Ptolemy's Geographica

Ptolemaeus auctus, restitutus, emaculatus: cum tabulis veteribus ac novis. Strasbourg: Ionnes Scotus, 1520. Translated by J. Angelus.


Claudius Ptolemaeus was born c. AD 90 in Egypt and was known as a mathematician, geographer, astronomer and astrologer. He lived in Egypt under Roman rule, but few reliable details of his life are known. He died in Alexandria around AD 168.

Ptolemy was the author of several scientific treatises, at least three of which were of continuing importance to later Islamic and European science. The first is the astronomical treatise now known as the Almagest. The second is the astrological treatise known as the Tetrabiblos. The third is now commonly called the Geographia, which is a thorough discussion of the geographic knowledge of the Greco-Roman world.

The Geographia relies somewhat on the work of an earlier geographer, Marinos of Tyre, and on gazetteers of the Roman and ancient Persian Empire. The first part is a discussion of the data and of the methods he used. Following Marinos, he assigned coordinates to all the places and geographic features he knew, in a grid that spanned the globe. In the second part of the Geographia, he provided the necessary topographic lists, and captions for the maps. Ptolemy was well aware that he knew about only a quarter of the globe, and an erroneous extension of China southward suggests his sources did not reach all the way to the Pacific Ocean.

The maps in surviving manuscripts of Ptolemy’s Geographia, however, only date from about 1300, after the text was rediscovered by Maximus Planudes. The Italian Jacopo d’Angelo translated the work into Latin in 1406.

Trinity’s copy of the Geographia is bound in sixteenth century board Oxford roll binding with gold tooled labels to the spine. Thomas Pope’s signature is on the title page. It was subject of extensive conservation work in 2010.



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