Some of my recent posts have talked about the harvesting, threshing, and winnowing of grain, and how vital grains were as a food source in medieval times. But before grains could be used for baked goods and alcohol production, they had to be processed. For the most part, this happened at the local mill. There were two different types commonly used, depending on the climate and landscape; water, or wind.

It took a sizeable amount of money to build and maintain a mill. The entire building was basically a large machine, where water or wind powered a number of large gears that moved the grinding stones inside. Mill stones couldn’t be just any old stones. They had to have specific qualities, which often required that they be purchased and carted from quarries long distances away. Because the stones were so large, they might also have to be broken into pieces then reassembled at the mill using iron to hold them together. Mill stones were not completely flat. Grooves were chiseled into the stones to help with the grinding process, but also to move the ground grain outward from the center where it could be collected and bagged. Once mill stones were properly assembled and chiseled (“dressed”), they were set in place, balanced with weights, and spaced with the help of gears.

Building the mill was not the only difficulty millers faced. It was also their job to make sure it ran at the right speed. When the flow of water, or the force of wind, varied, the miller had to make adjustments. If the mill ran too fast, the friction between the stones would become too great and the resulting heat would ruin the grain. If the mill ran too slowly, or stopped completely, so did production. For water mills, ice blocking the flow of water was a constant problem in winter. Ice could also damage or destroy the water wheel, as could floods. Drought in summer was also a common problem that could stop all work at the mill. People were well advised to keep extra grain on hand for times when the mill was not running.

It is not surprising that for the most part, mills were built by wealthy lords or monasteries. In exchange for the expense and responsibility of constructing, maintaining, and running the required number of mills for each community, the people were obligated to support the mill by taking their grain to it and paying one sixteenth of their harvest in payment for its usage. Sometimes households got around this by keeping a small hand mill, but often such hand mills were forbidden.

The position of miller, especially in rural settings, was typically hereditary. He was considered a serf under the lord, and not a free man. Millers were notorious for being dishonest–sometimes stealing from the grain they were entrusted with, or collecting inflated toll payments. The lord’s grain, of course, was ground for free and took priority over that of anyone else.

Mills were used for other purposes besides grinding grain. They were also used to extract oil from things like nuts, seeds, or olives. In places where there was a large wool industry, mills were used for the fulling process. Windmills had another surprising purpose as a defensive device used against attacking armies. Their immense height allowed them to be used as a lookout tower, or even as a fort. Sometimes they were even built directly onto a castle tower.

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