He released himself from the safety belt and dived across the cabin in which there was now no weight at all. In the blackness he opened a cabinet door. What he did inside was customarily done by a man wearing thick insulating gloves, in the landing grid back at Headquarters. He threw certain switches which would allow the discharge of the power-storage cells which worked the Med Ship's overdrive. Monstrous quantities of energy were required to put even a fifty-ton ship into overdrive, and monstrous amounts were returned when it came out. The power amounted to ounces of pure, raw energy, and as a safety-precaution such amounts were normally put into the Duhanne cells only just before a Med Ship's launching, and drained out again on its return. But now, Calhoun threw switches which made a rather incredible amount of power available for dumping into the landing-grid field about him--if necessary. He floated back to the control chair. * * * * * The ship lurched--violently. It was being moved by the grid field without any gentleness at all. Calhoun's hands barely grasped the back of his pilot's chair before the jerk came, and it almost tore them free. He just missed being flung against the back wall of the cabin by the applied acceleration. But he was a long way out from the planet. He was at the end of a lever fifty thousand miles long. For that lever to be used to shake him too brutally would require special adjustments. But somebody was making them. The jerk reversed directions. He was flung savagely against the chair to which he'd been clinging. He struggled. Another yank, in another direction. Another one still. It flung him violently into the chair. Behind him, Murgatroyd squealed angrily as he went hurtling across the cabin. He grabbed for holding-places with all four paws and his tail. Another shake. Calhoun had barely clipped the safety belt fast before a furious jolt nearly flung him out of it again to crash against the cabin ceiling. Yet another vicious surge of acceleration. He scrabbled for the controls. The yanks and plungings of the ship increased intolerably. He was nauseated. Once he was thrust so furiously into the control chair that he was on the verge of blacking out, and then the direction of thrust was changed to the exact opposite so that the blood rushing to his head seemed about to explode it. His arms flailed out of control. He became dazed. But when his hands were flung against the control board, despite their bruising he tried to cling to the control knobs, and each time he threw them over. Practically all his circuits were blown, but there was one--