Compasses
A compass, magnetic compass or mariner`s compass is a navigational instrument for determining direction relative to the earth`s magnetic poles. It consists of a magnetized pointer (usually marked on the North end) free to align itself with Earth`s magnetic field. The compass greatly improved the safety and efficiency of travel, especially ocean travel. A compass can be used to calculate heading, used with a sextant to calculate latitude, and with a marine chronometer to calculate longitude. It thus provides a much improved navigational capability that has only been recently supplanted by modern devices such as the Global Positioning System (GPS).
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