© Science Museum / Science & Society Picture Library
Model (scale 1:12). This automatic windmill, originally patented by John Warner of the United States in 1868, provides the energy to drive a waterpump. It uses a number of means to keep its waterpump at a constant speed. Any change of direction by the windmill, is corrected by putting more wind presure on the particular vane. A further mechanism controls the speed and prevents damage in high winds.