erm: he combined his love of mathematical theory with a zeal for experimentation. Consequently he produced a number of major insights into the realm of mechanical engineering and physics. He was a major contributor to the study of geometry and the science of weights and measures. He also came very close to inventing the calculus (that honor ultimately went to Newton 1,900 years later). He also was famed in his days for the inventive defense devices he provided his native city of Syracuse (Sicily) in its (ultimately unsuccessful) defense effort against the besieging Romans. Eratosthenes (ca. 276-192 BC)Eratosthenes was the librarian of the great museum/library of Alexandria. Based on the knowledge that at noon at the summer solstice shone directly down a well in Syene (Aswan) Egypt--and calculating the angle of the shadow that the sun made over a vertical pole at Alexandria Egypt at exactly the same moment--and having an accurate measure of the distance between the well at Syene and his rod at Alexandria, Eratosthenes estimated the earth's circumference at 24,660 miles--only about 200 miles less than the actual measure! He also claimed that a person could sail around the earth and arrive back at his starting point, provided that he never changed course along the way. He likewise catalogued nearly 700 stars. And he devised a system of calculating prime numbers. Euclid (ca. 276-194 BC)Euclid taught mathematics in Alexandria, Egypt and is even today considered the "father" of Western geometry. His work was clear and precise and well accepted in his days. Indeed, his writing Elements was used down into modern times as the major text on the subject of geometry. But we know little about him personally except through his many preserved works. Hipparchus (fl. 145-130 BC)He was one who put forth strong arguments against the heliocentric theory of Aristarchus--on the grounds that a mathematical system of eccentrics and epicycles seemed to account ...
