Archimedes (287-212 B.C.) was a Greek mathematician, who produced classic works on geometry, arithmetic, and mechanics. Among his many inventions was a water pump to raise water from lower to higher elevations, and he is credited with the discovery of the principle of the lever.
Archimedes may be best known for his discovery of the law of hydrostatics--that is, the Archimedes principle that a body in a fluid is buoyed up by a force equal to the weight of the fluid it displaces. He is supposed to have discovered the principle in a flash of insight as he stepped into a bath and observed the displacement of water, after which he ran naked through the streets yelling, “Eureka!” (Such are the ways of some scientists and mathematicians, but such behavior is not mandatory in science.)