Four times that morning they made the circuit, and the same number in the afternoon, until they were nearly half a mile away from the ruin, but no tunnel showed.

"Well, we'll have to keep at it to-morrow," suggested Tom. "It's too soon to give up."

But the morrow brought no better success, nor did the following two days. In fact for a week they kept up the search for the tunnel, but did not come upon it, and they had now pretty well covered the big plain. They found a few ruins of the ancient city of Poltec.

"Well, what about it?" asked Ned one night as they sat in the balloon, talking it over. "What next, Tom?"

"We've got to keep at it, that's all. I think we'll go up in the balloon, circle around over the plain at just a little elevation, and maybe we can spot it that way."

"All right, I'm with you."

But they did not try that plan. For in the middle of the night Ned suddenly awakened. Something had come to him in his sleep.

"Tom! Tom!" he cried. "I have it! What chumps we were!"

"What's the matter, old man?" asked Tom anxiously. "Are you sick—talking in your sleep?"

"Sleep nothing! I've just thought of it. That tunnel entrance is INSIDE the temple. That's the most natural place in the world for it. I'll bet it's right in the middle of the big inner chamber, where the priests could control it. Why didn't we look there before?"

"That's right; why didn't we?" agreed Tom. "I believe you're right, Ned! We'll look the first thing in the morning."

They did not wait for breakfast before trying the experiment, and Mr. Damon and Eradicate went with Tom and Ned. It was no easy work to make their way over the ruins to the inner auditorium. Wreckage and ruin was all around, and they had to avoid the yawning holes on every side. But when they got to the main, or sacrificial chamber, as Ned insisted on calling it, they found the floor there solid. In the centre was a great altar, but to their chagrin there was not a sign of a tunnel opening.

"Fooled again!" said Tom bitterly.

"Maybe some of those holes outside is the entrance," suggested Mr. Damon.

"I don't believe so," objected Tom. "They seemed to go only to the cellar, if a temple has such a thing."

Bitterly disappointed, Tom strolled over and stood in front of the big stone altar. It seemed that he must give up the search. Idly he looked at the sacrificial stone. Projecting from it was a sort of a bundle.

Tom took hold of it, and to his surprise he found that it could be moved. Hardly knowing what he was doing, he pulled it toward him.

The next instant he uttered a cry of horror, for the immense stone altar, with a dull rumbling, rolled back as though on wheels, and there, over where it had stood was a hole of yawning blackness, with a flight of stone steps leading down into it. And Tom stood so near the edge that he almost toppled in.

"Look! Look!" he cried when he could get his gasping breath, and step back out of danger.

"The tunnel entrance!" cried Ned. "That's what it is! You've found it, Tom! The entrance to the city of gold at last!"



CHAPTER XIX

THE UNDERGROUND RIVER

They gathered around the opening so unexpectedly disclosed to them, and stared down into the black depths. Beyond the first few steps of the flight that led to they knew not where, nothing could be seen. In his impatience Tom was about to go down.

"Bless my match box!" cried Mr. Damon. "What are you going to do, Tom, my boy?"

"Go down there, of course! What else? I want to get to the underground city."

"Don't!" quickly advised the odd man. "You don't know what's there. It may be a trap, where the old Aztecs used to throw their victims. There may be worse things than bats there. You'll need torches—lights—and you'd better wait until the air clears. It may have been centuries since that place was opened."

"I believe that's right," agreed Ned. "Whew; Smell it! It's as musty as time!"

An unpleasant odor came up the tunnel entrance, and it was stifling to stand too close. Tom lighted a match and threw it down. Almost instantly the flame was snuffed out.

"We couldn't live down there a minute," said the young inventor. "We've got to wait for it to clear. We'll go back to the balloon and get some electric flash lamps. I brought along a lot of 'em, with extra strong batteries. I thought we'd need some if we did find the city of gold, and it looks as if we were almost there now."

Tom's plan was voted good so they hurried out of the temple, their feet echoing and re-echoing over the stone floor. The place, ruined and desolate as it was, had no terrors for them now. In fact they were glad of the very loneliness, and Tom and Ned actually looked about apprehensively as they emerged, fearing they might see a sign of the Mexicans or the Fogers.

"Guess they can't pick up our trail," said Tom, when, he saw of what Ned was thinking.

"No, we've got the place to ourselves. I wonder how long it will take for the air to get fresh?"

"Not so very long, I guess. There was a good draught. There must be some opening in the underground city by which the air is sucked in. They'd never have only one opening to it. But we don't need to look for the other. Come on, we'll get out the torches."

These electrical contrivances are familiar to all boys. A small electric lamp is set in the end of a hollow tube of tin, and about the lamp is a reflector. Dry electrical batteries are put in the tin tube, and by means of a push button the circuit is closed, illuminating the lamp, which gives a brilliant glow. Tom had a special kind of lamp, with tungsten filaments, which gave a very powerful light, and with batteries designed to last a long time. A clip on the spring controlling the push button made it so that the lamp could be made to give a steady glow. Thus they were well prepared for exploring the tunnel.

It took some little time to get the flash lamps ready, and when they were all charged and they had eaten, they went back to the opening to see if the air had cleared. Tom tested it by dropping a match down, and, to his delight it burned with a clear flame.

"It's all right!" he exclaimed. "The air is pure. Now to see where we will bring up. Come on, everybody."

"Jest one minute, Massa Tom," begged Eradicate, as the young inventor was about to descend the steps, which even the brightness of his lamp did not disclose the end. "Is yo' gwine down dar, Massa Tom?"

"Certainly, Rad."

"An' is yo'—'scuse me—but is yo' expectin' me fo' t' follow yo'?"

"Certainly, Rad."

"Den, all I's got t' say is dat yo' is 'spectin' too much. I ain't gwine t' bury mahse'f alive not yit."

"But, Rad, this is where the gold images are. If you don't come down with us you won't get any gold."

"Am dat so? No gold?" The colored man scratched his head. "Well, I shore does want gold," he murmured. "I reckon I'd better trot along. But one thing mo', Massa Tom."

"What is it, Rad?"

"Was yo' all aimin' t' stay down thar any length ob time? 'Case if yo' is yo' all'd better take along a snack ob suffin' t' eat. 'Case when I gits among gold I don't want t' come out very soon, an' we might stay dar all day."

"Good advice, Rad," exclaimed Ned with a laugh. "I think we may get hungry. You go back and put us up a lunch. We'll wait for you."

"Bless my napkin ring! I think you're right!" exclaimed Mr. Damon, and Eradicate hurried back to the balloon to get some of the condensed food.

He was soon back and then, with Tom in the lead, and with everyone carrying an electric torch, with a spare one in reserve, and with their weapons in readiness the party descended the stone steps.

Their footfalls echoed solemnly as they went down—down into the unknown blackness. They kept their bright lights playing here and there, but even these did not dispell the gloom. On every side was stone—stone walls—stone steps. It was like going down into some vast stretch of catacombs.

"Say, will we ever get to the bottom?" asked Ned, when they had counted several hundred steps. "Maybe this goes down to the middle of the earth."

"Well, ef it do I'm gwine right along!" called Eradicate. "I's gwine t' hab one ob dem gold images or bust!"

"And I'm with you!" cried Tom. "We'll have to get to the bottom sooner or later."

Hardly had he spoken than he came to the last step, and saw stretching off before him a long tunnel, straight and level, lined on both sides, and bottom, with smooth stones that gleamed like marble.

"Now we are really in the tunnel," declared Ned. "I wonder what's at the end?"

"The city of gold, of course," answered Tom confidently.

Eagerly they hurried on. There was a slightly musty smell to the air, but it was fresher than might have been expected.

Suddenly Tom, who was in advance, uttered a cry. It sounded like one of alarm, and Ned yelled:

"What's the matter?"

"Look here!" cried Tom. They hurried up to him, to find him standing before a sort of niche in the wall. And the niche was lined with a yellow metal that gleamed like gold, while in it was one of the golden images, the second one they had seen, and the third they heard about.

"We're on the trail! We're on the trail!" cried Tom.

"Heah! Let me hab dat!" cried Eradicate. "I may not git anudder," and he reached up for the statue.

"Let it stay until we come back," suggested Mr. Damon.

"Somebody might take it," said the colored man.

"Who?" laughed Tom. "There's not a soul here but ourselves. But take it, if you want it, Rad," and Eradicate did so, stuffing the image, which was only about four inches high, into his pocket.

Then they went on, and they saw several other images, though not of gold. Several niches were lined with yellow metal, but whether it was gold or not they could not tell. They did not want to stop, as they were anxious to get to the underground city.

"Hark! What's that?" asked Tom, when they had gone about a mile along the tunnel. "Don't you hear something?"

"Sounds like a roaring," agreed Ned. "Maybe it's more of the bats."

"Doesn't sound like bats," declared Tom. "It's more like a waterfall. Come on."

They hurried forward, the strange sound increasing at every step, until it filled the tunnel with its menacing roar.

"That's strange," said Tom in worried tones. "I hope we don't come to a waterfall."

Suddenly the tunnel made a turn, and as they went around the curve in the wall the sound smote on their ears with increased violence. Tom raced forward, focusing his electric lamp down on the stone corridor. The next instant he cried out:

"A river! It's an underground river and we can't go any further! We're blocked!"

The others came to his side, and there, in the glare of their lamps, they saw rushing along, between two walls of stone, a dark stream which caused the roaring sound that had come to them. The tunnel was cut squarely in two by the stream, which was at least thirty feet wide, and how deep they could only guess. Swiftly it flowed on, its roar filling the tunnel.



CHAPTER XX

THE CITY OF GOLD

"Well, I guess this is the end of it," remarked Ned ruefully, as they stood contemplating the roaring stream by the gleam of their electric flash lamps. "We can't go on to the city of gold unless we swim that river, and—"

"And none of us is going to try that!" interrupted Tom sharply. "The strongest swimmer in the world couldn't make a yard against that current. He'd be carried down, no one knows where."

"Bless my bathing suit, yes!" exclaimed Mr. Damon. "But what are we to do? Can't we make a raft, or get a boat, or something like that?"

"Hab t' be a mighty pow'ful boat t' git across dat ribber ob Jordan," spoke Eradicate solemnly.

"That's right," agreed Ned. "But say, Tom, don't you think we could go back, get a lot of trees, wood and stuff and make some sort of a bridge? It isn't so very wide—not more than thirty or forty feet. We ought to be able to bridge it."

"I'm afraid not," and Tom shook his head. "In the first place any trees that would be long enough are away at the far edge of the big plain, and we'd have a hard job getting them to the temple, to say nothing of lugging them down the tunnel. Then, too, we don't know much about building a bridge, and with no one on the other side to help us, we'd have our hands full. One slip and we might be all drowned. No, I guess we've got to go back," and Tom spoke regretfully. "It's hard luck, but we've got to give up and go back."

"Den I's pow'ful glad I got ma golden image when I did, dat's suah!" exclaimed Eradicate. "Ef we doan't git no mo' I'll hab one. But I'll sell it and whack up wid yo' all, Massa Tom."

"You'll do nothing of the sort, Rad!" exclaimed the young inventor. "That image is yours, and I'm sorry we can't get more of them."

He turned aside, and after another glance at the black underground river which flowed along so relentlessly he prepared to retrace his steps along the tunnel.

"Say, look here!" suddenly exclaimed Ned. "I'm not so sure, after all that we've got to turn back. I think we can go on to the city of gold, after all."

"How do you mean?" asked Tom quickly. "Do you think we can bring the balloon down here and float across?"

"Bless my watch chain!" exclaimed Mr. Damon, "but that WOULD be a way. I wonder—"

"No, I don't mean that way at all," went on Ned. "But it seems to me as if this river isn't a natural one—I mean that it flows along banks of smooth stone, just as if they were cut for it, a canal you know."

"That's right," said Tom, as he looked at the edge of the channel of the underground stream. "These stones are cut as cleanly as the rest of the tunnel. Whoever built that must have made a regular channel for this river to flow in. And it's square on the other side, too," he added, flashing his lamp across.

"Then don't you see," continued Ned, "that this river hasn't always been here."

"Bless my gaiters!" gasped Mr. Damon, "what does he mean? The river not always been here?"

"No," proceeded Tom's chum. "For the ancients couldn't have cut the channel out of stone, or made it by cementing separate stones together while the water was here. The channel must have been dry at one time, and when it was finished they turned the water in it."

"But how is that going to help us?" asked Tom. "I grant you that the river may not have been here at one time, but it's here NOW, which makes it all the worse for us."

"But, Tom!" cried his chum, "if the river was turned aside from this channel once it can be done again. My notion is that the ancients could make the river flow here or not, just as they choose. Probably they turned it into this channel to keep their enemies from crossing to the city of gold, like the ancient moats. Now if we could only find—"

"I see! I see!" cried Tom enthusiastically. "You mean there must be some way of shutting off the water."

"Exactly," replied his chum. "We've got to shut that stream of water off, or turn it into some other channel, then we can cross, and keep on to the city of gold. And I think there must be some valve—some lever, or handle or something similar to the one that moved the altar-near here that does the trick. Let's all look for it."

"Bless my chopping block!" cried Mr. Damon. "That's the strangest thing I ever heard of! But I believe you're right, Ned. We'll look for the handle to the river," and he laughed gaily.

Every one was in better spirits, now that there seemed a way out of the difficulty, and a moment later they were eagerly flashing their lamps on the sides, floor and ceiling of the tunnel, to discover the means of shutting off the water. At first they feared that, after all, Ned's ingenious theory was not to be confirmed. The walls, ceiling and floor were as smooth near the edge of the river as elsewhere.

But Eradicate, who was searching as eagerly as the others, went back a little, flashing his lamp on every square of stone. Suddenly he uttered a cry.

"Look yeah, Massa Tom! Heah's suffin' dat looks laik a big door knob. Maybe yo' kin push it or pull it."

They rushed to where he was standing in front of a niche similar to the one where he had found the golden image. Sunken in the wall was a round black stone. For a moment Tom looked at it, and then he said solemnly:

"Well, here goes. It may shut off the water, or it may make it rise higher and drown us all, or the whole tunnel may cave in, but I'm going to risk it. Hold hard, everybody!"

Slowly Tom put forth his hand and pushed the knob of stone. It did not move. Then he pulled it. The result was the same—nothing.

"Guess it doesn't work any more," he said in a low tone.

"Twist it!" cried Ned. "Twist it like a door knob."

In a flash Tom did so. For a moment no result was apparent, then, from somewhere far off, there sounded a low rumble, above the roar of the black stream.

"Something happened!" cried Mr. Damon.

"Back to the river!" shouted Tom, for they were some distance away from it now. "If it's rising we may have a chance to escape."

They hurried to the edge of the stone channel, and Ned uttered a cry of delight.

"It's going down!" he yelled, capering about. "Now we can go on!"

And, surely enough, the river was falling rapidly. It no longer roared, and it was flowing more slowly.

"The water is shut off," remarked Tom.

"Yes, and see, there are steps which lead across the channel," spoke Ned, pointing to them as the receding water revealed them. "Everything is coming our way now."

In a short time the water was all out of the channel, and they could see that it was about twenty feet deep. Truly it would have been a formidable stream to attempt to swim over, but now it had completely vanished, merely a few little pools of water remaining in depressions on the bottom of the channel. There were steps leading down to the bottom, and other steps ascending on the other side, showing that the river was used as a barrier to further progress along the tunnel.

"Forward!" cried Tom gaily, and they went on.

They went down into the river channel, taking care not to slip on the wet steps, and a few seconds later they had again ascended to the tunnel, pressing eagerly on.

Straight and true the tunnel ran through the darkness, the only illumination being their electric flash lamps. On and on they went, hoping every minute to reach their goal.

"Dish suah am a mighty long tunnel," remarked Eradicate. "Dey ought t' hab a trolley line in yeah."

"Bless my punching bag!" cried Mr. Damon, "so they had! Now if those ancients were building to-day—"

He stopped suddenly, for Tom, who was in the lead, had uttered a cry. It was a cry of joy, there was no mistaking that, and instinctively they all knew that he had found what he had sought.

All confirmed it a moment later, for, as they rushed forward, they discovered Tom standing at the place where the tunnel broadened out—broadened out into a great cave, a cave miles in extent, for all they could tell, as their lamps, powerful as they were, only illuminated for a comparatively short distance.

"We're here!" cried Tom. "In the city of gold at last!"

"The city of gold!" added Ned. "The underground city of gold!"

"And gold there is!" fairly shouted Mr. Damon. "See it's all over! Look at the golden streets—even the sides of the buildings are plated with it—and see, in that house there are even gold chairs! Boys, there is untold wealth here!"

"An' would yo' all look at dem golden statues!" cried Eradicate, "dey mus' be millions ob 'em! Oh, golly! Ain't I glad I comed along!" and he rushed into one of the many houses extending along the street of the golden city where they stood, and gathered up a fairly large statue of gold—an image exactly similar to the one he already had, except as to size.

"I never would have believed it possible!" gasped Tom. "It's a city of almost solid gold. We'll be millionaires a million times over!"



CHAPTER XVI

THE BIG IMAGE

Could the light of day have penetrated to that mysterious and ancient underground city of gold our friends might have had some idea of its magnificence. As it was they could only view small parts of it at a time by the illumination of their electric torches. But even with them they saw that it was a most wonderful place.

"I don't believe there's another city like it in all the world," spoke Tom in awed accents, "there never was, and never will be again. Those Aztecs must have brought all their treasures of gold here."

"Bless my cake box! that's so," agreed Mr. Damon.

"Let's take a look around," advised Ned, "and then we can decide on what will be best to take away."

"It won't take me long t' make up mah mind," spoke Eradicate. "I's goin' t' take all dem images I kin find."

"I was going to say we'd have plenty of time to look about and pick what we wanted," said Tom, "but I think perhaps we'd better hurry."

"Why?" asked Mr. Damon.

"There's no telling when Delazes and his gang may find this place, and even the Fogers may be nearer than we think. But I believe our best plan would be this: To take some gold now, and several of the statues, go back to our balloon, and make some kind of big lamps, so we can light this place up. Then, too, I think we'd better move the balloon into the old temple. It will be safer there. Then we can come back here, pack up as much gold as we can carry, and be off. I don't like to think of being underground when Delazes and the Fogers are on the surface. It might not be altogether safe for us."

"Bless my insurance policy!" cried the odd man. "Now YOU'RE giving me the cold shivers, Tom. But I believe you're right. We must look ahead a bit."

With all their electric flash lamps turned on, the four advanced farther into the underground city of gold. As they went on they saw the precious yellow metal on every side of them. It was used lavishly, showing that to the ancients it was as common as iron or steel is to-day. But they did not use the gold merely as common material in the construction of buildings or objects of use. Instead, the gold seemed to be brought into play to beautify the city. An artistic scheme was carried out, and while it was true that in many buildings common objects were made of gold, yet each one was beautiful in itself.

"What a wonderful place this must have been when it was lighted up," spoke Tom.

"Do you think it was ever lighted up?" asked his chum.

"It must have been," declared the young inventor. "My idea is that this city was the home of the priests of the temple, and their friends. I don't believe the common people ever came here. Perhaps the officers of the army, the rulers and the royal family were admitted, but not the ordinary people. That's why it's so far underground, and so well guarded by the river."

"Probably the priests and others collected so much gold they didn't know what to do with it, and built this city to use it up, and, at the same time have a safe place to store it. And they must have had some means of lighting the place, for they couldn't go about in darkness—they couldn't have seen the gold if they did. Yes, this must have been wonderfully beautiful then. The priests probably came here to study, or perhaps to carry out some of their rites. Of course it's only guesswork, but it seems true to me."

"I believe you're right, Tom," said Mr. Damon.

As our friends walked about they saw that the city, while smaller than they had at first supposed, was laid out with regular streets. Each one was straight, and at certain places in the stone pavement plates of gold were set, so that literally the streets were paved with gold. There were houses or buildings on each side of the streets, and most of these were open at the doors or windows, for there was no need of heat in that buried city.

All about were the golden images such as they had seen in the Mexican's house, and like the one in far off Africa. Some of the images were almost life size, and others were only an inch or two inches in height. Not a house but had half a dozen or more in various places, and there were also the images on golden pedestals about the streets.

"This must have been their chief god, or else a representation of some great personage to whom they paid the highest honor," said Mr. Damon. "Perhaps he was the reigning king or ruler, and he, himself, might have ordered the images made out of vanity, like some men of to-day."

The boys agreed that this was a natural theory. As for Eradicate he was busy collecting numbers of the small golden statues, and stuffing them in his pockets.

"Why don't you take bigger ones, and not so many of them?" asked Tom.

"'Case as how I doan't want all mah eggs in one basket," replied the colored man. "I kin carry mo' ob de little fellers," and he persisted in this plan.

They found in some of the houses utensils of solid gold, but there appeared to be no way of cooking food, and that was probably done outside, or in the great temple. In many houses were articles evidently used in the sacrificial rites or in worship of strange gods. They did not stay to half examine the wonderful city of gold, for it would have taken several days. But on Tom's advice, they took up a considerable quantity of the precious metal in the most convenient form to carry, including a number of the statues and art objects and started back along the tunnel.

"We'll rig up some sort of lamps," Tom explained, "and come back to make a thorough examination of this place. I think the scientific men and historians will be glad to know about this city, and I'm going to make some notes about it."

They soon came again to the place of the underground river and found no water there. Ned wanted to turn the stream back into the channel again, but Tom said they might not be able to work the ancient mechanism, so they left the black knob as it was, and hurried on. They decided that the knob must have worked some counter-balance, or great weight that let down a gate and cut off the river from one channel, to turn it into another.

When they emerged at the top of the steps, and came out at the opening which had been revealed by the rolling back of the great altar, they saw there that counter weights, delicately balanced, had moved the big stone.

"We might close that opening," said Tom, "and then if any one SHOULD come along and surprise us, they wouldn't know how to get to the underground city." This was done, the altar rolling back over the staircase.

"Now to get the balloon in the temple, make the lamps, and go back," suggested Tom, and, storing the gold they had secured in a safe place in the temple, they went back to move the airship.

This was an easy matter, and soon they had floated the big gas bag and car in through one of the immense doorways and so into the great middle part of the temple where the big stone altar was located.

"Now we're prepared for emergencies," remarked Tom, as he looked up at the yawning hole in the dome-like roof. "If worst comes to worst, and we have to run, we can float right up here, out of the temple, and skip."

"Do you think anything is going to happen?" asked Mr. Damon anxiously.

"You never can tell," replied Tom. "Now to make some lamps. I think I'll use gas, as I've got plenty of the chemicals."

It took two days to construct them, and Tom ingeniously made them out of some empty tins that had contained meat and other foods. The tins were converted into tanks, and from each one rose a short piece of pipe that ended in a gas tip. On board the dirigible were plenty of tools and materials. Into the cans were put certain chemicals that generated a gas which, when lighted, gave a brilliant glow, almost like calcium carbide.

"Now, I guess we can see to make our way about," remarked Tom, on the morning of the third day, when they prepared to go back to the city of gold. "And we'll take plenty of lunch along, for we may stay until nearly night."

It did not take them long to roll back the altar, descend into the tunnel, and reach the underground city. The river channel was now dry, even the small pools of water in the depressions having evaporated.

The gas torches worked to perfection, and revealed the beauties and wonders of the city of gold to the astonished gaze of our friends. It was even richer in the precious metal than they had at first supposed.

"Before we do any exploring, I think we'd better take some more gold back to the balloon," suggested Tom, "and I think I'll just move the balloon itself more out of sight, so that if any persons come along, and look into the temple, they won't see our airship without looking for it."

This was done, and a considerable quantity of the precious metal, including a number of the larger-sized statues, were stored in the balloon car.

"We can't take much more," Tom warned his friends, "or we'll be over-weighted."

"We've got enough now, to make us all rich," said Ned, contentedly.

"I want moah," spoke Eradicate with a grin.

They went back to the underground city and began to explore it with a view of taking back to civilization some word of its wonders and beauties.

"Didn't Mr. Illingway, in his letters, say something about an immense golden statue here?" asked Ned, when they had almost completed a circuit of the underground place.

"So he did!" exclaimed Tom. "I'd almost forgotten. It must be somewhere in the centre of this place I should think. Let's have a hunt for it. We can't take it with us, but maybe we could get part of an arm or a leg to keep as a relic. Come on."

It was easy to reach the centre of the underground city, for it was laid out on a regular plan. In a short time they were in sight of the central plaza and, even before they reached it the glare of their gas lamps showed them something glittering golden yellow. It was on a tall, golden pedestal.

"There it is!" cried Ned.

"Yes, there's the big golden image all right," agreed Tom, hurrying forward, and a moment later they stood before a most wonderful statue.



CHAPTER XXII

TRAPPED

"Well, that sure is a big statue!" exclaimed Ned as he walked around it.

"An' to t'ink dat it's SOLID GOLD!" cried Eradicate his eyes big with wonder. "I suah wish I had dat all fo' mahse'f!"

"We never could carry that in the balloon," spoke Tom with a shake of his head. "I guess we'll have to leave it here. But I would like to take say the head. It would be worth a lot as a relic to some museum—worth more than the value of the gold itself. I've a notion to do it."

"How could you get the head off?" asked Mr. Damon.

"Oh, pull the statue down or overturn it, as the American patriots did to the Bowling Green, New York, lead statue of King George III during the Revolutionary days," answered Tom. "I think that's what I'll do."

"I say, look here!" called Ned, who had made a circuit of the statue. "There's some sort of an inscription here. See if you can read it, Tom."

They went around to the front of the big, golden image where Ned stood. On a sort of a plate, with raised letters, was an inscription in a strange language. Part of it seemed to be the name of the person or god whom the statue represented, and what followed none could make out.

"It's something like the ancient Greek or Persian language," declared Mr. Damon, who was quite a scholar. "I can make out a word here and there, and it seems to be a warning against disturbing the statue, or damaging it. Probably it was put there to warn small boys thousands of years ago, if they ever allowed small boys in this place."

"Does it say what will be done to whoever harms the statue?" asked Tom with a laugh.

"Probably it does, but I can't make out what it is," answered Mr. Damon.

"Then here goes to see if we can't overturn it and hack off the head," went on Tom. "I've got a sharp little hatchet, and gold is very soft to cut. Over she goes."

"You never can upset that statue," declared Ned.

"Yes, I can," cried the young inventor. "I brought a long, thin, but very strong rope with me, and I think if we all pull together we can do it."

Tom made a noose and skillfully threw it over the head of the statue. It settled about the neck, and then, all taking hold, and walking away a short distance, they gave a "long pull, a strong pull, and a pull altogether."

At first the statue would not move, but when they strained on the rope, the image suddenly tilted, and, a moment later it tumbled to the stone pavement. But the fall was not as heavy as should have resulted from a statue of solid metal. There was a tinkling sound.

"That's queer!" cried Tom. "It didn't make half the fuss I expected," and he hurried up to look at the fallen statue. "Why!" he cried in astonishment, "it's hollow—the big golden statue is hollow—it's a fake!"

And so it was. The big image was only a shell of gold.

"Not so valuable as it looked," commented Ned. "We could take that with us in the balloon, if it wasn't so big."

"Well, here goes for the head, anyhow!" exclaimed Tom, and with a few blows of his keen little axe he severed the neck. As he held it up for all to see—rather a grewsome sight it was, too, in the flickering light of the gas torches—there sounded throughout the underground city, a dull, booming noise, like distant thunder.

"What's that?" cried Ned.

"Bless my bath sponge!" exclaimed Mr. Damon, "I hope the water isn't rising in the river."

"Oh land a massy!" gasped Eradicate.

Without a word Tom dropped the golden head and made for the street that led to the tunnel. The others followed, and soon caught up to the young inventor. On and on they ran, with only the light of their electric flash torches to guide them. Suddenly Tom stopped.

"Go on!" cried Ned. "See what's happened! Go on!"

"I can't," answered Tom, and they all wondered at his voice. "There's a big block of stone across the tunnel, and I can't go another step. The stone gate has fallen. We're trapped here in the underground city of gold!"

"Bless my soul! The tunnel closed?" cried Mr. Damon.

"Look," said Tom simply and in hopeless tones, as he flashed his light. And there, completely filling the tunnel, was a great block of stone, fitting from ceiling to floor and from side wall to side wall, completely cutting off all escape.

"Trapped!" gasped Ned. "The Mexicans or Andy Foger did this."

"No, I don't think so," spoke Tom solemnly. "I think the pulling down of the statue released this stone gate. We trapped ourselves. Oh, why didn't I leave the statue alone!"

"That can't have done it!" declared Ned.

"We can soon tell," spoke Mr. Damon. "Let's go back and look. Later maybe we can raise the block," and they returned to the fallen gold statue. Tom casting back a hopeless look at the barrier that had buried them alive in the city of gold.



CHAPTER XXIII

"IS IT A RESCUE?"

"Can you see anything, Tom? Any lever or anything by which we can raise the stone gate?"

It was Ned who spoke, and he addressed his chum, who was closely examining the pedestal of the fallen golden statue.

"Bless my soul!" exclaimed Mr. Damon, "we've get to find some way out of here soon—or—"

He did not finish the sentence, but they all knew what he meant.

"Oh good landy!" cried Eradicate. "What's gwine t' become ob us?"

"Don't you see anything, Tom?" repeated Ned.

"Not a thing. Not a sign of a lever or handle by which the stone might be raised. But wait, I'm going to get on top of the pedestal."

He managed to scramble up by stepping on and clinging to various ornamental projections, and soon gained the flat place where the big golden statue had rested. But he saw at a glance that it was as smooth as a billiard table.

"Nothing here!" he called down to Ned.

"Then how do you suppose the gate closed down when the statue was pulled off?" asked Ned.

"It must have been because of the disturbance of the equilibrium, or due to a change of weight. Probably this pedestal rests on a platform, like the platform of a large scale. Its weight, with that of the statue, rested on certain concealed levers, and held the stone up out of sight in the roof of the tunnel. When I yanked down the statue I made the weight uneven, and the stone fell, and there doesn't seem to be any way of putting the weight back again."

"No, we never could get the statue back on the pedestal," said Ned. "But maybe there's some mechanism at the stone gate, or near it, like the black knob which turned off the water. We may be able to work that and raise the big stone slab."

"It's the only thing to try, as long as we haven't dynamite to blast it," agreed Tom. "Come on, we'll take a look."

They went back to where the rock closed the tunnel, but a long and frantic search failed to show the least projection, lever, handle or any other thing, that could be moved.

"What in the world do you suppose those ancients made such a terrible contrivance for?" Ned wanted to know.

"Well, if we could read the warning on the statue we might know," replied Mr. Damon. "That probably says that whoever disturbs the status will close up the golden city forever."

"Maybe there's another way out—or in," suggested Tom hopefully. "We didn't look for that. It must be our next move. We must not let a single chance go by. We'll look for some way of getting out, at the far end of this underground city."

Filled with gloomy and foreboding thoughts, they walked away from the stone barrier. To search for another means of egress would take some time, and the same fear came to all of them—could they live that long?

"It was a queer thing, to make that statue hollow," mused Ned as he walked between Mr. Damon and Tom. "I wonder why it was done, when all the others are solid gold?"

"Maybe they found they couldn't melt up, and cast in a mould, enough gold to make a solid statue that size," suggested Mr. Damon. "Then, too, there may have been no means of getting it on the pedestal if they made it too heavy."

They discussed these and other matters as they hurried on to seek for some way of escape. In fact to talk seemed to make them less gloomy and sad, and they tried to keep up their spirits.

For several hours they searched eagerly for some means of getting out of the underground city. They went to the farthest limits of it, and found it to be several miles in diameter, but eventually they came to solid walls of stone which reached from roof to ceiling, and there was no way out.

They found that the underground city was exactly like an overturned bowl, or an Esquimo ice hut, hollow within, and with a tunnel leading to it—but all below the surface of the earth. The city had been hollowed out of solid rock, and there was but one way in or out, and that was closed by the seamless stone.

"There's no use hunting any longer," declared Tom, when, weary and footsore, they had completed a circuit of the outer circumference of the city, "the rock passage is our only hope."

"And that's no hope at all!" declared Ned.

"Yes, we must try to raise that stone slab, or—break it!" cried Tom desperately. "Come on."

"Wait a bit," advised Mr. Damon. "Bless my dinner plate! but I'm hungry. We brought some food along, and my advice to you is to eat and keep up our strength. We'll need it."

"By golly gracious, that's so!" declared Eradicate. "I'll git de eatin's."

Fortunately there was a goodly supply, and, going in one the houses they ate off a table of solid gold, and off dishes of the precious, yellow metal. Yet they would have given it all—yes, even the gold in their dirigible balloon—for a chance for freedom.

"I wonder what became of the chaps who used to live here?" mused Ned as he finished the rather frugal meal.

"Oh, they probably died—from a plague maybe, or there may have been a war, or the people may have risen in revolt and killed them off," suggested Tom grimly.

"But then there ought to be some remains—some mummies or skeletons or something."

"I guess every one left this underground city—every soul." suggested Mr. Damon, "and then they turned on the river and left it. I shouldn't be surprised but what we are the first persons to set foot here in thousands of years."

"And WE may stay here for a thousand years," predicted Tom.

"Oh, good land a' massy; doan't say dat!" cried Eradicate. "Why we'll all be dead ob starvation in dat time."

"Before then, I guess," muttered Tom. "I wonder if there's any water in this hole?"

"We'll need it—soon," remarked Ned, looking at the scanty supply they had brought in with them. "Let's have a hunt for it."

"Let Rad do that, while we work on the stone gate," proposed the young inventor. "Rad, chase off and see if you can find some water."

While the colored man was gone, Tom, Ned and Mr. Damon went back to the stone gate. To attack it without tools, or some powerful blasting powder seemed useless, but their case was desperate and they knew they must do something.

"We'll try chipping away the stone at the base," suggested Tom. "It isn't a very hard rock, in fact it's a sort of soft marble, or white sand stone, and we may be able to cut out a way under the slab door with our knifes."

Fortunately they had knives with big, strong blades, and as Tom had said, the stone was comparatively soft. But, after several hours' work they only had a small depression under the stone door.

"At this rate it will take a month," sighed Ned.

"Say!" cried Tom, "we're foolish. We should try to cut through the stone slab itself. It can't be so very thick. And another thing. I'm going to play the flames from the gas torches on the stone. The fires will make it brittle and it will chip off easier."

This was so, but even with that advantage they had only made a slight impression on the solid stone door after more than four hours of work, and Eradicate came back, with a hopeless look on his face, to report that he had been unable to find water.

"Then we've got to save every drop of what we've got," declared Tom. "Short rations for everybody."

"And our lights, too," added Mr. Damon. "We must save them."

"All out but one!" cried Tom quickly. "If we're careful we can make them gas torches last a week, and the electric flashes are good for several days yet."

Then they laid out a plan of procedure, and divided the food into as small rations as would support life. It was grim work, but it had to be done. They found, with care, that they might live for four days on the food and water and then—

Well—no one liked to think about it.

"We must take turns chipping away at the stone door," decided Tom. "Some of us will work and some will sleep—two and two, I guess."

This plan was also carried out, and Tom and Eradicate took the first trick of hacking away at the door.

How they managed to live in the days that followed they could never tell clearly afterward. It was like some horrible nightmare, composed of hours of hacking away at the stone, and then of eating sparingly, drinking more sparingly, and resting, to get up, and do it all over again.

Their water was the first to give out, for it made them thirsty to cut at the stone, and parched mouths and swollen tongues demanded moisture. They did manage to find a place where a few drops of water trickled through the rocky roof, and without this they would have died before five days had passed.

They even searched, at times for another way out of the city of gold, for Tom had insisted there must be a way, as the air in the underground cave remained so fresh. But there must have been a secret way of ventilating the place, as no opening was found, and they went back to hacking at the stone.

Just how many days they spent in their horrible golden prison they never really knew. Tom said it was over a week, Ned insisted it was a month, Mr. Damon two months, and Eradicate pitifully said "it seem mos' laik a yeah, suah!"

It must have been about eight days, and at the end of that time there was not a scrap of food left, and only a little water. They were barely alive, and could hardly wield the knives against the stone slab. They had dug a hole about a foot deep in it, but it would have to be made much larger before any one could crawl through, even when it penetrated to the other side. And how soon this would be they did not know.

It was about the end of the eighth day, and Tom and Ned were hacking away at the rocky slab, for Mr. Damon and Eradicate were too weary.

Tom paused for a moment to look helplessly at his chum. As he did so he heard, amid the silence, a noise on the other side of the stone door.

"What—what's that?" Tom gasped faintly.

"It sounds—sounds like some one—coming," whispered Ned. "Oh, if it is only a rescue party!"

"A rescue party?" whispered Tom. "Where would a rescue party—"

He stopped suddenly. Unmistakably there were voices on the other side of the barrier—human voices.

"It IS a rescue party!" cried Ned.

"I—I hope so," spoke Tom slowly.

"Mr. Damon—Eradicate!" yelled Ned with the sudden strength of hope, "they're coming to save us! Hurry ever here!"

And then, as he and Tom stood, they saw, with staring eyes, the great stone slab slowly beginning to rise!



CHAPTER XXIV.

THE FIGHT

The talk sounded more plainly now—a confused murmur of voices—many of them—the sound coming under the slowly raising stone doorway.

"Who can it be—there's a lot of them," murmured Ned.

Tom did not answer. Instead he silently sped back to where they had slept and got his automatic revolver.

"Better get yours," he said to his companions. "It may be a rescue party, though I don't see how any one could know we were in here, or it may be—"

He did not finish. They all knew what he meant, and a moment later four strained and anxious figures stood on the inner side of the stone door, revolvers in hand, awaiting what might be revealed to them. Would it be friend or foe?

At Tom's feet lay the golden head—the hollow head of the statue. The scene was illumined by a flickering gas torch—the last one, as the others had burned out.

Slowly the stone went up, very slowly, for it was exceedingly heavy and the mechanism that worked it was primitive. Up and up it went until now a man could have crawled under. Ned made a motion as if he was going to do so, but Tom held him back.

Slowly and slowly it went up. On the other side was a very babble of voices now—voices speaking a strange tongue. Tom and his companions were silent.

Then, above the other voices, there sounded the tones of some one speaking English. Hearing it Tom started, and still more as he noted the tones, for he heard this said:

"We'll be inside in a minute, dad, and I guess we'll show Tom Swift that he and his crowd can't fool us. We've got to the city of gold first!"

"Andy Foger!" hoarsely whispered Tom to Ned.

The next moment the stone gate went up with a rush, and there, in the light of the gas torch, and in the glare of many burning ones of wood, held by a throng of people on the other side, stood Andy Foger, his father, Delazes, and a horde of men who looked as wild as savages.

For a moment both parties stood staring at one another, too startled to utter a sound. Then as Tom noticed that some of the natives, who somewhat resembled the ancient Aztecs, had imitation human heads stuck on the ends of poles or spears, he uttered two words;

"Head-hunters!"

Like a flash there came to him the warning of the African missionary: "Beware of the head-hunters!" Now they were here—being led on by the Mexican and the Fogers—the enemies of our friends.

For another moment there was a silence, and then Andy Foger cried out:

"They're here! Tom Swift and his party! They got here first and they may have all the gold!"

"If they have they will share it with us!" cried Delazes fiercely.

"Quick!" Tom called hoarsely to Ned, Mr. Damon and Eradicate. "We've got to fight. It's the only way to save our lives. We must fight, and when we can, escape, get to the airship and sail away. It's a fight to the finish now."

He raised his automatic revolver, and, as he did so one of the savages saw the golden head of the statue lying at Tom's feet. The man uttered a wild cry and called out something in his unknown tongue. Then he raised his spear and hurled it straight at our hero.

Had not Mr. Damon pulled Tom to one side, there might have been a different ending to this story. As it was the weapon hissed through the air over the head of the young inventor. The next minute his revolver spat lead and fire, but whether he hit any one or not he could not see, as the place was so filled with smoke, from the powder and from the torches. But some one yelled in pain.

"Crouch down and fire!" ordered Tom. "Low down and they'll throw over our heads." It was done on the instant, and the four revolvers rang out together.

There were howls of pain and terror and above them could be heard the gutteral tones of Delazes, while Andy Foger yelled:

"Look out dad! Here, help me to get behind something or I may be hit. Mr. Delazes, can't you tell those savages to throw spears at Tom Swift and his gang?"

"They are doing it, Senor Foger," replied the Mexican. "Oh, why did I not think to bring my gun! We haven't one among us." Then he called some command to the head-hunters who had apparently been enlisted on the side of himself and the two Fogers.

The automatic revolvers were soon emptied, and the place was now so full of smoke that neither party could see the other. The torches burned with a red glare.

"Reload!" ordered Tom, "and we'll make a rush for it! We can't keep this up long!"

It took but an instant to slip in another lot of cartridges and then, on Tom's advice, they slipped the catches to make the automatic weapons simple ones, to be fired at will.

They sent several more shots through the door-way but no cries of pain followed, and it was evident that their enemies had stepped back out of the line of fire.

"Now's our chance!" cried Tom. "The way is clear. Come on!"

He and the others dashed forward, Tom carrying the golden head, though it was hard work. It was not very heavy but it was awkward.

As they rushed through the now open gateway they crouched low to avoid the spears, but, as it was one grazed Tom's shoulder, and Eradicate was pierced in the fleshy part of his arm.

"Forward! Forward!" cried Tom. "Come on!"

And on they went, through the smoke and darkness, Ned flashing his electric torch which gave only a feeble glow as the battery was almost exhausted. On and on! Now they were through the stone gateway, now out in the long tunnel.

Behind them they could hear feet running, and several spears clattered to the stone floor. Lights flickered behind them.

"If only the river bed is dry!" gasped Tom. "We may yet escape. But if they've filled the channel—"

He did not dare think of what that would mean as he ran on, turning occasionally to fire, for he and the others had again reloaded their revolvers.



CHAPTER XXV

THE ESCAPE—CONCLUSION

The noise behind our friends increased. There were shouts of rage, yells of anger at the escape of the prey. High above the other voices were the shrill war-cries of the head-hunters—the savages with their grewsome desires.

"Can—can we make it, Tom?" panted Ned.

They were almost at the river channel now, and in another instant they had reached it.

By the feeble rays of Ned's electric torch they saw with relief that it was empty, though they would have given much to see just a trickle of water in it, for they were almost dead from thirst.

Together they climbed up the other side, and as yet their pursuers had not reached the brink. For one moment Tom had a thought of working the black knob, and flooding the channel, but he could not doom even the head-hunters, much less the Fogers and Delazes, to such a death as that would mean.

On ran Tom and his companions, but now they could glance back and see the foremost of the other crowd dipping down into the dry channel.

"The steps! The steps!" suddenly cried Ned, when they had run a long distance, as a faint gleam of daylight beyond shewed the opening beneath the stone altar. "We're safe now."

"Hardly, but a few minutes will tell," said Tom. "The balloon is in shape for a quick rise, and then we'll leave this horrible place behind."

"And all the gold, too," murmured Ned regretfully. "We've got some," said Mr. Damon, "and I wouldn't take a chance with those head-hunters for all the gold in the underground city."

"Same here!" panted Tom. Then they were at the steps and ran up them.

Out into the big auditorium they emerged, weak and faint, and toward the hidden dirigible balloon they rushed.

"Quick!" cried Tom, as he climbed into the car, followed by Mr. Damon and Eradicate. "Shove it right under the broken dome, Ned, and I'll turn on the gas machine. It's partly inflated."

A moment later the balloon was right below the big opening. The blue sky showed through it—a welcome sight to our friends. The hiss of the gas was heard, and the bag distended still more.

"Hop in!" cried Tom. "She'll go up I guess."

"There they come!" shouted Ned, as he spoke the foremost of the head-hunters emerged from the hole beneath the stone altar. He was followed by Delazes.

"Stop them! Get them! Spear them!" cried the contractor. They evidently thought our friends had all the gold from the underground city.

Fortunately the temple was so large that the balloon was a good distance from the hole leading to the tunnel, and before the foremost of the head-hunters could reach it the dirigible began to rise.

"If they throw their spears, and puncture the bag in many places we're done for," murmured Tom. But evidently the savages did not think of this, though Delazes screamed it at them.

Up went the balloon, and not a moment too soon, for one of the head-hunters actually grabbed the edge of the car, and only let go when he found himself being lifted off the temple floor.

Up and up it went and, as it was about to emerge from the broken dome, Tom looked down and saw a curious sight.

Mr. Foger and Andy, who brought up in the rear of the pursuing and attacking party, had just emerged from the hole by the great stone altar when there suddenly spouted from the same opening a solid column of water. A cry of wonder came from all as they saw the strange sight. A veritable geyser was now spurting in the very middle of the temple floor, and the head-hunters, the Mexicans and the Fogers ran screaming to get out of the way.

"Look!" cried Ned. "What happened?"

"The underground river must be running the wrong way!" answered Tom, as he prepared to set in motion the motor. "Either they accidentally turned some hidden lever, or when they raised the stone door they did it. The tunnel is flooded and—"

"Bless my match box! So is the underground city!" cried Mr. Damon. "I guess we've seen the last of it and its gold. We were lucky to escape with our lives, and these fellows might have been drowned like rats in a trap, if they hadn't followed us. The underground city will never be discovered again."

"And now for home!" cried Tom, when they had eaten and drunk sparingly until they should get back their strength, and had seen to their slight wounds.

"And our trip wasn't altogether a failure," said Mr. Damon. "We'd have had more gold if the stone door hadn't trapped us. But I guess we have enough as it is. I wonder how the Fogers ever found us?"

"They must have followed our trail, though how we'll never know and they came up to where Delazes and his men were, joined forces with them, and hunted about until they found the temple," remarked Tom. "Then they saw the opening, went down, and found the stone door."

"But how did they get it open? and what were they doing with the head-hunters, and why didn't the head-hunters attack them?" Ned wanted to know.

"Well, I guess perhaps Delazes knew how to handle those head-hunters," replied Tom. "They may be a sort of lost tribe of Mexicans, and perhaps their ancestors centuries ago owned the city of gold. At any rate I think some of them knew the secret of raising the door." And later Tom learned in a roundabout way from the Fogers that this was so. The father and son had after much hardship joined forces with Delazes and he, by a promise of the heads of the party of our friends, and much tobacco, had gained the head-hunters as allies.

On and on sailed the balloon and our friends regained their strength after partaking of the nourishing food. They looked at their store of gold and found it larger than they had thought. Soon they left far behind them the great plain of the ruined temple, which, had they but known it was a lake now, for the underground river, perhaps by some break in the underground mechanism that controlled it, or a break in the channel, overflowed and covered temple, plain and underground city with water many fathoms deep.

"Are we going all the way home in the balloon?" asked Ned on the second day of their voyage in the air, when they had stopped to make slight repairs.

"No, indeed," replied Tom. "As soon as we get to some city where we can pack it up, and ship our gold without fear of being robbed, I'm coming to earth, and go home in a steamer."

This plan was carried out; and a week later, with the gold safely insured by an express company, and the balloon packed for transportation, our friends went to a railroad station, and took a train for Tampico, there to get a steamer for New York.

"Bless my top knot!" exclaimed Mr. Damon a few days after this, as they were on the vessel. "I think for queer adventures this one of ours in the city of gold, Tom, puts it all over the others we had."

"Oh, I don't know," answered the young inventor, "we certainly had some strenuous times in the past, and I hope we'll have some more in the future."

"The same here," agreed Ned.

And whether they did or not I will leave my readers to judge if they peruse the next book in this series, which will be called, "Tom Swift and His Air Glider; Or, Seeking the Platinum Treasure."

They arrived safely in Shopton in due course of time, and found Mr. Swift well. They did not become millionaires, for they found, to their regret that their gold was rather freely alloyed with baser metals, so they did not have more than half the amount in pure solid gold. But there was a small fortune in it for all of them.

In recognition of Mr. Illingway, the African missionary having put Tom on the track of the gold, a large sum was sent to him, to help him carry on his work of humanity.

Tom had many offers for the big golden head, but he would not sell it, though he loaned it to a New York museum, where it attracted much attention. There were many articles written about the underground city of gold from the facts the young inventor furnished.

Eventually the Fogers got home, but they did not say much about their experiences, and Tom and his friends did not think it worth while to prosecute them for the attack. As for Delazes, Tom never saw nor heard from him again, not in all his reading could he find any account of the head-hunters, who must have been a small, little known tribe.

"And you really kept your promise, and brought me a golden image?" asked Mary Nestor of Tom, when he called on her soon after reaching home.

"Indeed I did, the two that I promised and a particularly fine one that I picked up almost at the last minute," and Tom gave her the valuable relics.

"And now tell me about it," she begged, when she had admired them, and then sat down beside Tom: and there we will leave our hero for the present, as he is in very good company, and I know he wouldn't like to be disturbed.

THE END