Eratosthenes was born in Cyrene but worked and died in Alexandria, Egypt. He never married and was known for his haughty character. In 236 BC he was appointed librarian of the Alexandrian library. Eratosthenes made many contributions to mathematics and science and was good friends with Archimedes. In194 BC Eratosthenes became blind and a year later he starved himself to death. In "On the Circular Motions of the Celestial Bodies" by Cleomedes, Eratosthenes is credited with having calculated the Earth's circumference, in 240 BC, using knowledge of the angle of elevation of the Sun at noon on the summer solstice in Alexandria and in the Elephantine Island near Syene. He also created a map of the world based on available geographical knowledge of the era and devised a system of latitude and longitude.