What is "post mill"

Post \Post\, n. [AS., fr. L. postis, akin to ponere, positum, to place. See Position, and cf. 4th Post.]

1. A piece of timber, metal, or other solid substance, fixed, or to be fixed, firmly in an upright position, especially when intended as a stay or support to something else; a pillar; as, a hitching post; a fence post; the posts of a house.

   They shall take of the blood, and strike it on the two side posts and on the upper doorpost of the houses.
   --Ex. xii. 7.

   Then by main force pulled up, and on his shoulders bore, The gates of Azza, post and massy bar.
   --Milton.

   Unto his order he was a noble post.
   --Chaucer.

   Note: Post, in the sense of an upright timber or strut, is used in composition, in such words as king-post, queen-post, crown-post, gatepost, etc.

2. The doorpost of a victualer's shop or inn, on which were chalked the scores of customers; hence, a score; a debt.

   When God sends coin I will discharge your post.
   --S. Rowlands.

   From pillar to post. See under Pillar.

   Knight of the post. See under Knight.

   Post hanger (Mach.), a bearing for a revolving shaft, adapted to be fastened to a post.

   Post hole, a hole in the ground to set the foot of a post in.

   Post mill, a form of windmill so constructed that the whole fabric rests on a vertical axis firmly fastened to the ground, and capable of being turned as the direction of the wind varies.

   Post and stall (Coal Mining), a mode of working in which pillars of coal are left to support the roof of the mine.

n. A form of windmill constructed so that the whole building rests on a vertical axis firmly fastened to the ground. It is capable of being turned as the direction of the wind varies.

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.