A compass (or mariner's compass) is a navigational instrument for finding directions on the Earth. It consists of a magnetized pointer free to align itself accurately with
Earth's
magnetic field, which is of great assistance in
navigation. The face of the compass generally highlights the
cardinal points of north, south, east and west. A compass can be used in conjunction with a
marine chronometer to calculate
longitude) and a
sextant to calculate
latitude, providing a very accurate
navigation capability. This device greatly improved maritime trade by making travel safer and more efficient. An early form of the compass was invented in
China in the 11th century. The familiar mariner's compass was invented in
Europe around 1300, from whence later originated the liquid compass and the gyrocompass.
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