An idea that has been demonstrated as true or is assumed to be so demonstrable, The proposition that the velocity of a liquid flowing from a reservoir is equal to what it would have if it were to fall freely from the level in the reservoir; or, more generally, if p is the pressure, p the density, V the potential of the forces, q the resultant velocity, A a certain quantity constant along a streamline, then, given by Daniel Bernoulli (1700?82) in 1738