Eratosthenes: Encyclopedia II - Eratosthenes - Short summary of Eratosthenes' life

Eratosthenes - Short summary of Eratosthenes' life

He was born in Cyrene (in modern-day Libya), but worked and died in Ptolemaic Alexandria. He is noted for devising a system of latitude and longitude, and for being the first known to have computed the size of the Earth.

Eratosthenes was known under the name β, because he supposedly proved himself to be the second in the world in many fields. He was also reputedly known for his haughty character.

Eratosthenes studied at Alexandria and for some years in Athens. In 236 BC he was appointed by Ptolemy III Euergetes I as librarian of the Alexandrian library. He made several important contributions to mathematics and science, and was a good friend to Archimedes. Around 255 BC he invented the armillary sphere, which was widely used until the invention of the orrery in the 18th century. In 195 BC he became blind and a year later he supposedly starved himself to death.

He is credited by Cleomedes in On the Circular Motions of the Celestial Bodies with having calculated the Earth's circumference ca. 240 BC, using trigonometry and knowledge of the angle of elevation of the Sun at noon in Alexandria and Syene (now Aswan, Egypt).

Adapted from the Wikipedia article "Short summary of Eratosthenes' life", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki