Edmund GunterDied 10 Dec 1626 (born 1581).English mathematician who invented many useful measuring devices, including a forerunner of the slide rule. Gunter published seven figure tables of logarithms of sines and tangents in 1620 in Canon Triangulorum, or Table of Artificial Sines and Tangents. The words cosine and cotangent are due to him. He made a mechanical device, Gunter's scale, to multiply numbers based on the logs using a single scale and a pair of dividers. He also invented Gunter's chain which was 22 yards long with 100 links. It was used for surveying and the unit of area called an acre is ten square chains. Gunter also did important work on navigation, publishing New Projection of the Sphere in 1623. He also studied magnetic declination and was the first to observe the secular variation. |
