Post mill

The post mill is the earliest type of European windmill. The defining feature is that the whole body of the mill that houses the machinery is mounted on a single vertical post, around which it can be turned to bring the sails into the wind. The earliest post mills in England are thought to have been built in the 12th century. The earliest working post mill in England still used today is to be found at Outwood in Surrey. It was built in 1665. The earliest remaining example of a non-operational mill can be found in Great Gransden in Cambridgeshire, built in 1612. Their design and usage peaked in the 18th and 19th centuries and then declined after the introduction of high-speed steam-driven milling machinery. Many still exist today, primarily to be found in Northern Europe and Great Britain. The term peg mill or peg and post mill (in which the "post" was the tailpole used to turn the mill into the wind) was used in north west England, and stob mill in north east England, to describe mills of this type.

There are many variations amongst post mills.

The earliest post mills were quite small, and this led to problems with stability as they were liable to blow down in strong winds. A solution was found by burying the bottom of the trestle in a mound of earth. The last sunk post mills in England were at Warton, Lancashire, and Essington, Staffordshire.

As mills were made bigger, it was found that the trestle did not need to be buried. Thus the open trestle post mills were built. The oldest surviving is at Great Gransden, Cambridgeshire. Others exist in the UK at Bourn, Cambridgeshire; Great Chishill, Cambridgeshire; Nutley, Sussex and Chillenden, Kent. Open trestle post mills are also found in France, Belgium, the Netherlands, Germany and in New England, USA.

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