Gristmill

A gristmill (also known as a grist mill, corn mill, flour mill, feed mill or feedmill) grinds cereal grain into flour and middlings. The term can refer to either the grinding mechanism or the building that holds it. Grist is grain that has been separated from its chaff in preparation for grinding.

The Greek geographer Strabo reported in his Geography that a water-powered grain-mill existed near the palace of king Mithradates VI Eupator at Cabira, Asia Minor, before 71 BC.

The early mills had horizontal paddle wheels, an arrangement which later became known as the "Norse wheel", as many were found in Scandinavia. The paddle wheel was attached to a shaft which was, in turn, attached to the centre of the millstone called the "runner stone". The turning force produced by the water on the paddles was transferred directly to the runner stone, causing it to grind against a stationary "bed", a stone of a similar size and shape. This simple arrangement required no gears, but had the disadvantage that the speed of rotation of the stone was dependent on the volume and flow of water available and was, therefore, only suitable for use in mountainous regions with fast-flowing streams. This dependence on the volume and speed of flow of the water also meant that the speed of rotation of the stone was highly variable and the optimum grinding speed could not always be maintained.

Vertical wheels were in use in the Roman Empire by the end of the first century BC, and these were described by Vitruvius. The rotating mill is considered "one of the greatest discoveries of the human race". It was a very physically demanding job for workers, where the slave workers were considered little different from animals, the miseries of which were depicted in iconography and Apuleius' The Golden Ass. The peak of Roman technology is probably the Barbegal aqueduct and mill where water with a 19-metre fall drove sixteen water wheels, giving a grinding capacity estimated at 28 tons per day. Water mills seem to have remained in use during the post-Roman period.

Manually operated mills utilizing a crank-and-connecting rod were used in the Western Han dynasty.

There was an expansion of grist-milling in the Byzantine Empire and Sassanid Persia from the 3rd century AD onwards, and then the widespread expansion of large-scale factory milling installations across the Islamic world from the 8th century onwards. Geared gristmills were built in the medieval Near East and North Africa, which were used for grinding grain and other seeds to produce meals. Gristmills in the Islamic world were powered by both water and wind. The first wind-powered gristmills were built in the 9th and 10th centuries in what are now Afghanistan, Pakistan and Iran. The Egyptian town of Bilbays had a grain-processing factory that produced an estimated 300 tons of flour and grain per day.

From the late 10th century onwards, there was an expansion of grist-milling in Northern Europe. In England, the Domesday survey of 1086 gives a precise count of England's water-powered flour mills: there were 5,624, or about one for every 300 inhabitants, and this was probably typical throughout western and southern Europe. From this time onward, water wheels began to be used for purposes other than grist milling. In England, the number of mills in operation followed population growth, and peaked at around 17,000 by 1300.

Limited extant examples of gristmills can be found in Europe from the High Middle Ages. An extant well-preserved waterwheel and gristmill on the Ebro River in Spain is associated with the Real Monasterio de Nuestra Senora de Rueda, built by the Cistercian monks in 1202. The Cistercians were known for their use of this technology in Western Europe in the period 1100 to 1350.