De Modderige Bol is a Hollow Post mill in Goëngahuizen

Goëngahuizen

Goëngahuizen is a small village in Smallingerland in the province Friesland of the Netherlands and has around the 70 citizens .-Windmills:There are three windmills in Goëngahuizen, De Jansmolen, De Modderige Bol and Heechheim....

, Friesland

Friesland

Friesland is a province in the north of the Netherlands and part of the ancient region of Frisia.Until the end of 1996, the province bore Friesland as its official name. In 1997 this Dutch name lost its official status to the Frisian Fryslân...

, Netherlands

Netherlands

The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...

 which has been restored to working order. The mill is listed as a Rijksmonument

Rijksmonument

A rijksmonument is a National Heritage Site of the Netherlands, listed by the agency Rijksdienst voor het Cultureel Erfgoed acting for the Dutch Ministry of Education, Culture and Science.-History and criteria:...

, number 34001.

History

The date that De Modderige Bol was built is unknown. The earliest record is its appearance on a map dated 1848. Until 1952, the mill drained the polder Adamse, which had an area of 150 pondemaat. The mill was restored in 1954 and 1969. A further restoration was undertaken in 1978 by millwright

Millwright

A millwright is a craftsman or tradesman engaged with the construction and maintenance of machinery.Early millwrights were specialist carpenters who erected machines used in agriculture, food processing and processing lumber and paper...

s Bouwbedrijf Van Zuiden of Tjerkwerd

Tjerkwerd

Tjerkwerd is a small village in Wûnseradiel in the province Friesland of the Netherlands and has around 457 citizens ....

. On 9 November 1978, the mill was sold to Stichting de Fryske Mole (Frisian Mills Society). The mill was restored again in 1992-93.

Description

De Modderige Bol is what the Dutch describe as an spinnenkop -. It is a hollow post mill on a single storey square roundhouse. The mill is winded by tailpole and winch. The roundhouse is clad in pantiles and mill body is covered in vertical boards, while the roof of the mill is boarded and covered in felt. The sails are Common sails. They have a span of 11.9 metre. The sails are carried on a wooden windshaft. The windshaft also carries the brake wheel which has 43 cogs. This drives the wallower (21 cogs) at the top of the upright shaft. At the bottom of the upright shaft, the crown wheel, which has 31 cogs drives a gearwheel with 30 cogs on the axle of the Archimedes screw. The axle of the Archimedes screw is 250 millimetres (9¾ inches) diameter. The screw is 750 millimetre diameter and 3.4 metre long. It is inclined at 24°. Each revolution of the screw lifts 106 litres (23.3 imp gal) of water.