Conversation so far:
who is known as the founder of hydrostatics
Archimedes is most famous for discovering the law of hydrostatics, sometimes known as 'Archimedes' principle'.
when was the archimedes principle discovered
the archimedes principle was discovered in 250 BCE
what does archimedes' principle state
Archimedes' principle states that the upward buoyant force that is exerted on a body immersed in a fluid is equal to the weight of the fluid that the body displaces.

Question: what book was the principle in
Self-contained rewrite: what book was the archimedes principle in