Amill race,millrace ormillrun,[1]mill lade (Scotland) ormill leat (Southwest England) is the current of water that turns awater wheel, or the channel (sluice) conducting water to or from a water wheel. Compared with the broad waters of amill pond, the narrow current is swift and powerful. The race leading to the water wheel on a wide stream or mill pond is called thehead race (or headrace[2]), and the race leading away from the wheel is called thetail race[3] (or tailrace[2]).
A mill race has many geographically specific names, such asleat,[4] lade, flume, goit, penstock. These words all have more precise definitions and meanings will differ elsewhere. The original undershot waterwheel, described byVitruvius, 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. The example of Mill Lade inGodmanchester refers to a wide channel leading to moorings where laden vessels unload, similar waterways known by the similar name ofLode exist in neighbouring districts.
As technology advanced, the stream was dammed by aweir. This increased the head of water. Behind the weir was themillpond, or lodge. The water was channelled to the waterwheel by a sluice or millrace- this was thehead race. From the waterwheel, the water was channelled back to the course of the stream by a sluice known as thetail race. When the tail race from one mill led to another mill where it acted as the head race this was known as themid race. The level of water in the millrace could be controlled by a series of sluice gates.[5]
millrace ormillrun (ˈmɪlˌreɪs)—n;1. the channel in which the current of water driving a mill wheel flows to the mill. 2. the current itself.
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 ]
