Archimedes

Archimedes (287 BC - 212 BC) was an important Greek mathematician, physicist, engineer, astronomer and philosopher.
He became famous for his inventions which helped the city of Syracus, in which he lived, to defend itself against Roman conquerors. As the Romans finally conquered Syracus, Archimedes was killed by a Roman soldier.

Archimedes and the golden crown

Legend relates that the king asked Archimedes to determine whether his new crown was really made out of pure gold (The king suspected the goldsmith that he might have replaced some of the gold which was given to him by cheaper silver). The problem was, that Archimedes was not allowed to damage the crown while doing his investigations. Archimedes found the solution while taking a bath, in a bathtub which was filled up to the brim with water. He noticed that the volume of water which ran out over the bathtub was the same as the volume of his body. The crown, if it consisted out of pure gold, should therefore replace less water than a crown consisting of a mixture of silver and gold (the density of gold is higher than the density of silver). Archimedes was so happy that he found this solution that he jumped out of the bath and rushed naked out on the street shouting "Eureka! Eureka!" (Eureka = I have found it!)