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Henry Gellibrand (1597–1637) was an English mathematician. He is known for his work on the Earth's magnetic field. He discovered that magnetic declination – the angle of dip of a compass needle – is not constant but changes over time.〔http://www.phy6.org/earthmag/mill_3.htm〕 He announced this in 1635, relying on previous observations by others, which had not yet been correctly interpreted.〔Lloyd Arnold Brown, The Story of Maps (1979), p. 133.〕 He also devised a method for measuring longitude, based on eclipses.〔Michael Hoskin, ''The Cambridge Concise History of Astronomy'' (2003), p. 150.〕 The mathematical tables of Henry Briggs, consisting of logarithms of trigonometric functions, were published by Gellibrand in 1633 as ''Trigonometria Britannica''. He was Professor at Gresham College, succeeding Edmund Gunter in 1626. He was buried in St Peter Le Poer.〔http://www.dcs.warwick.ac.uk/bshm/zingaz/LondonPeopleD.html#gun〕 ==See also== *History of geomagnetism * List of geophysicists 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Henry Gellibrand」の詳細全文を読む スポンサード リンク
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