Millstones
The millstones in use, each 52.5" (133 cm) in diameter, are surrounded by a wooden cover or tun, with a trestle called a 'horse' supporting the hopper and shoe.
When operated commercially, grain fell from a grain bin in the garner, through a chute into the hopper then slowly fed into the grain shoe. This is agitated by the damsel, an iron rod located on the top of the rynd. Grain shaken from the shoe falls into the central eye (the hole) of the upper or runner stone to be milled into wholemeal flour as it moves to the outer edge of the stones.
The picture below shows the runner stone being held on edge by the stone crane. This enables millstones weighing up to a ton to be lifted and inverted to clean or dress the stone.
The runner and the bed stone are French stones, each created from a number of pieces of hard flint-like stone, or burrs, that were quarried near Paris. Specialised stone masons would select a number of burrs before cutting them to produce the millstones, holding them together by circular iron bands and plaster of Paris.
The iron bar or rynd across the central eye fits over the mace on the stone spindle, balanced on the pivot point of the spindle, and turns the stone as the spindle rotates.
Before being used, a new runner stone needs to be balanced to run smoothly by placing small lead weights into shallow holes in the top plaster surface. This runner stone is made from thirteen burrs with four inner and nine outer pieces. Many stones are made using more burrs, the open runner stone on the stone floor being made from 24 burrs.
The next picture shows the bed stone, fixed in position on the Stone Floor, and surrounded by the close-fitting wooden skirting.
A hole in the skirting, but inside the surrounding tun, allows the meal produced by the millstones to fall down a chute to the meal bagging area on the floor below. The stone spindle protrudes through the centre of the bed stone and is fitted with the thick cast-iron H-shaped mace, kept in position by the weight of the runner stone. The spindle emerges through the mace to form the pivot point upon which the rynd and runner stone rest. This bed stone is made from four inner and eight outer burrs.
As the water fills the waterwheel buckets, the weight of the water starts the wheel rotating. The power produced by the waterwheel turns the pitwheel on the waterwheel shaft to drive the wallower pinion on the main horizontal shaft.
The runner millstones are then turned by the bevel gears, stone nuts and stone spindles. The main shaft also carries a large pulley that powers an overhead shaft fitted with pulley wheels for the canvas belts driving the aspirator in the garner and the archimedes screw meal conveyer.