Ptolemy’s Geography

The Geography (Geographike hyphegesis, “guide to drawing the Earth”), Ptolemy’s second major work after the Almagest, was written in Greek around 150. Its eight books explain how to project the globe onto a flat map and, in books 2–7, list some 8,000 place-names, about 6,300 of them with coordinates in degrees. The prime meridian runs through the Fortunate Isles (the Canaries), and the map spans 180 degrees of longitude, as far as China. Ptolemy revised the lost atlas of Marinus of Tyre, drawing on Roman and Persian gazetteers, and took the circumference of the Earth as 180,000 stadia instead of Eratosthenes’ 252,000.

In the east his map reaches beyond India to the Golden Chersonese (the Malay Peninsula), the Great Gulf and Cattigara, “a port of the Sinae”, known from the report of a Greek sailor named Alexander; one proposed identification is Óc Eo in the Mekong Delta, where Roman coins of the Antonine age have been found. The Indian Ocean appears as an enclosed sea bounded to the south and east by unknown lands.

The text survived in Byzantium: in 1295 Maximus Planudes searched for a copy, and the maps in the surviving manuscripts go back to the reconstructions of his time. Jacobus Angelus translated the Geography into Latin in Florence in 1406 or 1407, and its Bologna edition of 1477 was the first printed book with engraved illustrations; the work shaped the cartography of the Renaissance.