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更新日期：2017-04-19
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compass is a navigational instrument for determining direction in the form of a free magnetic arrows align itself with Earth's magnetic field accurately. Compass provides references a particular direction, so it is very helpful in the field of navigation. Designated wind direction is north, south, east, and west. When used together with a clock and a sextant, the compass will be more accurate in indicating the direction. This tool helps the development of maritime trade by making travel safer and much more efficient than when humans are still guided by the position of stars to determine the direction.
The magnetic compass was first discovered as a fixture for the forecast at the beginning of the Han Dynasty of China (ca. 206 BC), [1] [2] and later adopted for navigation by the Song Dynasty during the 11th century. [3] [4] [5] The first use of the compass was recorded in Western Europe and the Persian occur around the beginning of the 13th century. [6]
The discovery that a magnetic needle always point to the north and south happening in China and is described in the book Loven Heng. In the ninth century, the Chinese had developed a form of needle compass needle floating and spinning. Persian sailors obtained from the Chinese compass and then trade them. But only in 1877 the Englishman, William Thomson, 1st Baron Kelvin (Lord Kelvin) make a compass that can be accepted by all countries. By fixing the errors arising from the magnetic deviation due to the increasing use of iron in ship architecture.
Whatever tool has a rod or a magnetic needle that is free to move pointing direction of the magnetic north of a planet's magnetosphere can already be considered as a compass. Compass watch is a compass equipped with a sundial. Compass variation fragile structure is a specialized tool used by observing variations in the movement of the needle. Gyrocompass used to determine true north.
The location of magnetic North Pole is always shifted from time to time. The latest research conducted by the Geological Survey of Canada reported that the position of the magnet is moved approximately 40 km per year to the northwest.
