Screw turbine connected to a generator through a gearbox. The Archimedean screw is an ancient invention, attributed to Archimedes of Syracuse (287–212 BC.), and commonly used to raise water from a watercourse for irrigation purposes. In 1819 the French engineer Claude Louis Marie Henri Navier (1785–1836) suggested using the Archimedean screw as a type of water wheel. In 1916 William Moerscher applied for a U.S. patent on the hydrodynamic screw turbine. The Archimedean screw turbine is applied on rivers with a relatively low head (from 1 m to 10 m) and on low flows (0.01 m³/s up to around 10 m³/s on
Archimedes' quadruplets Archimedes' quadruplets In geometry, Archimedes' quadruplets are four congruent circles associated with an arbelos. Introduced by Frank Power in the summer of 1998, each have the same area as Archimedes' twin circles, making them Archimedean circles. An arbelos is formed from three collinear points "A", "B", and "C", by the three semicircles with diameters "AB", "AC", and "BC". Let the two smaller circles have radii "r" and "r", from which it follows that the larger semicircle has radius "r" = "r"+"r". Let the points "D" and "E" be the center and midpoint, respectively, of the semicircle with the radius "r".