in 1866, california millwright samuel knight invented a machine that worked off a completely different concept. inspired by the high pressure jet systems used in hydraulic mining in the gold fields, knight developed a bucketed wheel which captured the energy of a free jet, which had converted a high head (hundreds of vertical feet in a pipe or penstock) of water to kinetic energy. this is called an impulse or tangential turbine. the water's velocity, roughly twice the velocity of the bucket periphery, does a u-turn in the bucket and drops out of the runner at 0 velocity.