- 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.