In Northumberland, for much of the 19th century, water was the main source of power for corn-mills, though steam took over in many mills in the later Victorian period.
There were several types of water-wheels:-
Over-shot wheels were turned by the water from the mill-race being brought to a high level where it shot over the top blades, turning the wheel in the same direction as the flow of the stream.
Breast-shot wheels were powered by a head of water striking the wheel at a point from one-third to two-thirds the height of the wheel.
Under-shot wheels were turned by water striking the lower blades causing the wheel to turn in the opposite direction to the current in the mill-race.
Heatherslaw Mill on the Ford and Etal Estate is a fully-working, restored corn-mill of the Victorian period. Visitors can see the under-shot wheel and mill-machinery in action, processing cereals, grains and flours for use and sale in local bakeries and shops.