Eratosthenes

  • Eratosthenes (c. 275-194 BCE) was Chief Librarian of the Great Library of Alexandria and made great advances in science and geography.
  • Although none of his works have survived, they were recorded in the works of other scientists and geographers.

Eratosthenes and the Tower of Winds

  • The Tower was built in Athens by Andronicus of Cyrrhus c.50 BCE.
    • It was built on Eratosthenes system of eight not twelve, principle winds.
    • Greek Wind Rose
  • The Eight Winds on the Tower were named:
    • (N) Boreas (not Aparctius)
    • (NE) Caecias
    • (E) Apeliotes
    • (SE) Eurus
    • (S) Notus
    • (SW) Lips
    • (W) Zephyrus
    • (NW) Sciron (a variant of Argestes)

Sieve of Eratosthenes

  • A mathematical Formulae which permits the calculation of Prime Numbers between 1 to 100.

Eratosthenes’ World Map

  • Eratosthenes produced an ‘Oikeumene’ or World Chart, which included Parallels of Latitude and Longitude for the first time.
  • His Chart was based on the Earth being a Sphere and information derived from Alexander the Great‘s conquests in the East.
  • Eratosthenes associated the Pillars of Hercules with the mountains of Gibraltar and Morocco.

Distances to the Sun and Moon

  • Erastosthenes calculated the distance from the Earth to the Sun to be 804,000,000 Stadia.
  • He calculated the distance to the Moon to be 780,000 Stadia.
  • (One stadion was 600 Greek feet. Possibly, 522 imperial feet or 157 m.)

Circumference of the Earth

  • Eratosthenes calculated the Earth’s circumference at 250,000 Stadia. Depending on the interpretation of the length of a Stadion, he is considered to have been remarkably accurate.

 

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