Mill race

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Mill Race, Redbournbury Mill, River Ver, near St Albans. Mill Race, Redbournbury Mill - - 1561163.jpg
Mill Race, Redbournbury Mill, River Ver, near St Albans.

A mill race, millrace or millrun, [1] mill lade (Scotland) or mill leat (Southwest England) is the current of water that turns a water wheel, or the channel (sluice) conducting water to or from a water wheel. Compared with the broad waters of a mill pond, the narrow current is swift and powerful. The race leading to the water wheel on a wide stream or mill pond is called the head race (or headrace [2] ), and the race leading away from the wheel is called the tail race [3] (or tailrace [2] ).


A mill race has many geographically specific names, such as leat, [4] lade, flume, goit, penstock. These words all have more precise definitions and meanings will differ elsewhere. The original undershot waterwheel, described by Vitruvius, was a 'run of the river wheel' placed so a fast flowing stream would press against and turn the bottom of a bucketed wheel. [5] In the first meaning of the term, the millrace was the stream; in the sense of the word, there was no separate channel, so no race.

As technology advanced, the stream was dammed by a weir. This increased the head of water. Behind the weir was the millpond, or lodge. The water was channelled to the waterwheel by a sluice or millrace- this was the head race. From the waterwheel, the water was channelled back to the course of the stream by a sluice known as the tail race. When the tail race from one mill led to another mill where it acted as the head race this was known as the mid race. The level of water in the millrace could be controlled by a series of sluice gates. [5]

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A leat is the name, common in the south and west of England and in Wales, for an artificial watercourse or aqueduct dug into the ground, especially one supplying water to a watermill or its mill pond. Other common uses for leats include delivery of water for hydraulic mining and mineral concentration, for irrigation, to serve a dye works or other industrial plant, and provision of drinking water to a farm or household or as a catchment cut-off to improve the yield of a reservoir.

Watermill Structure that uses a water wheel or turbine

A watermill or water mill is a mill that uses 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 comprise gristmills, sawmills, paper mills, textile mills, hammermills, trip hammering mills, rolling mills, wire drawing mills.

Water wheel Machine for converting the energy of flowing or falling water into useful forms of power

A water wheel is a machine for converting the energy of flowing or falling water into useful forms of power, often in a watermill. A water wheel consists of a wheel, with a number of blades or buckets arranged on the outside rim forming the driving car.


A weir or low head dam is a barrier across the width of a river that alters the flow characteristics of water and usually results in a change in the height of the river level. They are also used to control the flow of water for outlets of lakes, ponds, and reservoirs. There are many weir designs, but commonly water flows freely over the top of the weir crest before cascading down to a lower level.

Sluice A water channel controlled at its head by a gate

A sluice is a water channel controlled at its head by a gate. A mill race, leet, flume, penstock or lade is a sluice channelling water toward a water mill. The terms sluice, sluice gate, knife gate, and slide gate are used interchangeably in the water and wastewater control industry.

River Cole, West Midlands

The River Cole is a 25 miles (40 km) river in the English Midlands. It rises on the lower slopes of Forhill, one of the south-western ramparts of the Birmingham Plateau, at Red Hill and flows south before flowing largely north-east across the plateau to enter the River Blythe below Coleshill, near Ladywalk, shortly before the Blythe meets the Tame. This then joins the Trent, whose waters reach the North Sea via the Humber Estuary. Its source is very near the main watershed of Midland England : tributaries are few and very short except in the lower reaches, so the Cole is only a small stream.

Flume Human-made channel for water

A flume is a human-made channel for water, in the form of an open declined gravity chute whose walls are raised above the surrounding terrain, in contrast to a trench or ditch. Flumes are not to be confused with aqueducts, which are built to transport water, rather than transporting materials using flowing water as a flume does. Flumes route water from a diversion dam or weir to a desired materiel collection location. Flumes are usually made up of wood, metal or concrete.

River Kent river in Cumbria, England

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Tumbling Weir

The Tumbling Weir is a circular weir in the town of Ottery St. Mary, Devon, England that allows water from a leat or man-made stream to reach the River Otter.

Penstock Intake structure that controls water flow to turbines or sewerage systems

A penstock is a sluice or gate or intake structure that controls water flow, or an enclosed pipe that delivers water to hydro turbines and sewerage systems. The term is inherited from the earlier technology of mill ponds and watermills.

Dalgarven Mill – Museum of Ayrshire Country Life and Costume

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Mill pond Body of water used as a reservoir for a water-powered mill

A mill pond is a body of water used as a reservoir for a water-powered mill.

River Mun

The River Mun or Mundesley Beck is a river in the north of the county of Norfolk, England. The source of the river can be found in the Parish of Northrepps. The river finally runs into the North Sea in the village of Mundesley.

River Teise

The River Teise is a tributary of the River Medway in Kent, England.

The Abbey River is a right-bank backwater of the River Thames in England, in Chertsey, Surrey — in the town's northern green and blue buffers. The L-shaped conduit adjoins mixed-use flood plain: water-meadows landscaped for a golf course, a motorway and a fresh water treatment works on the island it creates, Laleham Burway to its east and north in turn. Its offtake from the Thames is at the apex of Penton Hook, Staines upon Thames below its lower weir close to the Chertsey-Thorpe boundary in the Borough of Runnymede. Its outfall is the weir pool of Chertsey Lock back into the Thames, visible from Chertsey Bridge. The Environment Agency plans to build similar channels to the upstream Jubilee River, one of which will intersect the watercourse, another of which will be close to its outfall, thereby compensating for loss of its historic bypass functions.

River Gavenny A river in Monmouthshire, Wales

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Meikle Millbank Mill Human settlement in Scotland

Millbank Mill or Meikle Millbank Mill was an old corn mill in Burnbank Glen overlooking the Barr Loch near Lochwinnoch in Renfrewshire, south-west Scotland. The present ruins date from at least the end of the 18th century with structural evidence for six phases of development that finally ceased when the mill closed circa 1950. The mill was a two storey building, developed to become 'T' shaped complex when at a later stage a grain kiln was added.

Coldstream Mill

Coldstream Mill, near Beith in North Ayrshire, Scotland was an early 19th century meal mill powered by the Dusk Water and Whitestone Burn that was enlarged from an existing much earlier watermill. The mill worked until 1991 and was the last traditional working water mill in Ayrshire and one of the last continuously worked watermills in Scotland. The mill buildings have been converted into a private dwelling and the mill pond has been retained.


  1. "Millrace". World English Dictionary (10th ed.). HarperCollins. Retrieved 7 September 2013. millrace or millrun (ˈmɪlˌreɪs)— n; 1. the current of water that turns a millwheel.  2. the channel for this water.
  2. 1 2, word definition
  3. Chamber's Twentieth Century Dictionary, 1968, p=674
  4. "Leat". World English Dictionary (10th ed.). HarperCollins. Retrieved 7 September 2013. leat (liːt) — n ( Brit ) 1. a trench or ditch that conveys water to a mill wheel.   [Old English -gelǣt (as in wætergelǣt water channel), from let 1 ]
  5. 1 2 Yorke, Stan (2005). The Industrial Revolution explained. Newbury, Berks: Countryside Books. pp. 20–31. ISBN   978 1 85306 935 2.