"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 moon-beams, 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 nearby 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 look-out."

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.

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 wer rger 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 accomodated 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 there 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.

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 XXVI

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! Came 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 try:

"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 propeller, worked by compressed air, furnished motive power.

The food supply consisted of compressed capsules on which a man could subsist for several days. There was also some water, but not much, since that can not be compressed and would, therefore, take considerable room.

"The only thing for us to do," said the professor, "is to get into the cylinder, seal it up, and trust to Providence. This is what I intended to use when we were caught in the draught."

"How can we get into the column of water after we shut ourselves into the cylinder?" asked Mark.

"The cylinder fits into a sort of improvised cannon," said Mr. Henderson. "It is fired by electricity and compressed air. "We will aim it at the column, press the button and be projected into the midst of the water. Then——" He did not finish the sentence, but the others knew what he meant.

"When are we to start?" asked Mark.

"As soon as possible," replied the professor. "I must arrange the cylinder, compress the air and lay out the food supply."

It took the rest of the day to do this, as the inventor found it would be advisable to attach a weight to the end of the cylinder, to hold it upright in the column of water. The weight could be detached automatically when they were shot up into the midst of the ocean, where, as Hankos had told them, the column spurted forth.

Then some food was stored in the tiny ship that was destined to be their last hope, and some tanks of water were placed in it.

"I think we are almost ready," Mr. Henderson said about noon the next day.

"What about our gold and diamonds?" asked Jack suddenly. "Can we take them with us in the cylinder?"

"That's so!" exclaimed Mr. Henderson. "I forgot about them. I'm afraid we'll have to leave the riches behind. We will not be able to carry them and the food we need, for it may be a week or more before we can leave the cylinder. Gold and diamonds will be a poor substitute for something to eat."

"I'm goin' t' take mine!" said Washington with much conviction. "I might as well starve rich as starve poor!"

"We may be able to take a few diamonds," the professor answered. "The gold will be too heavy. Let each one select the largest of the diamonds he has and put them in his pockets."

Then began a sorting of the wealth. It was strange, as they recalled afterward, throwing away riches that would have made millionaires envious, but it had to be done. All the wealth in the world would not equal a beef capsule when they were starving, and they realized it. So they only saved a few pieces of gold as souvenirs, and took the best of the diamonds. But even then they had a vast fortune with them.

At last all was in readiness. The cylinder had been placed in the tube from which it was to be shot gently forth by compressed air, so that it would fall into the upward spouting column of water. The charge of compressed air was put in and the electric wires arranged.

"Are we all ready?" asked Mr. Henderson.

"I think so," said Jack, in what sounded like a whisper, but which was loud, only the noise of the water muffled it.

"Then we had better enter the cylinder," spoke the inventor. "Take a last look at the Flying Mermaid, boys, for you will never see again the ship that has borne us many thousand miles. She served us well, and might again, but for the freak of nature that has placed us in this position."

For the first time the adventurers realized that they must abandon the craft in which they had reached the new world. So it was with no little feeling of sadness that they climbed up the ladder that had been arranged and slid down into the cylinder. One by one they took their places in the padded berths arranged for them. It was a snug fit, for the professor knew if there was too much room he and the others might be so tossed about as to be killed.

Mr. Henderson was the last to enter. Standing at the manhole he took a final look at his pet creation, the Mermaid. Through the opened windows the colored lights came, shifting here and there. Outside the terrible column of water was roaring as if anxious to devour them.

"Good-bye, Mermaid!" said the professor softly.

Then he closed down the manhole cover and tightened the screws that held it in place. He touched a button that turned on the electric lights and the interior of the cylinder was illuminated with a soft glow.

"Are you all ready?" he asked.

"Jest as much as I ever will be," replied Washington, who, as the crisis approached, seemed more light-hearted than any of the others.

"Then here we go!" exclaimed Mr. Henderson.

His fingers touched the button that connected with the electric machine, which operated the compressed air.

There sounded a muffled report. Then it seemed to those in the cylinder that the end of the world had come. They shot upward and outward, through the top of the conning tower which had been removed. The cylinder, launched straight at the column of water struck it squarely and, an instant later was caught in the grasp of the giant force and hurled toward the upper world.

Up and up and up the mass of metal with its human freight went. Now it was spinning like a top, again it shot toward the earth's crust like an arrow from the archer's bow.

It was moving with the velocity of a meteor, yet because of being surrounded with water, and traveling with the same velocity as the column, there was no friction. Had there been, the heat generated would have melted the case in an instant.

For the first few seconds those in the cylinder were dazed by the sudden rush. Then as it became greater and greater there came a curious dull feeling, and, one after another lost consciousness. The terror of the water column, and the frightful speed, had made them senseless.

It seemed like a month later, though, of course, it could have been only a few hours or a day at most when Jack opened his eyes. He saw his companions, white and senseless all around him, and at first thought they were dead. Then he saw Mark looking at him, and Washington asked:

"Is any one livin' 'sides me?"

"I am," replied Jack decidedly.

Then, one after another they regained their senses. But they were in a strange daze, for they were being carried along like a shooting star, only, as they went at the same rate as did the element carrying them, they did not realize this.

"I think I'm hungry," said Bill, who had the best appetite of any of the travelers.

"You'll find a beef capsule in the little compartment over your head," spoke the professor.

Bill was about to reach for it, when they were all startled by a sudden side motion of the cylinder. Then came a violent shock, and a sound as of splashing water. Next the cylinder seemed to be falling, and, a few minutes later to be shooting upward. Following this there was another splash and the cylinder began to bob about like a cork on a mill pond.

"We have reached the sea! We are afloat on the ocean!" cried the professor.

Hurriedly he disengaged himself from the straps that held him to his bunk. He pushed back the lever that opened the manhole. Into the opening glowed the glorious sunlight, while to the occupants came the breath of salt air.

"Hurrah!" cried Jack. "We are safe at last!"

"Safe at last!" the professor answered, and then they all gave a cheer.

For their cylinder, which might now be termed a boat, was floating on the great Atlantic. The blue sky was overhead and the air of the sea fanned their cheeks.

They had shot up from the underground earth, in the column of water, had been tossed high into the air, had fallen back when the liquid shaft broke into spray, had descended into the ocean, gone down a hundred feet or more, and then had shot up like a cork to bob about the surface.

For a week they were afloat, and then they were picked up by a passing vessel, rather weak and very much cramped, but otherwise in good shape. They said nothing of their adventures, save to explain that they were experimenting in a new kind of boat. About a month later, for the ship that had rescued them was a slow sailer, they were back on the island whence that wonderful voyage was begun.

"Well, we solved the mystery of the center of the earth," remarked Jack, one evening, when they were gathered in the old shack where so many wonderful adventures had been planned.

"Yes, we did," said Mr. Henderson. "And no one else is ever likely to go there."

"Why?"

"Because the only way of getting there was destroyed by the earthquake, and no one could ever force his way down through that upward-shooting column of water."

"That's so. Well, we have the diamonds, anyway," spoke Mark. "They ought to make us rich."

And the jewels did, for the stones proved to be of great value, even though the adventurers had saved only a few of the many they found in the ruined temple.

But there was money enough so that they all could live in comfort; the rest of their lives. As the professor was getting quite old, and incapable of making any more wonderful inventions, he closed up his workshop and settled down to a quiet life. As for Washington, Andy, and Bill and Tom, they invested their money received from the sale of the diamonds in different business ventures, and each one did well.

"I am going in for a good education," said Jack to Mark.

"Just what I am going to do," answered his chum. "And after we've got that——" He paused suggestively.

"We'll go in for inventing airships, or something like that, eh?"

"Yes. We've learned a great deal from Mr. Henderson, and in the course of time we ought to be able to turn out something even more wonderful than the Electric Monarch, the Porpoise, or the Flying Mermaid."

"Yes, and when we've invented something better——"

"We'll take another trip."

"Right you are!"

And then the two chums shook hands warmly; and here we will say good-bye.

THE END.