Archimedes (c.287–212 B.C.), Greek mathematician and physicist who spent most of his life in Syracuse, Sicily, where he was born. In mathematics he worked on the areas and volumes of conic sections, determined the value of π as lying between 3–1/7 and 3–10/71, and defined the Archimedean spiral. He founded the science of hydrostatics with his enunciation of Archimedes' principle, that the force acting to buoy up a body partially or totally immersed in a fluid is equal to the weight of the fluid displaced. He is also credited with the invention of Archimedes' screw, a machine for raising water that is still used to irrigate fields in Egypt. In physics he was the first to prove the law of the lever.