The Swiss engineer Schmid invented an improved form of water-pres sure engine which attained a degree of utilization of the water power of 8o per cent. Sclnnid's construction is a horizontal single-cylinder oscillating engine (p. 64, 2). On the lower side of the horizontal cylinder is a convex projection which forms the arc of a circle and which fits water-tight in its concave bed. In this projection and leading to the piston are the water-channels, which automatically become alternately induction and eduction passages by the oscillation of the cylinder. The water-supply is conducted to and the discharge received from the cylinder by suitably arranged pipes in the bed of the machine. In competition with a number of other water motors, mostly turbines, Schmid received the prize offered by the city of Zurich in 1876 for the best hydraulic motor for utilizing the power of a city water-conduit for small industries.
Figure 6 illustrates an American water-pressure engine, which is exten sively employed for supplying house-tanks with water where the pressure in the street-main service is not sufficient in itself to force the water to the tanks. A certain proportion of the water from the main in such cases is used to drive the motor and to lift a smaller proportion to the tank. In
construction the engine does not materially differ from a steam-pump (p. 330, except that the driving cylinders are provided with ports and pistons suitable for water-pressure. In the larger sizes the driving cylinder-valves are balanced; such engines are constructed with proportions suitable for any condition of service, and are capable of supplying towns or cities with water.
Backus Water 5 exhibits a class of water motors adapted for driving light machinery, such as lathes, sewing-machines, etc. They arc constructed on the principle of the application of a water-wheel in a case; their action, however, depends upon the impact of the water under pressure, and not by its weight. The greater the elevation of the reser voir or the stand-pipe the higher the speed. The water-jet of the small est type of these motors has a diameter of but of an inch. Their gen eral points of excellence, briefly stated, are availability, steady motion and noiseless operation, safety and freedom from derangement, and economy of water.