He inserted his hand into a cup-like contraption with a lever inside. Out of porthole in front of him he could see the distant line of cliffs. "We were afraid there might never be another river running by this mountain, weren't we?" he asked, exultantly. "Yes, Sim, but--" "There _will_ be a river. And I _will_ come back, tonight! And I'll bring men with me. Five hundred men! Because with this machine I can blast a river bottom all the way to the cliffs, down which the waters will rush, giving myself and the men a swift, sure way of traveling back!" He rubbed the machine's barrel-like body. "When I touched it, the life and method of it shot into me! Watch!" He depressed the lever. A beam of incandescent fire lanced out from the ship, screaming. Steadily, accurately, Sim began to cut away a river bed for the storm waters to flow in. The night was turned to day by its hungry eating. * * * * * The return to the cliffs was to be carried out by Sim alone. Lyte was to remain in the ship, in case of any mishap. The trip back seemed, at first glance, to be impossible. There would be no river rushing to cut his time, to sweep him along toward his destination. He would have to run the entire distance in the dawn, and the sun would get him, catch him before he'd reached safety. "The only way to do it is to start _before_ sunrise." "But you'd be frozen, Sim." "Here." He made adjustments on the machine that had just finished cutting the river bed in the rock floor of the valley. He lifted the smooth snout of the gun, pressed the lever, left it down. A gout of fire shot toward the cliffs. He fingered the range control, focused the flame end three miles from its source. Done. He turned to Lyte. "But I don't understand," she said. He opened the air-lock door. "It's bitter cold out, and half an hour yet till dawn. If I run parallel to the flame from the machine, close enough to it, there'll not be much heat but enough to sustain life, anyway." "It doesn't sound safe," Lyte protested. "_Nothing_ does, on this world." He moved forward. "I'll have a half hour start. That should be enough to reach the cliffs." "But if the machine should fail while you're still running near its beam?" "Let's not think of that," he said. A moment later he was outside. He staggered as if kicked in the stomach. His heart almost exploded in him. The environment of his world forced him into swift living again. He felt his pulse rise, kicking through his veins. The night was cold as death. The heat ray from the ship sliced across the valley, humming, solid and warm. He moved next to it, very close. One misstep in his running and-- "I'll be back," he called to Lyte. He and the ray of light went together. * * * * * In the early morning the peoples in the caves saw the long finger of orange incandescence and the weird whitish apparition floating, running along beside it. There was muttering and superstition.