Al-Idrisi Completes the Tabula Rogeriana World Map

Arab geographer Muhammad al-Idrisi, working at the Norman court in Palermo, completed a geographic compendium for King Roger II after 15 years of research. The work comprised 70 sectional maps organized into seven climatic zones, an accompanying geographic text called Nuzhat al-Mushtaq, and a 140-kilogram silver disc engraved with the composite world map. Oriented with south at top, it synthesized accounts from Arab, Greek, and Norman travelers. Its calculation of Earth's circumference at 37,000 kilometers came within 10 percent of the actual value.