GUNTER, Edmund, an excellent English mathematician and astronomer, was born in Hertfordshire in 1581, and studied at Westminster-school, whence he removed to Oxford, where he took the degree of master of arts in 1606, and afterwards entered into holy orders. In 1615 he took the degree of bachelor of divinity; but being peculiarly eminent for his knowledge in the mathematics, he had two years before been chosen professor of astronomy in Gresham College, London, where he distinguished himself by his lectures and writings. He invented a small portable quadrant; and also the line of proportions which, after the inventor, is called Gunter’s scale. He likewise published Canon Triangulorum ; and a work on the sector, cross-staff, and other instruments. This last was published, with an English translation of the Canon Triangulorum, in 4to, by Samuel Foster, professor of Gresham College. Mr Gunter died at that college in 1626.

Gutter's Line, a logarithmic line, usually graduated upon scales, sectors, and the like. It is also called the line of lines and line of numbers ; being only the logarithms graduated upon a ruler, which therefore serves to solve problems instrumentally in the same manner as logarithms do arithmetically. It is usually divided into 100 parts, every tenth of which is numbered, beginning with 1 and ending with 10; so that if the first great division, marked 1, stand for one tenth of any integer, the next division, marked two, will stand for two tenths, 3 for three tenths, and so on; and the intermediate divisions will in like manner represent hundredth parts of the same integer. If each of the great divisions represent 10 integers, then will the lesser divisions stand for integers; and if the greater divisions be supposed to be each 100, the subdivisions will be each 10.

Use of Gunter's Line. 1. To find the product of two numbers. From 1 extend the compasses to the multiplier; and the same extent, applied the same way from the multiplicand, will reach to the product. Thus if the product of 4 and 8 be required, extend the compasses from 1 to 4, and that extent laid from 8, the same will reach to 32, [7:11:87]their product. 2. To divide one number by another. The extent from the divisor to unity will reach fibm the dividend to the quotient. Thus, to divide 36 by 4, extend the compasses from 4 to 1, and the same extent will reach from 36 to 9, the quotient sought. 3. To three given numbers, to find a fourth proportional. Suppose the numbers 6, 8, 9: extend the compasses from 6 to 8; and this extent, laid from 9 the same way, will reach to 12, the fourth proportional required. 4. To find a mean proportional between any two given numbers. Suppose 8 and 32: extend the compasses from 8, in the left-hand part of the line, to 32 in the right; then bisecting this distance, its half will reach from 8 forward, or from 32 backwards, to 16, the mean proportional sought. 5. To extract the squareroot of any number. Suppose 25. Bisect the distance between 1 on the scale and the point representing 25; then the half of this distance, set off from 1, will give the point representing the root 5. In the same manner the cube root, or that of any higher power, may be found by dividing the distance on the line between 1 and the given number into as many equal parts as the index of the power expresses; then one of those parts, set from 1, will find the point representing the root required.

Gunter's Quadrant, an instrument made of wood, brass, or other substance, containing a kind of stereographic projection of the sphere, on the plane of the equinoctial; the eye being supposed to be placed in one of the poles.

Gunter's Seale, called by navigators simply the Gunter, is a large plain scale, generally two feet long, and about an inch and a half broad, with artificial lines delineated on it, of great use in solving questions in trigonometry, navigation, &c.