<P> There is disagreement as to exactly when the compass was invented . These are noteworthy Chinese literary references in evidence for its antiquity: </P> <Ul> <Li> The magnetic compass was first invented as a device for divination as early as the Chinese Han Dynasty (since about 206 BC). 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 . </Li> <Li> The earliest Chinese literature reference to magnetism lies in the 4th century BC writings of Wang Xu (鬼谷子): "The lodestone attracts iron ." 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 . </Li> <Li> 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 ." 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 ." </Li> <Li> The first clear account of magnetic declination occurs in the Kuan Shih Ti Li Chih Meng ("Mr. Kuan's Geomantic Instructor"), dating to 880 . 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 . </Li> <Li> 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 ." </Li> <Li> 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 ." 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 . 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 . </Li> <Li> 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 . </Li> <Li> 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 . </Li> </Ul> <Li> The magnetic compass was first invented as a device for divination as early as the Chinese Han Dynasty (since about 206 BC). 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 . </Li> <Li> The earliest Chinese literature reference to magnetism lies in the 4th century BC writings of Wang Xu (鬼谷子): "The lodestone attracts iron ." 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 . </Li>

When were the first magnetic compasses used by chinese ships