Eratosthenes' measurement of the Earth's circumference and world map (c. 240 BCE)

1. Alexandria becomes a Hellenistic research hub

   Jan 1, 300 BCELabels: Alexandria, Library of

   • Britannica
   • OUP

2. Eratosthenes is born in Cyrene

   Jan 1, 276 BCELabels: Eratosthenes, Cyrene

   • Britannica

3. Eratosthenes studies in Athens and Alexandria

   Jan 1, 255 BCELabels: Eratosthenes, Athens

   • Britannica
   • OUP

4. Eratosthenes becomes head librarian at Alexandria

   Jan 1, 245 BCELabels: Eratosthenes, Great Library

   • Britannica
   • APS

5. Eratosthenes writes “On the Measurement of the Earth”

   Jan 1, 240 BCELabels: Eratosthenes, On the

   • Britannica
   • MAA

6. Solstice observations at Syene and Alexandria are compared

   Jun 21, 240 BCELabels: Syene, Alexandria

   • Britannica
   • Nature

7. Shadow angle in Alexandria is measured as 1/50 circle

   Jun 21, 240 BCELabels: Alexandria, Shadow angle

   • Britannica
   • APS

8. Distance Alexandria–Syene is set at about 5,000 stadia

   Jun 21, 240 BCELabels: Alexandria Syene, Stadion

   • APS
   • MAA

9. Earth’s circumference is computed at about 250,000–252,000 stadia

   Jun 21, 240 BCELabels: Earth circumference, Eratosthenes

   • Britannica
   • Nature

10. Eratosthenes composes a systematic world map in his “Geography”

    Jan 1, 235 BCELabels: Geography, World map

    • Britannica
    • WHE

11. Hipparchus critiques and refines scientific geography

    Jan 1, 130 BCELabels: Hipparchus, Critique

    • Hipparchus
    • Strabo

12. Cleomedes preserves the best-known account of the method

    Jan 1, 1 BCELabels: Cleomedes, Method account

    • Britannica
    • MAA

13. Strabo evaluates Eratosthenes’ geography and measurements

    Jan 1, 20Labels: Strabo, Geography

    • Nature
    • Strabo

14. Legacy: measurement-based geography becomes a lasting model

    Jan 1, 200Labels: Legacy, Measurement-based geography

    • Britannica
    • Cambridge