Clemens Herschel (March 23, 1842 – March 1, 1930) was an American hydraulic engineer. His career extended from about 1860 to 1930, and he is best known for inventing the Venturi meter, which was the first large-scale, accurate device for measuring water flow. He developed this device while serving as director of the Holyoke Testing Flume, a turbine testing facility which he would redesign, which became the first modern hydraulics laboratory in the United States and the world.