"Torricelli's theorem gives the relation of the velocity of a fluid flowing from an opening to the distance from the fluid's surface. The speed is not influenced by the direction of flow. This is the speed of a drop of water falling freely under the force of gravity alone, disregarding friction. Torricelli's theorem is actually a particular case of Bernoulli's principle."
"Bernoulli's principle states that a fluid's speed is inversely proportional to its pressure and potential energy. It holds true only for an incompressible fluid with an unvarying flow and negligible friction. The principle can be transferred to gases under certain conditions."
"History and etymology"