Boulting machine sieves the meal. There are two sorts of boulter at Sarehole:
one uses a wire mesh and the other uses a wooden frame with a piece of cloth
wound around it to form a cylinder. The cloth is missing now, but it probably
was a material like muslin which would allow the fine flour to pass through
but catch the larger particles of bran. The boulter works on the same principle
as a washing machine when it is spinning the water out of the clothes. Theses
machines are driven by a leather belt that is connected to a pulley, which is
driven by water wheel.