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Compass: Difference between revisions
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[[Image:Compass in a wooden frame.jpg|thumb|Compass in a wooden box]] | [[Image:Compass in a wooden frame.jpg|thumb|Compass in a wooden box]] | ||
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|Earth]]'s [[magnetic field]], which is of great assistance in [[navigation]]. The [[cardinal points]] are [[north]], [[south]], [[east]] and [[west]]. A compass can be used in conjunction with a [[chronometer]] and a [[sextant]] to provide a very accurate [[navigation]] capability. This device greatly improved maritime trade by making travel safer and more efficient. An early form of compass was invented in | 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|Earth]]'s [[magnetic field]], which is of great assistance in [[navigation]]. The [[cardinal points]] are [[north]], [[south]], [[east]] and [[west]]. A compass can be used in conjunction with a [[chronometer]] and a [[sextant]] to provide a very accurate [[navigation]] capability. This device greatly improved maritime trade by making travel safer and more efficient. An early form of compass was invented in China in the 11th century. The familiar mariner's compass was invented in Europe around 1300. | ||
More technically, a ''compass'' is a magnetic device using a needle to indicate the direction of the magnetic north of a planet's [[magnetosphere]]. Any [[Measuring instrument|instrument]] with a magnetized bar or needle turning freely upon a pivot and pointing in a [[north]]erly and [[south]]erly direction can be considered a compass. A '''compass dial''' is a small pocket compass with a [[sundial]]. A '''variation compass''' is a specific instrument of a delicate type of construction. It is used by observing variations of the needle. A [[gyrocompass]] or [[astrocompass]] can also be used to ascertain [[True north]]. | More technically, a ''compass'' is a magnetic device using a needle to indicate the direction of the magnetic north of a planet's [[magnetosphere]]. Any [[Measuring instrument|instrument]] with a magnetized bar or needle turning freely upon a pivot and pointing in a [[north]]erly and [[south]]erly direction can be considered a compass. A '''compass dial''' is a small pocket compass with a [[sundial]]. A '''variation compass''' is a specific instrument of a delicate type of construction. It is used by observing variations of the needle. A [[gyrocompass]] or [[astrocompass]] can also be used to ascertain [[True north]]. | ||
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=== Developments in China === | === Developments in China === | ||
Due to the place of its first appearance, most scholars credit at present the invention of the compass to | Due to the place of its first appearance, most scholars credit at present the invention of the compass to China. Since there has been frequently confusion as to when a compass was introduced for the first time, it may be appropriate to list the important events leading up to its invention in chronological order: | ||
* The earliest Chinese literary reference to '''magnetism''' lies in a [[4th century BC]] book called ''Book of the Devil Valley Master'' (鬼谷子): "The [[lodestone]] makes [[iron]] come or it attracts it."<ref>Li Shu-hua, “Origine de la Boussole 11. Aimant et Boussole,” ''Isis'', Vol. 45, No. 2. (Jul., 1954), p.175</ref> | * The earliest Chinese literary reference to '''magnetism''' lies in a [[4th century BC]] book called ''Book of the Devil Valley Master'' (鬼谷子): "The [[lodestone]] makes [[iron]] come or it attracts it."<ref>Li Shu-hua, “Origine de la Boussole 11. Aimant et Boussole,” ''Isis'', Vol. 45, No. 2. (Jul., 1954), p.175</ref> | ||
* The first mention of the '''magnetic attraction of a needle''' is to be found in a Chinese work composed between 20 and 100 AD (''Louen-heng''): "A lodestone attracts a needle."<ref>Li Shu-hua, “Origine de la Boussole 11. Aimant et Boussole,” ''Isis'', Vol. 45, No. 2. (Jul., 1954), p.176</ref> In 1948, the scholar Wang Tchen-touo tentatively constructed a 'compass' in the form of south-indicating spoon on the basis of this text. However, it should be noted that "there is no explicit mention of a magnet in the ''Louen-heng''" and that "beforehand it needs to assume some hypotheses to arrive at such a conclusion".<ref>Li Shu-hua, “Origine de la Boussole 11. Aimant et Boussole,” ''Isis'', Vol. 45, No. 2. (Jul., 1954), p.180</ref> | * The first mention of the '''magnetic attraction of a needle''' is to be found in a Chinese work composed between 20 and 100 AD (''Louen-heng''): "A lodestone attracts a needle."<ref>Li Shu-hua, “Origine de la Boussole 11. Aimant et Boussole,” ''Isis'', Vol. 45, No. 2. (Jul., 1954), p.176</ref> In 1948, the scholar Wang Tchen-touo tentatively constructed a 'compass' in the form of south-indicating spoon on the basis of this text. However, it should be noted that "there is no explicit mention of a magnet in the ''Louen-heng''" and that "beforehand it needs to assume some hypotheses to arrive at such a conclusion".<ref>Li Shu-hua, “Origine de la Boussole 11. Aimant et Boussole,” ''Isis'', Vol. 45, No. 2. (Jul., 1954), p.180</ref> | ||
