"Eureka" was said by:

Eureka means "I found it".The Greek mathematician and inventor Archimedes discovered the physical law of buoyancy, which states that any body completely or partially submerged in a fluid (gas or liquid) at rest is subject to an upward, or buoyant, force whose magnitude is equal to the weight of the fluid displaced by the body. The volume of fluid that has been displaced is equal to the volume of an object that is completely submerged in the liquid or to the portion of the volume below the surface for an object that is only partially submerged.