Cromford Mill was the world's first water-powered cotton spinning mill, developed by Richard Arkwright in 1771 in Cromford, Derbyshire. These small water wheels are there just as a demonstration I think, as the main giant waterwheel was almost underground to where this river is heading, beneath the mill itself to work the machinery.

'He chose the site at Cromford because it had year-round supply of warm water from the Cromford Sough which drained water from nearby Wirksworth lead mines, together with Bonsall Brook. Here he built a five-storey mill, with the backing of Jedediah Strutt, Samuel Need and John Smalley. Starting from 1772, he ran the mills day and night with two twelve-hour shifts.

He started with 200 workers, more than the locality could provide, so he built housing for them nearby, one of the first manufacturers to do so. Most of the employees were women and children, the youngest being only seven years old. Later, the minimum age was raised to ten and the children were given six hours of education a week, so that they could do the record-keeping that their illiterate parents could not. The gate to Cromford Mill was shut at precisely 6 a.m. and 6 p.m. every day, and any worker who failed to get through it not only lost a day's pay but also was fined another day's pay.' Wiki

Enjoy large.