The Great Laxey Water Wheel.
The accompanying illustration represents an over-shot or gravity wheel, constructed about forty years ago, at Laxey, on the Isle of Man, a small island in the Irish Sea, off the west coast of England. The diameter of the wheel is seventy-two feet, and it develops 150 horse-power, which is transmitted a distance of several hundred feet to a lead mine, where it is employed in operating a system of pumps, the function of which is to raise 250 gallons of water per minute to an elevation of 1200 feet. An underground conduit is used in bringing the water, which comes from some distance, to the wheel, where it is forced up the masonry tower by pressure, and flows over the top into buckets.
The estimated efficiency of the Laxey wheel—taking resistance into account—is about sixty-five per cent of the theoretical power.