Ptolemy’s Geographia

• The Geographia is a chart of the known world by the Roman Geographer, Ptolemy.

Description

• Ptolemy produced a Chart of the World, the ‘Oikoumene’, based on a Chart by Marinus of Tyre.
• ‘Oikoumene’ or ‘Ecumene’ was Greek for the ‘inhabited world’. The Term was used in Antiquity and the Middle Ages to describe a Chart of the known part of the inhabited world.
• The earliest known Chart was by Eratosthenes (c.275-194 BCE).

Longitude

• Prime Meridian (0°)
  • Ptolemy placed the Roman Prime Meridian or Zero Meridian, in the Fortunate Islands, thought to have been Mount Teide in Tenerife in the Canary Islands, the most westerly known point.
• He placed China at 80° of Longitude, the most easterly known point.

Latitude

• Ptolemy based his Parallels of Latitude of the known World on the following:
  • Parallel of Thule (63° N)
    • He did not place this at 66 ° as had Eratosthenes. This was the most northerly known point, possibly Iceland.
  • Parallel of Rhodes (36° N)
  • Parallel of Syene (23° N)
  • The Equator (0°)
  • Parallel of Anti Meroe (16° S)
    • The most southerly known point on the African coast in the Gulf of Guinea.