1600’s – Windmill
This mill is built almost entirely of wood. The power of the wind turns the sails round and the drive to the internal machinery is taken from the heavy wind-shaft to which they are attached. A simple contracting brake acts on the rim of the larger 'head' wheel. The smaller gear or 'wallower' drives a pair of stones directly. Using the long tailpole, the mill can be turned around on the central post so it faces into the wind. The weight of the mill is carried on the timber trestles underneath. Besides grinding corn, windmills were used to pump or drain water, but they could not provide the continuous power output most industries needed. What happens when the wind rises and dies down?
The principle of the water wheel was later adapted to wind power, and one of the earliest references to a windmill in this country is dated 1191. The original type was the post mill. A box-like body, housing milling machinery driven by the sails, was pivoted on a central post. It could be turned into the wind by means of the tiller-like tailpole at the rear. The sails would originally have been covered in canvas, which needed to be set like the sails of a ship. If the wind changed, the mill had to be stopped and the canvas readjusted, one sail at a time. Later designs used shutters which, in the case of William Cubitt's patent sails, could be set automatically. The weight of the post mill was carried on four sturdy timbers called quarterbars. From the 18th century, these were usually enclosed in a brick or wooden roundhouse to provide storage space, and few now survive still with their original open trestles. Two that do - which are among the oldest mills in the country, dating back to the early 1600s - are barely three miles apart at Caxton and Great Gransden in Cambridgeshire. They were contemporary with the earliest tower mills, in which the machinery was contained in a tall tower of brick or stone, only the cap that carries the sails being turned. With an ever-rising population to feed, the technology of corn milling was constantly improved, and the working parts of most mills in Britain would have been renewed many times over.
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