nearly crawled. Then they came to a tiny lake, where the stone pipe ended. This was in a small room.
The walls of this room had been but partially hewn by human hands. Water had excavated a great deal. The stream ran on the floor.
Ahead stretched the cavern. It seemed to go on infinitely.
Doc now realized the cavern was partially the work of the underground stream. It probably extended for miles. Originally, the Mayans had found gold in the stream mouth. They had ventured into the cavern, knowing it must have washed out of there.
And they had found this fabulous lode.
Princess Monja put a query. 'Do you wish to go on?'
'Of course,' Doc replied. 'We are seeking an outlet. Some manner in which the Mayans can escape starvation or surrender.'
They continued into the depths. The air was quite cool. There was a wide path, hewn by human hands.
Sizable stalagmites, like icicles of stone growing upward from the path's middle, showed convincingly that ages had passed since feet had last trod here.
Often, great rocks near blocked the trail. They had fallen from the ceiling. And everywhere, gold inlaid the stone in an ore of fantastic richness.
Doc and his friends had lost interest in the ore. After the vast riches in the storage cavern, nothing could excite them much.
Upward wound the underground stream. Two hours, they toiled ahead. By then, they had gotten beyond the area of gold ore. There was no path now. No gold glistened in the stone.
The way grew more tortuous. The character of the rock walls changed. Johnny stopped often to examine the formations. Monk ranged off into every cranny they came to, hoping to find an exit.
'There is one, somewhere!' Doc declared. 'Not far off, either.'
'How can you tell?' Princess Monja wanted to know. Doc indicated the flame of their torch. It was blowing about in a manner that showed a distinct breeze.
Johnny dropped behind as far as he could, and still kept them in sight. In darkness as he was, he knew he would be more liable to discover an opening into the outer sunlight.
For the same reason, Monk went ahead. The hairy anthropoid of a fellow had more confidence in his ability to get over unknown ground.
Doc was himself an interested observer of the formations of rock through which they were now passing. A villainous, yellowish-gray deposit attracted him. He scratched it with a thumbnail, and burned a little in the torch flame. It was a sulphur deposit.
'Sulphur,' he repeated aloud. But no solution to their troubles presented.
They came soon to a rather large side cavern. The formation was mostly limestone here.
While they waited, Johnny ventured up the side cavern to explore for an opening. Five minutes passed. Ten.
Johnny returned, shaking his head.
'No luck!' He shrugged.
He was juggling a white, crystalline bit of substance in a hand.
Doc looked at this. 'let me inspect that, Johnny!'
Johnny passed it over. Doc touched the end to his tongue. It had a saline taste.
'Saltpeter,' he said. 'Not pure, but pure enough.'
'I don't understand,' Johnny murmured.
Doc recited a formula: 'Saltpeter, charcoal, and sulphur! I noticed the sulphur back a short distance. We can burn wood and get the charcoal. What does that add up to?'
Johnny got it: 'Gun powder!'
Even as he exclaimed the word, they received fresh cause for elation.
Monk had gone ahead a hundred yards, exploring. His howl of delight came to them.
'I see a hole — '
Monk's hole proved to be a rip in solid rock of considerable size. Sunlight blazed through.
Doc, Princess Monja, Johnny, and Monk clambered up to it. They found crude steps, proof the ancient Mayans had known of this exit. They sidled cautiously outside, squinting in the sun glare.
They stood on a shelf. Above, to each side, and below, stretched a sheer wall of rock. It looked almost vertical.
But a close inspection showed a procession of steps leading downward. Only from close range could these be discovered. They offered a way to safety, precarious though it might be.
Doc addressed his companions:
'Monk, you go back inside and start work on that sulphur deposit. Get it out as rapidly as you can. Select the purest stuff.' He told Monk where he had noticed the sulphur.
'Johnny, you harvest a supply of the saltpeter. Was there much of it?'
'Quite a little,' Johnny admitted.
'Dig it out. I think it is pure enough for our purpose. Maybe we can refine it a little.'
Doc turned to pretty Princess Monja. He hesitated, then said: 'Monja, you've been a brick.'
'What's that?' she asked. Evidently her supply of English slang was limited.
'A wonderful girl,' Doc grinned. 'Now, will you do something else. It'll save time.'
She smiled. 'I will do anything you say.'
The unmistakable adoration in her voice escaped Doc's notice.
He directed: 'Return to the Mayans gathered under the pyramid. Select the most powerful and active among the men, and send them here, along with Long Tom, Renny, and Ham.'
'I understand,' she nodded.
'One thing more — send along a number of those gold vases. Select those with thick walls, very heavy. Say about fifty of them. Tell Renny, Long Tom, and Ham I want to make bombs out of them. They will know which ones will serve best.'
'Bombs of gold!' Monk gulped.
'The only thing handy,' Doc pointed out. 'And when the men reach you fellows, load them up with the saltpeter and sulphur.'
Before departing, Johnny asked a question. 'Know where we are?'
Doc smiled and pointed. There was another wall of rock opposite them a few hundred yards. A thousand feet or so below poured a rushing stream.
'We're in the chasm. The Valley of the Vanished is somewhere upstream. And it can't be very far.'
'The entrance to the valley is through the chasm, isn't it?' Monk queried.
'It is. Unless you count the new entrance we've just found.'
Johnny, impatient, said: 'Come on, Princess. Come on, Monk. Let's get going!'
WHEN the three had left him, Doc made his way along the precarious steps to more level footing. He found a patch of jungle. Gathering the proper woods, he selected a spot for making his charcoal where the smoke not be noticed.
The charcoal oven he built of stone and mortar. Two rocks flinty enough to spark a fire could not be located. So, with a leather string from his mantle, and a curved stick, he made a fire bow. This twirled a stick until friction started a tiny glow. In a moment he had a fire.
The charcoal-manufacturing process was well under way when his friends appeared. They had about a hundred of the most manly Mayan men. And from the way they were laden with golden jars, they might have thought they would not have another chance at the fabulous wealth.
The making of the charcoal was tedious. Work on the saltpeter and sulphur called for a great deal of Doc's vast ingenuity and knowledge.
All that afternoon and through the night, they prepared and mixed.
'We won't rush it,' Doc explained. 'This time we want to settle this red-fingered warrior menace for once and all.'
He was ominously silent a bit, then added. 'And one in special — the man in the snake suit.'
