Washington, appearing in the door, with a broad
grin on his good-natured face.

“Which, being interpreted,” the professor said, “means, I suppose, that
we had better eat something to keep our digestive apparatus in good
working order?”

“Yo’ done guessed it!” exclaimed the colored man, relapsing into his
ordinary speech. “I’se got a meal all ready.”

They agreed that they might not have another opportunity soon to partake
of food, so they all gathered about the table, on which Washington had
spread a good meal.

“Come on, let’s go outside and view this new and strange land at closer
quarters,” the professor said, when they had satisfied their appetites.
“We can’t see much from inside the ship.”

Accordingly the heavy door in the side of the _Mermaid_ was slid back,
and, for the first time the travelers stepped out on the surface of the
land in the interior of the earth.

At first it seemed no different than the ordinary land to which they
were accustomed. But they soon found it had many strange attributes. The
queer shifting and changing light, with the myriad of hues was one of
them, but to this the adventurers had, by this time, become accustomed,
though it was, none the less, a marvel to them. It was odd enough to see
the landscape blood red one instant, and a pale green the next, as it
does when you look through differently colored glasses.

Then, too, they noticed that the grass and flowers grew much more
abundantly than in the outer part of the world. They saw clover six feet
high, and blades of grass even taller. In some places the growth of
grass was so big that they were in danger of getting lost in it.

“If the grass is like this, what will the trees be?” asked Mark.

“There are some away over there,” Jack replied. “We’ll have to take a
sail over. They must be several hundred feet high.”

“Well, at any rate, here’s a little brook, and the water looks good to
drink,” went on Mark. “I’m thirsty, so here goes.”

He hurried to where a stream was flowing sluggishly between grassy
banks. The water was as clear as crystal, and Mark got down on his face
and prepared to sip some of the liquid up.

But, no sooner had his lips touched it, than he sprang up with a cry and
stood gazing at the water.

“What’s the matter?” asked Jack. “Hot?”

“No, it isn’t hot,” Mark replied, “but it isn’t water. It’s white
molasses!”

“White molasses?” repeated the professor, coming up at that moment.
“What are you talking about?”

He stooped down and dipped his finger into the stream. He drew it up
quickly, and there ran from it big drops that flowed as slowly as the
extract of the sugarcane does in cold weather.

“You’re about right, Mark,” he said. “It’s water but it’s almost as
thick as molasses.” He touched his finger to his tongue. “It’s good to
drink, all right,” he went on, “only it will be a little slow going
down.”

Then he dipped up a palm full, and let it trickle down his throat.

“It is the strangest water I ever saw,” he added. “It must be that the
lack of some peculiar property of air, which we have on the surface, has
caused this. I must make some notes on it,” and he drew out pencil and
paper. He was about to jot down some facts when he was interrupted by a
cry from Washington.

“Come and see what’s the matter with this stone!” he cried.

CHAPTER XVIII

CAUGHT BY A STRANGE PLANT

“Washington is in trouble!” exclaimed Mr. Henderson. Followed by the two
boys he ran to where the colored man stood in a stooping position over a
small pile of stones.

“What is it? Has something bit you?” asked the scientist, as he came up
on the run.

“No, but I can’t git this stone up!” Washington said. “Look at what a
little stone it is, but I can’t lift it. Something must have happened to
me. Maybe some one put th’ evil eye on me! Maybe I’m bewitched!”

“Nonsense!” exclaimed the professor, “what did you want the stone for?”

“Nothin’ in particular,” replied Washington, still tugging away at the
stone, which was the size of his head. “I was just goin’ t’ throw it at
a big bird, but when I went to lift it this little stone 'peared t’ be
glued fast.”

Washington moved aside to give Mr. Henderson a chance to try to pick up
the piece of rock. As the scientist grasped it a look of surprise came
over his features:

“This is most remarkable!” he exclaimed. “I can’t budge it. I wonder if
a giant magnet is holding it down.”

He tugged and tugged until he was red in the face. Then he beckoned to
the two boys, and they came to his aid. There was barely room for them
all to each get one hand on the rock, and then, only after a powerful
tug did it come up. Almost instantly it dropped back to the earth.

“This is remarkable!” the professor said. “I wonder if the other stones
are the same.”

He tried several others, and one and all resisted his efforts. It was
only the small stones he was able to lift alone, and these, he said,
were so weighty that it would have been a task to throw them any
distance.

“The water and the stones are strangely heavy in this land,” he said. “I
wonder what other queer things we shall see.”

“I saw a bird a little while ago, when I went to pick up that stone,”
observed Washington.

“What kind was it?” asked the inventor.

“I don’t know, only it was about as big as an eagle.”

The travelers wandered about a quarter of a mile from the ship. They
avoided the tall grass and the lofty nodding flowers that seemed to grow
in regular groves, and kept to places where they could walk with
comparative freedom.

“Have you formed any idea, Professor, as to the nature of this country?”
asked Mark, who liked to get at the bottom of things.

“I have, but it is only a theory,” Mr. Henderson answered. “I believe we
are on a sort of small earth that is inside the larger one we live on.
This sphere floats in space, just as our earth does and we have passed
through the void that lies between our globe and this interior one. I
think this new earth is about a quarter the size of ours and in some
respects the same. In others it is vastly different.

“But we will not think of those things now. We must see what our
situation is, whether we are in any danger, and must look to repairing
our ship. There will be time enough for other matters later.”

The travelers were walking slowly along, noting the strange things on
every side. As they advanced the vegetation seemed to become more
luxuriant, as if nature had tried to out-do herself in providing
beautiful flowers and plants. The changing lights added to the beauty
and weirdness of the scene.

The plain was a rolling one, and here and there were small hills and
hollows. As the travelers topped a rise Jack, who was in advance, called
out:

“Oh what queer plants! They are giant Jacks-in-the-pulpit!”

The others hastened forward to see what the boy had discovered. Jack was
too eager to wait, and pressed on. The hill which sloped away from the
top of the little plateau on which he stood, was steeper than he had
counted on. As he leaned forward he lost his balance and toppled, head
foremost, down the declivity, rolling over.

“Look out!” cried Mark, who had almost reached his comrade’s side.

The scene that confronted the travelers was a strange one. Before them
in a sort of hollow, were scores of big plants, shaped somewhat like a
Jack-in-the-pulpit, or a big lily, with a curved top or flap to it.

The plants were about eight feet tall, three feet across the top, and
the flap or covering was raised about two feet. They were nodding and
swaying in the wind on their short stems.

“He’s headed right for one of them!” Mr. Henderson exclaimed. “I hope
he’ll not fall into one of the openings.”

“Is there any danger?” asked Mark.

“I’m afraid there is,” the inventor added. “Those plants are a variety
of the well-known pitcher plant, or fly-trap, as they are sometimes
called. In tropical countries they grow to a large size, but nothing
like these. They are filled, in the cup, with a sort of sticky, sweet
mixture, and this attracts insects. When one enters the cup the top flap
folds over, and the hapless insect is caught there. The plant actually
devours it, nature providing a sort of vegetable digestive apparatus.
These giant plants are the same, and they seem large enough to take in a
man, to say nothing of Jack!”

With anxious faces the adventurers turned to watch the fate of their
comrade. Jack was slipping, sliding and rolling down the hill. He could
not seem to stop, though he was making desperate efforts to do so. He
was headed straight for one of the largest of the terrible plants.

In vain, as he saw what was in front of him, did he try to change the
course of his involuntary voyage. Over and over he rolled, until, at
length, he struck a little grassy hummock, bounced into the air, and
right into the opening of a monster pitcher plant.

“It has him!” cried Mark. “We must save him! Come on everyone!”

He raced down the hill, while the others came closely after him. They
reached the plant into which Jack had bounced. The flap, or top piece,
had closed down, tightly over the unfortunate boy.

“Quick! We must save him or he will be smothered to death or drowned in
the liquid the cup contains!” Mr. Henderson exclaimed. “Attack the plant
with anything you can find!”

“Let’s cut through the side of the flower-cup!” suggested Mark. “That
seems softer than the stem.”

His idea was quickly put into operation. Andy’s long hunting knife came
in very handy. While the sides of the long natural cup were tough, the
knife made an impression on them, and, soon, a small door or opening had
been cut in the side of the pitcher plant, large enough to enable a
human body to pass through.

When the last fibre had been severed by Andy, who was chosen to wield
the knife because of his long practice as a hunter, there was a sudden
commotion within the plant. Then a dark object, dripping water, made a
spring and landed almost at the feet of the professor.

It was Jack, and a sorry sight he presented. He was covered from head to
foot with some sticky substance, which dripped from all over him.

With hasty movements he cleared the stuff from his eyes and mouth, and
spluttered:

“It’s a good thing you cut me out when you did. I couldn’t have held on
much longer!”

CHAPTER XIX

THE BIG PEACH

Jack soon recovered from his remarkable experience. The terrible plant
that had nearly eaten him alive was a mass of cut-up vegetable matter
which attracted a swarm of insects. Most of them were ants, but such
large ones the boys had never seen before, and the professor said they
exceeded in size anything he had read about. Some of them were as large
as big rats. They bit off large pieces of the fallen plant and carried
them to holes in the ground which were big enough for Washington to slip
his foot into, and he wore a No. 11 shoe.

But the adventurers felt there were more important things for them to
look at than ants, so they started away again, the professor telling
them all to be careful and avoid accidents.

It was while they were strolling through a little glade, which they came
upon unexpectedly, that Washington, who was in the lead called out:

“Gracious goodness! It must be Thanksgivin’!”

“Why so?” asked Jack.

“'Cause here’s th’ remarkablest extraordinary and expansionist of a
pumpkin that ever I laid eyes on!” the colored man cried.

They all hurried to where Washington had come to a halt. There, on the
ground in front of him, was a big round object, about the size of a
hogshead. It was yellow in color, and was not unlike the golden
vegetable from which mothers make such delicious pies.

“I allers was fond of pumpkins,” said Washington, placing his hand on
the thing, which was almost as tall as he was, “but I never thought I’d
come across such a one as this.”

The professor and the two boys went closer to the monstrosity. Mr.
Henderson passed his hand over it and then, bending closer, smelled of
it.

“That’s not a pumpkin!” he exclaimed.

“What is it then?” asked Washington.

“It’s a giant peach,” the inventor remarked. “Can’t you see the fuzz,
and smell it? Of course it’s a peach.”

“Well I’ll be horn-swoggled!” cried Washington, leaning against the big
fruit, which easily supported him.

“Hurrah!” cried Jack, drawing his knife from his pocket and opening the
largest blade. “I always did like peaches. Now I can have all I want,”
and he drove the steel into the object, cutting off a big slice which he
began to eat.

“It may be poisonous!” exclaimed Mark.

“Too late now,” responded Jack, the juice running down from his mouth.
“Taste’s good, anyhow.”

They all watched Jack while he devoured his slice of fruit. Washington
acted as if he expected his friend to topple over unconscious, but Jack
showed no bad symptoms.

“You’d better all have some,” the boy said. “It’s the best I ever
tasted.”

Encouraged by Jack’s example, Mark thought he, too, would have some of
the fruit. He opened his knife and was about to take off some of the
peach when suddenly the thing began to roll forward, almost upon him.

“Hi! Stop your shoving!” he exclaimed. “Do you want to have the thing
roll over me, Jack?”

“I’m not shoving!” replied Jack.

“Some one is!” Mark went on. He dodged around the far side of the
immense fruit and what he saw made him cry out in astonishment.

Two grasshoppers, each one standing about three feet high, were standing
on their hind legs, and with their fore feet were pushing the peach
along the ground. They had been attracted to the fruit by some juice
which escaped from a bruise on that side, which was the ripest, and,
being fond of sweets had, evidently decided to take their find to some
safe place where they could eat it at their leisure. Or perhaps they
wanted to provide for their families if grasshoppers have them.

“Did you ever see such monsters?” asked Jack. “They’re as big as dogs!”

At the sound of his voice the two grasshoppers, becoming alarmed, ceased
their endeavors to roll the peach along, and, assuming a crouching
attitude seemed to be waiting.

“They certainly are remarkable specimens,” Mr. Henderson said. “If the
other animals are in proportion, and if there are persons in this new
world, we are likely to have a hard time of it.”

This time the immense insects concluded the strangers were not to their
liking. With a snapping of their big muscular legs and a whirr of their
wings that was like the starting of an automobile, the grasshoppers rose
into the air and sailed away over the heads of the adventurers. Their
flight was more than an eighth of a mile in extent, and they came down
in a patch of the very tall grass.

“Let’s go after them!” exclaimed old Andy. “I was so excited I forgot to
take a shot at them. Come on!”

“I think we’d better not,” counseled the professor. “In the first place
we don’t need them. They would be no good for food. Then we don’t know
but what they might attack us, and it would be no joke to be bitten by a
grasshopper of that size. Let them alone. We may find other game which
will need your attention, Andy. Better save your ammunition.”

Somewhat against his will, Andy had to submit to the professor’s ruling.
The old hunter consoled himself with the reflection that if insects grew
to that size he would have some excellent sport hunting even the birds
of the inner world.

“I wonder what sort of a tree that peach grew on,” Jack remarked, as he
cut off another slice, when the excitement caused by the discovery of
the grasshoppers had subsided. “It must be taller than a church steeple.
I wonder how the fruit got here, for there are no trees around.”

“I fancy those insects rolled it along for a good distance,” Mr.
Henderson put in. “You can see the marks on the ground, where they
pushed it. They are wonderful creatures.”

“Are we going any farther?” asked Mark. “Perhaps we can find the peach
tree, and, likely there are other fruit trees near it.”

At the professor’s suggestion they strolled along for some distance.
They were now about three miles from the airship, and found that what
they had supposed was a rather level plain, was becoming a succession of
hills and hollows. It was while descending into a rather deep valley
that Jack pointed ahead and exclaimed:

“I guess there’s our peach orchard, but I never saw one like it before.”

Nor had any of the others. Instead of trees the peaches were attached to
vines growing along the ground. They covered a large part of the valley,
and the peaches, some bigger than the one they first discovered, some
small and green, rose up amid the vines, just as pumpkins do in a corn
field.

“Stranger and stranger,” the professor murmured. “Peaches grow on vines.
I suppose potatoes will grow on trees. Everything seems to be reversed
here.”

They made their way down toward the peach “orchard” as Jack called it,
though “patch” would have been a better name. Besides peaches they found
plums, apples, and pears growing in the same way, and all of a size
proportionate to the first-named fruit.

“Well, one thing is evident,” Mr. Henderson remarked, “we shall not
starve here. There is plenty to eat, even, if we have to turn
vegetarians.”

“I wonder what time it is getting to be,” Jack remarked. “My watch says
twelve o’clock but whether it’s noon or midnight I can’t tell, with this
colored light coming and going. I wonder if it ever sets as the sun
does.”

“That is something we’ll have to get used to,” the professor said. “But
I think we had better go back to the ship now. We have many things to do
to get it in order again. Besides, I am a little afraid to leave it
unguarded so long. No telling but what some strange beast—or persons,
for that matter—might injure it.”

“I’m going to take back some slices of peaches with me, anyhow,” Mark
said, and he and Jack cut off enough to make several meals, while Bill,
Tom and Washington took along all they could carry.

As they walked back toward the ship the strange lights seemed to be
dying out. At first they hardly noticed this, but as they continued on
it became quite gloomy, and an odd sort of gloom it was too, first
green, then yellow, then red and then blue.

“I believe whatever serves as a sun down here is setting,” the professor
observed. “We must hurry. I don’t want to be caught out here after
dark.”

They hurried on, the lights dying out more and more, until, as they came
in sight of their ship, it was so black they could hardly see.

Mark who was in the rear turned around, glancing behind him. As he did
so he caught sight of a gigantic shadow moving along on top of the
nearest hill. The shadow was not unlike that of a man in shape, but of
such gigantic stature that Mark knew it could be like no human being he
had ever seen. At the same time it bore a curious resemblance to the
weird shadow he had seen slip into the _Mermaid_ that night before they
sailed.

“I wonder if it can be the same—the same thing—grown larger, just as
the peach grows larger than those in our world,” Mark thought, while a
shiver of fear seemed to go over him. “I wonder if that—that thing
could have been on the ship——”

Then the last rays of light died away and there was total darkness.

CHAPTER XX

OVERHAULING THE SHIP

“Keep together!” shouted the professor. “It will not do to become lost
now. We are close to the ship, and will soon be there. Come after me.”

It was more by following the sound of the scientist’s voice, than by any
sight which the others could get of him, that they managed to trail
along behind. They reached the ship in safety, however, and entered.
There was no sound as of beasts or insects within, and, though Mark felt
a little apprehensive on account of what he had seen, he and the others
as well, were glad to be again in something that seemed like home.

“I wish we had some candles, or some sort of a light to see by,” the
professor remarked. “We can do nothing in the dark, and there is no
telling how long this night is going to last once it has set in. If I
could have a little illumination, I might be able to fix the dynamo, and
then we could turn on the incandescents. That portable light we had is
broken.”

“By cracky!” exclaimed Andy. “I believe I have the very thing!”

“You don’t mean to say you have a torch or a candle with you, do you?”
asked Mr. Henderson.

“No, but I have my patent pipe lighting apparatus,” the hunter said. “I
always carry it. It gives a little light, but not much, though it may be
enough to work by.”

Not until after several hours work, handicapped as they were by lack of
light, were the repairs to the ship completed.

“Now we’ll start the engine and see how we will come out,” the inventor
exclaimed, as he wiped his hands on some waste.

It did not take long to generate enough power to turn the dynamo. Soon
the familiar hum and whirr was heard, and, a few seconds later the
filaments in the lamps began to glow a dull red, which gradually
brightened until they were shining in all their usual brilliancy.

“Hurrah!” cried the boys. “Now we can see!”

They all felt in better spirits with the restoration of the lights, and,
washing off the grease and dirt of their labors in the engine room, they
prepared to sit down to the meal which Washington prepared.

As soon as the dynamo was working well, care had to be taken not to
speed it too much on account of a mended belt. The professor turned off
part of the lights and switched some of the current into the storage
batteries, to provide for emergencies. For there was no telling how long
the night might last.

Jack was the first one to finish the meal—they did not know whether to
call it dinner, supper or breakfast. He went into the conning tower,
and, as soon as he reached it he called out:

“Come on up here, professor! There’s something strange going on!”

Mr. Henderson, followed by Mark, hurried to the tower. As he reached it
and looked out of the forward window, a beautiful white glow illuminated
the whole scene, and then, from below the horizon, there arose seven
luminous disks. One was in the centre, while about it circled the other
six, like some immense pin-wheel.

“It’s the moon!” cried Mark.

“It’s seven moons!” Jack exclaimed. “Why it’s almost as light as day!”

And so it was, for the seven moons, if that is what they were, gave an
illumination not unlike the sun in brilliancy though it was like the
beams from the pale moon of the earth.

“I guess we need not have worried about the darkness,” the professor
remarked. “Still it is a good thing I fixed the dynamo.”

For some time he and the other adventurers watched the odd sight of the
moons, as they rose higher and higher overhead. The scene was a
beautiful, if weird one, for the whole plain was bathed in the soft
light.

“I guess we can turn off the incandescents, and use all the power for
the storage batteries,” Mr. Henderson went on, as he descended into the
ship, and opened the port shutters which had been closed when they
started off on their exploring tour. The interior of the _Mermaid_ was
almost as light as when the odd colored beams had been playing over the
new earth to which they had come.

“I think we had better continue with our work of making repairs,” Mr.
Henderson said. “We can’t count on these moons remaining here any length
of time, and I want to take advantage of them. So though some of us
perhaps need sleep, we will forego it and fix up the _Mermaid_. I want
to take a trip and see what other wonders await us.”

They all agreed that they would rather work than sleep, and soon the
entire force was busy in the engine room. There was much to be done, and
the most important things were attended to first. The motive power was
overhauled and found to be in need of several new parts. These were put
in and then the gas generator, and the negative gravity machine, were
put in shape.

It would have taken something very substantial to have awakened any one
on board the _Mermaid_ that night. They all slept soundly and awoke to
find the strange colored lights shining in through the glass covered
port holes.

“Well, the sun, or what corresponds to it, is up,” observed Jack, “and I
guess we had better do as the little boy in the school reader did, and
get up, too, Mark.”

Soon all the travelers were aroused, and the sound of Washington
bustling about in the kitchen, whence came the smell of coffee, bacon
and eggs, told the hungry ones that breakfast was under way.

After the meal work was again started on repairing the ship, and by noon
the professor remarked:

“I think we shall try a little flight after dinner. That is, if one
thing doesn’t prevent us.”

“What is that?” asked Jack.

“We may be held down, as were those stones,” was the grave answer.

CHAPTER XXI

THE FISH THAT WALKED

It was with no little apprehension that the professor prepared to take
his first flight aboard the ship in the realms of the new world. He knew
little or nothing of the conditions he might meet with, the density of
the atmosphere, or how the _Mermaid_ would behave under another
environment than that to which she was accustomed.

Yet he felt it was necessary to make a start. They would have to attempt
a flight sooner or later, and Mr. Henderson was not the one to delay
matters. So, the last adjustment having been made to the repaired
machinery, they all took their places in the ship.

The boys and the professor went to the conning tower to direct matters,
while Washington and the others were in the engine room to see that the
machinery worked properly. Mark gave a last look outside as he closed
the big steel cover over the hole through which admission was had to the
craft. He thought he might catch a glimpse of the queer shadow, but
nothing was in sight. It was like a beautiful summer’s day, save for the
strange lights, shifting and changing. But the travelers had become
somewhat used to them by this time.

The professor turned the valve that allowed the gas to enter the holder.
There was a hissing sound and a sort of trembling throughout the entire
ship. The dynamos were whizzing away and the negative gravity machine
was all ready to start.

For several minutes the travelers waited until the big lifting tank was
filled with the strong vapor. They watched the gages which indicated the
pressure to be several hundred pounds.

“I think we can chance it now,” remarked Mr. Henderson, as he threw over
several levers. “We’ll try, at any rate.”

With a tremor the _Mermaid_ left the surface of the inner earth and went
sailing upward toward the—well it wasn’t exactly the sky, but it was
what corresponded to it in the new world, though there were no clouds
and no blue depths such as the boys were used to. At all events the
_Mermaid_ was flying again, and, as the adventurers felt themselves
being lifted up they gave a spontaneous cheer at the success which had
crowned their efforts.

The ship went up several hundred feet, and then, the professor, having
brought her to a stop, sent her ahead at a slow pace. He wanted to be
sure all the apparatus was in good working order before he tried any
speed.

The _Mermaid_ responded readily. Straight as an arrow through the air
she flew.

“Well, this is almost as good as being on the regular earth!” exclaimed
Jack.

“It’s better,” put in Mark. “We haven’t seen half the wonders yet. Let’s
open the floor shutter, and see how it looks down below.”

He and Jack went to the room where there was an opening in the floor of
the ship, covered by heavy glass. They slid back the steel shutter and
there, down below them, was the strange new world they had come to,
stretched out like some big map.

They could see mountains, forests, plains, and rivers, the water
sparkling in the colored light. Over green fields they flew, then across
some stretches where only sand and rocks were to be seen. Faster and
faster the ship went, as the professor found the machinery was once more
in perfect order. Jack was idly watching the play of tinted lights over
the surface of the ground.

“I wonder what makes it,” he said.

“I have tried to account for it in several ways,” said the professor,
who had called Washington to the conning tower and come to join the
boys. “I have had first one theory and then another, but the one I am
almost sure is correct is that hidden volcanic fires cause the
illumination.

“I think they flare up and die away, and have become so regular that
they produce the same effect as night and day with us. Probably the
fires go out for lack of fuel, and when it is supplied they start up
again. Perhaps it is a sort of gas that they burn.”

“Well, it’s queer enough, whatever it is,” Jack remarked. “What strikes
me as funny, though, is that we haven’t seen a single person since we
came here. Surely this place must be inhabited.”

Mark thought of the strange shadow he had seen, but said nothing.

“I believe it is,” the professor answered. “We will probably come upon
the inhabitants soon. I only hope they are a people who will do us no
harm.”

“If they tried any of their tricks we could mount up in our ship and
escape them,” said Andy.

“Provided they gave us the chance,” Mr. Henderson put in. “Well, we’ll
not worry about that now.”

For several hours the ship traveled on, until it had come to a different
sort of country. It was wilder and not so level, and there were a number
of streams and small lakes to be seen.

“Are you going to sail all night?” asked Jack.

“No,” replied the professor. “I think we’ll descend very soon now, and
camp out for a while. That lake just ahead seems to offer a good place,”
and he pointed to a large sheet of water that sparkled in the distance,
for by this time they had all gone back to the conning tower.

The lake was in the midst of a wood that extended for some distance on
all sides, and was down in a sort of valley. The ship headed toward it,
and in a short time a landing was made close to shore.

“Maybe we can have some fresh fish for supper,” exclaimed Jack as he ran
from the ship as soon as the sliding door in the side was opened. “Looks
as if that lake had some in it. It is not thick water like in that
stream we stopped at,” he added.

“I believe you’re right,” old Andy put in, as he turned back to look for
some lines and hooks among his traps. He soon found what he wanted, and
gave them to the boys, taking his trusty gun along for himself.

While the professor, Washington, Tom and Bill remained behind to make
some adjustments to the machinery, and to get things in shape for the
night, which, they calculated would soon be upon them, Jack, Mark and
Andy went down to the shore of the lake. The boys cut some poles from
the trees, and baiting the hooks with some fat worms found under the
bark, threw in.

“Let’s see who’ll get the first bite,” spoke Jack. “I’m pretty generally
lucky at fishing.”

“Well, while you’re waiting to decide that there contest, I think I’ll
take a stroll along shore and see if I can see anything to shoot,” Andy
remarked.

For several minutes the boys sat in silence on the bank of the lake,
watching the play of the vari-colored lights on the water. Suddenly Jack
felt a quiver on his line, and his pole began to shake.

“I’ve got something!” he cried. Then his pole bent almost double and he
began to pull for all he was worth. “It’s a whopper!” he cried. “Come
and help me, Mark!”

Mark ran to his friend’s aid. Whatever was on the other end of the line
was strong enough to tax the muscles of both boys. They could hear the
pole beginning to break. But for the excellent quality of Andy’s line
that would have parted some time before.

All at once there came a sudden slacking of the pull from whatever was
in the water. And so quickly did it cease that both boys went over
backward in a heap.

“He’s got away!” cried Jack, getting up and brushing some of the dirt
from his clothes.

“There’s something that didn’t get away!” cried Mark, who had risen to
his knees, and was pointing at the lake. Jack looked and what he saw
made him almost believe he was dreaming.

For, emerging from the water, dragging the pole and line the boys had
dropped along with it, was a most curious creature. It was a big fish,
but a fish with four short legs on which it was walking, or rather
waddling along as much as a duck, with a double supply of feet, might
do.

“Say, do I see that or is there something the matter with my eyes?” sung
out Jack, making ready to run away.

“It’s there all right!” exclaimed Mark. “Hi! Andy! Here’s something to
shoot!” he yelled, for indeed the creature was big enough to warrant
attack with a gun. It was about five feet long and two feet through.

On and on it came, straight at the boys, as if to have revenge for the
pain the fish hook must have caused it, for the barb could be seen
dangling from its lip. On and on it came, waddling forward, the water
dripping from it at every step. It had the body and general shape of a
fish, save that the tail was rather large in proportion. As it came
nearer the boys noted that the feet were webbed, like those of a water
fowl.

“Come on!” cried Jack. “It may attack us!”

At that moment the creature opened its mouth, showing a triple row of
formidable teeth, and gave utterance to a sort of groan and grunt
combined.

This was enough to send Jack and Mark off on a run up the bank, and did
they stop until they heard Andy’s voice hailing them.

“What’s the matter, boys?”

“Come here! Quick!” answered Jack.

The fish-animal had halted and seemed to be taking an observation. To do
this, as it could not turn its neck, it had to shift its whole body. Old
Andy came up on the run, his gun held in readiness.

“Where is it?” he asked, and the boys pointed silently.

The hunter could not repress a start of astonishment as he saw the
strange creature. But he did not hesitate a second. There was a crack of
the rifle, and the thing, whatever it was, toppled over, dead.

Andy hurried up to it, to get a closer view.

“Well, this is the limit!” he exclaimed. “First we have grasshoppers
that can roll peaches as big as hogsheads, and now we come across fish
that walk. I wonder what we will see next.”

“I don’t want to go fishing in this lake any more,” spoke Jack, as he
looked at the repulsive creature. “I never want to eat fish any more.”

“Same here,” agreed Mark, and old Andy was of the opinion that the thing
killed would not make a wholesome dish for the table.

“There don’t seem to be any game in this section,” he remarked. “Not a
sign could I see, nor have I since we have been here, unless you count
those grasshoppers. But the fruit is good, I’ll say that.”

“Come on, we’d better be getting back,” Mark said, as he noticed it was
getting dark. “I’m hungry.”

CHAPTER XXII

THE SNAKE-TREE

They managed to make a good meal of the food supplies they had brought
along, and as a dessert Washington made some peach short-cake from the
slices of the giant fruit they had found the day before. Just as they
finished supper it got very dark, but, in about an hour, the moonbeams,
as the travelers called them, came up, and illuminated the lake with a
weird light.

As the machinery of the _Mermaid_ was now in working order there was no
further alarm because of the darkness. The ship rested on a level keel
about a hundred yards back from the lake, and, seeing that all was snug,
and the fastenings secure, the travelers went to bed.

Though they had to forego fish for breakfast the travelers made a good
meal. After seeing that the ship was in readiness for a quick start, the
professor suggested they take a walk around and see what sort of country
they might be in now.

They tramped on for several miles, meeting with no adventures, and
seeing nothing out of the ordinary. It was a pleasant day, just warm
enough to be comfortable, and a little wind was blowing through the
trees.

“It would be almost like home if it wasn’t for the strange lights, and
the memory of the queer things here,” said Jack. “I feel fine. Let’s see
if you can hit that dead tree over there, Mark.”

Jack stooped to grab up a stone, but no sooner had his fingers touched
it than he called out:

“There! I forgot all about the stones here being heavier than lead.
Guess we can’t throw any of ’em. But come on. I’ll race you to the dead
tree!”

Mark was willing, so the two boys set off at a fast pace.

“Look out where you’re going!” the professor called after them. “No
telling what may be in those woods,” for the boys were approaching a
little glade, on the edge of which the dead tree stood.

Jack reached the goal first, and stood leaning against the trunk,
waiting for Mark.

“You’d better practice sprinting!” exclaimed the victor.

Mark was about to excuse himself for his poor showing, on the plea of
having eaten too much breakfast, when to his horror he saw what seemed
to be a long thin snake spring out from the branches of a near-by tree
and twine itself about Jack.

“Help me! Save me!” cried the unfortunate boy, as he was lifted high
into the air and pulled within the shadow of the wood.

For an instant Mark was too horror-stricken to move. Then with a shout
that alarmed the others, who were coming along more slowly, he made a
dash for the place he had last seen Jack.

Had old Andy not been on the watch, with those keen eyes of his, there
might have been a double tragedy. He had seen from afar the sudden
snatching up of Jack, and noted Mark’s rush to save his chum.

“Stand still! Don’t go in there for your life!” yelled the hunter, at
the same time running forward with gun ready.

His example was followed by the professor, Washington and the other two
men.

“A snake has Jack!” called Mark, when Andy was at his side.

“No! It’s not a snake!” replied the hunter. “It’s worse. It’s the
snake-tree!”

“What’s that?” asked Mr. Henderson, hurrying up.

“The snake-tree has Jack,” the hunter went on. “It is a plant, half
animal, half-vegetable. It has long branches, not unlike a snake in
shape. They can move about and grab things.”

“One of them got a grip on Jack as he leaned against the dead tree
trunk. I just caught a glimpse of it, and called to prevent Mark from
running into danger.”

“Can’t we save him?” asked Mr. Henderson.

“I’m going to try!” replied Andy. “Quick! Gather up some pieces of dry
wood. I have some paper, and my pipe lighter. We must fight the
snake-tree with fire!”

CHAPTER XXIII

THE DESERTED VILLAGE

Jack’s cries were growing fainter and fainter. Peering in through the
branches of the dead tree the professor could see the whip-like limbs
winding closer and closer about the boy.

“I am afraid we will be too late!” he said.

Andy had twisted some paper into a rude torch. He set fire to it with
his pocket lighter, and, when Bill and Mark brought him some little
pieces of dead wood the old hunter added them to his bundle, which was
now blazing brightly.

“How are you going to do it?” asked the professor.

“I’ll show you,” replied Andy. He bound the sticks and paper together
with wisps of grass and then, when it was so hot he could hardly hold it
longer, he ran as close as he dared to the snake-tree and tossed the
torch at the foot of it.

The blazing bundle fell among some damp leaves and grass, as Andy had
intended it should, and soon a dense smoke arose, pouring straight up
through the branches of the animal-tree, the limbs of which were
gathered in a knot about the half-unconscious form of the boy.

For a few minutes they all waited anxiously. Would Andy’s trick succeed?
Had the terrible tree not already squeezed the life from Jack?

But, while they watched, there seemed to come a change over the tree.
The snake-like arms waved less and less. They seemed to straighten out,
as though deprived of power by the smoke which was now so dense as to
hide Jack from sight. Then the arms suddenly relaxed and something
rolled from them and fell to the ground. With a quick movement Andy
darted in, crawling on his hands and knees beneath the limbs, and
brought Jack out. The boy was white and his eyes were closed.

“Get some water!” cried the old hunter.

Mark ran toward a stream a little distance away. He brought some of the
curiously thick liquid in his hat, and while Andy held the boy the
professor sprinkled some of the drops on his face, and forced some
between his lips. In a little while Jack’s eyes slowly opened.

“Don’t let it eat me!” he begged.

“You’re all right now,” said Andy heartily. “Not a bit harmed, Jack.
But,” he added in a low tone, “it was a close call.”

A few whiffs from a bottle of ammonia the professor carried soon brought
Jack’s color back.

“Do you feel better now?” asked Mark.

“I guess so. Yes, I’m all right,” replied Jack, struggling to his feet.
“What happened? Feels as if I had been tied up with a lot of rope.”

“That’s about what you were,” Andy replied, “only it was the worst kind
of rope I ever saw. Those snake-trees are terrible things. I’ve read of
’em, but I never saw one before. The book that told of them says they
squeeze their victims to death just as a snake does. The only way to do
is to make some smoke and fire at the bottom. This sort of kills the
branches or makes them stupid and they let go. The trees are half
animal, and awful things. I hope we don’t meet with any more.”

“Same here,” added Jack fervently, as he grasped Andy’s hand, and
thanked him for saving his life.

“Do you think you can go on, or shall we return to the ship?” the
professor asked.

“Oh I can trail along, if you move a little slowly,” Jack replied. “I’m
a bit stiff, that’s all.”

So they resumed their journey. They had gone, perhaps, three miles when
Washington, who was in the lead, suddenly stopped and called:

“Sounds like thunder.”

The others listened. Sure enough there was a dull rumble and roar
audible. It seemed off to the left, but they could see no clouds in the
sky, nor any signs of a storm.

“Let’s take a walk over that way and see what it is,” Mr. Henderson
suggested.

As they walked on the noise became louder, until in about half an hour
it was like the sound from a blast furnace.

“What do you suppose it can be?” asked Mark.

“Perhaps some new freak of nature,” the professor replied. “We seem to
have a good many of them here.”

They were all on their guard now, for there was no telling into what
danger they might run. As they went up a little hill the noise became
much louder. The professor and Andy, who had taken the lead, kept a
sharp lookout ahead, that they might not unexpectedly fall into some
hidden stream or lake. As they topped the hill they saw before them a
deep valley, and in the midst of it was that which was causing the
roaring sound.

From the centre of an immense mound of rock and earth there spouted up a
great column of water, three hundred feet or more, as straight as a flag
staff. It was about ten feet in diameter, and at the top it broke into a
rosette of sparkling liquid, which as the vari-colored lights played on
it, resembled some wonderful flower.

“It’s a great geyser!” the professor exclaimed. “We have come to a place
like Yellowstone Park. We must be very careful. The crust may be very
thin here, and let us down into some boiling spring.”

The others gathered around the professor, and, from a safe distance
watched the ever rising and falling shaft of water.

It was not regular in motion. Sometimes it would shoot up to a great
distance, nearly a thousand feet, the professor estimated. Again it
would sink down, as the power sending it out lessened, until it was only
a few hundred feet above the rounded top of the mound from which it
spurted. But it never fell below this. All the while there was the
constant roaring sound, as though the forces of nature below the surface
were calling to be let out.

“I hope there are not many of those about,” Mr. Henderson remarked after
a pause. “If the ship should hit one during the night it would be all up
with us. We must keep a careful lookout.”

The spouting column had a fascination which held them to the spot for
some time. From the hill they had a good view of the surrounding
country, but did not see any more geysers.

“Do you think it is hot water?” asked Mark.

“There is no vapor,” the professor answered, “but most of the geysers
are produced by the action of steam in the interior of the earth.
However we’ll not take any chances by investigating. I fear it would not
be safe to go into that valley.”

“Look there!” cried Andy. “I guess we’re better off here!” He pointed a
little to the right of where the water spouted. The others looked, and
saw, coming from a hole in the ground, some shaggy black object.

“What is it?” asked Jack.

“It looks like a bear,” replied the hunter, “but I never saw one like it
before.”

Nor had any of the others, for the creature was a terrible one. It had
the body of a bear, but the feet and legs were those of an alligator,
while the tail trailed out behind like a snake, and the head had a long
snout, not unlike the trunk of an elephant. The creature was about ten
feet long and five feet in height.

“Let me try a shot at it!” exclaimed Andy. “That is something worth
shooting,” and he cocked his rifle.

“Don’t!” exclaimed the professor shortly. “You might only wound it, and
it would pursue us. We are not ready to fight such creatures as that,
and you are the only one armed.”

“I never missed anything I aimed at yet,” said Andy, a little hurt that
any one should doubt his ability to kill at the first shot.

“Perhaps not, but how do you know but what this creature has a bullet
proof armor under its hide. This is a strange world, Andy. It is better
to take no chances.”

“I hate to see him get away,” the hunter said.

But, as it happened, the beast was not to get away. As they watched they
saw the horrible animal approach the mound from which the water spurted.
Up the sides it climbed.

“I guess he’s going to get a drink,” said Mark.

That was evidently the beast’s intention. It went close to the spouting
column of water, and thrust its head out so that its tongue could lap
from the side. It seemed to have been in the habit of doing this.

For once, and for the last time, however, it made a mistake. The water
seemed to veer to one side. In its eagerness to get a drink the animal
took another step forward. At that moment the direction of the column
changed again, and it tilted over toward the beast.

Suddenly, as the travelers watched, the full force of the big column
caught the beast just under the fore shoulders. Up into the air the
creature shot, propelled by thousands of pounds pressure. Right up to
the top of the column it went, and this time the water rose a thousand
feet into the air.

Up and up went the animal, struggling to get away from the remorseless
grip. Then, when the water had reached its height, it shot the beast off
to one side. Then the brute began to fall, twisting, turning, wiggling
and struggling. Down it came with a thud that could be heard above the
noise of the geyser.

“I reckon that finishes him,” observed Andy. And it had, for there was
not a sign of life from the creature.

“I guess we have seen enough for one morning,” the professor said.
“Let’s go back to the airship. It must be nearly dinner time.”

They started away. Mark gave a last look at the queer column of water
and the dead body of the strange animal. As he passed down the hill he
thought he saw the creature move, and stayed to see if this was so. But
a second glance convinced him he was mistaken.

The others had gone on and were some distance ahead. Mark hurried on to
join them. As he got a last glance at the top of the column, over the
brow of the hill, he happened to look off to the left. There was another
hill, about the size of the one they had been on.

[Illustration: UP IN THE AIR THE CREATURE SHOT]

And, as Mark looked he saw something move. At first he thought it was
another beast. But, to his terror he saw that the creature had only two
legs, and that it stood upright like a man, but such a man as Mark had
never seen before, for he was nearly twelve feet tall.

He was about to cry out and warn the others, when the thing, whatever it
was, sunk down, apparently behind some tall bushes, and disappeared as
if the earth had opened and swallowed it.

“I wonder if I had better tell them,” thought Mark. “I can’t show them
anything. I wonder if I really saw it, or if it was only a shadow. I
guess I’ll say nothing. But it is very strange.”

Then he hurried on to join the others.

“What makes you so pale?” asked Jack of his chum.

“Nothing,” said Mark, somewhat confused. “I guess I’m a little tired,
that’s all.”

They reached the ship in safety, and, having dinner started the
machinery and took the _Mermaid_ up into the air.

“We’ll travel on and see if we can’t find some human beings,” the
professor said.

All that afternoon they sailed, the country below them unfolding like a
panorama. They passed over big lakes, sailing on the surface of some,
and over rivers, and vast stretches of forest and dreary plains. But
they never saw a sign of human inhabitants.

It was getting on to five o’clock, the hour when the brilliant lights
usually disappeared, when Mark, who was steering in the conning tower,
gave a cry.

“What is it?” asked the professor, looking up from a rude map he was
making of the land they had just traversed.

“It looks like a town before us,” said the boy.

Mr. Henderson and Jack looked to where Mark pointed. A few miles ahead
and below them were great mounds, not unlike that from which the geyser
had spouted. But they were arranged in regular form, like houses on a
street, row after row of them. And, as they approached nearer, they
could see that the mounds had doors and windows to them. Some of the
mounds were larger than others, and some were of double and triple
formation.

“It’s a city! The first city of the new world!” cried Jack.

“It is a deserted village!” said the professor. “We have found where the
people live, but we have not found them.” And he was right, for there
was not a sign of life about the place, over which the airship was now
suspended.

CHAPTER XXIV

THE GIANTS

“Let’s go down and investigate,” suggested Jack.

“Better wait,” counseled the professor. “It will soon be dark, and,
though we will have moonlight, we can not see to advantage. I think it
will be best to keep the ship in the air to-night, and descend in the
morning. Then we can look about and decide on what to do.”

They all agreed this was the best plan, and, after making a circle above
the deserted village, and noting no signs of life, the _Mermaid_ was
brought to a halt over the centre of the town, and about three hundred
feet above it. There the travelers would be comparatively safe.

It was deemed best to keep watch that night, and so, Mark, Jack, Bill
and Tom took turns, though there was nothing for them to do, as not a
thing happened. With the first appearance of dawn Mr. Henderson gave
orders to have the ship lowered, and it came to rest in the middle of
what corresponded to a street in the queer mound village.

“Now to see what kind of people have lived here!” cried Jack. “They must
have been a queer lot. Something like the Esquimaux, only they probably
had more trouble keeping cool than the chaps up at the north pole do.”

Now that they were down among the mound houses, they saw that the
dwellings were much larger than they had supposed. They towered high
above the boys’ heads, and some of them were large enough in area to
have accommodated a company of soldiers.

“Say, the chaps who lived in these must have been some pumpkins,” said
Jack. “Why the ceilings are about fifteen feet high, and the doors
almost the same! Talk about giants! I guess we’ve struck where they used
to hang out, at any rate.”

The houses were a curious mixture of clay and soft stone. There were
doors, with big skins from animals as curtains, and the windows were
devoid of glass. Instead of stairs there were rude ladders, and the
furniture in the mound houses was of the roughest kind.

There were fire-places in some of the houses, and the blackened and
smoked walls showed that they must have been used. In one or two of the
houses clay dishes, most of them broken, were scattered about, and the
size of them, in keeping with everything else, indicated that those who
used them were of no small stature.

“Some of the bowls would do for bath tubs,” said Jack, as he came across
one or two large ones.

By this time the professor, Bill and Tom had joined the boys, and the
five went on with the exploring tour, while Washington and Andy remained
in the ship to get breakfast.

“The inhabitants are evidently of a half-civilized race,” the professor
said. “Their houses, and the manner in which they live, show them to be
allied to the Aztecs, though of course they are much larger than that
race.”

“What’s bothering me,” Bill said, “is not so much what race they belong
to, as what chance we’d stand in a race with them if they took it into
their heads to chase after us. I’ve read that them there Azhandled
races——”

“You mean the Aztecs,” interrupted the professor.

“Well the Aztecs, then. But I’ve read they used to place their enemies
on a stone altar and cut their hearts out. Now I’m not hankerin’ after
anything like that.”

“Don’t be foolish,” spoke Mr. Henderson. “Wait until you meet some of
the giants, if that is what they are, and then you can decide what to
do.”

“It may be too late then,” remarked Bill in a low tone, and the boys
were somewhat inclined to agree with him.

However, there seemed to be no immediate danger, as there was no sign of
any of the big people about the village. The adventurers walked about
for some time, but made no discoveries that would throw any light on the
reason for the place being left uninhabited. It seemed as if there had
been a sudden departure from the place, for in a number of the houses
the remains of half-cooked meals were seen.

“Well, I think we have noted enough for the time being,” the professor
remarked, after they had traversed almost half the length of what seemed
to be the principal street. “Let’s go back to the ship and have
something to eat. Washington may have become alarmed at our absence.”

They made a circle in order to take in another part of the town on their
way back. While passing through a sort of alley, though it was only
narrow by comparison with the other thoroughfares that were very wide,
Mark came to a place where there was a circular slab of stone, resting
on the ground. In the centre was a big iron ring.

“Hello! Here’s something new!” he exclaimed. “Maybe it leads to a secret
passage, or covers some hidden treasure.”

“I guess it will have to continue to cover it then,” Jack spoke. “That
probably weighs several tons. None of us could move it.”

They made their way back to the ship, where they found Washington and
Andy discussing the advisability of going off in search of them.

“Breakfast is mighty near spoiled,” said the colored man with an injured
air.

But the travelers did full justice to the meal, notwithstanding this.
Deciding there was nothing to be gained by staying in that vicinity, the
professor started the ship off again.

They traveled several hundred miles in the air, and, as the afternoon
was coming to a close, Jack, who was in charge of the conning tower,
spied, just ahead of them, another village.

“We will descend there for the night,” the professor said. “Does there
seem to be any sign of life about?”

“None,” replied Mark, who was observing through a telescope the town
they were approaching. “It’s as dead as the other one.”

The airship settled down in a field back of some of the mound houses.

“Now for supper!” cried Jack. “I’m as hungry as——”

He stopped short, for, seeming to rise from the very ground, all about
the ship, there appeared a throng of men. And such men as they were! For
not one was less than ten feet tall, and some were nearly fifteen!

“The giants have us!” cried Bill, as he saw the horde of creatures
surrounding the ship.

CHAPTER XXV

HELD BY THE ENEMY

“Keep the doors closed!” cried the professor. “It is our only hope! I
will send the ship up again!”

But it was too late. Washington, who had obeyed the signal from the
conning tower to shut off the engines, had disconnected most of them so
they could not be started again save from the main room. At the same
time there came a yell of dismay from the colored man, who had slid back
the steel covering of the main side entrance to the _Mermaid_.

“I’m caught!” cried Washington.

As the professor and the boys hurried from the tower, they could hear a
struggle from where Washington was, and his voice calling:

“Let me go! Let me go!”

Reaching the engine room, which opened directly on the side entrance,
the professor saw a pair of enormous hands and arms dragging poor
Washington, feet first, out of the ship. Bill and Tom were crouched in
one corner, pale with fright.

“Wait until I get my gun!” cried Andy, as he ran for his rifle.

“Hold on!” called the professor in a loud voice. “It will be folly to
shoot them! We must try strategy!”

Washington’s cries ceased as he was drawn entirely from the ship, the
giant hands disappearing at the same time.

“Follow me!” yelled Mr. Henderson, running out of the door.

Hardly knowing what they did, the boys went after him, and their hearts
almost stopped beating in fright as they saw the terrible things, which,
in the glare of the changing lights, were on every side of them.

For the men were very repulsive looking. They were attired in clothes,
very similar in cut to those worn by the travelers, and which seemed to
be made of some sort of cloth. But they were loose and baggy and only
added to the queer appearance of the giants. Veritable giants they were
too. Their faces seemed as large as kegs, and they were so clumsy in
shape that Mark, even, frightened as he was, exclaimed:

“They look like men made of putty!” At the same time he saw they bore a
resemblance to the creature he had observed on the hill top.

“What shall we do?” asked Andy of the professor. “They are really
carrying Washington away!”

Three of the giants were dragging the colored man along the ground,
while the other terrible beings stood about as if waiting to see the
outcome of the first sally.

“I will try to speak to them,” Mr. Henderson said. “I know several
languages. They may understand one.”

But before he could start on his parley a surprising thing happened.
There was a struggle in the little group about Washington. The colored
man seemed to be fighting, though the odds, it would appear, were too
great to enable him to accomplish anything. But, making a desperate
effort to escape, Washington quickly wrenched himself free from the
giants’ hands and then, striking out with his fists, knocked the three
down, one after another.

“I never knew Washington was so strong!” exclaimed Jack.

“Nor I,” put in Mark. “Why I should think the men could carry him in one
arm as if he was a baby.”

The three giants rose slowly to their feet. They uttered strange cries,
and motioned with their hands toward the professor, the boys, and the
others in the crowd.

“Look out! They’re goin’ t’ grab yo’!” cried Washington.

Three of the giants approached Mark, and a like number closed in on
Jack.

“Back to the ship!” cried the professor. “We must defend ourselves!”

But by this time the big men had grabbed the two boys. Then a strange
thing took place. Mark and Jack, though they felt that the giants must
overcome them in a test of strength, struggled with all their might
against being captured. They fought, as a cornered rat will fight,
though it knows the odds to be overwhelming. But in this case the
unexpected happened.

Both boys found they could easily break the holds of the giants, and
Mark, by a vigorous effort, pushed the three men away from him, one at a
time violently so that they fell in a heap, one on top of the other.

“Hurrah! We can fight ’em!” cried Mark. “Don’t be afraid. They’re like
mush! They’re putty men!”

And, so it seemed, the giants were. Though big in size they were flabby
and had nothing like the muscle they should have had in proportion to
their build. They went down like meal sacks and were slow to rise.

[Illustration: THE BIG MEN HAD GATHERED IN A COMPACT MASS]

Jack, seeing how successful his comrade was, attacked the three giants
who were striving to make him a captive. He succeeded in disposing of
them, knocking one down so hard that the man was unable to rise until
his companions helped him.

“That’s the way!” cried Washington. “They’re soft as snow men!”

The vanquished giants set up a sort of roar, which was answered by their
fellows, and soon there was a terrible din.

“All get together!” called the professor. “They are evidently going to
make a rush for us. If we stand by one another we may fight them off,
though they outnumber us a hundred to one. Besides it will soon be dark,
and we may be able to escape!”

Washington, Jack and Mark retreated toward the ship, in the direction of
which the others had also made their way. The big men had gathered in a
compact mass and were advancing on the adventurers.

“What do you suppose makes them so soft?” asked Mark. “I believe I could
manage half a dozen.”

“It must be the effect of the climate and conditions here,” the
professor replied. “Probably they have to be big to stand the pressure
of the thick water, and the increased attraction of gravitation. Then
too, being without the weight of the atmosphere to which we are
accustomed, they have probably expanded. If they were to go up to earth,
they might shrink to our size.”

“Do you think that possible?”

“Of course. Why do you ask?”

“Nothing in particular,” replied Mark. But to himself, he added: “That
would explain it all.”

It was getting dusk now. The travelers had reached their ship, and
rushed inside and tried to close the doors in the face of the advancing
horde. But, by this time the giants were so close that one or two of
them thrust their big feet in, and prevented this movement. At the same
time they set up a great howling.

“Quick!” cried the professor. “We must start the ship and get away!”

“I can’t close the door!” yelled Washington, who had been the last to
enter.

“Never mind that! _Go_ up with it open! Drag them along if they won’t
let go!” answered Mr. Henderson, as he ran toward the engine room.

There was a sudden rush among the giants, and a sound as if something
was being thrown over the top and ends of the ship. Mark turned the gas
machine on, while Jack worked the negative gravity apparatus. They
waited for the ship to rise.

“Why don’t we go up?” asked the professor.

“'Cause they’ve caught us!” called out Washington.

“Caught us? How?”

“They’ve thrown ropes over the top and ends of the ship, and fastened
them to their big houses!”

Running to a side window the professor saw that the _Mermaid_ was
fastened down by a score of cables, each one six inches thick. They were
held captives by the enemy.

CHAPTER XXVII

A FRIEND INDEED

Though the giants, man for man, were no match for the travelers,
collectively the horde proved too much. They had swarmed about the ship,
and, by passing the big cables over her, effectively held her down.

“Let me get out and I’ll cut ’em!” cried Andy. “We must get away from
these savages!”

“No, no, don’t go out!” exclaimed the professor. “They would eventually
kill you, though you might fight them off for a time. We must wait and
see what develops. They can have no object in harming us, as we have not
injured them.”

“I’d rather fight ’em,” insisted the old hunter.

But the professor had his way and Andy was forced to obey. The giants
had withdrawn their big feet from the side door and Washington had
closed it. But nothing else had been accomplished, and the ship could
not rise. The gas and negative gravity machines were stopped, as they
were only under a useless strain.

Suddenly, the colored lights which had been growing dimmer and dimmer,
with the approach of night, went out altogether. Almost as suddenly,
Mark, who was watching the giants from the conning tower, as they made
fast the loose ends of the cables, saw them make a dash for the mound
houses.

“They’re afraid of the dark!” he cried. “Come on! We can go out now and
loosen the ropes!“

He hurried to tell the professor what he had noticed.

“Good!” exclaimed Mr. Henderson. “Perhaps we can escape now!”

They waited a few minutes, listening to the sound of many big feet
running away from the ship, and then, Bill cautiously opened the side
door. The others were behind him, waiting, with knives and hatchets in
their hands, to rush out and cut the restraining cables.

“All ready!” called Bill. “There doesn’t seem to be a one in sight!”

He stepped out but no sooner had he set foot on the ground than there
came a thud, and Bill went down as if some one had knocked his feet from
under him.

“Go back! Go back!” he cried. “They hit me with something. I’m being
smothered!”

“Bring a light!” cried the professor, for the sally had been started in
the dark.

Jack brought the portable electric it having been repaired and flashed
it out of the door. In the gleam of it, Bill was seen lying prostrate,
half covered by an orange, about half as big as himself. The fruit was
as soft and mushy as some of the giants themselves, or Bill would not
have fared so easily.

Then, as the others stood watching, and while Bill arose and wiped some
of the juice from his face, there came a regular shower of the monstrous
oranges.

“Get inside quick! We’ll be smothered under them!” Mr. Henderson cried.

Pausing only to rescue Bill, the adventurers retreated inside the ship,
and made fast the door. Outside they could hear the thud as the oranges
were thrown, some hitting the _Flying Mermaid_ and many dropping all
about her.

“I guess they are going to have things their own way,” observed Bill, as
he gazed down on his clothes, which were covered with juice from the
fruit.

The night was one of anxiety. The travelers took turns standing guard,
but nothing more occurred. The giants remained in their houses, and the
heavy ropes still held the ship fast.

“We must hold a council of war,” the professor decided as they gathered
at breakfast, which was far from a cheerful meal.

With the return of the colored lights the giants again made their
appearance. They came swarming from the mound houses, and a great crowd
they proved to be. Several thousand at least, Jack estimated, and when
he went up into the conning tower and took a survey he could see the
strange and terrible creatures pouring in from the surrounding country.

“I’m afraid there will be trouble,” he said, as he came down and
reported what he had seen.

“We must hold a council of war,” repeated the professor. “Has any one
anything to suggest?”

“Get a lot of powder and blow ’em up!” cried Andy.

“Arrange electric wires and shock ’em to death!” was Bill’s plan.

“Can’t we slip the ropes in some way and escape?” asked Jack. “I don’t
believe we can successfully fight the giants. They are too many, even if
they are weak, individually.”

“I think you’re right there,” Mr. Henderson said. “We must try some sort
of strategy, but what? That is the question.”

For a few minutes no one spoke. They were all thinking deeply, for their
lives might hang in the balance.

“I think I have a plan,” said Mark, at length. “Did we bring any diving
suits with us?”

“There may be one or two,” the professor replied. “But what good will
they do?”

“Two of us could put them on,” continued Mark, “and, as they afford good
protection from any missiles like fruit, we could crawl out on the deck
of the ship. From there, armed with hatchets or knives we could cut the
ropes. Then the ship could rise.”

“That’s a good plan!” cried the scientist. “We’ll try it at once!”

Search revealed that two diving suits were among the stores of the
_Mermaid_. Jack and Mark wanted to be the ones to don them, but as the
suits were rather large, and as the professor thought it would take more
strength than the boys had to do the work, it was decided that Andy and
Washington should make the attempt to cut the ropes.

The hunter and colored man lost little time in getting into the modern
armor. In the meanwhile Jack, who had been posted as a lookout, reported
that there seemed to be some activity among the giants. They were
running here and there, and some seemed to be going off toward the
woods, that were not far away.

“Now work quickly,” urged the professor. “We will be on the watch, and
as soon as the last rope is cut we will start the machinery and send the
ship up. We will not wait for you to come back inside, so hold fast as
best you can when the _Mermaid_ rises.”

“We will,” answered Andy, just before the big copper helmet was fastened
on his head, and Washington nodded to show he understood.

The two who were to attempt the rescue of their comrades were soon on
deck. In the conning tower Jack and the professor kept anxious watch,
while Mark, Bill and Tom were at the various machines, ready, at the
signal, to start the engines.

The giants had now become so interested in whatever plan they had afoot,
that they paid little attention to the ship. Consequently Washington and
Andy, crawling along the deck in their diving suits, did not, at first
attract any attention.

In fact they had cut several of the big ropes, and it began to look as
if the plan would succeed, particularly as they were partly hidden from
view by the upper gas holder. They were working with feverish haste,
sawing away at the big cables with keen knives.

“I guess we’ll beat ’em yet!” cried Jack.

“I hope so,” replied the professor. “It looks——”

He stopped short, for at that moment a cry arose from the midst of the
giants, and one of them pointed toward the ship. An instant later the
air was darkened with a flight of big oranges, which the queer creatures
seemed to favor as missiles. Probably they found stones too heavy.

“Well, those things can’t hurt ’em much with those heavy suits on,”
observed Mr. Henderson. “There, Washington got one right on the head
that time, and it didn’t bother him a bit.”

Jack had seen the fruit strike the big copper helmet and observed that
the colored man only moved his head slightly in order to get rid of the
orange.

In fact the giants, seeing for themselves that this mode of warfare was
not going to answer, since the two men on the ship continued to cut the
restraining cables, gave it up. There was a good deal of shouting among
them, and a number ran here and there, seemingly gathering up long
poles.

“I wonder if they are going to try the flailing method, and beat poor
Andy and Washington,” said Mr. Henderson. “It looks so.”

The two rescuers were now about a quarter through their hard task. The
throwing of the oranges had ceased. But the giants were up to a new
trick. They divided into two sections, one taking up a position on one
side of the ship, and the other on the opposite. There were about two
hundred in each crowd, while the others in the horde drew some distance
back.

“They’re up to some queer dodge,” observed Jack. “What are they placing
those sticks to their mouths for?”

The professor observed the throng curiously for a few seconds. Then he
exclaimed:

“They are using blow-guns! They are going to shoot arrows at Washington
and Andy! We must get them in at once!”

He darted toward a door that opened from the conning tower out on the
deck.

“Don’t go!” cried Jack. “It’s too late! They are beginning to blow!”

He pointed to the throng of giants. The professor could see their cheeks
puffed out as the big creatures filled their lungs with air and prepared
to expel it through the hollow tubes.

Then there came a sound as if a great wind was blowing. It howled and
roared over the ship, not unlike a hurricane in its fury. But there was
no flight of arrows through the air, such as would have come from
regular blow guns.

“That is strange,” said the professor. He thought for a moment. “I have
it!” he cried, “They are trying to blow Washington and Andy off the ship
by the power of their breaths! They are not blowing arrows at them! My,
but they, must have strong lungs!”

And, in truth, that was the plan of the giants. The hollow tubes, made
from some sort of big weed, sent a blast of air at the two men on the
ship’s deck, that made them lie flat and cling with both hands to avoid
being sent flying into the midst of the giants, on one side or the
other. But the giants had reckoned without the weight of the diving
suits, and it was those, with the big lead soles of the shoes, that
helped to hold Washington and Andy in place.

“Come back! Come back!” cried the professor, opening the conning tower
door and calling to the two brave men. “Come back, both of you! Do you
hear?”

As the portal slid back the rush of air was almost like that of a
cyclone. Then it suddenly ceased, as the giants saw their plan was not
likely to succeed.

But now there arose from the outer circle of the horde a shout of
triumph. It was caused by the return of those who had, a little while
before, hurried off to the woods. They came back bearing big trees, tall
and slender, stripped of their branches, so that they resembled flag
staffs. It took a dozen giants to carry each one.

The whole throng was soon busy laying the poles in a row in front of the
ship.

“What can they be up to now?” asked Jack.

“It looks as if they were going to slide the ship along on rollers,” the
professor replied.

Sure enough this was the giant’s plan. A few minutes later those in the
_Mermaid_ felt her moving forward, as the giants, massed behind, shoved.
On to the poles she slid. The ropes were loosened to permit this, but
not enough to enable the boat to rise.

Then the travelers felt the ship being lifted up.

“They are going to carry us away, with the poles for a big stretcher!”
cried the professor.

Looking from the side windows the boys saw that a great crowd of the big
men were on either side of the _Mermaid_, each giant grasping a pole,
and lifting. Farther out were others, holding the ends of the cables
which Washington and Andy had not succeeded in cutting.

The ship was being carried along by a thousand or more giants, as the
ancient warriors, slain in battle, were carried home on the spears of
their comrades.

“This is the end of the _Mermaid_!” murmured Mr. Henderson in sorrowful
tones.

As they looked from the conning tower the professor and the two boys
observed a commotion among the leaders of the giants. They seemed to be
wavering. Suddenly the forward part of the ship sank, as those ahead
laid their poles down on the ground. Then those behind did the same, and
the _Mermaid_, came to a stop, and once more rested on the earth.

“What does this mean?” asked the scientist in wonder.

All at once the entire crowd of giants threw themselves down on their
faces, and there, standing at the bow of the ship, was a giant, half
again as large as any of the others. He was clad in a complete suit of
golden armor on which the changing lights played with beautiful effect,
and in his hand he held an immense golden sword. He pointed the weapon
at the ship as if he had raised it in protection, and his hand was
stretched in commanding gesture over the prostrate giants.

“Perhaps he has come to save us!” cried Mark.

CHAPTER XXVII

A GREAT JOURNEY

Such indeed, seemed to be the case. The golden-armored giant, after
standing for a few moments in an attitude of command, waved his sword
three times about his head, and uttered a command, in a voice that
sounded like thunder. Then the prostrate ones arose, and, making low
bows hurried away in all directions.

Watching them disappear, the golden one sheathed his weapon and
approached the ship. He caught sight of the professor and the two boys
in the conning tower, for Mark had gone there when he found the ship
being transported, and held up his two hands, the palms outward.

“It is the sign of peace in the language all natives employ,” said the
professor. “I think I shall trust him.”

Followed by the boys he descended from the little platform in the tower,
and to the door that opened on the deck.

“Shall we go out?” he asked.

“We can’t be much worse off,” replied Mark. “Let’s chance it.”

So, not without many misgivings, they slid back the portal and stepped
out to face the strange and terrible being who had so suddenly come to
their rescue.

The giant in the golden armor did not seem surprised to see them. In
fact he acted as though he rather expected them. He continued to hold up
one hand, with the palm, outward, while, with the other, he removed his
helmet and bowed low. Then he cast his sword on the ground and advanced
toward the ship. When within ten feet he sat down on the ground, and
this brought his head nearer the earth, so that his auditors could both
see and hear him to better advantage.

As soon as the giant saw the travelers were outside their ship he began
to speak to them in a voice, which, though he might have meant it to be
low and gentle, was like the bellowing of a bull. At the same time he
made many gestures, pointing to the ship, to himself and to Mark.

“What is he saying, professor?” asked Jack.

“I can’t understand all he says,” Mr. Henderson replied. “He uses some
words derived from the Latin and some from the Greek. But by piecing it
out here and there, and by interpreting his motions I am able to get at
something.”

“And what is it all about?”

“It is a strange story,” the scientist replied. “He has only gone about
half way through it. Wait until he finishes and I will tell you.”

The golden-armored giant, who had stopped in his narrative while Jack
was speaking, resumed. His gestures became more rapid, and his words
came faster. Several times Mr. Henderson held up his hand for him to
cease, while he puzzled out what was meant.

At one point, the professor seemed much startled, and motioned for the
strange being to repeat the last part of his discourse. When this had
been done Mr. Henderson shook his head as though in doubt.

At length the story was finished, and the lone giant, for there were no
others in sight now, folded his arms and seemed to await what the
professor’s answer might be. Mr. Henderson turned to the boys, and to
the others of the _Mermaid’s_ company, who, by this time, had joined
him, and said:

“Friends, I have just listened to a strange story. It is so strange
that, but for the fact that our own adventures are verging on the
marvelous, I could hardly believe it. In the first place, this man here
is the king of this country. That is why all the other natives obeyed
him.

“In the second place it seems he has been a passenger in our boat, and
came here from the earth’s surface with us!”

“What’s that?” cried Jack.

“That explains the strange happenings!” ejaculated Mark. “No wonder I
could never solve the secret of the storeroom.”

“You are right, it does,” replied Mr. Henderson. “I will not go into all
the details of how it happened, but it seems the big hole through which
we came is only one of two entrances to this inner world. Rather it is
the entrance, and there is another, close to it, which is the exit.
Through the latter a big stream of water spouts up, just as one pours
down through the opening we used.

“Hankos, which is the name of the king, was for many years a student of
science. He longed to see where the big stream of upward spurting water
went, and wanted to know whence came the down-pouring one. So he
undertook a daring experiment.

“He constructed a great cylinder, and, keeping his plans a secret,
conveyed it to the spouting water, entered it, and, by means of pulleys
and levers, after he had shut himself inside, cast himself into the
up-shooting column. He took along compressed air cylinders to supply an
atmosphere he could breathe, and some food to eat, for it appears our
giant friends are something of inventors in their way. The current of
water bore him to the surface of the earth, and he was cast up on the
ocean, in what was probably taken for a waterspout if any one saw it.

“Then a strange thing happened. No sooner did Hankos open his cylinder,
which served him as a boat, than he lost his gigantic size, owing to the
difference of the two atmospheres. He became almost of the same size as
ourselves, except that his skin hung in great folds on him, and he
seemed like a wrinkled old man. His clothes too, were a world too large.

“He had a terrible time before he reached shore, and a hard one after
it, for his strange appearance turned almost every one against him. He
was sorry he had ventured to solve the mystery of the up-shooting stream
of water, for he was worse than an outcast.

“Then he began to plan to get back to his own inner world. But he could
not find the downward stream, and, not knowing the language of the
countries where he landed, he had no means of ascertaining. He traveled
from place to place, always seeking for something that would lead him
back to his own country.

“Finally he heard of us, and of our ship, though how I do not know, as I
thought I had kept it a great secret. By almost superhuman struggles he
made his way to our island. He says he concealed himself aboard the
_Mermaid_ the night before we sailed, but I hardly believe it possible.
It seems——”

“He did it, for I saw him!” interrupted Mark.

“You saw him!” cried Mr. Henderson.

Then Mark told of the many things that had puzzled him so, how he had
seen the queer figure slinking aboard the boat, of the disappearance of
food from time to time, and of the strange noises in the storeroom.

“That bears out what he told me,” the professor said. “Hankos says he
used to steal out nights and take what food he could get, and he also
mentions some one, answering to Mark’s description, who nearly
discovered him once as he hurried back into the apartment.

“However, it seems to be true, since Mark confirms it. At any rate
Hankos stayed in hiding, and made the entire trip with us, and, just as
we all became overcome with the strange gas he escaped, having begun to
expand to his original giant size, and being unable to remain any longer
in his cramped quarters.”

“That’s so, he did!” cried Mark. “I saw him come out of the place just
before I lost my senses. It was a terrible sight, and none of you would
believe me when I told you some of the occurrences afterward.”

“You must forgive us for that,” the professor said. “We have learned
much since then.”

“What did Hankos do after he left the ship when it landed in this
country?” asked Jack.

“He traveled until he came to this village, which is the chief one of
this country,” replied the professor. “Part of the time he followed us
at a distance, being able to travel very fast.”

Mark remembered the strange figure of a giant he had seen on the hill
tops several times, and knew that he had been observing the being who
had played such a queer part in their lives.

“When he came back among his own people,” went on Mr. Henderson, “they
would not receive him at first, believing him to be an impostor. But
Hankos convinced them of his identity and was allowed to don the golden
armor, which is the badge of kingship. He had only been in office for a
little while when he heard of the arrival of the strange thing, which
turned out to be our ship. He recognized it from the description, and,
learning that we were likely to be sacrificed to the fury and ignorance
of the giants, he hurried here and saved our lives.

“He says he can never thank us enough for being the means whereby he was
able to get back to his own country, and says the freedom of this whole
inner world is ours. He has given orders that we are to go wherever we
like, and none will molest us. He tells me the land is a wonderful one,
compared to our own, and urges us to make a long journey. He would like
to go with us, only, now that he has resumed his natural size, he can
not get inside the ship.”

“Hurrah for King Hankos!” cried Jack and the others joined him in a
hearty cheer.

The giant in the golden armor evidently understood the compliment which
was paid him, for he waved his helmet in the air and responded with a
shout of welcome that made the ground tremble.

Hankos waited until the professor had translated all of the story to the
other travelers. Then the genial giant began to talk some more, and the
professor listened intently.

“He says,” spoke Mr. Henderson to his friends, “that we will be supplied
with all the fruit we want, and with the best of the houses to sleep in
on our journey. He also tells me he has great stores of shining stones
and piles of the metal of which his armor is made, and that we are
welcome to as much as we want. If this means unlimited gold and
diamonds, we may make our fortunes.”

“Jest let me git ma’ hand on a few sparklers an’ I’ll quit work!”
exclaimed Washington.

“I have told him,” the scientist went on, “that we will take advantage
of his kind offer. We will start on our trip in a day or so, after we
have looked over the ship to see if it is not damaged. He tells me the
gold and sparkling stones are several thousand miles away, on top of a
high mountain. We will make that our objective point.”

The interview between the king and Mr. Henderson having ended, the
former waved his sword in the air and the swarm of big men came back.
They had been hiding back in the woods. Now their manner was very
different. They carefully, removed the rollers and ropes, and soon there
was brought to the adventurers an immense pile of fine fruits. If our
friends had stayed there a year they could not have eaten it all. The
giants were judging the appetites of the travelers by their own.

That night the adventurers slept more soundly than they had since
entering the strange world. They felt they had nothing to fear from the
giants. In the morning they were not molested, though big crowds
gathered to look at the ship. But they kept back a good distance. The
machinery was found to be in good shape, save for a few repairs, and
when these were made, the professor announced he would start on a long
journey.

For several weeks after that the travelers swung about in their ship,
sometimes sailing in the air and again on big seas and lakes viewing the
wonders of the inner world. They were many and varied, and the professor
collected enough material for a score of books which he said he would
write when he got back to the outer world once more.

One afternoon, as they were sailing over a vast stretch of woodland,
which did not seem to be inhabited, Mr. Henderson, looking at one of the
gages on the wall, asked:

“Boys do you know how far you have traveled underground?”

“How far?” asked Jack, who hated to guess riddles.

“More than four thousand miles,” was the answer.

“But we haven’t come to that mountain of gold and diamonds,” said Mark.
“I am anxious to see that.”

“Have patience,” replied the professor. “I have not steered toward it
yet. There are other things to see.”

Just then Washington’s voice could be heard calling from the conning
tower:

“We’re coming to a big mountain!”

CHAPTER XXVIII

THE TEMPLE OF TREASURE

“What’s that?” fairly yelled the professor.

“We am propelling ourselves in a contiguous direction an’ in close
proximity to an elevated portion of th’ earth’s surface which rises in
antiguous proximity t’ th’ forward part of our present means of
locomotion!” said the colored man in a loud voice.

“Which means there may be a collision,” the professor said, as he and
the boys hurried toward the tower.

“Jest what I said,” retorted Washington. “What’ll I do?”

“Send the ship a little higher,” answered Mr. Henderson. “We mustn’t hit
any mountains.”

Washington forced more gas into the holder, and speeded the negative
gravity machine up some, so that the _Mermaid_, which was flying rather
low, ascended until it was in no danger of colliding with the peak which
reared its lofty height just ahead of them.

As the ship sailed slowly over the mountain, Mark gazed down and
exclaimed:

“Doesn’t that look like the ruins of some building?”

The professor took a pair of field glasses from a rack in the wall and
took a long view.

“It must be the place,” he said in a low voice.

“What place?” asked Jack.

“The temple of treasure,” was the answer. “Hankos told me it was on top
of the highest mountain in the land, and this must be it, for it is the
loftiest place we have seen. But we must be careful, for there is danger
down there.”

“What kind?” asked Mark.

“The place was long ago deserted by the giants,” Mr. Henderson went on.
“Ages ago it was one of their storehouses for treasure, but there were
wars among themselves, Hankos said, and this part of the country was
laid waste. Savage beasts took up their abode in the temple, and since
then, in spite of the great size of the giants, they have not dared to
venture here. If we brave the animals we may have all the gold and
diamonds we can take away.”

“Then for one, I’m willin’ t’ go down an’ begin th’ extermination at
once,” put in Andy. “I’ve always wanted t’ be rich.”

“We must proceed cautiously,” the professor said. “We are ill prepared
to fight any such beasts as we saw at the big geyser. At the same time
they may have deserted this place. I think we will lower the ship down
over the temple, and spend several hours in observation. Then, if
nothing develops, we can enter and see if the treasure is there.”

This plan was voted a good one, and the _Mermaid_ after having been
steered directly over the ruined temple, was brought to a halt, and
enough gas let out so that it fell to about fifty feet in the air above
it.

The adventurers began their watch. The afternoon waned and there were no
signs of any beasts in or about the temple.

“I reckon we can take a chance,” said Andy, who was anxious to get his
hands on some diamonds.

“Better wait until morning,” counseled Mr. Henderson. “It will soon be
dark, and it doesn’t look like a nice place to go stumbling about in by
moonlight.”

So, though all but the scientist were anxious, they had to wait until
the night had passed. Several times Washington got up to see if the
temple had, by any chance, taken wings during the long hours of
darkness, but each time he found it was still in place.

“Seems laik it’ll never come mornin’,” he said.

But dawn came at length, and, after a hasty breakfast, preparations to
enter the temple were made. Andy loaded his gun for “bear” as he
expressed it, and the boys each took a revolver.

The ship was lowered to as level a place as could be found, and then,
seeing that everything was in readiness for a quick departure, the
professor led the way out of the _Mermaid_.

The entrance to the temple was through a big arched gateway. Some of the
stones had fallen down, and the whole structure looked as if it might
topple over at any moment.

“Go carefully,” cautioned Mr. Henderson. “Watch on all sides and up
above. Better let Andy and me go ahead.”

The scientist and the old hunter led the way. Through the arch they
went, and emerged into what must at one time have been a magnificent
courtyard. Before them was the temple proper, a vast structure, with an
opening through which fifty men might have marched abreast. But the
doors were gone, and the portal was but a black hole.

“I hope there ain’t any ghosts in there,” said Washington, with a
shiver.

“Nonsense!” exclaimed the professor. “There may be things as bad, but
there are no such things as ghosts. Have your gun ready, Andy.”

With every sense on the alert, the old hunter advanced. Every one was a
bit nervous, and, as Mark and Jack afterward admitted, they half
expected some terrible beast to rush out at them. But nothing of the
kind happened, and they went into the interior of the temple.

At first it was so dark they could see nothing. There were vast dim
shapes on every side, and from the hollow echo of their footsteps they
judged the roof must be very high and the structure big in every way.

Then, as their eyes became used to the darkness, they could make out, up
front, something like an altar or pulpit.

“Perhaps that’s where they offered up the gold and diamonds as a
sacrifice to their gods,” spoke Mark in a whisper.

“Sacrifice to their gods!” came back a hundred echoes and the sound made
every one shudder.

“Oh!” said Washington, in a low voice.

“Oh! Oh! Oh!” repeated the echoes in voices of thunder.

“Well, this is pleasant,” spoke Andy, in his natural tones, and, to the
surprise of all there was no echo. It was only when a person whispered
or spoke low that the sound was heard. After that they talked naturally.

“You stay here, and Andy and I will go up front and see what there is,”
said Mr. Henderson. “Be on your guard, and if you hear us coming back in
a hurry, run!”

It was with no little feeling of nervousness that the boys, Bill, Tom
and Washington watched the two men move off in the darkness. They could
hear their footsteps on the stone flags and could dimly see them.

“They must be almost to the altar by this time,” said Mark, after a long
pause.

Hardly had he spoken than there came a loud sound from where Mr.
Henderson and Andy had gone. It was as if some giant wings were beating
the air. Then came shrill cries and the voice of the old hunter could be
heard calling:

“Kneel down, Professor! Let me get a shot at the brute!”

Those waiting in the rear of the temple huddled closer together. What
terrible beast could have been aroused?

The next instant the place seemed illuminated as if by a lightning
flash, and a sound as of a thousand thunder claps resounded.

“I think I winged him!” cried Andy’s voice, and the boys knew he had
fired at something.

Then there came a crash, and from the roof of the old temple a dozen
stones toppled off to one side, letting in a flood of colored light.

By this illumination could be seen, flapping through the big space
overhead, an enormous bat, as large as three eagles. And, as it flew
about in a circle it gave utterance to shrill cries.

“Bang!” Andy’s gun spoke again, and the bat with a louder cry than
before, darted through the hole in the roof made by the falling stones,
which had been loosened by the concussion from the rifle.

“Come on!” cried the old hunter. “That was the guardian of the treasure!
We are safe now!”

Then, in the light which streamed through the broken roof, the
adventurers could see, heaped up on a great altar, behind which sat a
horrible graven image, piles of yellow metal, and sparkling stones. In
little heaps they were, arranged as if offerings to the terrible god of
the giants. There were bars and rings of gold, dishes of odd shape, and
even weapons. As for the sparkling stones, they were of many colors, but
the white ones were more plentiful than all the others.

“Gold and diamonds! Diamonds and gold!” murmured the professor. “There
is the ransom of many kings in this ancient temple.”

“Wish I had a big bag!” exclaimed Washington, as he began filling all
his pockets with the precious metal and gems. “If I had a-thought I’d
have brought a dress-suit case!”

“A dress-suit case full of diamonds!” exclaimed Mark.

Then he too, as did all the others, fell to filling his pockets with the
wealth spread so lavishly before them. There was the riches of a whole
world in one place and no one but themselves to take it.

For several minutes no one spoke. The only sound was the rattle of the
stones and the clink of gold, and when some of the diamonds dropped on
the floor they did not bother to gather them up. There were too many on
the altar.

“We will be rich for life!” gasped old Andy, who had been poor all his
years.

“I can’t carry any more!” gasped Washington. “I’m goin’ back for——”

What he was going back for he never said, for, at that instant,
happening to look up at the hole in the roof, he gave a startled cry:

“Here come the terrible bats!”

They all gazed upward. Through the opening they could see a great flock
of the awful birds, headed for the temple, and they were led by one
which seemed to fly with difficulty. It was the guardian of the treasure
that Andy had wounded.

“Quick! We must get out of here!” shouted the old hunter. “They are big
enough and strong enough to tear us all to pieces. Hurry!”

Down the centre of the temple they rushed, and not a moment too soon,
for, ere they had passed half way to the entrance, the opening in the
roof was darkened by the coming of the bats, and soon the flapping of
their wings awoke the thundering echoes in the ruined structure, while
their shrill cries struck terror to the hearts of the travelers.

Up to the altar circled the bats, and then wheeling they flapped down
the dim aisles toward the adventurers.

“Hurry! Hurry!” shouted Andy, who was in the rear.

He raised his rifle and fired several shots into the midst of the
terrible creatures.

A number of the bats were wounded, and the others were so frightened by
the sound of the shots and the flashes of fire that they turned back.
This enabled the fleeing ones to gain the entrance to the temple, and
soon they were outside.

“To the ship!” yelled Bill.

“There’s little danger now!” called Andy, panting, for the run had
winded him. “They will hardly attack us in the light!”

And he was right, for, though they could hear the bats flying about
inside the temple, and uttering their cries, none came outside.

But no one felt like staying near the uncanny structure, and little time
was lost in reaching the _Mermaid_. Then the doors were fastened, and
the ship was sent high up into the air.

“Which way?” asked Jack, when Mr. Henderson told him to go to the
conning tower and steer.

“Back to where we first met the giants,” replied the professor. “We must
prepare to start for our own earth again soon.”

“I’ve almost forgotten how real sunlight looks,” thought Jack, as he
headed the ship around the other way. As he turned the levers a big
diamond dropped from his pocket and rolled on the floor.

“This will be a good reminder of our trip though,” he added.

The travelers, even including Mr. Henderson, were so taken up with their
suddenly acquired riches that they hardly thought of meals. At the
professor’s suggestion they tied their gold and stones up in small
packages convenient to carry.

“Better place them where you can grab them in a hurry in case of
accident,” the old scientist went on. “Of course if there should be too
bad an accident they would never be of any use to us down here, but
we’ll look on the bright side of things.”

“Do you anticipate any accident?” asked Jack anxiously.

“No, Oh no,” replied Mr. Henderson, but Jack thought the aged man had
something weighing on his mind.

CHAPTER XXIX

BACK HOME—CONCLUSION

On and on sped the _Mermaid_. Now that the travelers felt their journey
accomplished they were anxious to begin the homeward trip. They made a
straight course for the village where they had so nearly met with
disaster, and where the king of the giants had saved them. They went in
a direct line, and did not travel here and there, as they had after they
left the town. Consequently they shortened the route by a great
distance. Yet it was long enough, and when they finally came in sight of
the place the dial registered a trip of five thousand miles underground.

It was one evening when they landed almost at the spot whence they had
taken flight eventually to reach the temple of the treasure. Most of the
giants had betaken themselves to their mound houses, but Hankos was
walking in the fields, and, when he caught sight of the airship hovering
above him he waved his great sword in welcome.

He rushed up to shake hands with the travelers when they came out of the
ship, though to greet him it was only possible for the adventurers to
grasp one of his immense fingers.

As soon as the greetings were over Hankos began to speak rapidly to the
professor, at the same time going through many strange motions.

“It is as I feared!” suddenly exclaimed the scientist.

“What is the matter?” asked Mark.

“The worst has happened!” went on Mr. Henderson. “The great hole by
which we came into this place has been closed by an earthquake shock!”

“The hole closed?” repeated Jack.

“An earthquake shock!” murmured Mark.

“Then how are we going to get back to earth?” asked old Andy.

A terrible fear entered the hearts of the travelers. The closing of the
opening by which they had come to the strange world meant, in all
probability that they would have to spend the rest of their lives in
this underground place.

“What good did it do us to get all those diamonds and that gold?” asked
Mark in a sorrowful tone.

Hankos began to speak again, using his gestures which were almost as
eloquent as words. The professor watched and listened intently. Then
there seemed to come a more hopeful look to his face. He nodded
vigorously as Hankos went on with what seemed to be an explanation.

“It’s worth trying, at all events!” the scientist exclaimed. “It is our
only hope!”

“What is?” asked Jack.

“Friends,” began the professor in solemn tones. “I must admit our plight
is desperate. At the same time there is a bare chance of our getting
back to our own earth. As you remember, Hankos went from this place to
the upper regions through the upward spouting column of water.”

“If we had our submarine we might also,” interrupted Jack. “But the
_Mermaid_ isn’t built to sail in that fashion.”

“Nor would the _Porpoise_ have served us in this emergency,” said the
professor. “It would prove too heavy. But, nevertheless, I think I have
a plan. Now, Mark, you are about to learn the secret of the storeroom.
The real one, not the hiding of Hankos in there, which you imagined to
be the cause of my desire to keep something hidden. When we planned a
trip to this underground world I had a dim idea that we might meet with
trouble. So I planned and made a cylinder lifeboat.”

“A cylinder lifeboat?” repeated Mark.

“Yes,” replied Mr. Henderson. “I have it in the storeroom. I did not
want any of you to see it for fear you would have faint hearts. I
thought there might be no necessity of using it. But, since there is, we
must do our best. I will admit it may be a fearful ordeal, but we will
have to risk something in order to escape.

“I have in the storeroom a large cylinder, capable of holding us all. It
will also contain food and drink for a month, but we will all have to
go, packed almost like sardines in a box. My plan is to take the
_Mermaid_ to the place where the column of water shoots up. There we
will get into the cylinder, close it, and trust ourselves to the
terrible force that may bring us back to the upper world. What do you
say? Shall we attempt it?”

For a few seconds no one spoke. Then Jack said slowly:

“I don’t see that we can do anything else. I don’t want to stay here all
my life.”

“I wants a chance t’ wear some of them sparklers,” put in Washington.

“Then we will make the attempt,” the professor added. “Now all aboard
for the place where the water shoots up!”

Questioning Hankos, the professor learned how to reach the strange
place. It was in the midst of a desolate country where none of the
giants ever went, so afraid were they of the strange phenomenon.

It was a week’s journey. Sometimes the _Mermaid_ flew through the air,
and again it sailed on vast lakes or inland seas. On the trip they met
with big waterfalls and terrible geysers that spouted a mile or more
into the air. They traveled by night as well as day, though it was
necessary to keep a sharp watch.

Sometimes the ship passed through great flocks of birds that surrounded
her and sought to pierce the aluminum hull with their sharp beaks and
talons. Over the mountains and valleys the ship sailed until, one
evening, there sounded through the air a strange rumbling sound.

“It is thunder,” said Old Andy.

“It is the water column,” replied the scientist. “We are at the end of
our trip. May the remainder be as successful!”

The ship was lowered to the surface, as it was deemed best to approach
the column when the lights were shining. No one slept much that night,
for the roaring and rumbling never ceased.

In the morning the ship was sent forward slowly. Ever and ever the
terrific sound increased, until it was almost deafening. They had to
call to each other to be heard.

Then, as the _Mermaid_ passed over a mountain, the adventurers saw, in a
valley below them, the up-shooting water.

It was a vast column, nearly three hundred feet in thickness, and as
solid and white as a shaft _of_ marble. Up, up, up, it went, until it
was lost to sight, but there were no falling drops, and not even a spray
came from the watery shafts.

“There is a terrible power to it,” the professor said. “May it prove our
salvation!”

The ship was lowered about a hundred feet away from the waterspout. All
around them the ground was vibrating with the force of the fluid.

“To think that connects with the world above!” exclaimed Jack.

“It’s a good thing for us that it does,” Mark answered.

“We must lose no time,” the professor put in. “If the earthquake
destroyed the downward shaft, it may effect this one in time. We must
escape while we can.”

Then, for the first time, he opened the storeroom and the big cylinder
was disclosed to view. It was made of aluminum, and shaped like an
immense cigar. The hull was double, and it was strongly braced. Inside
were padded berths for the occupants, and there was just room enough for
the seven adventurers. Once they had entered they could not move about,
but must stay in their little compartment.

Compressed air in strong cylinders furnished a means of breathing, and
there were tiny electric lights operated by a storage battery. There was
also a chamber to be filled with the lifting gas. The cylinder was so
arranged that it would float on it’s long axis if thrown into the water.
A trap door hermetically sealed gave access to the interior. A small
propellor, worked by compressed air, furnished motive power.

The food supply consisted of compressed capsules on which a man could
subsist for several days. There was also some water, but not much, since
that can not be compressed and would, therefore, take considerable room.

“The only thing for us to do,” said the professor, “is to get into the
cylinder, seal it up, and trust to Providence. This is what I intended
to use when we were caught in the draught.”

“How can we get into the column of water after we shut ourselves into
the cylinder?” asked Mark.

“The cylinder fits into a sort of improvised cannon,” said Mr.
Henderson. “It is fired by electricity and compressed air. We will aim
it at the column, press the button and be projected into the midst of
the water. Then——” He did not finish the sentence, but the others knew
what he meant.

“When are we to start?” asked Mark.

“As soon as possible,” replied the professor. “I must arrange the
cylinder, compress the air and lay out the food supply.”

It took the rest of the day to do this, as the inventor found it would
be advisable to attach a weight to the end of the cylinder, to hold it
upright in the column of water. The weight could be detached
automatically when they were shot up into the midst of the ocean, where,
as Hankos had told them, the column spurted forth.

Then some food was stored in the tiny ship that was destined to be their
last hope, and some tanks of water were placed in it.

“I think we are almost ready,” Mr. Henderson said about noon the next
day.

“What about our gold and diamonds?” asked Jack suddenly. “Can we take
them with us in the cylinder?”

“That’s so!” exclaimed Mr. Henderson. “I forgot about them. I’m afraid
we’ll have to leave the riches behind. We will not be able to carry them
and the food we need, for it may be a week or more before we can leave
the cylinder. Gold and diamonds will be a poor substitute for something
to eat.”

“I’m goin’ t’ take mine!” said Washington with much conviction. “I might
as well starve rich as starve poor!”

“We may be able to take a few diamonds,” the professor answered. “The
gold will be too heavy. Let each one select the largest of the diamonds
he has and put them in his pockets.”

Then began a sorting of the wealth. It was strange, as they recalled
afterward, throwing away riches that would have made millionaires
envious, but it had to be done. All the wealth in the world would not
equal a beef capsule when they were starving, and they realized it. So
they only saved a few pieces of gold as souvenirs, and took the best of
the diamonds. But even then they had a vast fortune with them.

At last all was in readiness. The cylinder had been placed in the tube
from which it was to be shot gently forth by compressed air, so that it
would fall into the upward spouting column of water. The charge of
compressed air was put in and the electric wires arranged.

“Are we all ready?” asked Mr. Henderson.

“I think so,” said Jack, in what sounded like a whisper, but which was
loud, only the noise of the water muffled it.

“Then we had better enter the cylinder,” spoke the inventor. “Take a
last look at the _Flying Mermaid_, boys, for you will never see again
the ship that has borne us many thousand miles. She served us well, and
might again, but for the freak of nature that has placed us in this
position.”

For the first time the adventurers realized that they must abandon the
craft in which they had reached the new world. So it was with no little
feeling of sadness that they climbed up the ladder that had been
arranged and slid down into the cylinder. One by one they took their
places in the padded berths arranged for them. It was a snug fit, for
the professor knew if there was too much room he and the others might be
so tossed about as to be killed.

Mr. Henderson was the last to enter. Standing at the manhole he took a
final look at his pet creation, the _Mermaid_. Through the opened
windows the colored lights came, shifting here and there. Outside the
terrible column of water was roaring as if anxious to devour them.

“Good-bye, _Mermaid_!” said the professor softly.

Then he closed down the manhole cover and tightened the screws that held
it in place. He touched a button that turned on the electric lights and
the interior of the cylinder was illuminated with a soft glow.

“Are you all ready?” he asked.

“Jest as much as I ever will be,” replied Washington, who, as the crisis
approached, seemed more light-hearted than any of the others.

“Then here we go!” exclaimed Mr. Henderson.

His fingers touched the button that connected with the electric machine,
which operated the compressed air.

There sounded a muffled report. Then it seemed to those in the cylinder
that the end of the world had come. They shot upward and outward,
through the top of the conning tower which had been removed. The
cylinder, launched straight at the column of water struck it squarely
and, an instant later was caught in the grasp of the giant force and
hurled toward the upper world.

Up and up and up the mass of metal with its human freight went. Now it
was spinning like a top, again it shot toward the earth’s crust like an
arrow from the archer’s bow.

It was moving with the velocity of a meteor, yet because of being
surrounded with water, and traveling with the same velocity as the
column, there was no friction. Had there been, the heat generated would
have melted the case in an instant.

For the first few seconds those in the cylinder were dazed by the sudden
rush. Then as it became greater and greater there came a curious dull
feeling, and, one after another lost consciousness. The terror of the
water column, and the frightful speed, had made them senseless.

* * * * *

It seemed like a month later, though, of course, it could have been only
a few hours or a day at most when Jack opened his eyes. He saw his
companions, white and senseless all around him, and at first thought
they were dead. Then he saw Mark looking at him, and Washington asked:

“Is any one livin’ 'sides me?”

“I am,” replied Jack decidedly.

Then, one after another they regained their senses. But they were in a
strange daze, for they were being carried along like a shooting star,
only, as they went at the same rate as did the element carrying them,
they did not _realize_ this.

“I think I’m hungry,” said Bill, who had the best appetite of any of the
travelers.

“You’ll find a beef capsule in the little compartment over your head,”
spoke the professor.

Bill was about to reach for it, when they were all startled by a sudden
side motion of the cylinder. Then came a violent shock, and a sound as
of splashing water. Next the cylinder seemed to be falling, and, a few
minutes later to be shooting upward. Following this there was another
splash and the cylinder began to bob about like a cork on a mill pond.

“We have reached the sea! We are afloat on the ocean!” cried the
professor.

Hurriedly he disengaged himself from the straps that held him to his
bunk. He pushed back the lever that opened the manhole. Into the opening
glowed the glorious sunlight, while to the occupants came the breath of
salt air.

“Hurrah!” cried Jack. “We are safe at last!”

“Safe at last!” the professor answered, and then they all gave a cheer.

For their cylinder, which might now be termed a boat, was floating on
the great Atlantic. The blue sky was overhead and the air of the sea
fanned their cheeks.

They had shot up from the underground earth, in the column of water, had
been tossed high into the air, had fallen back when the liquid shaft
broke into spray, had descended into the ocean, gone down a hundred feet
or more, and then had shot up like a cork to bob about the surface.

For a week they were afloat, and then they were picked up by a passing
vessel, rather weak and very much cramped, but otherwise in good shape.
They said nothing of their adventures, save to explain that they were
experimenting in a new kind of boat. About a month later, for the ship
that had rescued them was a slow sailer, they were back on the island
whence that wonderful voyage was begun.

* * * * *

“Well, we solved the mystery of the center of the earth,” remarked Jack,
one evening, when they were gathered in the old shack where so many
wonderful adventures had been planned.

“Yes, we did,” said Mr. Henderson. “And no one else is ever likely to go
there.”

“Why?”

“Because the only way of getting there was destroyed by the earthquake,
and no one could ever force his way down through that upward-shooting
column of water.”

“That’s so. Well, we have the diamonds, anyway,” spoke Mark. “They ought
to make us rich.”

And the jewels did, for the stones proved to be of great value, even
though the adventurers had saved only a few of the many they found in
the ruined temple.

But there was money enough so that they all could live in comfort the
rest of their lives. As the professor was getting quite old, and
incapable of making any more wonderful inventions, he closed up his
workshop and settled down to a quiet life. As for Washington, Andy, and
Bill and Tom, they invested their money received from the sale of the
diamonds in different business ventures, and each one did well.

“I am going in for a good education,” said Jack to Mark.

“Just what I am going to do,” answered his chum. “And after we’ve got
that——” He paused suggestively.

“We’ll go in for inventing airships, or something like that, eh?”

“Yes. We’ve learned a great deal from Mr. Henderson, and in the course
of time we ought to be able to turn out something even more wonderful
than the _Electric Monarch_, the _Porpoise_, or the _Flying Mermaid_.”

“Yes, and when we’ve invented something better——”

“We’ll take another trip.”

“Right you are!”

And then the two chums shook hands warmly; and here we will say
good-bye.

THE END.

------------------------------------------------------------------------

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This is one of the last stories penned by that prince of all juvenile
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DOROTHY DALE: A GIRL OF TO-DAY

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[Illustration: small image of book cover]

THE YOUNG EXPRESS AGENT
Or, Bart Stirling’s Road to Success

Bart’s father was the express agent in a country town. When an explosion
of fireworks rendered him unfit for work, the boy took it upon himself
to run the express office. The tale gives a good idea of the express
business in general.

TWO BOY PUBLISHERS
Or, From Typecase to Editor’s Chair

This tale will appeal strongly to all lads who wish to know how a
newspaper is printed and published. The two boy publishers work their
way up, step by step, from a tiny printing office to the ownership of a
town paper.

MAIL ORDER FRANK
Or, A Smart Boy and His Chances

Here we have a story covering an absolutely new field—that of the
mail-order business. How Frank started in a small way and gradually
worked his way tip to a business figure of considerable importance is
told in a fascinating manner.

A BUSINESS BOY
Or, Winning Success

This relates the ups and downs of a young storekeeper. He has some keen
rivals, but “wins out” in more ways than one. All youths who wish to go
into business will want this volume.

CUPPLES & LEON CO., Publishers, NEW YORK

------------------------------------------------------------------------

MOTOR BOYS SERIES
(Trade Mark, Reg. U. S. Pat. Of.)
By Clarence Young

Cloth. 12mo. Illustrated. Price per volume. 60 cents, postpaid

[Illustration: small image of book cover]

THE MOTOR BOYS
Or, Chums Through Thick and Thin

In this volume is related how the three boys got together and planned to
obtain a touring car and make a trip lasting through the summer.

THE MOTOR BOYS OVERLAND
Or, A Long Trip for Fun and Fortune

With the money won at the great motorcycle race the three boys purchase
their touring car and commence their travels.

THE MOTOR BOYS IN MEXICO
Or, The Secret of the Buried City

From our own country the scene is shifted to Mexico, where the motor
boys journey in quest of a city said to have been buried centuries ago
by an earthquake.

THE MOTOR BOYS ACROSS THE PLAINS
Or, The Hermit of Lost Lake

Unraveling the mystery surrounding an old hermit and a poor boy.

THE MOTOR BOYS AFLOAT
Or, The Stirring Cruise of the Dartaway

In this volume the boys take to a motorboat, and have many adventures.

THE MOTOR BOYS ON THE ATLANTIC
Or, The Mystery of the Lighthouse

How the lads foiled the bad men who wanted to wreck a steamer by means
of false lights is dramatically related.

THE MOTOR BOYS IN STRANGE WATERS
Or, Lost in a Floating Forest

Telling of many adventures in the mysterious Everglades of Florida.

THE MOTOR BOYS ON THE PACIFIC
Or, The Young Derelict Hunters

The derelict was of great value, and the hunt for it proved full of
perils.

THE MOTOR BOYS IN THE CLOUDS
Or, A Trip for Fame and Fortune

The boys fall in with an inventor and invest in a flying machine. After
a number of stirring adventures in the clouds they enter a big race.

CUPPLES & LEON CO., Publishers, NEW YORK

------------------------------------------------------------------------

THE BOY HUNTERS SERIES
By Captain Ralph Bonehill

Cloth. 15mo. Illustrated. Price per volume, 60 cents, postpaid

[Illustration: small image of book cover]

FOUR BOY HUNTERS
Or, The Outing of the Gun Club

A fine, breezy story of the woods and waters, of adventures in search of
game, and of great times around the campfire, told in Captain Bonehill’s
best style. In the book are given full directions for camping out.

GUNS AND SNOWSHOES
Or, The Winter Outing of the Young Hunters

In this volume the young-hunters leave home for a winter outing on the
shores of a small lake. They hunt and trap to their heart’s content, and
have adventures in plenty, all calculated to make boys “sit up and take
notice.” A good healthy book; one with the odor of the pine forests and
the glare of the welcome campfire in every chapter.

YOUNG HUNTERS OF THE LAKE
Or, Out with Rod and Gun

Another tale of woods and waters, with some strong hunting scenes and a
good deal of mystery. The three volumes make a splendid outdoor series.

OUT WITH GUN AND CAMERA
Or, The Boy Hunters in the Mountains

Takes up the new fad of photographing wild animals as well as shooting
them. An escaped circus chimpanzee and an escaped lion add to the
interest of the narrative.

CUPPLES & LEON CO., Publishers, NEW YORK

------------------------------------------------------------------------

THE DAREWELL CHUMS SERIES
By Allen Chapman

Cloth. 12mo. Illustrated. 60 cents each, postpaid.

THE DAREWELL CHUMS
Or, The Heroes of the School

A bright, lively story for boys, telling of the doings of four chums, at
school and elsewhere. There is a strong holding plot, and several
characters who are highly amusing. Any youth getting this book will
consider it a prize and tell all his friends about it.

THE DAREWELL CHUMS IN THE CITY
Or, The Disappearance of Ned Wilding

From a country town the scene is changed to a great city. One of the
chums has disappeared in an extraordinary manner, and the others
institute a hunt for him. The youths befriend a city waif, who in turn
makes a revelation which clears up the mystery.

[Illustration: small image of book cover]

DAREWELL CHUMS IN THE WOODS
Or, Frank Roscoe’s Secret

The boys had planned for a grand outing when something happened of which
none of them had dreamed. They thought one of their number had done a
great wrong—at least, it looked so. But they could not really believe
the accusations made, so they set to work to help Frank all they could.
All went camping some miles from home, and when not hunting and fishing
spent their time in learning the truth of what had occurred.

THE DAREWELL CHUMS ON A CRUISE
Or, Fenn Masterson’s Odd Discovery

A tale of the Great Lakes. The boys run across some Canadian smugglers
and stumble on the secret of a valuable mine. Some curious adventures
underground are well told.

CUPPLES & LEON CO., Publishers, NEW YORK

*** End of this LibraryBlog Digital Book "Five Thousand Miles Underground; Or, the Mystery of the Centre of the Earth" ***

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