Eratosthenes

Eratosthenes of Cyrene (276-195 B.C.)
Eratosthenes was born in 276 B.C. in the Greek colony, Cyrene (present day Shahatt, Libya). In Cyrene, he started school at age 6 where he studied reading, writing and arithmetic as well as music and poetry. After going to school in Cyrene as a young boy, he ventured to Athens where he got the ancient world version of a college education. In Athens, Eratosthenes studied philosophy and poetry under the teachings of many famous ancient world scholars such as Ariston of Chios and Zeno. At age 30, Eratosthenes was summoned by King Ptolemy III to come to the city of Alexandria, which was a major city within the ancient world. Ptolemy asked Eratosthenes to come to Alexandria so that Eratosthenes could tutor his son, Philopator. In addition to this task, Eratosthenes became a librarian at the Great Library of Alexandria. Within five years of his arrival in Alexandria, Eratosthenes became the chief librarian, which was a big honor. Throughout his years in Alexandria, Eratosthenes edited many books that came into the library and made many accomplishments in mathematics, geography and literature. In mathematics he developed the Sieve of Eratosthenes, which was a theorem for finding prime numbers. He invented the scientific field of geography by writing a book entitled “Geographica” and not to mention that he also wrote many books including the 12 volume collection entitled “On the Old Comedy”. Eratosthenes remained in Alexandria until his death at age 80. It is believed that he went blind and couldn’t stand not being able to see the surrounding world, so he starved himself to death in the year 195 B.C.

Eratosthenes acquired 2 nicknames during his lifetime. The first, Pentathlos, means someone who competes in 5 events in the Olympics. This suited Eratosthenes because he was skilled in so many different fields of study, including geography, mathematics, astronomy, poetry and literature. Although he was involved in all these areas of study, he was not the top in any of them, which is where the second nickname comes in. It’s Beta, which is the second letter in the Greek Alphabet. Even though Eratosthenes is not considered to be the top in any specific subject, he did make major accomplishments in the ancient world. The one he’s most remembered for is making the first scientific measurement of the Earth’s circumference. It all started off when he found out that on the summer solstice at noon time, there were no shadows in Syene (present day Aswan, Africa). In Alexandria, where Eratosthenes lived at the time, on that same day and time, there were shadows. Eratosthenes already knew the Earth was round, so he figured by using the measurements of the shadows in Alexandria and Syene, he could use triangulation to eventually find the circumference of Earth. In the end, he ended up at a measurement of 252,000 stadia, which is approximately 250,000 miles. This was only a few thousand off of the actual circumference. The other major contribution to the mathematics world from Eratosthenes was his Sieve. It was a theorem developed by Eratosthenes to find prime numbers. Eratosthenes is also remembered as one of the chief librarians at the Great Library of Alexandria, for writing poems and many different books, one of which being “Geographica”, which talked about the study of the world. Eratosthenes gave this field of study its name, geography.
 * [[image:http://www.procedureman.com/uploaded_images/Animation_Sieb_des_Eratosthenes-719795.gif width="331" height="304" align="left" caption="Sieve of Eratosthenes"]]Contributions to the World **

Dicks, D. R.. "Eratosthenes." __Dictionary of Scienific Biography__. 1981 ed. McNeil, Rusell. __Eratosthenes__. Malaspina Great Books. February 26,2008 . Bailey, Ellen. "Eratosthenes of Cyrene: Greek Scholar." __Eratosthenes__. 2006. Middle Search Plus. February 25, 2008 . Bailey, Ellen. "Eratosthenes of Cyrene: Measuring the World." __Eratosthenes of Cyrene__. 2006. Middle Search Plus. February 25, 2008 . Bailey, Ellen. "Eratosthenes of Cyrene: Geography and Other Work." __Eratosthenes of Cyrene__. 2006. Middle Search Plus. February 25, 2008 . picture of Sieve of Eratosthenes website: http://www.procedureman.com/uploaded_images/Animation_Sieb_des_Eratosthenes-719795.gif
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