A Greek mathematician and philosopher credited with the principles of levers, the Archimedean screw as a pump, and a method of successive approximations which allowed him to determine the value of π to a good approximation. King Hiero is said to have asked Archimedes to check if a crown was pure gold throughout or contained a cheap alloy. While in a public bath and pondering on how to do this without damage to the crown, Archimedes is supposed to have suddenly thought of the possibility of immersing it in water and checking its density by way of displacement, and to have been so excited that he ran naked through the streets shouting ‘Eureka! Eureka! I have found it! I have found it!’ He was killed by a soldier in the Roman siege of Syracuse.