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Shen Kuo or Shen Gua (Chinese: 沈括; pinyin: Shěn Kuò; Wade–Giles: Shen K'uo) (1031–1095), courtesy name Cunzhong (存中) and pseudonym Mengqi (now usually given as Mengxi) Weng (夢溪翁), was a polymathic Chinese scientist and statesman of the Song dynasty (960–1279). Excelling in many fields of study and statecraft, he was a mathematician, astronomer, meteorologist, geologist, zoologist, botanist, pharmacologist, agronomist, archaeologist, ethnographer, cartographer, encyclopedist, general, diplomat, hydraulic engineer, inventor, academy chancellor, finance minister, governmental state inspector, poet, and musician. He was the head official for the Bureau of Astronomy in the Song court, as well as an Assistant Minister of Imperial Hospitality. At court his political allegiance was to the Reformist faction known as the New Policies Group, headed by Chancellor Wang Anshi (1021–1086).

In his Dream Pool Essays (夢溪筆談; Mengxi Bitan) of 1088, Shen was the first to describe the magnetic needle compass, which would be used for navigation (first described in Europe by Alexander Neckam in 1187). Shen discovered the concept of true north in terms of magnetic declination towards the north pole, with experimentation of suspended magnetic needles and "the improved meridian determined by Shen's [astronomical] measurement of the distance between the polestar and true north". This was the decisive step in human history to make compasses more useful for navigation, and may have been a concept unknown in Europe for another four hundred years (evidence of German sundials made circa 1450 show markings similar to Chinese geomancer compasses in regard to declination).