He sat at his desk, in the inner of three successively smaller offices on the second floor of the converted warehouse, checking over a symbolic-logic analysis of a relay system and, at the same time, sharpening a pencil, his knife paring off tiny feathery shavings of wood. He was a tall, sparely-built, man of indeterminate age, with thinning sandy hair, a long Gaelic upper lip, and a wide, half-humorous, half-weary mouth; he wore an open-necked shirt, and an old and shabby leather jacket, to the left shoulder of which a few clinging flecks of paint showed where some military emblem had been, long ago. While his fingers worked with the jackknife and his eyes traveled over the page of closely-written symbols, his mind was reviewing the eight different ways in which one of the efficient but treacherous Doernberg-Giardano reactors could be allowed to reach critical mass, and he was wondering if there might not be some unsuspected ninth way. That was a possibility which always lurked in the back of his mind, and lately it had been giving him surrealistic nightmares. "Mr. Melroy!" the box on the desk in front of him said suddenly, in a feminine voice. "Mr. Melroy, Dr. Rives is here." Melroy picked up the handphone, thumbing on the switch. "Dr. Rives?" he repeated. "The psychologist who's subbing for Dr. von Heydenreich," the box told him patiently. "Oh, yes. Show him in," Melroy said. "Right away, Mr. Melroy," the box replied. * * * * * Replacing the handphone, Melroy wondered, for a moment, why there had been a hint of suppressed amusement in his secretary's voice. Then the door opened and he stopped wondering. Dr. Rives wasn't a him; she was a her. Very attractive looking her, too--dark hair and eyes, rather long-oval features, clear, lightly tanned complexion, bright red lipstick put on with a micrometric exactitude that any engineer could appreciate. She was tall, within four inches of his own six-foot mark, and she wore a black tailored outfit, perfectly plain, which had probably cost around five hundred dollars and would have looked severe and mannish except that the figure under it curved and bulged in just the right places and to just the right degree. Melroy rose, laying down knife and pencil and taking his pipe out of his mouth. "Good afternoon," he greeted. "Dr. von Heydenreich gave me quite a favorable account of you--as far as it went. He might have included a few more data and made it more so.... Won't you sit down?" The woman laid her handbag on the desk and took the visitor's chair, impish mirth sparking in her eyes. "He probably omitted mentioning that the D. is for Doris," she suggested. "Suppose I'd been an Englishman with a name like Evelyn or Vivian?" Melroy tried to visualize her as a male Englishman named Vivian, gave up, and grinned at her.