A Revolution in Cartography: Mapping the World
A Revolution in Cartography: Mapping the World
Clarity. The evolution of sixteenth-century maps clearly reflects the Europeans’ expanding knowledge of the world around them. No longer were questions regarding the breadth of the Atlantic Ocean or the size and relative positions of the earth’s major continents matters of simple speculation. Nor did sixteenth-century geographers or navigators feel compelled to consult the texts of ancient authorities on such matters. Instead cartographers increasingly based their representations of the world on concrete data and empirical observation. In addition they developed new, more-accurate methods of portraying the three-dimensional globe on flat, two-dimensional surfaces. It is true that problems such as the inability of navigators and chartmakers to measure longitude accurately while at sea continued to lead to some distortion and imprecision in European maps of the era. Nonetheless, in terms of the general outlines and relative positions of the oceans and continents, late-sixteenth-century European world maps began to look similar to those that we produce today with our advanced surveying techniques and satellite technology.
State Secrets. Many of the most-comprehensive sixteenth-century maps were, at the time they were made, accessible only to a small group of government officials. This was because Spain and Portugal held the geographical data collected by their sailors to be critical state secrets. Navigators returning from voyages of exploration in the crown’s service were required to report their findings and charts to colonial administrators in charge of collecting such information. From the compiled data cartographers would draw and update secret official maps. These maps would then be kept under lock and key in order to prevent hard-won and strategically significant information from falling into unfriendly hands. One of the most interesting of these secret documents is a representation of the Atlantic world drawn by Spanish royal cartographer Juan de la Cosa in the year 1500, a map whose secrecy was guarded so effectively that historians learned of its existence only in the nineteenth century. De la Cosa almost certainly had personal experience navigating Caribbean waters, and he may even have accompanied Columbus on his first voyage in 1492. The map summarizes official Spanish understanding of the geography of the Caribbean and the Americas. The major Caribbean islands are represented with reasonable accuracy. The map also shows the South American mainland, and the North American mainland is marked with an English flag, indicating that de la Cosa had heard word of the 1497 voyage of John Cabot. Between 1525 and 1532 the cartographer Diego Ribeiro produced another set of official secret charts for the Spanish government. Ribeiro’s representation of the world incorporated the data collected by all Spanish voyages up to that point including that of the crew of the Magellan expedition that had circled the globe in 1519–1522. Not surprisingly the strategic and commercial value of secret maps such as these attracted occasional efforts at espionage. While working in Spain’s colonial administrative offices in Seville, for instance, Sebastian Cabot attempted to sell secret Spanish charts to the English and the Venetians.
Maps for Public Consumption. As the sixteenth century progressed, however, geographical knowledge could not be kept secret for long. Along with the official secret charts of the Spanish and Portuguese governments, other maps summarizing up-to-date geographical information began to be published and broadly distributed. The 1507 map drawn and published by Martin Waldseemüller and his colleagues at St. Die, France, quickly sold more than one thousand copies. Ironically, Waldseemüller himself later decided that he had erred in applying Amerigo Vespucci’s name to the New World, and in later editions of the map he deleted the name America. Waldseemüller’s change of heart, however, counted for little in the face of the power of the printing press. The name America on the original 1507 map was already too broadly disseminated and too widely used to be withdrawn, and the label stuck.
Mercator. The most skillful of all sixteenth-century cartographers was the Flemish scholar Gerardus Mercator. He is best remembered as the inventor of what came to be called the Mercator projection, a method of depicting the curved surface of the earth on a flat, two-dimensional chart without distorting compass-heading directional relationships between any two points on the map. The Mercator projection was particularly useful to navigators, and it remains even today one of the most commonly used projections in modern cartography. Mercator produced his first world map in 1538 and then spent much of the rest of his life working on various mapmaking projects. By the time of his death in 1594 he had nearly completed a comprehensive atlas of maps summarizing the best available geographic data of the day. Following his death, his son put the finishing touches on the work and published the landmark three-volume book in 1595. It was in fact the first printed collection of maps to carry the title atlas. Copies sold quickly, and thirty-one editions of Mercator’s atlas were published in the years following its original appearance.
Daniel J. Boorstin, The Discoverers: A History of Man’s Search to Know His World and Himself “(NewYork: Vintage, 1983);