When Archimedes discovered the principle of displacement, he was hot on the trail of a clever fraud.
Hiero II (?308 BC – 215 BC), ruler of Syracuse in Sicily (an ancient Greek colony), made a present of a golden crown to a temple in honour of the gods. The crown was commissioned and duly delivered, but Hiero suspected that the craftsman had kept some of the gold and mixed in some lesser metal. So he turned to a relative of his, the mathematican Archimedes, and asked him to do some detective work.