Eratosthenes (redirected from Eratosthenes of Alexandria)

Eratosthenes (ĕrətŏs`thənēz), c.275–c.195 B.C., Greek scholar, b. Cyrene. A pupil of Callimachus in Athens, he became (c.240 B.C.) head of the library at Alexandria. Known for his versatility, he wrote poetry and works (most of them lost) on literature, the theater (notably on ancient comedy), mathematics, astronomy, geography, and philosophy; he also drew a map of the known world and evolved a system of chronology. Especially noted as an astronomer, he is credited with measuring the circumference and tilt of the earth and the size and distance from the earth of the sun and the moon.

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Eratosthenes

?276--?194 bc, Greek mathematician and astronomer, who calculated the circumference of the earth by observing the angle of the sun's rays at different places

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Eratosthenes 

Born circa 276 B.C. in Cyrene; died circa 194 B.C. Greek scholar and scientist.

Eratosthenes was educated in Alexandria and Athens. He headed the library at Alexandria after the death of Callimachus and studied many branches of ancient science. In mathematics he discovered the famous method of finding prime numbers known as the sieve of Eratosthenes. He laid the foundations of mathematical geography; the first person to make an accurate determination of the size of the earth, he calculated the earth’s radius as 6,311 km. Eratosthenes contributed to the development of chronology and astronomy. In philology he produced a study of ancient comedy; his philosophical writings include the dialogue Platonicon. He also wrote on music. Only fragments of Eratosthenes’ works have survived.