Mercator, Gerardus (1512–1594)

Gerardus Mercator was a Flemish engraver and cartographer who lived during the so-called Age of Exploration, that is, the 16th century, when European capitalism and colonialism began their epochal period of global conquest, and his work both reflected and greatly enabled this expansion.

Born Gerhard Kremer, Mercator changed his name as a university student in Louvain, where he lived from 1530 to 1552. At an early age, he studied to be a priest at a monastic school in Hertogenbosch, where he learned calligraphy and Latin. In Louvain, he was trained in philosophy, surveying, scientific instruments, mathematics, astronomy, and geography, receiving his master's degree in 1532. He married in 1536 and eventually had six children. In 1544, he was jailed briefly under suspicion of heresy but released for lack of evidence. In 1552, he relocated to Duisberg, in what later became Germany, where he taught mathematics at the local gymnasium, or high school, until the cartographic workshop he founded acquired steady work under his longtime patron, the Duke of Cleves.

While his early talent lay in engraving, Mercator steadily moved from detailed maps of Flanders to globes to flat maps of the world, whose projections drew on his mathematical training. Some claim that Mercator coined the term atlas. In 1538, he published a double-cordiform (heart shaped) map of the world, the first to show two distinct continents in the Western Hemisphere; this map was lost but was eventually found in New York in 1878. In 1546, he produced a set of observational instruments for use in Charles V's campaigns. Thereafter, he took to producing a series of maps and globes, particularly concerning Europe. In 1578, he published a revised version of Ptolemy's classic, Geography, including 27 maps. A comprehensive global atlas begun in 1585 was completed and published by his sons in 1594, after Mercator's death.

Mercator is most famous, however, for his map projection, named after him, which he unveiled in 1569 with his Nova et Aucta Orbis Terrae Descriptio ad Usum Navigatium Emendate (New and Augmented Description of the Earth Designed [Page 1884]for Purposes of Navigation). It is a cylindrical projection with no distortion at the equator. Unlike earlier maps, this one employed a graticule of latitude and longitude lines that did not converge at the poles. Simon Winchester calls it “an adroitly contrived confection of secants and cosines; it was neat, tidy and hugely popular; and it was turned into charts that mariners used for generations.” The Mercator projection came to enjoy enormous popularity and fame due to the numerous advantages it offered. In particular, it was widely popular in nautical and seafaring circles because it allowed loxodromes or rhumb lines—lines of constant compass bearing—to be represented as straight lines. While shape and direction are preserved throughout the map, size is increasingly distorted with distance from the equator, greatly exaggerating the areas of regions at high latitudes (most famously, Greenland) and leaving it unable to represent the poles (Figure 1). Its application, however, was muted by the inability to measure longitude accurately during the 16th century.

...