Mercator, Gerardus

Mercator, Gerardus, Latin name of Gerhard Kremer (1512-1594), Flemish geographer, cartographer, and mathematician, born in Rupelmonde (now in Belgium), and educated at the University of Louvain. In 1537 he produced his first map, which depicted Palestine, and in the following year he completed his first map of the world, heavily influenced by Ptolemy's Geography. By 1540 he had completed a survey of Flanders. He also produced celestial and terrestrial globes. From 1552 he worked and lectured at Duisburg and was also employed by Charles V as his cartographer, while writing books and treatises on the subject (including Chronologia, 1569). His maps of Europe (1554) and Britain (1564), remarkable in their detail and precision, broke with the Ptolemaic tradition and introduced a much fuller description, particularly of inland areas.

In 1568 Mercator devised and produced a system of map projection, now called the Mercator projection, which he used in his ground-breaking map of the world. He also used this method in the three-volume atlas (1585-1595), which was completed by his son Rumold. The system represents meridians by parallel lines and parallels of latitude by straight lines intersecting the meridians at right angles. Widely used in navigation, the system allows a straight-line course to be plotted between any two points on the map and followed without changing compass direction. It quickly became popular with sailors and navigators throughout Europe.

Mercator is widely credited as being the first to use the term “atlas” to denote a collection of maps. He was also the first cartographer to distinguish between North and South America, which he called Americae pars septentrionalis and Americae pars meridionalis respectively.