The post mill is the earliest type of European windmill. Its defining feature is that the whole body of the mill that houses the machinery is mounted on a single central vertical post. The vertical post is supported by four quarter bars. These are struts that steady the central post.
The body of the windmill can be turned around the central post to bring the sails into the wind. All post mills have an arm projecting from them on the side opposite the sails and reaching down to near ground level. With some, as at Saxtead Green, the arm carries a fantail to turn the mill automatically. With the others the arm serves to rotate the mill into the wind by hand.
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, 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.[1] Their design and usage peaked in the 18th and 19th centuries and then declined after the introduction of high-speed steam-driven milling machinery.[2] Many still exist today, primarily 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.
Post mills dominated the scene in Europe until the 19th century when tower mills began to replace them.[3] The advantage of the tower mill over the earlier post mill is that it is not necessary to turn the whole mill ("body", "buck") with all its machinery into the wind; this allows more space for the machinery as well as for storage.
Types of post mill
There are many variations amongst post mills.
Sunk post mill
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.[4] The last sunk post mills in England were at Warton, Lancashire,[5] and Essington, Staffordshire.
Open trestle post mill
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.
Chillenden post mill, built in 1868.
Chillenden open trestle post mill (another view).
Post mill with roundhouse
The space around the trestle could be used for storage, but was open to the weather. Mill owners started to build roundhouses around the trestles, and later mills were built with a roundhouse from new. This had the dual advantage of creating a covered storage area and protecting the trestle from bad weather. In Suffolk, millwrights would build post mills mounted on tall, two or three storey roundhouses, as at Saxtead Green.
Garboldisham Post Mill; the mill is complete inside, externally only missing the sails.
Post mill with roundhouse.
Saxtead Green Post Mill roundhouse is partially obscured by a hedgerow.
Midlands post mill
In the Midlands and North West of England, the top of the roundhouse had a curb, and rollers affixed to the mill body enabled the roundhouse to bear some of the weight of the mill. Examples of Midlands post mills extant include Danzey Green mill, (preserved at Avoncroft Museum of Historic Buildings) and the mill at Wrawby, Lincolnshire.
Alternative ways to protect the trestle
In eastern Europe, instead of a roundhouse an "apron" was fitted to the bottom of the body of the mill, enclosing the trestle and thereby affording protection from the weather.
Medieval illustration of a sunk post mill.
Midlands post mill.
Post mill, rebuilt in the open-air museum at Cloppenburg, Germany.
Some post mills are hollow post mills. In these mills the main post is bored to take a driveshaft, similar to an Upright Shaft in a smock or tower mill. This enables the mill to drive machinery in the base or roundhouse. Hollow post mills were not common in the United Kingdom. In the Netherlands, they are called Wipmolen and were mostly used for drainage. In France, the Moulin Cavier was a type of hollow post mill used for corn milling.
A few mills looked like post mills, but were not post mills. These composite mills often had a post mill body mounted on a short tower resembling a roundhouse, as at Banham[6] and Thornham[7] in Norfolk. Composite mills lack the central post on which the body of the post mill is mounted and turns upon to enable the mill to face the wind.
Paltrok mill
In the Netherlands and Germany, a variety of mill called the paltrok (Low German spelling Paltrock, from High German Pfalzrock (palisade skirt); the shape of the millhouse resembles that kind of garment) was built. Though similar in name and appearance, Dutch and German paltrok mills differ in historical and technical regard.
The Dutch paltrok mill was invented around 1600 and specifically designed for sawing wood. Several hundred[8] have existed of this type of windmill; however, only five paltrok mills remain in the Netherlands, at Zaanse Schans, Haarlem, Zaandam, Amsterdam and at the Netherlands Open Air Museum, Arnhem. Dutch paltrok mills are, like post windmills, supported on a central wooden post around which the entire millhouse rotates. The central post, however, is short and, to provide stability, a rim bearing is added on a brick base, on which the millhouse rotates with numerous rollers. Side extensions protect the sawing floor and workmen from the weather.[9]
German paltrok mills were commonly converted from post mills where the post and trestle were replaced by a wooden or iron rim bearing, set into the ground or on a brick base. The millhouse was enlarged and supported on this rim by numerous rollers or small wheels. These mills are technically composite mills although the tower is very short and of large diameter. This type of mill provided more internal space than a post mill and was cheaper than the alternative of erecting a smock mill.[10]
A windmill is a structure that converts wind power into rotational energy using vanes called sails or blades, by tradition specifically to mill grain (gristmills), but in some parts of the English-speaking world the term has also been extended to encompass windpumps, wind turbines, and other applications. The term wind engine is also sometimes used to describe such devices.
Saxtead Green Post Windmill is a Grade II* listed post mill at Saxtead Green, Woodbridge, Suffolk, England which is also a Scheduled monument and has been restored.
Durrington or High Salvington Windmill is a Grade II listed post mill in High Salvington, Sussex that has been restored and is in full working order. The mill stands 320 feet (98 m) above sea level and is able to take advantage of incoming sea winds.
Outwood Windmill is a Grade I listed post mill in Outwood, Surrey. Built in 1665 by Thomas Budgen, a miller from Nutfield in Surrey, it is Britain's oldest working windmill.
A tower mill is a type of vertical windmill consisting of a brick or stone tower, on which sits a wooden 'cap' or roof, which can rotate to bring the sails into the wind.
Chillenden windmill is a grade II* listed open-trestle post mill north of Chillenden, Kent, England. It is the last post mill built in Kent.
Keston Windmill is a grade I listed Post mill in Keston, formerly in Kent and now in the London Borough of Bromley. The mill was built in 1716 and is conserved with its machinery intact but not in working order.
Windmill Hill Mill is a grade II* listed post mill at Herstmonceux, Sussex, England which has been restored and now operates as a working mill. The mill is open to the public on most Sundays from Easter until October.
De Os is an oil windmill in the Zaanse Schans, Zaanstad.
De Gekroonde Poelenburg is a paltrok mill in Zaandam, Netherlands which has been restored to working order. Like all Dutch paltrok mills it is a windpowered sawmill. The mill is listed as a Rijksmonument, number 40093. It is located at the Zaanse Schans in a group of several historic industrial windmills.
Roekmole is a hollow post mill in nature reserve It Eilân in Goëngahuizen, Friesland, Netherlands. It was moved there from polder Krieke near Aldeboarn and has been restored to working order. The mill is listed as a Rijksmonument, number 35972.
Arkens is a Hollow Post mill in Franeker, Friesland, Netherlands which has been restored to working order. The mill is listed as a Rijksmonument, number 15710. It shares its name with the eponymous hamlet, just north of Franeker, Arkens.
De Jansmolen or De Modden is a Hollow Post mill in Goëngahuizen, Friesland, Netherlands which has been restored as a landscape feature. The mill is listed as a Rijksmonument, number 34000.
De Haensmolen is a Hollow Post mill in Grou, Friesland, Netherlands which was rebuilt in 2007 after it was demolished by a boat in 2004. The mill is listed as a Rijksmonument, number 22917.
Mijn Genoegen is a paltrok mill in the Netherlands Open Air Museum in Arnhem, Gelderland, Netherlands which has been restored to working order. As are all Dutch paltrok mills, it is a wind-powered sawmill.
De Eenhoorn is a paltrok mill in Haarlem, Netherlands which has been restored to working order. As all Dutch paltrok mills it is a windpowered sawmill. The mill is listed as a Rijksmonument, number 19872.
De Akkermolen is a 17th-century windmill in Zundert, Netherlands. Built around 1605 to replace an earlier windmill, it was used as a gristmill until it was severely damaged in 1950. The mill was bought by the local government and restored in 1961, and it was listed as a national heritage site in 1974.
Huizermolen is a post mill in the Netherlands Open Air Museum, Arnhem, Netherlands which was built in 1919 and is in working order.
A hollow post mill at the Netherlands Open Air Museum, Arnhem, Gelderland, Netherlands was originally built at Gouda, South Holland, Netherlands. It was dismantled in 1946 and re-erected at the museum. The mill has been restored to working order.
A hollow post mill at the Netherlands Open Air Museum, Arnhem, Gelderland, Netherlands was originally built at Wormer, North Holland, Netherlands. During World War I, it was moved to Langweer, Friesland. It was dismantled in 1960 and re-erected at the museum in 1989. The mill has been restored to working order.
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