Gunter, Edmund (1581–1626)

English mathematician who became professor of astronomy at Gresham College, London in 1619. He is reputed to have invented a number of surveying instruments as well as the trigonometrical terms ‘cosine’ and ‘cotangent’.

Gunter was born in Hertfordshire and was educated at Westminster and Christ Church, Oxford.

He invented many measuring instruments including Gunter's Chain, the 22-yard-long, 100-link chain used by surveyors; Gunter's Line, the forerunner of the slide-rule; Gunter's Scale, a two-foot rule with scales of chords, tangents and logarithmic lines for solving navigational problems, and the portable Gunter's Quadrant. He made the first observation of the variation of the magnetic compass.