"I know it is. That's where the fun comes in." Over her shoulder she flung him a mocking glance from reckless eyes.

Winston dared make no quick move that would increase her danger. He could not understand the spirit of bravado that had come over her. A sigh of intense relief escaped him as she grasped one of the staying ropes and swung inside the enclosure, which, hanging far out over the abyss, railed in the space where the last stone was to be laid.

"It's no credit to you," he said sternly, "that your childish prank hasn't ended in tragedy."

Helen was conscious of a creeping thrill as she looked into Winston's eyes. They were like poles of a dynamo, with thousands of volts of energy waiting to leap out, if the safety line was crossed. She felt as if she were dangerously near the line.

"Be thankful for your mercies," she said lightly. "No tragedy has happened."

Winston wanted to say more, but an expectant crowd was waiting.

"Well, go ahead," he said. "You're in command now."

"I don't know where to begin, but I'm not old enough yet not to take a dare."

Out on one of the abutments, a great derrick rose; near its foot an engineer stood with his hand on the throttle of an engine. Helen waved her hand, looking defiantly at Winston.

There came the short, sharp bark of the engine, the groaning of rope and timber as the locking stone swung in the air, turned, poised high above them; them slowly began to sink to its position. Under Winston's directions, her small, firm hands guided the great block, as it settled, then came to a rest. The fall ropes slackened, and Helen unclasped the tackle. Amidst the cheers of the watchers on the abutments, the boom of the derrick swung free. The last stone had been laid in the Sangre de Cristo dam.