Gerardus Mercator Born

Gerardus Mercator Born

On this day in 1512, the celebrated Flemish cartographer Gerardus Mercator was born in Rupelmonde, in the Hapsburg county of Flanders, now situated in present day Belgium.

Mercator was educated at the ancient University of Leuven (which closed in 1797), where he gained knowledge of advanced mathematics and astronomy. His first achievements were not as a cartographer but as a master craftsman. He gained a reputation for producing fine mathematical instruments, and was sought after as an etcher and engraver. He started producing his own maps in the 1530s, and by the end of the decade had established himself a master cartographer.

One of Mercator’s greatest achievements was his design for a map that could aid nautical navigation. Conceived in 1569, the Mercator Projection was a cylindrical chart that divided the surface of the Earth into small geometric segments, utilising carefully spaced horizontal and vertical lines to represent longitude and latitude.

Mercator was aware of the shortcomings of earlier maps, in that they did not accurately reflect the curvature of the Earth. Drawing the Earth’s surface on a flat two-dimensional surface inevitably led to unwelcome distortions that could mislead anyone trying to accurately plot a course between two points.

Recognising these shortcomings, Mercator devised a system that rectified the problem of distortion through balancing east-west distortion with north-south distortion. Mercator’s design offset the east-west stretching of a conventional map, which increases as the distance from the Equator increases, by introducing a corresponding north-south stretching. This ensured that distances of longitude and latitude were to the same proportion, and meant that the map’s surface could be segmented by straight rather than arced lines.

The map was important for sailors as it allowed for increased accuracy in navigating large distances. It enabled sailors to plot ocean courses safe in the knowledge that the lines they followed were accurate. Plotting a course along one of Mercator’s straight, or rhumb, lines, was far easier than following the arced lines that were found on traditional navigational charts.

As well as devising the important Projection map, Mercator was also particularly adept at producing globes. He devised an ingenious method for globe production that involved it being manufactured in segments, to be later assembled. Up until this point, globes were commonly carved from a single large piece of wood or polished brass. Mercator’s globes attained higher levels of accuracy and detail, and became extremely sought after. Today, fewer than 25 of his globes remain in existence.

Mercator died in Duisburg in 1594, while producing an ambitious collection of maps that would represent the entire known world. Completed by the cartographer Jodocus Hondius, and published posthumously by his son, it is known as the Mercator-Hondius Atlas. The use of the word atlas, it should be noted, being another of Mercator’s unparalleled contributions to cartography.

Credit: Mary Evans Picture Library / Alamy
Caption: A Mercator world map from 1587.