

From Wikipedia, the free encyclopedia
  (Redirected from Magnetic compass)
Jump to: navigation, search
A simple dry magnetic portable compass.


The magnetic compass was first invented as a device for divination as early as the Chinese Han Dynasty (since about 206 BC).[1][2][3] The compass was used in Song Dynasty China by the military for navigational orienteering by 1040-1044,[4][5][6] and was used for maritime navigation by 1111 to 1117.[7] The use of a compass is recorded in Western Europe between 1187 and 1202,[8][9][10] and in Persia in 1232.[11] The dry compass was invented in Europe around 1300.[12] This was supplanted in the early 20th century by the liquid-filled magnetic compass.[13]

Types of compasses[edit]

A military compass that was used during World War I.

There are two widely used and radically different types of compass. The magnetic compass contains a magnet that interacts with the earth's magnetic field and aligns itself to point to the magnetic poles.[14] Simple compasses of this type show directions in a frame of reference in which the directions of the magnetic poles are due north and south. These directions are called magnetic north and magnetic south. The gyro compass (sometimes spelled with a hyphen, or as one word) contains a rapidly spinning wheel whose rotation interacts dynamically with the rotation of the earth so as to make the wheel precess, losing energy to friction until its axis of rotation is parallel with the earth's. The wheel's axis therefore points to the earth's rotational poles, and a frame of reference is used in which the directions of the rotational poles are due north and south. These directions are called true north and true south, respectively. The astrocompass works by observing the direction of stars and other celestial bodies.

There are other devices which are not conventionally called compasses but which do allow the true cardinal directions to be determined. Some GPS receivers have two or three antennas, fixed some distance apart to the structure of a vehicle, usually an aircraft or ship. The exact latitudes and longitudes of the antennas can be determined simultaneously, which allows the directions of the cardinal points to be calculated relative to the heading of the aircraft (the direction in which its nose is pointing), rather than to its direction of movement, which will be different if there is a crosswind. They are said to work "like a compass", or "as a compass".



Magnetic compass[edit]



How a magnetic compass works[edit]

An inexpensive compass, aligned so that its needle points through the "North" mark on its compass card.


A magnet or compass needle's "north" pole is defined as the one which is attracted to the North magnetic pole of the Earth. Since opposite poles attract ("north" to "south") the North magnetic pole of the Earth is actually the south pole of the Earth's magnetic field.[16][17][18] The compass needle's north pole is always marked in some way: with a distinctive color, luminous paint, or an arrowhead.



In geographic regions near the magnetic poles, in the Arctic and Antarctic, variations in the Earth's magnetic field cause magnetic compasses to have such large errors that they are useless, so other instruments must be used for navigation.


The geomagnetic reversal is a significant event that occurs, rapidly by geological standards, when the magnetic north and magnetic south are interchanged. In regions such as the Mid-Atlantic ridge, where rock is being continuously deposited by tectonic spreading, field reversals are recorded as alternating directions of the magnetization of the rock. There have been 184 polarity reversals in last 83 million years, with the most recent complete reversal known as the Laschamp event occurring 41,000 years ago during the last glacial period.


The compass was invented in China, during the Han Dynasty between the 2nd century BC and 1st century AD.[1] The first compasses were made of lodestone, a naturally magnetized ore of iron.[3] Ancient Chinese people found that if a lodestone was suspended so it could turn freely, it would always point in the same direction, toward the magnetic poles. Early compasses were used for geomancy "in the search for gems and the selection of sites for houses," but were later adapted for navigation during the Song Dynasty in the 11th century.[3] Later compasses were made of iron needles, magnetized by striking them with a lodestone. The dry compass was invented in medieval Europe around 1300.[12] This was supplanted in the early 20th century by the liquid-filled magnetic compass.[13]

Navigation prior to the compass[edit]

Prior to the introduction of the compass, position, destination, and direction at sea were primarily determined by the sighting of landmarks, supplemented with the observation of the position of celestial bodies. On cloudy days, the Vikings may have used cordierite or some other birefringent crystal to determine the sun's direction and elevation from the polarization of daylight; their astronomical knowledge was sufficient to let them use this information to determine their proper heading.[19] For more southerly Europeans unacquainted with this technique, the invention of the compass enabled the determination of heading when the sky was overcast or foggy. This enabled mariners to navigate safely far from land, increasing sea trade, and contributing to the Age of Discovery.[citation needed]

Geomancy and feng shui[edit]


Based on Krotser and Coe's discovery of an Olmec hematite artifact in Mesoamerica, radiocarbon dated to 1400-1000 BC, astronomer John Carlson has hypothesized that the Olmec might have used the geomagnetic lodestone earlier than 1000 BC for geomancy, a method of divination, which if proven true, predates the Chinese use of magnetism for feng shui by a millennium.[21] Carlson speculates that the Olmecs used similar artifacts as a directional device for astronomical or geomantic purposes but does not suggest navigational usage. The artifact is part of a polished hematite (lodestone) bar with a groove at one end (possibly for sighting). The artifact now consistently points 35.5 degrees west of north, but may have pointed north-south when whole. Carlson's claims have been disputed by other scientific researchers, who have suggested that the artifact is actually a constituent piece of a decorative ornament and not a purposely built compass.[22] Several other hematite or magnetite artifacts have been found at pre-Columbian archaeological sites in Mexico and Guatemala.[23][24]

Navigational compass[edit]

The discovery and development of magnetic usage as a navigational compass is in evidence by numerous ancient cultures, with early pre-history usage of lodestones suspended so they could turn. Early mechanical compasses are referenced in written records of the Chinese, who began using it for navigation sometime between the 9th and 11th century, "some time before 1050, possibly as early as 850."[25] A common theory by historians,[25][26] suggests that the Arabs introduced the compass from China to Europe, although current textual evidence only supports the fact that Chinese use of the navigational compass preceded that of Europe and the Middle East.[4]




  • The earliest Chinese literature reference to magnetism lies in the 4th century BC writings of Wang Xu (鬼谷子): "The lodestone attracts iron."[28] The book also notes that the people of the state of Zheng always knew their position by means of a "south-pointer"; some authors suggest that this refers to early use of the compass.[3][29]
  • The first mention of a spoon, speculated to be a lodestone, observed pointing in a cardinal direction is a Chinese work composed between 70 and 80 AD (Lunheng), which records that "But when the south pointing spoon is thrown upon the ground, it comes to rest pointing at the south."[30] Within the text, the author Wang Chong describes the spoon as a phenomenon that he has personally observed.[31] Although the passage does not explicitly mention magnetism,[32] according to Chen-Cheng Yih, the "device described by Wang Chong has been widely considered to be the earliest form of the magnetic compass."[27]
  • The first clear account of magnetic declination occurs in the Kuan Shih Ti Li Chih Meng ("Mr. Kuan's Geomantic Instructor"), dating to 880.[33] Another text, the Chiu Thien Hsuan Nu Chhing Nang Hai Chio Ching ("Blue Bag Sea Angle Manual") from around the same period, also has an implicit description of magnetic declination. It has been argued that this knowledge of declination requires the use of the compass.[33]
  • A reference to a magnetized needle as a "mysterious needle" appears in 923-926 in the Chung Hua Ku Chin Chu text written by Ma Kao. The same passage is also attributed to the 4th century AD writer Tshui Pao, although it is postulated that the former text is more authentic. The shape of the needle is compared to that of a tadpole, and may indicate the transition between "lodestone spoons" and "iron needles."[34]
  • The earliest reference to a specific magnetic direction finder device for land navigation is recorded in a Song Dynasty book dated to 1040-44. There is a description of an iron "south-pointing fish" floating in a bowl of water, aligning itself to the south. The device is recommended as a means of orientation "in the obscurity of the night." The Wujing Zongyao (武經總要, "Collection of the Most Important Military Techniques") stated: "When troops encountered gloomy weather or dark nights, and the directions of space could not be distinguished...they made use of the [mechanical] south-pointing carriage, or the south-pointing fish."[5] This was achieved by heating of metal (especially if steel), known today as thermoremanence, and would have been capable of producing a weak state of magnetization.[5] While the Chinese achieved magnetic remanence and induction by this time, in both Europe and Asia the phenomenon was attributed to the supernatural and occult, until about 1600 when William Gilbert published his De Magnete.[35]
  • The earliest explicit recorded use of a magnetic compass for maritime navigation is found in Zhu Yu's book Pingchow Table Talks (萍洲可談; Pingzhou Ketan) and dates from 1111 to 1117: The ship's pilots are acquainted with the configuration of the coasts; at night they steer by the stars , and in the daytime by the sun. In dark weather they look at the south pointing needle.[7]



Diagram of a Ming Dynasty mariner's compass

The first recorded use of a 48 position mariner's compass on sea navigation was noted in The Customs of Cambodia by Yuan Dynasty diplomat Zhou Daguan, he described his 1296 voyage from Wenzhou to Angkor Thom in detail; when his ship set sail from Wenzhou, the mariner took a needle direction of “ding wei” position, which is equivalent to 22.5 degree SW. After they arrived at Baria,[disambiguation needed] the mariner took "Kun Shen needle", or 52.5 degree SW.[40] Zheng He's Navigation Map, also known as "The Mao Kun Map", contains a large amount of detail "needle records" of Zheng He's expeditions.[41]

There is a debate over the diffusion of the compass after its first appearance with the Chinese. At present, according to Kreutz, scholarly consensus is that the Chinese invention predates the first European mention by 150 years.[4] However, there are questions over diffusion, because of the apparent failure of the Arabs to function as possible intermediaries between East and West because of the earlier recorded appearance of the compass in Europe (1190)[8] than in the Muslim world (1232, 1242, and 1282).[11][42] The first European mention of a magnetized needle and its use among sailors occurs in Alexander Neckam's De naturis rerum (On the Natures of Things), written in 1190.[8][10] The earliest reference to a compass in the Middle East is attributed to the Persians, who describe an iron fish-like compass in a talebook dating from 1232.[11] In the Arab world, the earliest reference comes in The Book of the Merchants' Treasure, written by one Baylak al-Kibjaki in Cairo about 1282.[42] Since the author describes having witnessed the use of a compass on a ship trip some forty years earlier, some scholars are inclined to antedate its first appearance accordingly. That the Arabic word for "Compass" (al-konbas) may be a derivation of the old Italian word for compass, is also used as evidence for the lack of diffusion from China to Europe. However, the Persian compass is described as fish-like, which is a characteristic of early Chinese compasses from the 11th century, suggesting transmission from China to Persia.[43]

Medieval Europe[edit]

Pivoting compass needle in a 14th-century copy of Epistola de magnete of Peter Peregrinus (1269).

Alexander Neckam reported the use of a magnetic compass for the region of the English Channel in the texts De utensilibus and De naturis rerum,[9] written between 1187 and 1202, after he returned to England from France[44] and prior to entering the Augustinian abbey at Cirencester.[45] In 1269 Petrus Peregrinus of Maricourt described a floating compass for astronomical purposes as well as a dry compass for seafaring, in his well-known Epistola de magnete.[9] In the Mediterranean, the introduction of the compass, at first only known as a magnetized pointer floating in a bowl of water,[46] went hand in hand with improvements in dead reckoning methods, and the development of Portolan charts, leading to more navigation during winter months in the second half of the 13th century.[47] While the practice from ancient times had been to curtail sea travel between October and April, due in part to the lack of dependable clear skies during the Mediterranean winter, the prolongation of the sailing season resulted in a gradual, but sustained increase in shipping movement; by around 1290 the sailing season could start in late January or February, and end in December.[48] The additional few months were of considerable economic importance. For instance, it enabled Venetian convoys to make two round trips a year to the Levant, instead of one.[49]

At the same time, traffic between the Mediterranean and northern Europe also increased, with first evidence of direct commercial voyages from the Mediterranean into the English Channel coming in the closing decades of the 13th century, and one factor may be that the compass made traversal of the Bay of Biscay safer and easier.[50] However, critics like Kreutz feel that it was later in 1410 that anyone really started steering by compass.[51]

Navigational sailor's compass rose.

At present, according to Kreutz, "barring the discovery of new evidence, it seems clear the first Chinese reference to" the compass "antedates any European mention by roughly 150 years."[4] However, there are questions over diffusion, because of the apparent failure of the Arabs to function as possible intermediaries between East and West because of the earlier recorded appearance of the compass in Europe (1190)[8] than in the Muslim world (1232, 1242, and 1282).[11][42] This is countered by evidence of the temporal proximity of the Chinese navigational compass (1117) to its first appearance in Europe (1190) and the common shape of the early compass as a magnetized needle floating in a bowl of water.[8]

Islamic world[edit]

The earliest reference to an iron fish-like compass in the Islamic world occurs in a Persian talebook from 1232.[11] This fish shape was from a typical early Chinese design.[43] The earliest Arabic reference to a compass — in the form of magnetic needle in a bowl of water — comes from the Yemeni sultan and astronomer Al-Ashraf in 1282.[42] He also appears to be the first to make use of the compass for astronomical purposes.[52] Since the author describes having witnessed the use of a compass on a ship trip some forty years earlier, some scholars are inclined to antedate its first appearance in the Arab world accordingly.[11]

In 1300, another Arabic treatise written by the Egyptian astronomer and muezzin Ibn Simʿūn describes a dry compass for use as a "Qibla (Kabba) indicator" to find the direction to Mecca. Like Peregrinus' compass, however, Ibn Simʿūn's compass did not feature a compass card.[9] In the 14th century, the Syrian astronomer and timekeeper Ibn al-Shatir (1304–1375) invented a timekeeping device incorporating both a universal sundial and a magnetic compass. He invented it for the purpose of finding the times of salat prayers.[53] Arab navigators also introduced the 32-point compass rose during this time.[54]


The compass was used in India for navigational purposes and was known as the matsya yantra, because of the placement of a metallic fish in a cup of oil.[55]

Medieval Africa[edit]

There is evidence that the distribution of the compass from China likely also reached eastern Africa by way of trade through the end of the Silk Road that ended in East African center of trade in Somalia and the Swahili city-state kingdoms.[56] There is evidence that Swahili maritime merchants and sailors acquired the compass at some point and used them for navigation of Swahili versions of dhows.[57]

Later developments[edit]

Dry compass[edit]

Early modern dry compass suspended by a gimbal (1570).


While pivoting needles in glass boxes had already been described by the French scholar Peter Peregrinus in 1269,[58] and by the Egyptian scholar Ibn Simʿūn in 1300,[9] traditionally Flavio Gioja (fl. 1302), an Italian pilot from Amalfi, has been credited with perfecting the sailor's compass by suspending its needle over a compass card, thus giving the compass its familiar appearance.[59] Such a compass with the needle attached to a rotating card is also described in a commentary on Dante's Divine Comedy from 1380, while an earlier source refers to a portable compass in a box (1318),[60] supporting the notion that the dry compass was known in Europe by then.[36]

Bearing compass[edit]

Bearing compass (18th century).

A bearing compass is a magnetic compass mounted in such a way that it allows the taking of bearings of objects by aligning them with the lubber line of the bearing compass.[61] A surveyor's compass is a specialized compass made to accurately measure heading of landmarks and measure horizontal angles to help with map making. These were already in common use by the early 18th century and are described in the 1728 Cyclopaedia. The bearing compass was steadily reduced in size and weight to increase portability, resulting in a model that could be carried and operated in one hand. In 1885, a patent was granted for a hand compass fitted with a viewing prism and lens that enabled the user to accurately sight the heading of geographical landmarks, thus creating the prismatic compass.[62] Another sighting method was by means of a reflective mirror. First patented in 1902, the Bézard compass consisted of a field compass with a mirror mounted above it.[63][64] This arrangement enabled the user to align the compass with an objective while simultaneously viewing its bearing in the mirror.[63][65]

In 1928, Gunnar Tillander, a Swedish unemployed instrument maker and avid participant in the sport of orienteering, invented a new style of bearing compass. Dissatisfied with existing field compasses, which required a separate protractor in order to take bearings from a map, Tillander decided to incorporate both instruments into a single instrument. It combined a compass with a protractor built into the base. His design featured a metal compass capsule containing a magnetic needle with orienting marks mounted into a transparent protractor baseplate with a lubber line (later called a direction of travel indicator). By rotating the capsule to align the needle with the orienting marks, the course bearing could be read at the lubber line. Moreover, by aligning the baseplate with a course drawn on a map - ignoring the needle - the compass could also function as a protractor. Tillander took his design to fellow orienteers Björn, Alvid, and Alvar Kjellström, who were selling basic compasses, and the four men modified Tillander's design.[66] In December 1932, the Silva Company was formed with Tillander and the three Kjellström brothers, and the company began manufacturing and selling its Silva orienteering compass to Swedish orienteers, outdoorsmen, and army officers.[66][67][68][69]

Liquid compass[edit]

A surface mount, liquid-filled compass on a boat.

The liquid compass is a design in which the magnetized needle or card is damped by fluid to protect against excessive swing or wobble, improving readability while reducing wear. A rudimentary working model of a liquid compass was introduced by Sir Edmund Halley at a meeting of the Royal Society in 1690.[70] However, as early liquid compasses were fairly cumbersome and heavy, and subject to damage, their main advantage was aboard ship. Protected in a binnacle and normally gimbal-mounted, the liquid inside the compass housing effectively damped shock and vibration, while eliminating excessive swing and grounding of the card caused by the pitch and roll of the vessel. The first liquid mariner's compass believed practicable for limited use was patented by the Englishman Francis Crow in 1813.[71][72] Liquid-damped marine compasses for ships and small boats were occasionally used by the British Royal Navy from the 1830s through 1860, but the standard Admiralty compass remained a dry-mount type.[73] In the latter year, the American physicist and inventor Edward Samuel Ritchie patented a greatly improved liquid marine compass that was adopted in revised form for general use by the United States Navy, and later purchased by the Royal Navy as well.[74]

Despite these advances, the liquid compass was not introduced generally into the Royal Navy until 1908. An early version developed by RN Captain Creak proved to be operational under heavy gunfire and seas, but was felt to lack navigational precision compared with the design by Lord Kelvin:


Typical aircraft-mounted magnetic compass.

However, with ship and gun sizes continuously increasing, the advantages of the liquid compass over the Kelvin compass became unavoidably apparent to the Admiralty, and after widespread adoption by other navies, the liquid compass was generally adopted by the Royal Navy as well.[13]

Liquid compasses were next adapted for aircraft. In 1909, Captain F.O. Creagh-Osborne, Superintendent of Compasses at the British Admiralty, introduced his Creagh-Osborne aircraft compass, which used a mixture of alcohol and distilled water to damp the compass card.[76][77] After the success of this invention, Capt. Creagh-Osborne adapted his design to a much smaller pocket model[78] for individual use[79] by officers of artillery or infantry, receiving a patent in 1915.[80]

In December 1932, the newly founded Silva Company of Sweden introduced its first baseplate or bearing compass that used a liquid-filled capsule to damp the swing of the magnetized needle.[66] The liquid-damped Silva took only four seconds for its needle to settle in comparison to thirty seconds for the original version.[66]

In 1933 Tuomas Vohlonen, a surveyor by profession, applied for a patent for a unique method of filling and sealing a lightweight celluloid compass housing or capsule with a petroleum distillate to dampen the needle and protect it from shock and wear caused by excessive motion.[81] Introduced in a wrist-mount model in 1936 as the Suunto Oy Model M-311, the new capsule design led directly to the lightweight liquid field compasses of today.[81]

History of non-navigational uses[edit]

Building orientation[edit]

Evidence for the orientation of buildings by the means of a magnetic compass can be found in 12th century Denmark: one fourth of its 570 Romanesque churches are rotated by 5-15 degrees clockwise from true east-west, thus corresponding to the predominant magnetic declination of the time of their construction.[82] Most of these churches were built in the 12th century, indicating a fairly common usage of magnetic compasses in Europe by then.[83]


The use of a compass as a direction finder underground was pioneered by the Tuscan mining town Massa where floating magnetic needles were employed for determining tunneling and defining the claims of the various mining companies as early as the 13th century.[84] In the second half of the 15th century, the compass became standard equipment for Tyrolian miners. Shortly afterwards the first detailed treatise dealing with the underground use of compasses was published by a German miner Rülein von Calw (1463–1525).[85]


Three astronomical compasses meant for establishing the meridian were described by Peter Peregrinus in 1269 (referring to experiments made before 1248)[86] In the 1300s, an Arabic treatise written by the Egyptian astronomer and muezzin Ibn Simʿūn describes a dry compass for use as a "Qibla indicator" to find the direction to Mecca. Ibn Simʿūn's compass, however, did not feature a compass card nor the familiar glass box.[9] In the 14th century, the Syrian astronomer and timekeeper Ibn al-Shatir (1304–1375) invented a timekeeping device incorporating both a universal sundial and a magnetic compass. He invented it for the purpose of finding the times of salat prayers.[53] Arab navigators also introduced the 32-point compass rose during this time.[54]

Modern compasses[edit]

A liquid-filled protractor or orienteering compass with lanyard.

Modern compasses usually use a magnetized needle or dial inside a capsule completely filled with a liquid (lamp oil, mineral oil, white spirits, purified kerosene, or ethyl alcohol is common). While older designs commonly incorporated a flexible rubber diaphragm or airspace inside the capsule to allow for volume changes caused by temperature or altitude, some modern liquid compasses utilize smaller housings and/or flexible capsule materials to accomplish the same result.[87] The liquid inside the capsule serves to dampen the movement of the needle, reducing oscillation time and increasing stability. Key points on the compass, including the north end of the needle are often marked with phosphorescent, photoluminescent, or self-luminous materials[88] to enable the compass to be read at night or in poor light. As the compass fill liquid is noncompressible under pressure, many ordinary liquid-filled compasses will operate accurately underwater to considerable depths.


Liquid filled lensatic compass.
Cammenga air filled lensatic compass.

Other features found on modern orienteering compasses are map and romer scales for measuring distances and plotting positions on maps, luminous markings on the face or bezels, various sighting mechanisms (mirror, prism, etc.) for taking bearings of distant objects with greater precision, "global" needles for use in differing hemispheres, adjustable declination for obtaining instant true bearings without resort to arithmetic, and devices such as clinometers for measuring gradients.[89] The sport of orienteering has also resulted in the development of models with extremely fast-settling and stable needles for optimal use with a topographic map, a land navigation technique known as terrain association.[90]


The U.S. M-1950 military lensatic compass does not use a liquid-filled capsule as a damping mechanism, but rather electromagnetic induction to control oscillation of it magnetized card. A "deep-well" design is used to allow the compass to be used globally with a card tilt of up to 8 degrees without impairing accuracy.[92] As induction forces provide less damping than liquid-filled designs, a needle lock is fitted to the compass to reduce wear, operated by the folding action of the rear sight/lens holder. The use of air-filled induction compasses has declined over the years, as they may become inoperative or inaccurate in freezing temperatures or extremely humid environments due to condensation or water ingress.[93]

Some military compasses, like the U.S. M-1950 (Cammenga 3H) military lensatic compass, the Silva 4b Militaire, and the Suunto M-5N(T) contain the radioactive material tritium (1H3) and a combination of phosphors.[94] The U.S. M-1950 equipped with self-luminous lighting contains 120 mCi (millicuries) of tritium. The purpose of the tritium and phosphors is to provide illumination for the compass, via radioluminescent tritium illumination, which does not require the compass to be "recharged" by sunlight or artificial light.[95] However, tritium has a half-life of only about 12 years,[96] so a compass that contains 120 mCi of tritium when new will contain only 60 when it is 12 years old, 30 when it is 24 years old, and so on. Consequently, the illumination of the display will fade.


Thumb compass[edit]

Thumb compass on left.






Solid state compasses[edit]

Small compasses found in clocks, mobile phones, and other electronic devices are solid-state compasses, usually built out of two or three magnetic field sensors that provide data for a microprocessor. The correct heading relative to the compass is calculated using trigonometry.


GPS receivers using two or more antennae can now achieve 0.5° in heading accuracy and have startup times in seconds rather than hours for gyrocompass systems. Manufactured primarily for maritime applications, they can also detect pitch and roll of ships.

Specialty compasses[edit]

A standard Brunton Geo, used commonly by geologists.


  • Optical or prismatic hand-bearing compass, most often used by surveyors, but also by cave explorers, foresters, and geologists. This compasses ordinarily uses a liquid-damped capsule[97] and magnetized floating compass dial with an integral optical (direct or lensatic) or prismatic sight, often fitted with built-in photoluminescent or battery-powered illumination.[89] Using the optical or prism sight, such compasses can be read with extreme accuracy when taking bearings to an object, often to fractions of a degree. Most of these compasses are designed for heavy-duty use, with high-quality needles and jeweled bearings, and many are fitted for tripod mounting for additional accuracy.[89]

Limitations of the magnetic compass[edit]

The compass is very stable in areas close to the equator, which is far from "magnetic north". As the compass is moved closer and closer to one of the magnetic poles of the Earth, the compass becomes more sensitive to crossing its magnetic field lines. At some point close to the magnetic pole the compass will not indicate any particular direction but will begin to drift. Also, the needle starts to point up or down when getting closer to the poles, because of the so-called magnetic inclination. Cheap compasses with bad bearings may get stuck because of this and therefore indicate a wrong direction.




Construction of a compass[edit]

Magnetic needle[edit]


Needle-and-bowl device[edit]


Points of the compass[edit]





Compass balancing (magnetic dip)[edit]



Compass correction[edit]





Using a compass[edit]

Turning the compass scale on the map (D - the local magnetic declination).



Soldier using a prismatic compass to get an azimuth.




See also[edit]


  1. ^ a b c Merrill, Ronald T.; McElhinny, Michael W. (1983). The Earth's magnetic field: Its history, origin and planetary perspective (2nd printing ed.). San Francisco: Academic press. p. 1. ISBN 0-12-491242-7. 
  2. ^ a b Li Shu-hua, p. 176
  3. ^ a b c d e Lowrie, William (2007). Fundamentals of Geophysics. London: Cambridge University Press. p. 281. ISBN 9780521675963. "Early in the Han Dynasty, between 300-200 BC, the Chinese fashioned a rudimentary compass out of lodestone... the compass may have been used in the search for gems and the selection of sites for houses... their directive power led to the use of compasses for navigation" 
  4. ^ a b c d e Kreutz, p. 367
  5. ^ a b c d Needham, p. 252
  6. ^ a b c Li Shu-hua, p. 182f.
  7. ^ a b c Colin A. Ronan; Joseph Needham (25 July 1986). The Shorter Science and Civilisation in China. Cambridge University Press. pp. 28–29. ISBN 978-0-521-31560-9. 
  8. ^ a b c d e Kreutz, p. 368
  9. ^ a b c d e f Schmidl, Petra G. (1996–1997). "Two Early Arabic Sources On The Magnetic Compass". Journal of Arabic and Islamic Studies 1: 81–132  http://www.uib.no/jais/v001ht/01-081-132schmidl1.htm#_ftn4
  11. ^ a b c d e f Kreutz, p. 370
  12. ^ a b c Lane, p. 615
  13. ^ a b c d W. H. Creak: "The History of the Liquid Compass", The Geographical Journal, Vol. 56, No. 3 (1920), pp. 238-239
  14. ^ The Earth's magnetic field is approximately that of a tilted dipole. If it were exactly dipolar, the compass would point to the geomagnetic poles, which would be identical to the North Magnetic Pole and South Magnetic Pole; however, it is not, so these poles are not equivalent and the compass only points 360' off at the geomagnetic poles.
  15. ^ Seidman, David, and Cleveland, Paul, The Essential Wilderness Navigator, Ragged Mountain Press (2001), ISBN 0-07-136110-3, p. 147: Since the magnetic compass is simple, durable, and requires no separate electrical power supply, it remains popular as a primary or secondary navigational aid, especially in remote areas or where power is unavailable.
  19. ^ Gábor Horváth et al. (2011). "On the trail of Vikings with polarized skylight". Philosophical Transactions of the Royal Society B 366 (1565): 772–782. doi:10.1098/rstb.2010.0194. 
  20. ^ "National High Magnetic Field Laboratory: Early Chinese Compass". Florida State University. Retrieved 2009-02-05. 
  21. ^ John B. Carlson, "Lodestone Compass: Chinese or Olmec Primacy? Multidisciplinary Analysis of an Olmec Hematite Artifact from San Lorenzo, Veracruz, Mexico", Science, New Series, Vol. 189, No. 4205 (5 September 1975), pp. 753-760 (1975)
  22. ^ Needham, Joseph; Lu Gwei-Djen (1985). Trans-Pacific Echoes and Resonances: Listening Once Again. World Scientific. p. 21. 
  23. ^ A. P. Guimarães, "Mexico and the early history of magnetism", Revista Mexicana de Fisica, Vol. 50, pp. 51-53 (2004)
  24. ^ http://www.dartmouth.edu/~izapa/CS-MM-Chap.%203.htm
  25. ^ a b Needham, Joseph (1986). The Shorter Science and Civilisation in China, Volume 3. Cambridge University Press. p. 176. ISBN 9780521315609. "the introduction of the mariner's compass on Chinese ships some time before 1050, possibly as early as 850" 
  26. ^ McEachren, Justin W. General Science Quarterly, Volumes 5-6. University of California Press. p. 337. "From the Chinese, the Arabs in all probability learned to use the magnetic needle, and in this round-about fashion it was brought to Europe" 
  27. ^ a b Selin, Helaine (1997). Encyclopaedia of the History of Science, Technology, and Medicine in Non-Western Cultures. Springer. p. 541. ISBN 9781402045592. "The device described by Wang Chong has been widely considered to be the earliest form of the magnetic compass" 
  28. ^ http://www.gutenberg.org/cache/epub/7209/pg7209.html
  29. ^ Needham p. 190
  30. ^ Needham p. 18
  31. ^ Needham p. 18 "here the author is contrasting a fable which he did not believe with actual events he has seen with his own eyes"
  32. ^ Li Shu-hua, p. 180
  33. ^ a b Needham, Joseph (1970). Clerks and Craftsmen in China and the West. Cambridge University Press. pp. 243–244. ISBN 9780521072359. "The geomantic book Kuan Shih Ti Li Chih Meng... has the first account of it... the Chiu Thien Hsuan Nu Chhing Nang Hai Chio Ching... includes an implicit reference to declination" 
  34. ^ Needham p. 273-274
  35. ^ Benjamin A. Elman (30 June 2009). On Their Own Terms: Science in China, 1550-1900. Harvard University Press. p. 242. ISBN 978-0-674-03647-5. 
  36. ^ a b c Kreutz, p. 373
  37. ^ a b c Needham p. 255
  38. ^ Needham, p. 289.
  39. ^ Needham, p. 290
  40. ^ Zhou
  41. ^ Ma, Appendix 2
  42. ^ a b c d Kreutz, p. 369
  43. ^ a b Needham p. 12-13 "...that the floating fish-shaped iron leaf spread outside China as a technique, we know from the description of Muhammad al' Awfi just two hundred years later"
  44. ^ Neckam, Alexander (1863). Alexandri Neckam De Naturis Rerum Libri Duoi. Longman, Roberts, and Green. p. xi. 
  45. ^ Gutman, Oliver (2003). Liber Celi Et Mundi. BRILL. p. xx. ISBN 9789004132283. "probably whilst teaching theology at Oxford before entering the Augustinian abbey at Cirencester in 1202" 
  46. ^ Kreutz, p. 368–369
  47. ^ Lane, p. 606f.
  48. ^ Lane, p. 608
  49. ^ Lane, p. 608 & 610
  50. ^ Lane, p. 608 & 613
  51. ^ Kreutz, p. 372–373
  52. ^ Emilie Savage-Smith (1988), "Gleanings from an Arabist's Workshop: Current Trends in the Study of Medieval Islamic Science and Medicine", Isis 79 (2): 246-266 [263]
  53. ^ a b (King 1983, pp. 547–8)
  54. ^ a b G. R. Tibbetts (1973), "Comparisons between Arab and Chinese Navigational Techniques", Bulletin of the School of Oriental and African Studies 36 (1): 97-108 [105-6]
  55. ^ The American journal of science - Google Books. 1919. Retrieved 2009-06-30. 
  56. ^ Stockwell, Foster (2003). Westerners in China : a history of exploration and trade, ancient times through the present. Jefferson, NC: McFarland & Co. Publishers. p. 14. ISBN 9780786414048. 
  57. ^ Bulliet et al., Richard W. The earth and its peoples : a global history (5th, Student ed.). Boston: Wadsworth Cengage Learning. p. 381. ISBN 9780538744386. 
  58. ^ Taylor
  59. ^ Lane, p. 616
  60. ^ Kreutz, p. 374
  61. ^ "Hand Bearing Compass". West Marine. 2004. Retrieved 2007-12-28. 
  62. ^ Frazer, Persifor, A Convenient Device to be Applied to the Hand Compass, Proceedings of the American Philosophical Society, Vol. 22, No. 118 (Mar., 1885), p. 216
  63. ^ a b The Compass Museum, The Bézard Compass, Article
  64. ^ Barnes, Scott, Churchill, James, and Jacobson, Cliff, The Ultimate Guide to Wilderness Navigation, Globe Pequot Press (2002), ISBN 1-58574-490-5, ISBN 978-1-58574-490-9, p. 27
  65. ^ Barnes, p. 27
  66. ^ a b c d Litsky, Frank, Bjorn Kjellstrom, 84, Orienteer and Inventor of Modern Compass, Obituaries, The New York Times, 1 September 1995
  67. ^ Seidman, p. 68
  68. ^ Kjellström, Björn, 19th Hole: The Readers Take Over: Orienteering, Sports Illustrated, 3 March 1969
  69. ^ Silva Sweden AB, Silva Sweden AB and Silva Production AB Become One Company: History, Press Release 28 April 2000
  71. ^ Fanning, A.E., Steady As She Goes: A History of the Compass Department of the Admiralty, HMSO, Department of the Admiralty (1986), pp. 1-10
  72. ^ Gubbins, p. 67
  73. ^ Fanning, A.E., pp. 1-10
  74. ^ Warner, Deborah, Compasses and Coils: The Instrument Business of Edward S. Ritchie, Rittenhouse, Vol. 9, No. 1 (1994), pp. 1-24
  75. ^ Gubbins, p. 67: The use of parallel or multiple needles was by no means a new development; their use in dry-mount marine compasses was pioneered by navigation officers of the Dutch East India Company as early as 1649.
  76. ^ Davis, Sophia, Raising The Aerocompass In Early Twentieth-century Britain, British Journal for the History of Science, published online by Cambridge University Press, 15 Jul 2008, pp. 1-22
  77. ^ Colvin, Fred H., Aircraft Mechanics Handbook: A Collection of Facts and Suggestions from Factory and Flying Field to Assist in Caring for Modern Aircraft, McGraw-Hill Book Co. Inc. (1918), pp. 347-348
  78. ^ The Compass Museum, Article: Though the Creagh-Osborne was offered in a wrist-mount model, it proved too bulky and heavy in this form.
  79. ^ Hughes, Henry A., Improvements in prismatic compasses with special reference to the Creagh-Osborne patent compass, Transactions of The Optical Society 16, London: The Optical Society (1915), pp. 17-43: The first liquid-damped compass compact enough for pocket or pouch was the Creagh-Osborne, patented in 1915 in Great Britain.
  80. ^ Hughes, Henry A., pp. 17-43
  81. ^ a b Suunto Oy, Suunto Company History, December 2001 Article
  82. ^ N. Abrahamsen: "Evidence for Church Orientation by Magnetic Compass in Twelfth-Century Denmark", Archaeometry, Vol. 32, No. 2 (1992), pp. 293-303 (293)
  84. ^ Ludwig and Schmidtchen, p. 62–64
  85. ^ Ludwig and Schmidtchen, p. 64
  86. ^ Taylor, p. 1f.
  87. ^ Gear Review: Kasper & Richter Alpin Compass, OceanMountainSky.Com
  89. ^ a b c d e f g h i j Johnson, G. Mark (2003-03-26). The Ultimate Desert Handbook. McGraw-Hill Professional. p. 110. ISBN 0-07-139303-X. 
  90. ^ Kjernsmo, Kjetil, '[www.learn-orienteering.org/old/buying.html How to use a Compass], retrieved 8 April 2012
  92. ^ 'Article MIL-PRF-10436N, rev. 31 October 2003, Washington, D.C.: U.S. Dept. of Defense
  93. ^ Kearny, Cresson H., Jungle Snafus...And Remedies, Oregon Institute Press (1996), ISBN 1-884067-10-7, pp. 164-170: In 1989, one U.S. Army jungle infantry instructor reported that about 20% of the issue lensatic compasses in his company used in a single jungle exercise in Panama were ruined within three weeks by rain and humidity.
  94. ^ Ministry of Defence, Manual of Map Reading and Land Navigation, HMSO Army Code 70947 (1988), ISBN 0-11-772611-7, ISBN 978-0-11-772611-6, ch. 8, sec. 26, pp. 6-7; ch. 12, sec. 39, p. 4
  95. ^ "Military Compass". Orau.org. Retrieved 2009-06-30. 
  96. ^ CRC Handbook of Chemistry and Physics. page B247
  98. ^ a b Global compasses, MapWorld.


  • King, David A. (1983). "The Astronomy of the Mamluks". Isis 74 (4): 531–555. doi:10.1086/353360 
  • Wright, Monte Duane (1972) Most Probable Position: A History of Aerial Navigation to 1941, The University Press of Kansas, Library of Congress Catalog Card Number 72-79318

External links[edit]

Wikipedia content is licensed under the GFDL License
  • Mashpedia © 2013