Edmund Gunter

Edmund Gunter (1581 to 1626) was an English clergyman, mathematician, geometer and astronomer of Welsh descent. Born in Hertfordshire and educated at Westminster School and Christ Church, Oxford, he took orders and became rector of St George's Church in Southwark. From 1619 until his death he was Gresham Professor of Astronomy in London. He is remembered for Gunter's chain, the 66 foot surveying chain, for Gunter's quadrant and Gunter's scale, and for his sector, described in a manual that was unusual for being published in English rather than Latin. In 1620 he published his Canon triangulorum. He coined the terms cosine and cotangent, was probably the first to notice, in 1622 or 1625, that the magnetic declination at one place changes over time, and was a friend and colleague of Henry Briggs.