"The math didn't show that progressive action," said Russ. "It showed repulsion, negative gravity that could be built up until it would shoot the ship outside the Solar System within an hour's time. Faster than light. We don't know how many times faster." "Forget it," advised Greg. "The way it stands, it's useless. You get repulsion by progressive steps. A series of squares with one constant factor. It wouldn't be any good for space travel. Imagine trying to use it on a spaceship. You'd start with a terrific jolt. The acceleration would fade and just when you were recovering from the first jolt, you'd get a second one and that second one would iron you out. A spaceship couldn't take it, let alone a human body." * * * * * "Maybe this will do it," said Wilson hopefully. "Maybe," agreed Russ. "Anyhow we'll try it. Equation 578." "It might do the trick," said Greg. "It's a new approach to the gravity angle. The equation explains the shifting of gravitational lines, the changing and contortion of their direction. Twist gravity and you have a perfect space drive. As good as negative gravity. Better, perhaps, more easily controlled. Would make for more delicate, precise handling." Russ laid down the sheaf of papers, lit his pipe and walked to the apparatus. "Here goes," he said. His hand went out to the power lever, eased it in. With a roar the material energy engine built within the apparatus surged into action, sending a flow of power through the massive leads. The thunder mounted in the room. The laboratory seemed to shudder with the impact. Wilson, watching intently, cried out, a brief, choked-off cry. A wave of dizziness engulfed him. The walls seemed to be falling in. The room and the machine were blurring. Russ, at the controls, seemed horribly disjointed. Manning was a caricature of a man, a weird, strange figure that moved and gestured in the mad room. Wilson fought against the dizziness. He tried to take a step and the floor seemed to leap up and meet his outstretched foot, throwing him off balance. His cigarette fell out of his mouth, rolled along the floor. Russ was shouting something, but the words were distorted, loud one instant, rising over the din of the apparatus, a mere whisper the next. They made no sense. There was a peculiar whistling in the air, a sound such as he had never heard before. It seemed to come from far away, a high, thin shriek that was torture in one's ears. Giddy, seized with deathly nausea, Wilson clawed his way across the floor, swung open the laboratory door and stumbled outdoors. He weaved across the lawn and clung to a sun dial, panting. He looked back at the laboratory and gasped in disbelief. All the trees were bent toward the building, as if held by some mighty wind. Their branches straining, every single leaf standing at rigid attention, the trees were bending in toward the structure. _But there was no wind._