Archimedes crying 'Eureka!', 3rd century BC, (1737).

The naked Archimedes (c 287-212 BC) running through the streets of Syracuse shouting 'Eureka!', ('I have found it'). He had just stepped into his bath and, noticing that the water overflowed, he realised that the volume of water that overflowed was equal to the portion of his body that had been immersed. After further experiments he concluded that the buoyant force on an object is equivalent to the weight of water displaced by that object. This is now called 'Archimedes' Principle' or the 'Principle of Buoyancy'. Vignette from the title page of 'Notizie istoriche e critiche intorno alla vita, alle invenzioni, ed agli scritti di Archimede siracusano' (Historical and critical information about the life, inventions and writings of Archimedes of Syracuse) by Count Giammaria Mazzuchelli (1707-1765), published in Brescia, Italy in 1737.