Fourteen tales, written between 1987 and 1994, from physicist and author Sheffield (Godspeed, 1993, etc.), showcasing an impressive range of themes, ranging from near-mainstream historical to hard SF. ``Millennium,'' a short-short, is Sheffield's wryly effective retort to religious extremism. In the novella ``Destroyer of Worlds,'' he dramatizes the alarming consequences of an attempt to create a sustainable, self-contained ecology for use in space colonies and habitats. Sometimes, he includes real-life friends and colleagues as characters, as in the Nebula Awardwinning title story, a splendid contemporary investigation of a Victorian mystery involving Babbage Engines, incest, weird aliens, and a knotty problem in modern computing. In ``The Feynman Saltation,'' a brain- cancer victim treated with an experimental drug experiences visions that move farther and farther back in time. The dying, ruthless 21st-century dictator of ``The Fifteenth Station of the Cross'' summons Christ from the past in order to demand a cure. And ``Beyond the Golden Road'' details the progress of a papal delegation to the court of Kublai Khan. Constrained by the discipline necessary to write convincingly at a shorter length, Sheffield here is better--considerably better- -than in his often precariously plotted or uninterestingly peopled novels.