CHAPTER XX.

MYSTERIOUS HAPPENINGS.

The travelers strolled for some time longer, the professor finding what he called rare relics at every turn.

"This is like another gold mine," he said. "There are treasures untold here. I have no doubt we will find a store of diamonds and other precious stones before we are through."

"I'd like to find a ham sandwich right now," observed Bob.

"It wouldn't be Chunky if he wasn't hungry," laughed Ned. "But I admit I feel somewhat the same way myself."

"Then we had better go back to the temple and get supper," advised Jerry.

So back they went, but their progress was slow, because the professor would insist on examining every bit of ruins he came to in order to see if there were not specimens to be gathered or relics to be picked up. His green box was full to overflowing and all his pockets bulged, but he was the happiest of naturalists.

It was dark when they reached the ancient place of worship where the auto had been left, and at Jerry's suggestion Bob lighted the search-lamp and the other two lights on the machine. This made a brilliant circle of illumination in one place, but threw the rest of the temple into a dense blackness.

"I wouldn't want to be here all alone," remarked Bob, looking about and shuddering a bit.

"Why, Chunky? Afraid of ghosts?" asked Ned.

"What was that?" exclaimed Bob, suddenly, starting at a noise.

"A bat," replied the naturalist. "The place is full of them. I must get some for specimens."

"I don't know but what I prefer ghosts to bats," said Bob. "I hope none of them suck our blood while we're asleep."

"No danger; I guess none of these are of the vampire variety," remarked the professor. "But now let's get supper."

In spite of the strangeness of the surroundings, the travelers managed to make a good meal. The gasolene stove was set up and some canned chicken prepared, with tortillas and frijoles.

"We'll have to replenish our larder soon," remarked Jerry, looking into the provision chest. "There's only a little stuff left."

"We'll have to go hunting some day," said the professor. "We can't starve in this country. Game is too plentiful."

"I wonder if the people who built this place didn't put some bedrooms in it," said Bob, as, sitting on the floor of the temple, he began to nod from sleepiness.

"Perhaps they did," put in Ned. "Let's take a look."

He unfastened one of the oil lamps from the auto and started off on an exploring trip. A little to the left of the corner where the auto stood he came to a door. Though it worked hard on the rusted hinges he managed to push it open. He flashed the light inside.

"Hurrah! Here are some beds or couches or something of the kind!" he shouted.

The others came hurrying up. The room seemed to be a sort of resting place for the priests of the ancient temple. Ranged about the side walls were wooden frames on which were stretched skins and hides of animals, in a manner somewhat as the modern cot is made.

"I wonder if they are strong enough to hold us," said Jerry.

"Let Chunky try, he's the heaviest," suggested Ned.

Accordingly, Bob stretched out on the ancient bed. It creaked a little, but showed no signs of collapsing in spite of the many years it had been in the place.

"This will be better than sleeping on a cold stone floor," remarked the professor. "Fetch in the blankets and we'll have a good night's rest."

"Shall we post a guard?" asked Jerry.

"I don't think it will be necessary," replied the naturalist. "I hardly believe there is any one in this old city but ourselves, and we can barricade the door to keep out any stray animals."

So, in a little while, the travelers were all slumbering. But the professor was wrong in his surmise that they were the only inhabitants of the underground city. No sooner had a series of snores proclaimed that every one was sleeping than from a dark recess on the opposite side of the temple to that where the automobile stood there came a strange figure, clad in white. If Bob had seen it he surely would have said it was a ghost.

"So you found my ancient city after all," whispered the figure. "You know now that the Mexican magician was telling the truth, and you realize that you found the place sooner than you expected, and in a strange manner. But there will be more strange things happen before you go from here, I promise you."

"Are the _Americano_ dogs asleep?" sounded a whisper from the recess whence came the aged Mexican, who had so strangely prophesied to the professor.

"Yes, San Lucia, they are asleep," replied the first figure, as another, attired as he was, joined him. "But speak softly, for they have sharp ears and wake easily."

"Have they the gold with them?" asked San Lucia, who was also quite old. "That is what we want, Murado. Have they the gold?"

"All _Americanos_ have gold," replied Murado. "That is why I lured them on. All my plans were made to get them here that we might take their gold."

"And you succeeded wonderfully well, Murado. Tell me about it, for I have not had a chance to talk to you since you arrived in such breathless haste."

"There is not much to tell," replied the other. "I heard of their arrival in a short time after they reached Mexico. Then, in a secret way, I heard what they were searching for. Chance made it possible for me to somewhat startle them by pretending to know more than I did. I met them on the road and told them of what they were in search and how to find it."

"That was easy, since you knew so well yourself," interrupted San Lucia. "We have not been brigands for nothing, Murado. Well do I remember the day you and I came upon this buried city. And it has been our headquarters ever since."

"As I said, it was easy to mystify them," went on Murado. "They traveled fast in their steam wagon, or whatever it is, but I knew several short cuts that enabled me to get ahead of them. I was hidden in the hollow stone image of the laughing serpent and saw, through the little eye-holes, how they came up and took the paper I had written and put between the lips of the reptile. Oh, it all worked out as I had planned, and now we have them here where we want them."

"And we will kill them and get their gold!" whispered San Lucia, feeling of a knife he wore in his belt. "But tell me, how did they happen to stumble on the right underground passage?"

"They didn't happen to," replied Murado. "That was one point where I failed. But it is just as well. You see, I had so managed things that I knew they would take the road to the left of the image. When I saw them depart I called my horse and galloped off to the right. I wanted to take a short cut and get here ahead of them.

"I succeeded. You were away; just when I needed your help, too. But I managed. I went out in the underground passage and waited for them.

"That passage, you know, goes right under the road they were traveling on. Whoever built this ancient city must have wanted it to remain hidden, for the only way to get to it is by the tunnels. If, by chance, some one approached on the roads leading to the top of the mountains the ancients had a plan to get rid of them."

"How?" asked San Lucia.

"At several places in the upper roadway there were false places. That is, they were traps. A portion of the road would be dug away, making a shaft down to the tunnel. Then boards would be placed over the hole and a light covering of dirt sprinkled on the planks. Watchers were stationed below, and at the sound of an enemy on the boards above the sentinels would pull a lever. This would take away the supports of the false portion of the road, and it would crash down into the tunnel, carrying the enemy with it.

"So I played the part of the watcher, and when I heard the _Americanos_ riding over the trap I pulled the lever and down they crashed.

"There, as I said, I made my only mistake. I expected the _Americanos_ would be killed, but their steam cart is strong, and the fall did not hurt them. Besides, only one end of the trap gave way, and the other, holding fast, made an inclined road on which they descended into the tunnel. That is how they came here, and now we must to work if we are to get their gold."

"And quickly, too," observed San Lucia, "for I learned that another party is following this; they, too, have a steam wagon, and we may trap them also."

"I know the crowd of whom you speak," said Murado. "They are not far behind. One is a youth called Nixy Nodnot, or some barbarous thing like it. They will be surprised not to find their friends. But come, they sleep!"

Then the two Mexican brigands began creeping toward the room where the professor and the boys were sleeping.