MERCATOR, Gerardus

(1512-1594)

Gerardus Mercator, a transforming figure in the history of cartography, de­vised the projection that bears his name when he created his world map of 1569 that revolutionized both mapmaking and, by extension, the way people came to view the world. Mercator was born in Flanders near Antwerp and studied as­tronomy, geography, and geometry at the University of Louvain. Mercator, like his mentor, Reiner Gemma Frisius,* became a well-known surveyor—he drew an acclaimed map of Europe in 1541—as well as a master engraver, making astrolabes, globes, and scientific instruments along with maps and charts. He also introduced italic type to northern Europe. However, in 1544 he ran afoul of the Inquisition.

Escaping punishment, Mercator moved in 1552 to Duisburg in the Rhineland, at that time a center of geographic study and a place where religion was less heated than in the Low Countries. There, under the patronage of William, duke of Cleves, he made another map of Europe in 1544—which reduced the size of the Mediterranean from Ptolemy's representation by ten degrees of latitude - and his celebrated map of the world five years later.

For his magnum opus, Mercator incorporated the European "discoveries" that had been made since the first decade of the sixteenth century. Thus the map more accurately depicted the western coasts of America and the southern coasts of Asia, although it retained the mythical Terra Australis.

However, its greater significance lay in the way in which it portrayed that knowledge. Sixteenth-century seafarers wanted to chart their courses by drawing a straight line between two points, without having to constantly reset their com­passes. Mercator, almost literally, had to square a circle to meet this need. Por­traying the rhumb lines—the curves of a course on a globe—as straight lines perpendicular to the equator enabled him to set latitudes parallel to the equator, with the lines of longitude, still inexact in Mercator's lifetime, intersecting lat­itudes at right angles. The result was a fundamentally more reliable map, al­though distortion of land masses increases the closer they are to the poles. Mercator also conceived of compiling a series of maps between two covers. He was working on such an atlas when he died, but an edition based on his plates edited by Jodocus Hondius first appeared in 1607.

Bibliography

J. N. Wilford, The Mapmakers, 1981.

Louis Roper