It was the river, million-colored in the torch-light, pouring from a half-mile-long slash in the cliff above them and plunging past them through the gloom toward the very middle of the world. Its width was a matter of memory, and its depth unguessable, for although dim moonlight filtered through it, he did not know where the moon was, nor how far such light could penetrate through moving water. Somewhere it met rock-bottom and boiled there, for a roar like the sea's came up from deeps unimaginable.

He watched the overturning dome until his senses reeled. Then he crawled on hands and knees to the ledge's brink and tried to peer over. But Ismail dragged him back.

"Come!" he howled; but in all that din his shout was like a whisper.

"How deep is it?" King bellowed back.

"Allah! Ask Him who made it!"

The fear of the falls was on the Afridi, and he tugged at King's arm in a frenzy of impatience. Suddenly he let go and broke into a run. King trotted after him, afraid too, to look to right or left, lest the fear should make him throw himself over the brink. The thunder and the hugeness had their grip on him and had begun to numb his power to think and his will to be a man. Suddenly when they had run a hundred yards, Ismail turned sharp to the right into a tunnel that led straight back into the cliff and sloped uphill. As the din of the falls grew less behind him and his power to think returned, King calculated that they must be following the main direction of the river bed, but edging away gradually to the right of it. After ten minutes' hurrying uphill he guessed they must be level with the river, in a tunnel running nearly parallel.

He proved to be right, for they came to a gap in the wall, and Ismail thrust the torch through it. The light shone on swift black water, and a wind rushed through the gap that nearly blew the torch out. It accounted altogether for the dryness of the rock and the fresh air in the tunnel. The river's weight seemed to suck a hurricane along with it—air enough for a million men to breathe.

After that there was no more need to stop at intervals and beat the torch against the wall to make it burn brightly, for the wind fanned it until the flame was nearly white. Ismail kept looking back to bid King hurry and never paused once to rest.

"Come!" he urged fiercely. "This leads to the 'Heart of the Hills'!" And after that King had to do his best to keep the Afridi's back in sight.

They began after a time to hear voices and to see the smoky glare made by other torches. Then Ismail set the pace yet faster, and they became the last two of a procession of turbaned men, who tramped along a winding tunnel into a great mountain's womb. The sound of slippers clicking and rutching on the rock floor swelled and died and swelled again as the tunnel led from cavern into cavern.

In one great cave they came to every man beat out his torch and tossed it on a heap. The heap was more than shoulder high, and three parts covered the floor of the cave. After that there was a ledge above the height of a man's head on either side of the tunnel, and along the ledge little oil-burning lamps were spaced at measured intervals. They looked ancient enough to have been there when the mountain itself was born, and although all the brass ones suggested Indian and Hindu origin, there were others among them of earthenware that looked like plunder from ancient Greece.