The door in the back of the lock clanked open. Joe tried to walk toward it. He discovered his astounding clumsiness. To walk in magnetic-soled shoes in weightlessness requires a knack. When Joe lifted one foot and tried to swing the other forward, his body tried to pivot. When he lifted his right foot, he had to turn his left slightly inward. His arms tried to float absurdly upward. When he was in motion and essayed to pause, his whole body tended to continue forward with a sedate toppling motion that brought him down flat on his face. He had to put one foot forward to check himself. He seemed to have no sense of balance. When he stood still—his stomach queasy because of weightlessness—he found himself tilting undignifiedly forward or back—or, with equal unpredictability, sidewise. He would have to learn an entirely new method of walking. .... They went out of the lock. Sanford suddenly peeled off his metal-soled slippers, put them in his pocket, and dived casually into a four-foot metal tube. He drifted smoothly away along the lighted bore, not touching the sidewalls. He moved in the manner of a dream, when one floats with infinite ease and precision in any direction one chooses.