In the early eighteenth century, England was flexing its muscles as an emerging world power. The foundation of this island nation’s might and income rested upon its maritime supremacy. Yet the increased trade and expanding navy of the British Empire were threatened by the uncertainty of oceangoing navigation. Quite simply, sailors were often quite ignorant of their position at sea. They had no reliable means of determining longitude, and the resulting disasters exacted a heavy toil on lives and shipping.

Parliament’s Longitude Act of 1714 was intended to remedy this by offering a reward of twenty thousand pounds to the person who could solve the riddle. Although the longitude problem baffled the great minds of the day, a self-taught clockmaker named John Harrison found a solution. Such facts might merely seem the stuff of trivia games, but Dava Sobel’s LONGITUDE is an intriguing biography. Through lucid prose and a compelling narrative, Sobel explains the longitude problem and the sometimes outlandish schemes that were designed to address it. Moreover, this is a moving account of one of history’s great unrecognized geniuses. The reader follows Harrison’s successful forty-year effort to create an accurate, portable timepiece for use at sea: the chronometer.

Sobel’s story does have its villains. Astronomers seeking a celestial solution hindered Harrison’s work and ridiculed his revolutionary timepieces. And while no one was ever actually awarded the prize, the clockmaker did receive ample recompense late in life. England’s long reign as a sea power owed much to this long-forgotten man. Sobel’s balanced narrative brings these seemingly arcane facts to life and will do much to restore Harrison’s reputation. Reading LONGITUDE is time well spent.