In the 1950s, Warren Rice attempted to re-create Tesla's experiments, but he did not perform these early tests on a pump built strictly in line with the Tesla's patented design (it, among other things, was not a Tesla multiple staged turbine nor did it possess Tesla's nozzle).[14] Rice's experimental single stage system's working fluid was air. Rice's test turbines, as published in early reports, produced an overall measured efficiency of 36–41% for a single stage.[14] Higher percentages would be expected if designed as originally proposed by Tesla.