The Westerner and the professor came creeping to his side.

"What is it?" asked Bushnell.

"Look," directed Frank. "What do you make of it?"

Peering down into the dark depths of the gorge, they saw black figures flitting silently past, men and horses, as they were able to make out.

"Hors.e.m.e.n!" breathed the professor. "They must be the bandits!"

"But look!" came cautiously from Frank's lips; "they are riding swiftly, yet the feet of their horses make no sound!"

"That's right!" gasped Scotch. "Great Jupiter! can they be more ghosts?"

"Mysteries are crowding each other," said Frank.

Bushnell was silent, but he was watching and listening.

Like a band of black phantoms, the silent hors.e.m.e.n rode along the ravine and disappeared. Frank could hear the professor's teeth chattering as if the man had a chill.

"This bub-bub-beats my tut-tut-tut-time!" confessed Scotch. "I rather think we'd better turn back and let the Silver Palace alone."

"Rot!" growled Bushnell. "Them varmints wuz Pacheco's gang, an' they hed the feet of their critters m.u.f.fled, thet's all. Don't git leery fer thet. All ther same, ef Jack Burk or his spook hedn't warned us, them onery skunks w'u'd hed us in a consarned bad trap."

This was the truth, as they all knew, and they were decidedly thankful to the mysterious individual who had warned them.

Bushnell now resorted to the trick of "covering the trail," in order to do which it was necessary to m.u.f.fle the feet of their horses and lead them over the rocky ground, where their bandaged hoofs could make no mark. At length he came to a stream, and he led the way into the water, following the course of the stream, and having the others trail along in single file directly behind him.

When they halted again Bushnell a.s.sured them that there was little danger that the bandits would be able to follow them closely, and they rested without molestation till morning.

At daybreak the Westerner was astir, being alive with eagerness and impatience, as he repeatedly declared they would behold the wonderful Silver Palace before another sunset.

Eating a hasty breakfast, they pushed forward, with the Westerner in the lead.

Once more the tower of smoke, which they had noted the day before, was before them, but now it seemed blacker and more ominous than on the previous day.

It was not far from midday when, away to the westward, they heard rumbling sounds, like distant thunder.

"Vot id vas, ain'd id?" asked Hans, in alarm. "I don'd seen no dunder shower coming up somevere, do I?"

"It did not seem like thunder," said Frank, soberly. "It was more like a rumbling beneath the ground, and I fancied the earth quivered a bit."

"Perhaps it is an earthquake," put in the professor, apprehensively. "I believe they have such convulsions of nature in this part of the world."

Bushnell said nothing, but there was a troubled look on his face, and he urged them all forward at a still swifter pace.

The smoke tower was now looming near at hand, and they could see it shift and sway, grow thin, and roll up in a dense, black ma.s.s. It cast a gloom over their spirits, and made them all feel as if some frightful disaster was impending.

Again and again, at irregular intervals, they heard the sullen rumbling, and once all were positive the earth shook.

It was noticed that directly after each rumbling the smoke rolled up in a thick, black ma.s.s that shut out the light of the sun and overcast the heavens.

The professor was for turning back, but Bushnell was determined to go forward, and Frank was equally resolute. Hans had very little to say, but his nerves were badly shaken.

"In less than an hour we shall be able to see the Silver Palace,"

a.s.sured Bushnell. "We would be fools to turn back now."

So they went on, and, at last, they climbed to the top of a rise, from which point the Westerner a.s.sured them that the palace could be seen.

An awe-inspiring spectacle met their gaze. They looked across a great gulf, from which the smoke was rolling upward in clouds, and out of which came the sullen mutterings they had heard.

"Merciful goodness!" cried Professor Scotch. "It must be the crater of a volcano!"

"Yah!" gasped Hans; "und der volcano vos doin' pusiness at der oldt standt alretty yet."

"The volcano may have been dormant for centuries," said the professor, "but it is coming to life now!"

"Where is the Silver Palace?" demanded Frank.

Bushnell clutched the boy's arm with a grip of iron, pointing straight through the smoke clouds that rose before them.

"Look!" he shouted, hoa.r.s.ely; "it is thar! See--the smoke grows thinner, an' thar she am! See her glitter! In thet thar palace is stored enough treasure ter make us richer then ther richest men in ther world, an' ten thousand volcanoes ain't goin' ter keep me from it, you bet yer boots!"

True enough, through the parted smoke clouds gleamed the towers and turrets of the wonderful palace that had remained hidden in the heart of the mountains hundreds of years, jealously guarded by the fierce natives, who believed it sacred, and who had kept the secret well from the outside world.

CHAPTER XII.

DOOM OF THE SILVER PALACE.

Bushnell leaped from his horse and began tearing the packs from the backs of the led animals. He worked with mad haste, and there was an awesome, insane glare in his eyes.

"The man is crazy!" roared Professor Scotch. "The volcano is certain to break forth before long--it must be on the verge of breaking forth now.

If we remain here we are doomed!"

"Oxcuse me!" fluttered Hans. "I vos retty to gone righd avay queek."

The professor turned to Frank with his appeal:

"Come, boy, let's get away before destruction comes upon us. We must not remain here."

Frank sprang down from his snorting horse, flung the rein to Hans, and leaped to Bushnell's side.

"You are mad to think of remaining here!" he said, swiftly. "Come away, and we will return when the volcano is at peace."

"No!" thundered the treasure-seeker, "I will not go! The Silver Palace is there, and I mean to have my share of the treasure. Go if you are afraid, but here I stay till the balloon is inflated, and I can cross the chasm. The wind is right for it, and nothing shall stop me!"