Henry Gellibrand
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.[1][2] He announced this in 1635, relying on previous observations by others, which had not yet been correctly interpreted.[3]
He also devised a method for measuring longitude, based on eclipses.[4] 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.[5]
References
- van Helden, Albert; Burr, Elizabeth (1995). "Gellibrand, Henry". The Galileo Project. Rice University. Retrieved 24 October 2011.
- http://www.phy6.org/earthmag/mill_3.htm
- Lloyd Arnold Brown, The Story of Maps (1979), p. 133.
- Michael Hoskin, The Cambridge Concise History of Astronomy (2003), p. 150.
- http://www.dcs.warwick.ac.uk/bshm/zingaz/LondonPeopleD.html#gun
- O'Connor, John J.; Robertson, Edmund F., "Henry Gellibrand", MacTutor History of Mathematics archive, University of St Andrews.
- Hunter, John Aubrey (2000). "Henry Gellibrand". Brief lives. Selected and edited with introduction, glossary and notes by John Buchanan-Brown. Foreword by Michael. Penguin Books. ISBN 978-0-14-043589-4.
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