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What is Ptolemy’s Guide to Geography about?
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Ptolemy
Ptolemy's theory of the solar system.
Ptolemy’s Guide to Geography is a foundational work that provided the essential techniques and data required to draw maps of the world as it was known during the height of the Roman Empire.1
Key aspects of the work include:
- Geographical Data: Ptolemy recorded longitudes and latitudes in degrees for approximately 8,000 locations, allowing for the creation of exact duplicates of his world map.1
- Methodology: He relied heavily on the earlier work of Marinus of Tyre, while incorporating updated information regarding the coasts of the Indian Ocean.1
- Cartographic Innovation: Ptolemy devised two methods for projecting the spherical surface of Earth onto a flat map using a grid of latitude and longitude lines, anticipating later projections.1
Although his maps contained distortions due to the limited accuracy of ancient trade and road data, the work profoundly influenced Renaissance humanists following its rediscovery and translation into Latin in the early 15th century.1