I Hardwick knew the Survey ship had turned end-for-end, because though there was artificial gravity, it does not affect the semicircular canals of the human ear. He knew he was turning head-over-heels, even though his feet stayed firmly on the floor. It was not a normal sensation, and he felt that queasy, instinctive tightening of the muscles with which one reacts to the abnormal, whether in things seen or felt. But the reason for turning the ship end-for-end was obvious. It had arrived very nea