He heard Lois tell Jock, "That's the place, down by that rock that looks like a wrecked spaceship." The helicopter began to fall forward. Tom felt Lois' hand on his. "You haven't answered my question," she said. "What?" he asked dully. "Whether you'll stay with us. At least for a while." He looked at her. Her smile was a comfort. He said, "If I possibly can." "What could possibly stop you?" "I don't know," he answered abstractedly. "You're strange," Lois told him. "There's a weight of sadness in you. As if you lived in a less happy age. As if it weren't 2050." "Twenty?" he repeated, awakening from his thoughts with a jerk. "What's the time?" he asked anxiously. "Two," Jock said. The word sounded like a knell. "You need cheering," Lois announced firmly. Amid a whoosh of air rebounding from earth, they jounced gently down. Lois vaulted out. "Come on," she said. Tom followed her. "Where?" he asked stupidly, looking around at the red rocks through the settling sand cloud stirred by the vanes. "Your camera," she told him, laughing. "Over there. Come on, I'll race you." He started to run with her and then his uneasiness got beyond his control. He ran faster and faster. He saw Lois catch her foot on a rock and go down sprawling, but he couldn't stop. He ran desperately around the rock and into a gust of up-whirling sand that terrified him with its suddenness. He tried to escape from the stinging, blinding gust, but there was the nightmarish fright that his wild strides were carrying him nowhere. Then the sand settled. He stopped running and looked around him. He was standing by the balancing rock. He was gasping. At his feet the rusty brown leather of the camera case peeped from the sand. Lois was nowhere in sight. Neither was the helicopter. The valley seemed different, rawer--one might almost have said younger. Hours after dark he trailed into Tosker-Brown. Curtained lights still glowed from a few cabins. He was footsore, bewildered, frightened. All afternoon and through the twilight and into the moonlit evening that turned the red rocks black, he had searched the valley. Nowhere had he been able to find the soot-roofed ranch house of the Wolvers. He hadn't even been able to locate the rock like a giant bobbin where he'd met Lois. During the next days he often returned to the valley. But he never found anything. And he never happened to be near the balancing rock when the time winds blew at ten and two, though once or twice he did see dust devils. Then he went away and eventually forgot. In his casual reading he ran across popular science articles describing the binary system of numbers used in electronic calculating machines, where one and one make ten. He always skipped them. And more than once he saw the four equations expressing Einstein's generalized theory of gravitation: [Illustration: Einstein's equation.] He never connected them with the little girl's chant: "Gik-lo, I-o, Rik-o, Gis-so."