The Hammock: A Celebration of a Summer Classic
By Daniel Mack
Stewart, Tabori & Chang, New York, $17.95

Say the word hammock and most people picture a stretch of knotted rope swaying invitingly between two leafy trees. But this quintessentially modern image bears little resemblance to the centuries-old sleeping sling discovered by Columbus that was made first from bark and then later from string woven into cloth.