Archimedes

Archimedes (287 B. C. - 212 A. D.) was an important Greek mathematician, physician, engineer, astronomer and philosopher.
He became famous because of his inventions which helped the city of Syracus, in which he lived, to resist the Roman conquerors for a long time. When the Romans finally conquered Syracus Archimedes was killed by a Roman soldier.

Archimedes and the golden crown

According to legend Archimedes was engaged by the King to find out if his newly manufactured golden crown is really made of pure gold. (The King suspected the goldsmith to have cheated him by having partially replaced the gold by cheap silver). The problem was that Archimedes was not allowed to damage the crown during his investigation. Archimedes found the solution while he wanted to take a bath and thus was stepping into the bath tub filled to the brim. He noticed that exactly that amount of water was overflowing which had been displaced by the volume of his body. Thus the crown must displace less water if it was made of pure gold than if it was made of a mixture of silver and gold (Gold has got a higher density than silver). Archimedes was so excited about having found the solution that he ran nakedly in the streets and shouted "Heureka! Heureka!". (Heureka = I have found it)