GEOGRAPHY EXPERT the ancient Greek scholar Eratosthenes is commonly called the father of Geography 4 he was de first 2 use de word Geography & he had a small-scale notion of de planet dat led him 2 be able 2 determine de circumference of de earth. BIOGRAPHY OF ERATOSTHENES Eratosthenes was born around 276 B.C.E at a Greek colony in cyrene, Libya. He was educbted at de academies of Athens & was appointed 2 run de Great library at Alexandria in 240. While serving as head librarian & scholar, Eratosthene wrote a comprehensive treatise about de world, called geography. Dis was de firs use of de word, which literally means writing about earth in Greek. Geography also introduced the climatic concepts of torrid, temperate & frhgid zones. ERATOSTHENES EXPERIMENT Having heard of a deep at syene (near de tropic of cancer & modern Aswan) where sunlight only struck de bottom of de well on de summer solstice, Eratosthenes determined dat he could discover de circumference of de earth. (Greek scholars knew dat de earth was indeed a sphere). To calculate de circumference, Eratosthenes two things. He knew de approximate distance b/w syene & Alexandria, as measured by camel-powered trade caravans. He den measured de angle of two shadow in Alexandria on de solstice. By taking de angle of de shadow(7degrees 12) & dividing it into 360degrees of a circle (360 divide by 7.2 yields 50), Eratosthenes could den multiply de distance b/w Alexandria & syene by 50 to determine de circumference. Eratosthenes determined de circumference to be 25,000miles, just 100miles actual circumference at de equator (24,901miles). While Eratosthenes made mathematical erros in his calculations, these fortunately canceled each other out & yielded an amazing accurate answer. A few decades later, de Greek geographer posidonius thought Eratosthenes circumference was to large.
Posted on: Fri, 03 Oct 2014 19:40:45 +0000
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