Knowing all the conditions, Ballard thought the masonry would never withstand the hammer-blow impact of the wreck-laden billow. Yet it stood, apparently undamaged, even after the splintered mass of wreckage, tossed high on the crest of the wave, had leaped the coping course to plunge thundering into the ravine below. The great wall was like some massive fortification reared to endure such shocks; and Elsa, facing the terrific spectacle beside her lover, like a reincarnation of one of the battle-maidens, gave him his rightful meed of praise.
"You builded well—you and the others!" she cried. "It will not break!"
But even as she spoke, the forces that sap and destroy were at work. There was a hoarse groaning from the underground caverns of the zirconium mine—sounds as of a volcano in travail. The wave retreated for a little space, and the white line of the coping showed bare and unbroken in the moonlight. Silence, the deafening silence which follows the thunderclap, succeeded to the clamour of the waters, and this in turn gave place to a curious gurgling roar as of some gigantic vessel emptying itself through an orifice in its bottom.
The white-haired king was nearest to the brink of peril. At the gurgling roar he turned with arms outspread and swept the onlooking group, augmented now by the men from Garou's cook camp, back and away from the dam-head. Out of the torrent-worn pit in the lower ravine a great jet of water was spurting intermittently, like the blood from a severed artery.
"That is the end!" groaned Ballard, turning away from the death grapple between his work and the blind giant of the Boiling Water; and just then Blacklock shouted, snatched, wrestled for an instant with a writhing captive—and was left with a torn mackintosh in his hands for his only trophy.
They all saw the Mexican when he slipped out of the rain-coat, eluded Blacklock, and broke away, to dart across the chasm on the white pathway of the dam's coping course. He was half-way over to the shore of escape when his nerve failed. To the spouting fountain in the gulch below and the sucking whirlpool in the Elbow above was added a second tidal wave from the cloud-burst sources; a mere ripple compared with the first, but yet great enough to make a maelstrom of the gurgling whirlpool, and to send its crest of spray flying over the narrow causeway. When the barrier was bared again the Mexican was seen clinging limpet-like to the rocks, his courage gone and his death-warrant signed. For while he clung, the great wall lost its perfect alignment, sagged, swayed outward under the irresistible pressure from above, crumbled, and was gone in a thunder-burst of sound that stunned the watchers and shook the solid earth of the mesa where they stood.
"Are you quite sure it wasn't all a frightful dream?" asked the young woman in a charming house gown and pointed Turkish slippers of the young man with his left arm in a sling; the pair waiting the breakfast call in the hammock-bridged corner of the great portico at Castle 'Cadia.
It was a Colorado mountain morning of the sort called "Italian" by enthusiastic tourists. The air was soft and balmy; a rare blue haze lay in the gulches; and the patches of yellowing aspens on the mountain shoulders added the needed touch of colour to relieve the dun-browns and grays of the balds and the heavy greens of the forested slopes. Save for the summer-dried grass, lodged and levelled in great swaths by the sudden freeing of the waters, the foreground of the scene was unchanged. Through the bowl-shaped valley the Boiling Water, once more an August-dwindled mountain stream, flowed murmurously as before; and a mile away in the foothill gap of the Elbow, the huge steel-beamed derrick lined itself against the farther distances.
"No, it wasn't a dream," said Ballard. "The thirty-mile, nerve-trying drive home in the car, with the half-wrecked railroad bridge for a river crossing, ought to have convinced you of the realities."