For three days they sailed along, sometimes over vast level plains on which grazed wild cattle, again over impenetrable jungles which they could never have gotten through in their ox carts. They crossed rivers and many small lakes, stopping each night on the ground, the airs.h.i.+p securely anch.o.r.ed to trees. Tom could make the lifting gas on board so what was wasted by each descent was not missed.

One day it rained, and they did not fly, spending rather a lonely and miserable twelve hours in the car. Another time a powerful wind blew them many miles out of their course. But they got back on it, and kept flying to the west.

"We must strike it soon," murmured Tom one day.

"Maybe we're too far to the north or south," suggested Ned.

"Then we'll have to beat back and forth until we get right," was Tom's reply. "For I'm going to locate that ruined temple."

They ate breakfast and dinner high in the air, Eradicate preparing the meals in the tiny kitchen. Ever did they keep looking downward for a sight of a great plain, with a ruined temple in the midst of it.

In this way a week pa.s.sed, the balloon beating back and forth to the North or South, and they were beginning to weary of the search, and even Tom, optimistic as he was, began to think he would never find what he sought.

It was toward the close of day, and the young inventor was looking for a good place to land. He was flying over a range of low hills, hoping the thick forest would soon come to an end when, as he crossed the last of the range of small mountains, he gave a cry, that drew the attention of Ned and Mr. Damon.

"What is it?" demanded his chum.

"Look!" said Tom. "There is the great plain!"

Ned gazed, and saw, spread out below them a vast level plateau. But this was not all he saw, for there, about in the centre, was a ma.s.s of something--something that showed white in the rays of the setting sun.

"Bless my chimney!" cried Mr. Damon. "That's some sort of a building."

"The ruined temple," said Tom softly. "We've found it at last," and he headed the balloon for it and put on full speed.

CHAPTER XVIII

FINDING THE TUNNEL

In silence, broken only by the noise of the motor, did the gold-seekers approach the temple. As they neared it they could see its vast proportions, and they noted that it was made of some white stone, something like marble. Then, too, as they drew closer, they could see the desolate ruin into which it had fallen.

"Looks as if a dynamite explosion had knocked it all apart,"

observed Ned.

"It certainly does," agreed Mr. Damon.

"Maybe Cortez, or some of those early explorers, blew it up with gunpowder after fighting the Aztecs, or whatever the natives were called in those days," suggested Tom.

"Bless my bookcase! You don't mean to say you think this temple goes back to those early days," spoke Mr. Damon.

"Yes, and probably farther," declared Tom. "It must be very ancient, and the whole country about here is desolate. Why, the way the woods have grown up everywhere but on this plain shows that it must be three or four hundred years ago. There must have been a city around the temple, probably Poltec, and yet there isn't a trace of it that we have seen as we came along. Oh, yes, this is very ancient."

"It will be jolly fun to explore it," decided Ned. "I wish it wasn't so near night."

"We can't do much now," decided Tom. "It will be too dark, and I don't altogether fancy going in those old ruins except by daylight."

"Do you think any of those old Aztec priests, with their knifes of gla.s.s, will sacrifice you on a stone altar?" asked Ned, with a laugh.

"No, but there might be wild beasts in there," went on the young inventor, "and I'm sure there are any number of bats. There must be lots of nooks and corners in there where a whole army could hide.

It's an immense place."

The ruined temple certainly was large in extent, and in its glory must have been a wonderful place. The balloon came nearer, and then Tom let it sink to rest on the sand not far from the ancient ruin.

Out he leaped, followed by his friends, and for a moment they stood in silent contemplation of the vast temple. Then as the last rays of the setting sun turned the white stones to gold, Tom exclaimed:

"A good omen! I'm sure the city of gold must be near here, and in the morning we'll begin our search for the secret tunnel that leads to it."

"That's the stuff!" cried Ned enthusiastically.

An instant later it seemed to get dark very suddenly, as it does in the tropics, and almost with the first shadows of night there came a strange sound from the ruined temple.

It was a low moaning, rumbling sound, like a mighty wind, afar off, and it sent a cold s.h.i.+ver down the spines of all in the little party.

"Good land a' ma.s.sy! What am dat?" moaned Eradicate, as he darted back toward the balloon.

"Bless my looking gla.s.s!" cried Mr. Damon.

A second later the noise suddenly increased, and something black, accompanied by a noise of rapidly beating wings rushed from one of the immense doorways.

"Bats!" cried Tom. "Thousands of bats! I'm glad we didn't go in after dark!" And bats they were, that had made the noise as they rushed out on their nightly flight.

"Ugh!" shuddered Mr. Damon. "I detest the creatures! Let's get under cover."

"Yes," agreed Tom, "we'll have supper, turn in, and be up early to look for the tunnel. We're here at last. I'll dream of gold to-night."

Eradicate soon had a meal in preparation, though he stopped every now and then to peer out at the bats, that still came in unbroken flight from the old temple. Truly there must have been many thousands of them.

Whether Tom dreamed of gold that night he did not say, but he was the first one up in the morning, and Ned saw him hurrying over the sands toward the temple.

"Hold on, Tom!" his chum called as he hastened to dress. "Where you going?"

"To have a hunt for that tunnel before breakfast. I don't want to lose any time. No telling when Delazes and his crowd may be after us. And the Fogers, too, may strike our trail. Come on, we'll get busy."

"Where do you think the tunnel will be?" asked Ned, when he had caught up to Tom.

"Well, according to all that Mr. Illingway could tell us, it was somewhere near this temple. We'll make a circle of it, and if we don't come across it then we'll make another, and so on, increasing the size of the circles each time, until we find what we're looking for."

"Let's have a look inside the temple first," suggested Ned. "It must have been a magnificent place when it was new, and with the processions of people and priests in their golden robes."

"You ought to have been an Aztec," suggested Tom, as he headed for one of the big doorways.

They found the interior of the temple almost as badly in ruins as was the outside. In many places the roof had fallen in, the side walls contained many gaping holes, and the stone floor was broken away in many places, showing yawning, black caverns below. They saw hundreds of bats clinging to projections, but the ugly creatures were silent in sleep now.

"Bur-r-r-r-r!" murmured Ned. "I shouldn't like any of 'em to fall on me."

"No, it's not a very nice place to go in," agreed Tom.