As an engineer John Smeaton was responsible for engineering work on approximately 60 manufacturing mills across the country. He designed waterwheels, windmills and machinery to provide the mills with power that could be turned into motion. The vast majority of his mill work concerned flour and grist mills, grinding cereals like corn into flour, but he also worked on a small number of gunpowder mills, forges, textile mills, ironworks and collieries.
Mills were usually located on rivers and streams, not only for easy access to water for manufacturing purposes but to harness the renewable energy source freely available from the moving water. Waterwheels were the most common power source for mills in the 18th Century.
The main two types of water wheel were undershot (where water travelled under the wheel) and overshot (where water travelled over the wheel) and there was much debate about which was the most efficient. Smeaton, being a methodical problem solver, built scale models of each type of waterwheel to make precise calculations under strict laboratory conditions. This research applied scientific rigor, testing hypotheses and experimenting to create testable, repeatable results which proved, once and for all, that overshot wheels were twice as efficient as undershot wheels. This led to overshot water wheels begin used in mills wherever possible.
Windmills were another way of providing power and motion to machinery in the 18th Century, and there were many different configurations of numbers of sails and angles of sails being used, with some configurations more efficient than others. Smeaton designed a rotating model that could be operated by hand which meant he could test the shape, angle and size of sails at different wind velocities. As a result he determined the best angle of the windmill blades and the power outputs of the windmill at different speeds. Smeaton designed six windmills including in Leeds, Wakefield, Newcastle Upon Tyne and Barking.
Smeaton’s work on wind and the movement of air had an impact on the pursuit of human flight. George Caley, a scientist from Scarborough, Yorkshire used Smeaton’s work on the effect of air moving over surfaces to develop his own work about aerodynamics including lift and drag, resulting in him designing the first human glider.
Smeaton’s calculations around the relationship of pressure to velocity of objects moving through air became known as the Smeaton Coefficient and was used and improved upon by the Wright brothers who went on to make the first successful airplane. This is why John Smeaton is also part of the history of flight.