90 STEAM TURBINES
claims relate also to the method of clamping the blades in position, and the use of spacing blocks, b b, between them. Richards' Patent.-The idea presented in the Zoelly patent of 1900 is carried a step further in a patent issued to J. Richards for a wheel in accordance with his ideas. The wheel consists of buckets, B, light in weight and drop forged on the ends of radial arms, which are attached to a central nave by pins inserted between the arms, as indicated in the illustration. The buckets are spaced further apart than is usual in turbines, because they are designed to be concave and reactive through a considerable angle of rotation, and thus will absorb the energy of the jet sufficiently throughout B Fig. 15. Turbine Wheel Proposed by Richards. this range. The arms of the wheels are not covered by plates at the sides, as in the Zoelly design; the intention of the inventor being that the inside of the turbine casing shall be machined smooth, and the steam allowed to rotate with the wheel within the casing. The claim is in substance for a wheel having a single hub, of a diameter within the zone of disruptive centrifugal strain, with equidistant radial sockets formed therein; strong radial stems fast- ened in the sockets; and concave reactive buckets integrally formed on the extremities of the stems. Turbine Designed by John Richards.-In Fig. 16 is a turbine proposed by John Richards and patented by him in 1903. In this turbine he uses a wheel like that outlined above. The casing for the wheel is finished smooth inside and the steam is supposed to rotate with the wheel in the casing. The gearing of transmission
