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John Jefferys
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John Jefferys
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Articles about John Jefferys
Marine Chronometer
A marine chronometer is a precision timekeeper accurate enough to be used as a portable reference for finding longitude at sea. The problem was urgent by the early eighteenth century, and in 1714 the British Parliament offered a £ 20,000 reward for a practical…
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Marine ChronometerA marine chronometer is a precision timekeeper accurate enough to be used as a portable reference for finding longitude at sea. The problem was urgent by the early eighteenth century, and in 1714 the British Parliament offered a £ 20,000 reward for a practical…