GERARD (the Latin name generally given to GERHARD KAUFFMANN), one of the most celebrated geographers of his time, was born at Rupelmonde in Flanders on the 5th of March 1512. After completing his elementary studies at Bois-le-Duc, he went through a course of philosophy at the university of Louvain, where he took his degree. Having applied himself with extraordinary ardour to the study of geography and mathematics, he soon received the patronage of the Emperor Charles V., and in 1599 was nominated cosmographer to the Duke de Juliers at Doesburg, where he died in 1594, at the advanced age of eighty-three years. He is principally known from having given his name to the projection generally employed in nautical maps, in which the meridians and parallels are represented by straight lines which mutually intersect at right angles. Besides executing tables of chronology and geography, he published many valuable maps, engraved and coloured by his own hand.

His works are.—Chronologia a Mundi exordio ad anni 1568, Köln, fol., 1569; Tabulae Geographicae ad mentem Ptolemaei restituta, fol., 1578; Globi Terrestris Sculptura, 1541; Globi Caletis Sculptura, 1551; Atlases, 1595, 1628, 1633. He also published two theological works,—Harmonia Evangelistarum, 1592; and De Creatione ac Fabrica Mundi; the latter forming a dissertation prefixed to his Atlas of 1595, and which was condemned by the church for setting forth certain heterodox views respecting the doctrine of original sin.

NICOLAS (the Latin name of NICOLAS KAUFFMANN), an eminent mathematician, was born at Holstein in Denmark in 1640. He visited England in 1660, when he was chosen a member of the Royal Society, and returned to Paris previous to his death in 1687. He was the first to detect the defect of Gerhard Mercator's projections, afterwards rectified by Edward Wright. Of all his works on cosmography and mathematics, by far the most original and valuable is his Logarithmotechnia, sive Methodus Constructi Logarithmos Nova; cui accedit Vera Quadratura Hyperbolae, et Inventio Summa Logarithmorum, London, 1668–1674, 4to.

MERCIA, one of the ancient kingdoms of the Saxon heptarchy in England, bounded on the N. by Northumbria,