Gerardus Mercator

Cartographer; Creator of Mercator Map Projection

Mercator was born on March 5, 1512, in Rupelmonde, Flanders (now Belgium). After earning a master’s degree in philosophy and theology from the University of Louvain in 1532, he studied under Gemma Frisius, a noted mathematician and astronomer. At this time he also improved his artistic and mechanical skills, mastering calligraphy, engraving, and instrument making.

In collaboration with Frisius and engraver Gaspar à Myrica, Mercator constructed a terrestrial globe in 1536. During the next few years, he produced a booklet of italic lettering and beautifully printed maps of Palestine, Flanders, and the world, establishing a reputation as a master cartographer.

Because he was a Protestant in a Catholic­ dominated region, Mercator was arrested for heresy in 1544 and imprisoned for several months. He moved permanently to Duisberg (now in Germany) in 1552, where he was free to practice his religion. He taught grammar school and became court cosmographer to Duke Wilhelm of Cleve.

Between 1554 and 1564 Mercator completed maps of Lorraine, the British Isles, and Europe, and perfected his projection method, which he applied to the 1569 world map that became his most famous accomplishment. The projection method entailed straightening the meridians (longitude lines) into parallel lines and lengthening the degrees of latitude, which distorted distance and land/sea areas but kept direction relatively intact. With this method, Mercator achieved his goal of devising a way for sailors to plot a straight line (crossing all meridians on a map at the same angle) and to follow the projected line without continual adjustment of compass direction.

In his later years, Mercator printed an updated edition of Ptolemy’s cartographic works and compiled a collection of accurate, detailed maps of western and southern Europe that remained unfinished at his death. A completed version of this collection, which was the first map collection to be titled Atlas, was published in 1595 (after Mercator’s death) by his son.

Mercator died in Duisberg on December 2, 1594.

Gerardus Mercator’s Legacy

Mercator changed the nature of cartography with his artistic enhancements and forever altered ocean navigation with his projection method, which was the most influential invention of early cartography.

Mercator’s talents inspired following generations of cartographers to hone their artistic skills in calligraphy and engraving. Thus, maps of Renaissance Europe were generally elegant pieces of art. In addition, the work of Mercator, Frisius, and Myrica made Louvain a center of cartography and navigational­ instrument making during the sixteenth and seventeenth centuries, times of expanding world exploration.

The value and importance of Mercator’s projection method was recognized only at the end of the sixteenth century, after his death. Navigators at first regarded the projection with suspicion because it greatly distorted distances; they were accustomed to their own methods and were reluctant to change. Material promoting Mercator’s projection was published in 1597 by William Barlowe and in 1599 by Edward Wright. Wright provided a table of “meridional parts” that explained how to compute a distance correctly, and sailors were eventually persuaded of the projections merit. It vastly facilitated navigation, sped ocean passages, and reduced sailing disasters from the seventeenth century to the present.

The Mercator projection is still used for most flat maps in modern cartography despite its gross distortion of high ­latitude land masses, such as Greenland and Antarctica, on many world maps.

Gerardus Mercator – 1512­-1594