Archimedes (c. 287-212 BC)

Greek scientist Archimedes' many contributions to scientific thought - and his ability to put his theories to practical use - have had a major impact on the development of modern civilization. His innovations are well documented, but little is known about his life. He lived in Syracuse until it was besieged by the Romans in 214 BC, when he created a series of ingenious war machines that kept the enemy at bay for nearly three years. When they finally entered the city, he was killed in the massacre. Archimedes' best-known invention is the Archimedean screw - a cylinder with a screw inside that lifts water when turned - which is still used in some places. He also proved that heavy loads could be moved with levers and pulleys, and his principle of displacement was the foundation of hydrostatics, a branch of physics dealing with the pressure of fluids. Despite their brilliant originality and technical skill, Archimedes' scientific and mathematical discoveries had little influence on scientific knowledge until the ninth century, when Islamic scholars discovered, translated, and circulated his works.