Movement 437

437. Volute wheel, having radial vanes, a, against which the water impinges and carries the wheel around. The scroll or volute casing, b, confines the water in such a manner that it acts against the vanes all around the wheel. By the addition of the inclined buckets, c, c, at the bottom, the water is made to act with additional force as it escapes through the openings of said buckets.