Gerardus Mercator

Flemish cartographer and geographer

• Born: March 5, 1512
• Birthplace: Rupelmonde, Flanders (now in Belgium)
• Died: December 2, 1594
• Place of death: Duisburg, Duchy of Cleves (now in Germany)

Mercator invented a map projection that is particularly useful for ocean navigation. He was the first person to use the word “atlas” for a volume of maps. His maps represented the best geographic knowledge available at his time.

Early Life

Gerardus Mercator (jeh-RAHR-duhs muhr-KAYT-uhr) was christened Gerhard Kremer at birth but took the Latinized form of his given name and surname; Latinizing one’s given name and surname was common practice for many scholars of his day. In a sense, Mercator upgraded his name. Kremer was the German word for trader, and mercator is the Latin word for world trader.

Mercator’s parents both died while he was young. He was provided for by his uncle, Gisbert Kremer, who financed his way at the University of Louvain, where he studied philosophy, mathematics, astronomy, and cosmography (geography of the cosmos).

After graduation, he established a workshop in Louvain, where he made globes, sundials, mathematical instruments, armillary spheres, astrolabes, and other measuring instruments. He drew, engraved, and colored maps. His first known map was of the Holy Land. In 1538, he engraved and published his first world map. It was drawn on a double, more or less heart-shaped projection that was interrupted at the equator. The Northern Hemisphere was drawn in the left-hand heart, and the Southern Hemisphere in the right. This map claims the distinction of being the first known map to give two names to the Americas: Americae pars septemtrionalis and Americae pars meridionalis, North and South America respectively. While in Louvain, he also published a map of Flanders that was based on his own survey rather than being an edited copy of another’s map or a compilation of data reported by others. He also made celestial and terrestrial globes, several of which have a certain renown because of their large size and the fact that they belonged respectively to Emperor Charles V and his prime minister.

Mercator lived at the time of the Protestant Reformation and the reactionary Counter-Reformation of the Roman Catholic Church. This religious conflict was particularly strong in the Low Countries. For some reason, Mercator was arrested for heresy in 1544. After Mercator was in prison for several months, some influential friends obtained his release, which very possibly may have saved his life. This experience caused Mercator to move his business to Duisburg, Germany, where he spent the rest of his life.

Life’s Work

Mercator’s 1554 map of Europe was one of the largest maps available at that time. It was enlarged on fifteen copper plates, and, when assembled, it was 132 by 159 centimeters (52 by 62.5 inches) in size. Mercator used italic lettering for the first time on a map drawn in northern Europe. These changes were important but superficial. The map is more important in three items of content that it corrected. A careful study of the accounts of navigators on the Mediterranean Sea and travelers in Eastern Europe led him to shorten the length of the Mediterranean Sea ten degrees of longitude. He increased the distance between the Black and the Baltic Seas by several degrees of latitude and made the Black Sea several degrees longer. These corrections made his map of Europe the most accurate of his day.

In 1564, Mercator produced a 129-by-89-centimeter (51-by-35-inch) map of the British Isles. This map seems unusual to a modern map reader in that it was oriented with West instead of North to the top of the map. Mercator is best known for his world map of 1569, which he drew on a projection that he invented and is known by his name. It was another large map in the Mercator tradition measuring 131 by 208 centimeters (51.5 by 82 inches). It contained the latest geographic information known by 1569. The map showed three land masses (Africa, Europe, and Asia), the New Indies (North and South America), and a large southern continent antipodal to Africa, Europe, and Asia. In the latter case, Mercator seems to have been perpetuating the belief of ancient philosophers rather than reporting the findings of explorers.

South America is more rectangular on this map than it is in reality, and North America is much wider. Baja California is shown as a peninsula in this map, correcting other maps of the time that showed it as an island. Little was known of the interior of North America, so Mercator used this space to explain the features of his projection. Mercator drew North America as separated from Asia, which encouraged explorers to mount efforts to find the Northwest Passage to China. Europe, the best-known part of the world to Mercator, was drawn with the most accuracy. The coastlines of Africa and Asia are easily recognized, except for eastern India, Southeast Asia, and China.

The interior of Asia was not well known. The Caspian Sea is not recognizable except for its general location. This map shows that Mercator was aware that the magnetic north pole was not located at the geographic North Pole. He placed it where the Bering Strait now appears. Mercator inserted items within cartouches placed in what would have been blank spaces in the area occupied by the great southern continent. These items included notes on measuring distances on this projection, a map of the North Polar Region, and the like. Today the map is an important historic document in that it reveals what was known about the world in the mid-sixteenth century.

The projection Mercator invented for this map was a very important cartographic invention that is still being used with modifications today. Yet the importance of this projection was not appreciated until almost one hundred years after his death. The Mercator projection draws the spherical earth within a rectangular frame. It is characterized by equally spaced parallel lines of longitude and parallel lines of latitude that become farther and farther apart as the distance from the equator increases. Since lines of longitude are not parallel and lines of latitude are equally spaced, the projection introduces two errors that magnify each other. The result is that the areas of places located away from the equator are significantly distorted.

The Mercator projection is soundly rejected by editors of modern-day textbooks, magazines, and atlases. It must be remembered, however, that Mercator drew this map for navigators, not geographers. The remarkable thing about his map was that every straight line drawn on this map plotted a course of constant compass direction. Thus, if the true locations of two places were known and correctly plotted on this projection, the navigator could connect the two places with a straight line and find the compass direction to follow in order to reach the place at the other end of the line. Mercator knew that this would not be the shortest possible course between two places, but he believed that the ease with which the course could be found fully compensated for the extra distance that would have to be traveled as the result of not following a great circle route.

While Mercator’s projection is little used for world maps, several forms or derivations of his projection are still in common use, and his name can still be seen on many large-scale maps of small areas and on many aeronautical maps. When Mercator drew his world map in 1569, he drew it as if a cylinder were placed around the globe, tangent at the equator. It is common now to place this cylinder tangent to the earth at the North and South poles. When this is done, it is called a transverse Mercator projection. This form is used for most U.S. military maps. It is also used for medium-scale topographic maps published by the United States Geological Survey and by the Canadian Department of Mines and Technical Surveys. Aeronautical maps are drawn with the cylinder tangent to the earth along the great circle, connecting the starting place with its destination.

Mercator had what could be called a life’s goal. He believed that the world needed a cosmography. His cosmography was made of three parts: The first part was about the beginnings of the world, the second part was the geography of the ancient world, and the third part was about the world geography of his day. The year 1569 marked the publication not only of his world map but also of the first part of his cosmography, Chronologia . Mercator tried to establish the beginning of the world and to reconcile the chronologies of the ancient Hebrews, Greeks, Egyptians, and Romans with that of the Christian world.

In 1578, he published his version of Ptolemy’s Geographike hyphegesis (geography), which contained twenty-seven plates engraved especially for this edition that are generally agreed to be the finest ever prepared for this work. This edition became the second part of his cosmography.

Mercator envisioned that the third part of his cosmography, Atlas sive cosmographicae meditationes de fabrica mundi et fabricati figura (1595; Historia mundi: Or, Mercator’s Atlas , 1635), would include some one hundred maps, and he spent the last sixteen years of his life working on it. Since this work contained many maps bound together in one volume, it has given its name Mercator’s atlas to all other such map collections.

Mercator’s atlas was long in coming. In fact, it was published in parts, the first of which covered France, Belgium, and Germany. The second part contained twenty-two maps covering Italy, Yugoslavia, and Greece. The last section, which contained thirty-four maps, twenty-nine drawn by Mercator and five by his son Rumold and two grandsons, was published in the year after his death.

Significance

Gerardus Mercator is renowned for four things: his terrestrial and celestial globes of 1541; his large map of Europe in 1554 and of the British Isles in 1564; his world map of 1569, particularly the projection on which it was drawn; and his three-part cosmography, which included a chronology of the world from creation to his day, an edition of the works of Ptolemy, and his atlas of the then-known world.

Few books in English are dedicated to Mercator and his work. What little is known about Mercator’s life came first from a very short biography written by a neighbor and fellow mapmaker, who described him as “a man of calm temperament and exceptional candor and sincerity.” Much is known about Mercator’s works, however, many of which have been preserved in rare-book libraries around the world. Mercator was the leading cartographer of the last half of the sixteenth century. He was more than a skilled engraver and publisher of maps; he was an innovator and geographer as well.

Bibliography

Brown, Lloyd A. Map Making: The Art That Became a Science. Boston: Little, Brown, 1960. This book contains a portrait of Mercator and a reproduction of his world map that first used separate names for North and South America. It also tells the story about his book of maps.

Brown, Lloyd A. The Story of Maps. Boston: Little, Brown, 1949. Reprint. New York: Dover, 1979. A scholarly book on the history of cartography that contains information on the life and work of Mercator. It puts Mercator into the historical context of his time. Contains extensive notes, bibliographic data, and several illustrations of Mercator’s maps.

Crane, Nicholas. Mercator: The Man Who Mapped the Planet. New York: H. Holt, 2003. Biography of Mercator that does an impressive job of assembling documents and evidence to cover the entire span of his life and accomplishments. Includes photographic plates, illustrations, maps, bibliographic references, and index.

Crone, Gerald R. Maps and Their Makers: An Introduction to the History of Cartography. London: Hutchinson University Library, 1966. This book contains some biographical material. It is more concerned, however, with Mercator’s works, particularly the geographic contents of his world map of 1569 and his cosmography. Illustrated, with bibliographic references.

Greenhood, David. Mapping. Chicago: University of Chicago Press, 1964. Contains little information about Mercator himself. Instead, the chapter on projections clearly describes Mercator’s projection and how it is constructed. Well illustrated.

LeGear, C. E. “Gerardus Mercator’s Atlas of 1595.” In A La Carte: Selected Papers on Maps and Atlases, compiled by Walter W. Ristow. Washington, D.C.: Library of Congress, 1972. This chapter is a reprint of an article that originally appeared in the Library of Congress Quarterly Journal of Acquisitions in May, 1950. It describes the contents of Mercator’s atlas and provides a short biography of Mercator. Contains three reproductions of illustrations that appeared in his atlas, Mercator’s portrait, and two of his maps, one of the New World and one of the British Isles.

Mercator, Gerardus. The Mercator Atlas of Europe: Facsimile of the Maps by Gerardus Mercator Contained in the “Atlas of Europe,” Circa 1570-1572. Edited by Marcel Watelet. Translated by Simon Knight. Pleasant Hill, Oreg.: Walking Tree Press, 1998. Reproduction of Mercator’s original maps of Europe with commentary by James R. Akerman. Includes bibliographic references.

Stevenson, Edward Luther. Terrestrial and Celestial Globes: Their History and Construction Including a Consideration of Their Value as Aids in the Study of Geography and Astronomy. New Haven, Conn.: Yale University Press, 1921. Reprint. New York: Johnson Reprint, 1971. In addition to the usual short biography and the study of Mercator’s projection and atlas, this book contains a lengthy description of Mercator’s globes.

Thrower, Norman J. W. Maps and Man. Englewood Cliffs, N.J.: Prentice-Hall, 1972. A short history of cartography. The unique contribution of the chapter on Renaissance cartography is Thrower’s description of Mercator’s map rather than the projection on which it is drawn. Contains bibliographic citations.

Wilford, John Noble. The Mapmakers. Rev. ed. New York: Alfred A. Knopf, 2000. History of mapmaking from antiquity to the present. Explains the importance of Mercator’s projection method, both at the time and for later cartographers. Includes illustrations, maps, bibliographic references, and index.