By Mary Roach
288 pages. Norton.
Mary Roach has done it again. Like Stiff, her improbable page-turner about cadavers, Bonk: The Curious Coupling of Science and Sex (Norton) proves that full-bodied research can be riveting—comic, too. Ever alert to "the cringe factor," Roach introduces her reader to all kinds of sexual arcana, e.g., the penis camera (invented because "you can't see the hangar when the airship's in the building"), farmers' pig-insemination techniques, and Napoleon's great-grandniece's surgically relocated clitoris. Roach even bribes her husband to join her as a guinea pig. Tip: For a good time, read the footnotes.