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Ptolemaic maps

A scientific approach to mapping the world was introduced at the beginning of the fifteenth century when the humanist Jacopo d'Angelo translated the Geographia of Claudius Ptolemy from Greek into Latin. Ptolemy (68-140) had been the librarian at Alexandria and the heir to several centuries of Greek studies in astronomy and geography. In the Geographia he established a systematic method for mapping the world based upon a grid structure of latitudinal and longitudinal lines for fixing the location of places, and he proposed methods for projecting a three-dimensional spherical world onto a two-dimensional drawing. Perhaps most important for later mapmakers, Ptolemy emphasized the necessity of careful observation as the basis for geographical description, and admitted that his work would need to be revised whenever new information was obtained. It is not known if Ptolemy himself made maps, but Byzantine scholars created maps drawn according to his principles when his works were rediscovered in the twelfth century. Similar maps were added to the Latin manuscripts made in the fifteenth century and in the dozen printed versions of Ptolemy's world map that had appeared by 1500.

A simplified version of the Ptolemaic world map was included in the Nuremberg Chronicle, the great illustrated history of the world published by Anton Koberger in 1493. While the map reflects Ptolemy's picture of the world, it also includes Christian and medieval features. Off to one side are depictions of the strange peoples reputed to live at the edges of the world in stories common throughout the Middle Ages. At three of the map's corners stand Noah's sons in contemporary dress, as the progenitors of the peoples of Europe, Asia and Africa.

One of Ptolemy's errors would have important consequences at the end of the fifteenth century. A predecessor at Alexandria, third-century B.C. scholar Eratosthenes, had estimated the circumference of the earth to within two hundred miles of the true circumference. Ptolemy discarded Eratosthenes's calculations and proposed that the earth was about one third smaller than it actually is. Using Ptolemy's numbers, Christopher Columbus came to the conclusion that the east coast of Asia was within sailing distance of Europe.

The new geographical information produced by the expeditions of Columbus and the Portuguese explorers slowly made its way into printed European maps. Ptolemy's Geographia was still the critical text for mapmakers, but it was sufficiently flexible to accommodate the new discoveries. The most popular sixteenth-century edition of Ptolemy was prepared by Sebastian Münster (1489-1552), a humanist scholar in Basel. In his Geographia, first printed in 1540, Münster integrated the new knowledge of the world into the existing maps based on Ptolemy. The work quickly became the authoritative world geography, and was reprinted, translated, updated and summarized in numerous editions through the rest of the century. His world map, shown here in the 1545 Basel edition, follows the format of the earlier Ptolemaic maps, but now Africa has taken on its familiar shape and the Americas, while far from complete, are nonetheless recognizable as continents. In addition to the world map, Münster's Geographia and his later massive Cosmographia included individual maps of the continents, such as the African map shown elsewhere in the exhibition.

Although the best cartographers and printers, like Münster, tried to present the most up-to-date information on their maps, many others did not see the need. The world map of the German theologian and geographer Johannes Honter (1498-1549) was published at about the same time as Münster's map, and it is interesting because it uses a different method to project the earth's surface, albeit one also based on Ptolemaic principles. But the more important difference is that it is noticeably less current than Münster's map. In fact, Honter essentially copied it from Martin Waldseemüller's ground-breaking maps of the world from thirty years earlier. However obsolete it was, Honter's world map had a long life, appearing in all eleven editions of his Rudimenta Cosmographica, the last of which was published in 1595. It also appeared in a number of other books, including this one on the history of Germany, France and Switzerland by the Swiss Reformation scholar Johannes Stumpf.

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