He pointed to the little hill. "That hasn't got a slope of more than ten degrees, honey. It couldn't have been an accident. The rock never could have gathered so much momentum on that hill." "Not an accident?" "No. Someone--something--pushed that rock." The boulder was unmoving now, fifty yards from the scrap heap which had been the Havelock Cruiser. Marcia said, "Someone pushed _that_? It's as big as the ship, Burt. It weighs five tons if it weighs an ounce. Maybe in this slight gravity--" Burt shook his head. "Even that wouldn't account for it. That rock was pushed." Marcia clung to him, shuddering. "Burt, let's get the children and leave this place!" He nodded, and he was about to call Johnny, when something bounded high into the air over the horizon, then floated down, gently. "Johnny!" Marcia cried. "He's detached his equalizer," Burt said. "That crazy kid--" Each of them had one of the little gravity equalizers at his belt. It was a clever invention: you wore it in space flight, and you never became weightless as space-travelers did in the old days. And you wore it on any planet, creating earth-norm gravity. Now Johnny had detached his, and he weighed no more than a couple of pounds here on the tiny asteroid. Something else bounded high into the air, came floating down. Johnny called: "Lookit us. We're birds, that's what we are. We're birds!" Burt knew that Johnny had removed Joan's equalizer as well. Two forms came bouncing toward them over the wild terrain. "Just press the button to the left," Burt pleaded. "Press it to the left like a good boy, Johnny. You do it and we'll give you a present." "Naa. This is fun. You try and get me." But Joan was crying, and she did not know what to do. Every time she landed, she tried to take a step forward and she soared high into the air again. Closer bounded the two figures, and Johnny soared right by, almost near enough to touch. Burt dove for him, and came up clutching air. Johnny bounded away again, and, calling threats and taunts behind him, he disappeared over the hill, in the direction from which the boulder had come. Marcia had been luckier. She held Joan by one arm now, re-adjusting the equalizer with her free hand. Joan sat down, crying. "I have Joan," Marcia told her husband. "You go and get Johnny, Burt. Get him--quick. I don't like this place." Burt didn't like it, either. _Something had pushed that rock._ Marcia screamed. "Burt--look." The rocks and rubble near the remains of the Havelock were rumbling and grinding. Burt heard a great cracking sound, like a huge dead branch breaking. The ground near the Havelock trembled and the shock of it reached them. Burt sat down hard, and he saw Joan and Marcia fall in a heap.