Eratosthenes ppt


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Eratosthenes ppt

  1. 1. Eratosthenes
  2. 2. His Life <ul><li>Eratosthenes was born in Cyrene. (in modern-day Libya). He was the third chief librarian of the Great Library of Alexandria, the center of science and learning in the ancient world, and died in the capital of Ptolemaic Egypt. </li></ul>
  3. 3. <ul><li>Eratosthenes studied in Alexandria, and claimed to have also studied for some years in Athens. In 236 BC he was appointed by Ptolemy III Euergetes I as librarian of the Alexandrian library, succeeding the second librarian, Apollonius of Rhodes, in that post.[7] He made several important contributions to mathematics and science, and was a good friend to Archimedes. Around 255 BC he invented the armillary sphere. In On the Circular Motions of the Celestial Bodies , Cleomedes credited him with having calculated the Earth's circumference around 240 BC, using knowledge of the angle of elevation of the sun at noon on the summer solstice in Alexandria and on Elephantine Island near Syene (now Aswan, Egypt). </li></ul>
  4. 4. <ul><li>Eratosthenes criticized Aristotle for arguing that humanity was divided into Greeks and barbarians, and that the Greeks should keep themselves racially pure, believing there was good and bad in every nation.[8] By 195 B.C., Eratosthenes became blind. He died in 194 B.C., at the age of 82. </li></ul>
  5. 5. His Achiements <ul><li>Measurement of the Earth's circumference. </li></ul><ul><li>Eratosthenes calculated the circumference of the Earth without leaving Egypt. </li></ul>
  6. 6. Prime numbers <ul><li>Main article: Sieve of Eratosthenes </li></ul><ul><li>Eratosthenes also proposed a simple algorithm for finding prime numbers. This algorithm is known in mathematics as the Sieve of Eratosthenes. </li></ul>
  7. 7. <ul><li>Achievement in astronomy </li></ul><ul><li>Eratosthenes measured the angle of the shadow to the Earth. </li></ul><ul><li>Eratosthenes believed that the sun was so far away that its rays were parallel. </li></ul><ul><li>It is also believed that Eratosthenes made a star catalog with approximately 675 stars and created a calendar that included leap years. </li></ul>
  8. 8. Achievements in History <ul><li>He decided to work on giving a systematic chronography of the known world by figuring out the dates of literary and political events from the siege of Troy up until his time. However, this was only a beginning. Others built on his foundation. </li></ul>
  9. 9. Achievements in Geography <ul><li>Eratosthenes also contributed to geographic source of the river. </li></ul>
  10. 10. <ul><li>Many scholars that preceded Eratosthenes in the study of the Nile river, tried to figure out the reason why parts of the river flooded while other parts did not. It was not until Eratosthenes that a correct answer was proposed. </li></ul><ul><li>He believed that heavy rains near the source of the Nile was the cause of Many of Eratosthenes' peers nicknamed him &quot;Beta&quot; which is the second letter of the Greek alphabet, indicating that he just fell short of first place. </li></ul>
  11. 11. <ul><li>Eratosthenes contributed greatly to many different areas of knowledge, more than I could cover in this short paper. Maybe in his time period, his peers did not feel that he contributed enough in one area or maybe they were jealous that he had contributed so much to so many areas. </li></ul><ul><li>For a man who was nicknamed Beta, it is pretty impressive that so much of his work in these areas is still discussed today, so many years later. </li></ul>
  12. 12. His death & Reasons <ul><li>&quot; On the Murder of Eratosthenes &quot; is a speech by Lysias, one of the &quot;Canon of Ten&quot; Attic orators (Speech 1 in Lamb's translation, ISBN 978-0-674-99269-6). The speech is a defense written for Euphiletos who is charged with the death of Eratosthenes. The case is heard before the Delphinion, a court which hears proceedings for justifiable homicide </li></ul>
  13. 13. <ul><li>Euphiletos is accused of killing Eratosthenes, who was caught in the act of adultery with Euphiletos's wife. Euphiletos's defense is that his killing of Eratosthenes was an act of justifiable homicide and therefore not punishable. </li></ul>
  14. 14. Made by Apollo Serious <ul><li>Isha </li></ul><ul><ul><li>Akasha </li></ul></ul><ul><ul><ul><li>Aditi </li></ul></ul></ul><ul><ul><ul><ul><li>Shalom </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Tarine </li></ul></ul></ul></ul></ul>