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Hercule-Progres turbine. Historical illustration of a vertical section through a US-French Hercule-Progres design of water turbine. Water turbines harness the power of moving water as it rotates the blades (lower centre). A variety of designs were developed in the 19th century. This one had a guaranteed efficiency of between 80 and 85 percent. Artwork from 'Moteurs' (1911) by French civil engineer Max de Nansouty (1854-1913), part of the 'Les merveilles de la science' series of 1867-1891 by Louis Figuier.
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