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The Discovery of Longitude

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An Historical Account


Maritime Navigational Practice

and the subsequent

Invention of the Chronometer

by Jonathan Medwin

It was known long before their sufficient refinement, that accurate clocks could be used to measure longitude with corresponding accuracy. John Harrison's chronometers were the first able to keep time on a ship within acceptable limits for measuring its position. The requirement is to have Greenwich Meantime available on board for comparison with local time.

This work describes position-keeping in navigation, the absence of methods for determining longitude, and hence the effect of the invention of the marine chronometer in the eighteenth century.

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