THE FLYING MERMAID SANK LOWER AND LOWER TOWARD THE MYSTERIOUS HOLE.

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.

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.

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.

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.