Post Mill

The post mill is the earliest type of European windmill, distinguished by having the whole body of the mill that houses its machinery mounted on a single central vertical post, supported by four diagonal struts called quarter bars. The entire body of the mill, including its sails, can be turned around this central post so the sails can be brought to face into the wind; most post mills have an arm projecting from the body opposite the sails, reaching down toward the ground, that is used to turn the mill by hand, and on some mills this arm carries a fantail that turns the mill into the wind automatically. The earliest post mills in England are thought to date from the 12th century; the oldest surviving working example in England, at Outwood in Surrey, was built in 1665, and the oldest surviving non-operational example, at Great Gransden in Cambridgeshire, dates from 1612. Post mills dominated European windmill design through the 18th and 19th centuries before being progressively replaced by tower mills, which did not require the whole body of the mill to be turned into the wind, and eventually by steam-driven milling machinery. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/