Kenilworth Castle in 1575
7. The Outer Court Water Mill
Grain for milling would be brought to the watermill, and checked by the miller for the correct moisture content. Sacks of grain are raised to the Grain Bin (more typically on a floor above the millstones) via a sack hoist. The grain flows from the bin down into the Hopper and then into the ‘Shoe’, which is continually vibrated by the ‘Damsel’ to ensure a regular flow. The Damsel and the ‘Runner Stone’ are rotated by the ‘Rynd’, a cross bar held by a ‘Mace’ which is keyed into the vertical drive shaft.
The Runner Stone sits above the ‘Bed Stone’, which is fixed to the floor. Each pair of millstones had the same offset radiating pattern of furrows, resulting in a scissor-like action to move the grain outwards and become ground progressively finer. The expelled flour is contained by the ‘Tun Case’, and collected by the ‘Sweeper’ to be deposited down the ‘Mill Eye’, and down a chute to be finally collected in a sack.
It is critical that the weight of the Runner Stone, which could be up to a tonne, is used for grinding, and not taken by the drive shaft - which would risk serious damage. Constant vigilance was required from the miller to ensure a constant supply of grain to the millstones to prevent them from touching, which would blunt the stones, risk adding grit to the flour, and possibly create a spark. The dust from some grains was more explosive than gunpowder and 35 times more explosive than coal dust - which is also why there couldn’t be any open fires within the mill. Typically a bell attached to the hopper would ring to warn of a faltering grain supply.
The Runner Stone rotated about 120 rpm (i.e. twice every second) and so had to be perfectly balanced. Not only did the miller have to maintain the ‘cut’, the optimum distance between the millstones, which varied according to the type of grain, but the millstones also had to remain perfected parallel, otherwise the product would be inconsistent and unusable. Every few weeks for gritstone (or every few months for burrstone), each millstone had to be ‘dressed’ – removed for resurfacing and resharpening. Dressing a millstone was a skilled task requiring about 3 days work using a sharp chisel.