Dava Sobel’s award-winning book Longitude describes a dilemma faced by early sailors. They could readily determine their latitude north or south of the equator by the length of the day or height of the sun. Calculating east/west longitude, however, remained complex and unreliable until English clockmaker John Harrison invented the marine chronometer. This was “a clock that would carry the true time from the home port . . . to any remote corner of the world,” thus enabling sailors to determine longitude.
via Our Daily Bread http://ift.tt/1zvcDSt
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