A mill race, millrace or millrun,
mill lade (Scotland) or mill leat (Southwest England) is the current of water that turns a
water wheel
A water wheel is a machine for converting the kinetic energy of flowing or falling water into useful forms of power, often in a watermill. A water wheel consists of a large wheel (usually constructed from wood or metal), with numerous b ...
, or the channel (
sluice
A sluice ( ) is a water channel containing a sluice gate, a type of lock to manage the water flow and water level. There are various types of sluice gates, including flap sluice gates and fan gates. Different depths are calculated when design s ...
) conducting water to or from a water wheel. Compared with the broad waters of a
mill pond
A mill pond (or millpond) is a body of water used as a reservoir for a water-powered mill.
Description
Mill ponds were often created through the construction of a mill dam or weir (and mill stream) across a waterway.
In many places, the co ...
, 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
[Dictionary.com, word definition]), and the race leading away from the wheel is called the tail race
[Chamber's Twentieth Century Dictionary, 1968, p=674] (or tailrace
).
A mill race has many geographically specific names, such as ''
leat
A leat (; also lete or leet, or millstream) 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. Othe ...
,
lade, flume, goit, penstock''. These words all have more precise definitions and meanings will differ elsewhere. The original undershot waterwheel, described by
Vitruvius
Vitruvius ( ; ; –70 BC – after ) was a Roman architect and engineer during the 1st century BC, known for his multi-volume work titled . As the only treatise on architecture to survive from antiquity, it has been regarded since the Renaissan ...
, was a 'run of the river wheel' placed so a fast flowing stream would press against and turn the bottom of a bucketed wheel.
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.
The example of Mill Lade in
Godmanchester
Godmanchester ( ) is a town and Civil parishes in England, civil parish in the Huntingdonshire district of Cambridgeshire, England. It is separated from Huntingdon, to the north, by the valley of the River Great Ouse. Being on the Roman roads ...
refers to a wide channel leading to moorings where laden vessels unload, similar waterways known by the similar name of
Lode
In geology, a lode is a deposit of metalliferous ore that fills or is embedded in a fracture (or crack) in a rock formation or a vein of ore that is deposited or embedded between layers of rock. The current meaning (ore vein) dates from th ...
exist in neighbouring districts.
As technology advanced, the stream was dammed by a
weir
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 water level. Weirs are also used to control the flow of water for outlets of l ...
. This increased the head of water. Behind the weir was the
millpond
A mill pond (or millpond) is a body of water used as a reservoir for a water-powered mill.
Description
Mill ponds were often created through the construction of a mill dam or weir (and mill stream) across a waterway.
In many places, the co ...
, 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.
Image gallery
River Meon
The River Meon () is a chalk stream in Hampshire in the south of England. It rises at East Meon then flows in a generally southerly direction to empty into the Solent at Hill Head near Stubbington.Hampshire County Council (2006). Activitie ...
: a covered head race and the by-pass weir
15-19-077, mingus creek - panoramio.jpg, millrace for