Clocks and Navigation (Dava Sobel, Longitude, 1996)

Dava Sobel. Longitude (1996) A well done account of John Harrison’s invention and development of the chronometer, a term first used in a satire on impossible inventions. The device was necessary for accurate determination of time, in order to calculate longitude. Sobel writes clear descriptions of the essential features of Harrison’s clocks, which made them far more accurate than any others built at the time. Clocks were the high-tech machines of their day, the cheapest ones cost the equivalent of several week’s artisan’s pay.

     Harrison’s engineering success wasn’t matched by political or economic success, as the alternative methods of using the relative positions of the moon and sun to each other and against the background of fixed stars was preferred by the astronomers. Political infighting delayed adoption of the chronometer until after Harrison’s death, when his successors and other watchmakers developed simplified versions of his inventions, which cheapened the chronometers enough that they became standard equipment on all sea-going vessels. Recommended. ***½