Mercator Map Published
Mercator's world map, published in 1569, is among the most influential maps ever made. Its projection let sailors plot a course of constant compass bearing as a straight line, and a version of that projection still shapes how many people picture the world, especially on web maps. (The map is usually dated to 1569; 1570 is sometimes given because of its circulation and the publication of Abraham Ortelius's atlas that year, so the date is best treated as approximate.)
Gerardus Mercator was a Flemish geographer, cartographer and instrument maker, born in 1512 and trained at the University of Leuven. By the mid-sixteenth century, European voyages across the Atlantic and around Africa had enormously expanded the known world, yet navigators struggled with existing charts. On most maps, a ship holding a steady compass heading followed a curved path called a rhumb line, and plotting it accurately was hard. Mercator had already made globes, scientific instruments and maps, and he later settled in Duisburg, in the territory of the Duke of Cleves, where he found a more tolerant climate after a brief imprisonment on suspicion of heresy in the 1540s.
His large map, titled in Latin and printed on multiple sheets, showed the world on a cylindrical projection. Meridians were drawn as parallel vertical lines, and the spacing between lines of latitude increased toward the poles. This stretching was calculated so that angles stayed true, meaning a straight line on the map matched a constant compass bearing. The price was distortion of size: areas far from the equator, such as Greenland, Europe and Russia, appear much larger relative to tropical regions. Mercator explained his purpose in a text on the map, but he did not publish the mathematics behind the spacing. English mathematician Edward Wright later worked out the underlying tables, publishing them in 1599.
Adoption was gradual. Mariners took time to embrace the projection, partly because of the difficulty of navigating by it in practice and the limits of measuring longitude at sea. By the seventeenth and eighteenth centuries, however, it became a standard for nautical charts. Mercator's name also became linked with the word "atlas," since his later collection of maps, issued in full after his death in 1594, popularized the term for a bound book of maps.
The projection's legacy is both practical and contested. It remains valuable for navigation, and a close variant, Web Mercator, is used by many online mapping services. Yet critics have long argued that it gives a misleading impression of the relative size of countries and continents, leading to alternatives such as the Gall–Peters and Winkel Tripel projections. Historians generally agree that Mercator intended a navigational tool rather than a general picture of the world, and the later debate reflects how a specialized solution became a widely shared image.