The last bit of blue sky yielded to the on-sweep of clouds. Like angry surf the pale gleams of gray, amid the purple of that scudding front, swept beyond the eastern rampart of the valley.

The purple deepened to black. Broad sheets of lightning flared over the western wall. There were not yet any ropes or zigzag streaks darting down through the gathering darkness. The storm center was still beyond Surprise Valley.

"Listen!...Listen!" cried Bess, with her lips close to Venters's ear. "You'll hear Oldring's knell!"

"What's that?"

"Oldring's knell. When the wind blows a gale in the caves it makes what the rustlers call Oldring's knell. They believe it bodes his death. I think he believes so, too. It's not like any sound on earth....It's beginning. Listen!"

The gale swooped down with a hollow unearthly howl. It yelled and pealed and shrilled and shrieked. It was made up of a thousand piercing cries. It was a rising and a moving sound. Beginning at the western break of the valley, it rushed along each gigantic cliff, whistling into the caves and cracks, to mount in power, to bellow a blast through the great stone bridge. Gone, as into an engulfing roar of surging waters, it seemed to shoot back and begin all over again.

It was only wind, thought Venters. Here sped and shrieked the sculptor that carved out the wonderful caves in the cliffs. It was only a gale, but as Venters listened, as his ears became accustomed to the fury and strife, out of it all or through it or above it pealed low and perfectly clear and persistently uniform a strange sound that had no counterpart in all the sounds of the elements. It was not of earth or of life. It was the grief and agony of the gale. A knell of all upon which it blew!

Black night enfolded the valley. Venters could not see his companion, and knew of her presence only through the tightening hold of her hand on his arm. He felt the dogs huddle closer to him. Suddenly the dense, black vault overhead split asunder to a blue-white, dazzling streak of lightning. The whole valley lay vividly clear and luminously bright in his sight. Upreared, vast and magnificent, the stone bridge glimmered like some grand god of storm in the lightning's fire. Then all flashed black again--blacker than pitch--a thick, impenetrable coal-blackness.

And there came a ripping, crashing report. Instantly an echo resounded with clapping crash. The initial report was nothing to the echo. It was a terrible, living, reverberating, detonating crash. The wall threw the sound across, and could have made no greater roar if it had slipped in avalanche. From cliff to cliff the echo went in crashing retort and banged in lessening power, and boomed in thinner volume, and clapped weaker and weaker till a final clap could not reach across the waiting cliff.