How a mill works
Most of the surviving mills in Wessex are water-powered, but the workings are essentially the same for both water and wind except that the drive from the power source usually comes from below in the first case and from above in the second.
The example shown here is Ashton windmill near Chapel Allerton in Somerset. Ashton formerly produced flour and also cattle feed. Explanatory notes follow the diagram, which is reproduced here by permission of Sedgemoor District Council Museums Service.
Wind acting on the sails (26) turns the wind shaft (4), thereby turning the attached brake wheel (2). This drives the wallower (8), which is attached to the upright shaft (25). At Ashton mill the sails are turned into the wind manually by the winding gear (5 & 6) acting on the circular curb on top of the mill walls and operated by the miller standing on the ground outside the building. In some other "tower" mills like Ashton the cap is turned into the wind automatically by a "fantail".
A sack of grain enters the mill via the door on the ground floor and is then raised to the top floor by the sack hoist (12), driven by the upright shaft via the crown wheel (9). The sack of grain is lifted through successive drop flaps which automatically return to the closed position after the sack has passed.
On the top floor the grain is emptied by the miller into the grain bin (10). From the bin the grain falls through a chute into the hopper (14) and thence into the shoe (16). The shoe is gently shaken by a "damsel", a pin with irregular sides driven off the stone spindle (22), so that the grain falls in a steady trickle through the central hole in the runner stone (18) on to the bed stone (19). The miller adjusts the rate of production by altering the angle of the shoe.
The runner stone is itself rotated by the stone spindle so that the grain is gradually ground into flour which eventually appears at the edge of the stone and then falls via another chute into a sack on the ground floor.
The distance between the two stones is controlled by the tentering gear (24), and this governs the grade of flour produced. The stone spindle is turned via its attached stone nut (21) by the great spur wheel (20) attached to the upright shaft.
In a water-powered mill the wallower is usually found at the bottom of the upright shaft rather than at the top, driven by a pit wheel in place of the brake wheel. The pit wheel, on the inside of the building, is attached to the same drive shaft as the water wheel itself, which is often mounted on the outside of the building.
Detailed information with photographs and diagrams of the internal workings of one watermill may be found on the web site of the Town Mill at Lyme Regis.
Further information about Ashton windmill may be found in its guidebook, Ashton windmill: a brief history and guide, and also on the web site for the Allerton villages.