T he Celestia , gliding through space toward Titan, major satellite of Saturn, faltered in her course. Her passengers, mostly mining engineers and their wives, stockholders, and a sprinkling of visitors, were aware of a cessation of the heavens' apparent gyrations, due to the halting of the ship's rotation on its axis. At the same time the ship's fictitious gravity, engendered by the centrifugal force of its rotation, ceased, so that passengers, most of whom were assembled in the main salon, whi