Water-mill

A watermill or water mill is a mill that utilizes hydropower. It is a structure that uses a water wheel or water turbine to drive a mechanical process such as milling (grinding), rolling, or hammering. Such processes are needed in the production of many material goods, including flour, lumber, paper, textiles, and many metal products. These watermills may be comprise gristmills, sawmills, paper mills, textile mills, hammermills, trip hammering mills, rolling mills, wire drawing mills.

One major way to classify watermills is by wheel orientation (vertical or horizontal), one powered by a vertical waterwheel through a gearing mechanism, and the other equipped with a horizontal waterwheel without such a mechanism. The former type can be further divided, depending on where the water hits the wheel paddles, into undershot, overshot, breastshot and pitchback (backshot or reverse shot) waterwheel mills. Another way to classify water mills is by an essential trait about their location: tide mills use the movement of the tide; ship mills are water mills onboard (and constituting) a ship.

According to Terry S. Reynolds and R. J. Forbes, the water wheel may have originated from the ancient Near East in the 3rd century BC for use in moving millstones and small-scale corn grinding. Reynolds suggests that the first water wheels were Norias and, by the 2nd century BC, evolved into the vertical watermill in Syria and Asia Minor, from where it spread to ancient Greece and the Roman Empire. S. Avitsur also supports a Near-Eastern origin for the watermill.

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