History of the compass
The compass is a magnetometer used for navigation and orientation that shows direction in regard to the geographic cardinal points. The structure of a compass consists of the compass rose, which displays the four main directions on it: East, South, West and North. The angle increases in the clockwise position. North corresponds to 0°, so east is 90°, south is 180° and west is 270°.
The history of the compass started more than 2000 years ago during the Han dynasty. The first compasses were made of lodestone, a naturally magnetized stone of iron, in Han dynasty China. It was called the "South Pointing Fish" and was used for land navigation by the mid-11th century during the Song dynasty. Shen Kuo provided the first explicit description of a magnetized needle in 1088 and Zhu Yu mentioned its use in maritime navigation in the text Pingzhou Table Talks, dated 1111–1117. Later compasses were made of iron needles, magnetized by striking them with a lodestone. Magnetized needles and compasses were first described in medieval Europe by the English theologian Alexander Neckam. The first literary description of a compass in Western Europe was recorded in around 1190 and in the Islamic world 1232. Dry compasses begin appearing around 1269 in medieval Europe and 1300 in the medieval Islamic world. This was replaced in the early 20th century by the liquid-filled magnetic compass.
Navigation prior to the compass
Before the introduction of the compass, geographical position and direction at sea were primarily determined by the sighting of landmarks, supplemented with the observation of the position of celestial bodies. Other techniques included sampling mud from the seafloor, analyzing the flight path of birds, and observing wind, sea debris, and sea state. Objects that have been understood as having been used for navigation by measuring the angles between celestial objects were discovered in the Indus Valley site of Lothal. The Norse are believed to have used a type of sun compass to locate true north. On cloudy days, the Norse 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. The invention of the compass made it possible to determine a heading when the sky was overcast or foggy, and when landmarks were not in sight. This enabled mariners to navigate safely far from land, increasing sea trade, and contributing to the Age of Discovery.Geomancy and Feng Shui
The compass was invented in China during the Han dynasty between the 2nd century BC and 1st century AD where it was called the "south-governor" or "South Pointing Fish". The magnetic compass was not, at first, used for navigation, but for geomancy and fortune-telling by the Chinese. The earliest Chinese magnetic compasses were possibly used to order and harmonize buildings by the geomantic principles of feng shui. These early compasses were made with lodestone, a form of the mineral magnetite that is a naturally occurring magnet and aligns itself with the Earth's magnetic field. People in ancient China discovered that if a lodestone was suspended so it could turn freely, it would always point toward the magnetic poles. Early compasses were used to choose areas suitable for building houses, growing crops, and to search for rare gems. Compasses were later adapted for navigation during the Song dynasty in the 11th century.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. 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 bar with a groove at one end, possibly used for sighting. 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. Several other hematite or magnetite artifacts have been found at pre-Columbian archaeological sites in Mexico and Guatemala.
Early navigational compass
A number of early cultures used lodestone so they could turn, as magnetic compasses for navigation. Early mechanical compasses are referenced in written records of the Chinese, who began using it for navigation "some time before 1050, possibly as early as 850." At present, according to Kreutz, scholarly consensus is that the Chinese invention used in navigation pre-dates the first European mention of a compass by 150 years. The first recorded appearance of the use of the compass in Europe is earlier than in the Muslim world, as a description of a magnetized needle and its use among sailors occurs in Alexander Neckam's De naturis rerum, written in 1190.However, there are questions over diffusion. Some historians suggest that the Arabs introduced the compass from China to Europe. Some suggested the compass was transmitted from China to Europe and the Islamic world via the Indian Ocean, or was brought by the crusaders to Europe from China. However, some scholars have proposed an independent European invention of the compass.
China
These are noteworthy Chinese literary references in evidence for its antiquity:- The magnetic compass was first invented as a device for divination as early as the Chinese Han dynasty and Tang dynasty. The compass was used in Song dynasty China by the military for navigational orienteering by 1040–44, and was used for maritime navigation by 1111 to 1117.
- The earliest Chinese literature reference to magnetism lies in the 4th century BC writings of Wang Xu : "The lodestone attracts iron." The book also notes that the people of the state of Zheng always knew their position using a "south-pointer"; some authors suggest that this refers to early use of the compass.
- 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, which records that "But when the south-pointing spoon is thrown upon the ground, it comes to rest pointing at the south." Within the text, the author Wang Chong describes the spoon as a phenomenon that he has personally observed. Although the passage does not explicitly mention magnetism, according to Chen-Cheng Yih, the "device described by Wang Chong has been widely considered to be the earliest form of the magnetic compass."
- The first clear account of magnetic declination occurs in the Kuan Shih Ti Li Chih Meng, dating to 880. Another text, the Chiu Thien Hsuan Nu Chhing Nang Hai Chio Ching 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.
- 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."
- 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 stated: "When troops encountered gloomy weather or dark nights, and the directions of space could not be distinguished...they made use of the south-pointing carriage, or the south-pointing fish." This was achieved by heating of metal, known today as thermoremanence, and would have been capable of producing a weak state of magnetization. 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.
- The first incontestable reference to a "magnetized needle" in Chinese literature appears in 1088. The Dream Pool Essays, written by the Song dynasty polymath scientist Shen Kuo, contained a detailed description of how geomancers magnetized a needle by rubbing its tip with lodestone and hung the magnetic needle with one single strain of silk with a bit of wax attached to the center of the needle. Shen Kuo pointed out that a needle prepared this way sometimes pointed south, sometimes north.
- The earliest explicit recorded use of a magnetic compass for maritime navigation is found in Zhu Yu's book Pingchow Table Talks 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.
- Earliest recorded description of a dry suspension needle. The Shilin Guang Ji compiled between 1100 and 1250 mentions a wooden turtle suspended by a pin in its concave underbelly that always points north due to a needle attached to its tail.
The typical Chinese navigational compass was in the form of a magnetic needle floating in a bowl of water. According to Needham, the Chinese in the Song dynasty and continuing Yuan dynasty did make use of a dry compass, although this type never became as widely used in China as the wet compass. Evidence of this is found in the Shilin Guang Ji, published in 1325 by Chen Yuanjing, although its compilation had taken place between 1100 and 1250. The dry compass in China was a dry suspension compass, a wooden frame crafted in the shape of a turtle hung upside down by a board, with the lodestone sealed in by wax, and if rotated, the needle at the tail would always point in the northern cardinal direction. Although the European compass-card in a box frame and dry pivot needle was adopted in China after its use was taken by Japanese pirates in the 16th century, the Chinese design of the suspended dry compass persisted in use well into the 18th century. However, according to Kreutz there is only a single Chinese reference to a dry-mounted needle which is dated to between 1150 and 1250 and claims that there is no clear indication that Chinese mariners ever used anything but the floating needle in a bowl until the 16th century.
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, the mariner took "Kun Shen needle", or 52.5 degree SW. 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.