National Mills Weekend
National Mill weekend which celebrates the heritage of wind and watermills taking place on May 10th and 11th so it’s interesting to take a look at Edinburgh’s rich watermill heritage. Before the steam age, the main source of power for mills was water and so the Water of Leith, not far from our Craiglockhart campus, was a hotbed of production from the 12th century onwards. At one point there were 76 mill sites along 23 miles of the river. There was a large concentration of mills around Juniper Green, which was a village that became incorporated into Edinburgh as the population grew. Mills such as Kinleith, Woodhall and Upper Spylaw produced a variety of items, including paper, grain, cloth, snuff, and they were also used for cutting wood and stone and in tanning hides.
The Mill Wheel
Before steam and electrical power were invented, power for the mills was generated by the rotating mill wheel. A large wheel with blades or buckets attached was driven by the water flow. This rotating motion was used to power various machines in the mill,s depending on what was being produced. The three main types of waterwheels used were:
Undershot – A vertical wheel with a horizontal axis. The water hits the wheel low down and turns the wheel as it hit the blades. Efficiency was around 50 to 60%.
Overshot – A vertical wheel with a horizontal axis. The water hits near the top of the wheel, and this type of wheel was 80 to 90% efficient.
Breastshot – A vertical wheel with a horizontal axis. The water hits the wheel roughly centrally and this type of wheel was 50 to 60% efficient.
Water and The Wheel
The main difficulty of waterwheels is their dependence on flowing water – an inconsistent water flow caused problems for the millers with flooding in the winter and a vastly reduced flow in the summer. This became a major problem in 1843 when springs on the north side of the Pentland Hills were tapped to provide a supply of pure water to the Edinburgh population. Compensation reservoirs were built at Harperrig, Threipmuir and Harlaw and these were regulated by a committee of mill owners and tenants. As a regular supply of water was essential to the mills, this required various means of controlling the flow. A system of weirs, sluices and lades was used to facilitate this. Above the weirs (or damheads) were deep pools out of which the water flowed into lades (or millraces)- narrow channels to increase the force of the flow.
Mills around Juniper Green mostly produced paper or grain, but were able to adapt from one use to another fairly easily. If the demand for a product eg. snuff vastly reduced the mills were able to change to production of a different product.
All the mills have now gone due to fall in demand for their products, environmental concerns and technological advancements. The last mill to close was Woodhall Mill in 2001. Many sites have been replaced by housing developments, but they are remembered in place names such as Woodhall Mill a development of modern flats which has a replica wheel beside an ornamental millpond. However, if you take a walk along the Water of Leith and you look carefully you can still find evidence of the mills such as Woodhall Mill weir and sluice and Kinleith Mill Weir.
If you would like to see a working watermill why not try visiting Blair Atholl Watermill, which still uses water to grind oatmeal.
Windmill at St. Monans
Although many abandoned and converted watermills can be found around Scotland, windmills are much rarer. The St. Monans Windmill in Fife, which dates from 1772 is one of the surviving ones and was constructed to aid the salt panning process, extracting salt from seawater. It was widely used in food preservation at a time before refrigeration. The salt extraction process was as follows:
- Seawater was stored in an artificial reservoir on the coast.
- Water was pumped from the reservoir to saltpans using a combination of wooden pipes and energy from the windmill.
- Water was evaporated using coal-fired saltpans. The coal was sourced locally. Approximately thirty-two tons of seawater were required to produce one ton of salt.
- Overseeing the operation was a Salt Master, an assistant and numerous employees. The work was dirty, arduous and dangerous.
- The salt industry prospered between 1783 and 1815. However, decline set in when salt tax duties were abolished in 1823. After this the St Monans industry went into decline.
If you would like to visit the windmill it is just a short walk from the village of St. Monans and keys to the windmill can be collected from the local Post Office.
You can find books and articles on heritage and engineering using Library Search.
By Vivienne Hamilton
Read more interesting articles on the blog, such as this one on Scottish bridges
