From an energy exchange point of view axial compressors are reversed turbines. Steam-turbine designer Charles Algernon Parsons, for example, recognized that a turbine which produced work by virtue of a fluid's static pressure (i.e. a reaction turbine) could have its action reversed to act as an air compressor, calling it a turbo compressor or pump. His rotor and stator blading described in one of his patents had little or no camber although in some cases the blade design was based on propeller theory. The machines, driven by steam turbines, were used for industrial purposes such as supplying air to blast furnaces. Parsons supplied the first commercial axial flow compressor for use in a lead smelter in 1901. Parsons' machines had low efficiencies, later attributed to blade stall, and were soon replaced with more efficient centrifugal compressors.