Eratosthenes Timeline

Eratosthenes of Cyrene 276 – 194 BCE *310 BCE Challimachus (310 – 240), the teacher to Apollonius and Eratosthenes is born. (Schmidt. 302). *ca. 280 BCE Alexandrina, or the Great Library and Museum at Alexandria, was thought to have been built during the time of Philadelphos (Ptolemy II). *276 BCE Eratosthenes is born in Cyrene (Lybia, Africa) to a father, named Aglaos or Ambrosios. (Nicastro, 60). *274 BCE First Syrian war wages until 271 BCE. Philadelphos (also known as Ptolemy II) took Asia Minor and Samos for himself. (Shipley. 204) *260 BCE Second Syrian war until ca. 253 BCE Philadelphos loses his territory in Asia Minor and Samos to Antiochos the Seleukid king. (Shipley. 204) *260 BCE Archimedes determined that the value of pi lies between 3 1/7th and 3 10/71st and that Pi times the radius of a circle squared is its area. *255 BCE Eratosthenes invented the Armillary, which was a spherical structure with the model of an Earth at the center, surrounded by other celestial bodies and constellations. This was later designed to represent the sun at the middle, instead of the earth. *250 BCE A true Zero was being used at this time by the Olmecs of Meso-America. As opposed to the placeholder used by Babylonians in ca. 2000 BCE, which wasn’t a true zero. *ca. 250 BCE Eratosthenes wrote of his studies on the Earth. This was the first use of the word Geography, which means “writing about the Earth”. Eratosthenes used the summer solstice sun in Syene (known then as Swenet), and the angle of the same summer solstice sun at Alexandria (which was about 7º) and the distance between the two cities to

calculate the curve and circumference of the Earth. (Crease. 4). He was also the first scholar to deal with longitudes and latitudes. (Graham. 361). *250 BCE. Eratosthenes is invited by Philadelphos to tutor his son. (Crease. 5) *246 BCE Third Syrian (Laodikean) Ptolemy III (Also known as Euergetes) took back Asia Minor and Samos once more, but failed to take Mesopotamia. (Shipley. 205) *245 BCE Erathosthenes becomes the head librarian at Alexandria, succeeding Zenodotos. (Nicastro. 1). *240 BCE Eratosthenes uses an algorithm he created to find the prime numbers. This is called the Sieve of Eratosthenes. *225 BCE Appollonius records his studies of conic sections and names the ellipse, parabola, and hyperparabola. (Turnbull. 45). *224 BCE While Eratosthenes was head of Alexandrina when a large scale earthquake hit, Eugretes made a more than generous donation (Nicastro. 43). *214 BCE The building of the Great Wall of China had begun at this time. *206 BCE Rome defeats Carthage in Northern Italy at the battle of Metaurus. *200 BCE The word Geography was accepted as a term. *ca. 196 BCE The Rosetta Stone is inscribed in Egypt, giving us insight to Egyptian Hieroglyphics. *195 BCE Eratosthenes became blind, and later starved himself in 194 BCE *ca. 1700 CE the Armillary was replaced by the Orrery, which is a platform with the sun in the center, and arms extending outward which hold the celestial bodies that orbit around the sun. *1706 CE The symbol π wasn’t used until Jones Williams suggested it.