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Gunpowder factory at Powder Mills, a partially enclosed stone hut circle settlement and round cairn

List Entry Summary

This monument is scheduled under the Ancient Monuments and Archaeological Areas Act 1979 as amended as it appears to the Secretary of State to be of national importance. This entry is a copy, the original is held by the Department for Culture, Media and Sport.

Name: Gunpowder factory at Powder Mills, a partially enclosed stone hut circle settlement and round cairn

List entry Number: 1016635

Location

The monument may lie within the boundary of more than one authority.

County: Devon

District: West Devon

District Type: District Authority

Parish: Dartmoor Forest

National Park: DARTMOOR

Grade: Not applicable to this List entry.

Date first scheduled: 09-Oct-1981

Date of most recent amendment: 02-Jul-1999

Legacy System Information

The contents of this record have been generated from a legacy data system.

Legacy System: RSM

UID: 28718

Asset Groupings

This list entry does not comprise part of an Asset Grouping. Asset Groupings are not part of the official record but are added later for information.

List entry Description

Summary of Monument

Legacy Record - This information may be included in the List Entry Details.

Reasons for Designation

Gunpowder was the only explosive available for military use and for blasting in mines and quarries until the mid-19th century. Water-powered manufacturing mills were established in England from the mid-16th century, although powder had been prepared by hand for at least 200 years. The industry expanded until the late 19th century when high explosives began to replace gunpowder. Its manufacture declined dramatically after the First World War with British production ceasing in 1976. The technology of gunpowder manufacture became increasingly complex through time with the gradual mechanisation of what were essentially hand-worked operations. Waterwheels were introduced in the 16th century, and steam engines and water turbines from the 19th century. Pressing and corning were also introduced between the 16th and 19th centuries to improve the powders. Pressing improved the explosive power of the mill cake and corning broke the pressing cake into different sizes and graded it with respect to its fineness. Additional techniques were developed throughout the 17th, 18th and 19th centuries to improve the quality and consistency of the finished product, and this in turn resulted in a variety of types of powders; ranging from large coarse-grained blasting powders used in mines and quarries, to fine varieties used, for example, in sporting guns. Gunpowder manufacturing sites are a comparatively rare class of monument with around 60 examples known nationally. Demand for gunpowder centred on the London area (for military supply), other ports (for trade), and the main metal mining areas. Most gunpowder production was, therefore, in Cumbria, the south west, and the south east around the Thames estuary. The first water-powered mills were established in south east England from the mid-16th century onwards, and many of the major technological improvements were pioneered in those mills. All sites of gunpowder production which retain significant archaeological remains and technological information and survive well will normally be identified as nationally important.

The gunpowder factory at Powder Mills survives well and contains a complete range of buildings and other structures and features associated with the industry. Many of the buildings remain essentially intact, with only the roofs and machinery having been removed. The system of leats and trackways provides useful additional information concerning the character of the factory. The unique survival of the associated proving mortar emphasises the quality of the surviving archaeology. Together with a comprehensive historical background this represents a fine example of a gunpowder production site. The prehistoric settlement and cairn associated with the Powder Mills are of national importance in their own right and contain information relating to the exploitation of the central part of Dartmoor during the Bronze Age.

History

Legacy Record - This information may be included in the List Entry Details.

Details

The monument, which falls into five areas, includes a gunpowder factory, a partially enclosed stone hut circle settlement and a round cairn situated adjacent to the Cherry Brook. The gunpowder factory, which is Listed Grade II, comprises at least 18 buildings involved in the production, storage and management of gunpowder. Many of these buildings contained machinery which was powered by water which was carried to the site by three large leats from the East Dart and Cherry Brook rivers. These are included in the scheduling. A system of trackways link the buildings and the river was crossed by way of clapper bridges. The gunpowder factory established in 1844 by George Frean, was certainly operational by 1846 and remained in use until 1897, when it closed as a result of increasing competition from dynamite and a slump in local mining activity. The production of gunpowder involved combining a mixture of saltpetre, sulphur and charcoal and the buildings in which the different stages of the process were carried out survive at Powder Mills. The process was inherently dangerous and to reduce the chances of cataclysmic explosions, the buildings were situated at a safe distance from each other and each had a flimsy roof which would have allowed any explosion to be carried upwards. Several explosions are known to have occurred at Powder Mills and fortunately these precautions may have ensured that no workers were ever killed. Amongst the buildings identified at Powder Mills are: grinding mills, where the ingredients were crushed separately between horizontal rotating millstones; blending mills, where the ingredients were mixed in rotating barrels; incorporation mills, where the material from the blending mills was mixed further into a single compound; a range of buildings where the gunpowder was broken, pressed, corned, dried, dusted and glazed; and finally charge magazines, where the gunpowder was stored. Further buildings on the site may have been used as storage or office accommodation. The quality of the finished gunpowder had to be tested and at Powder Mills this appears to have been carried out using two very different techniques. At SX 63777681 a proving mortar, which was used to test the strength of the gunpowder, still sits on a restored carriage. Whilst at SX 62757750 a number of large boulders have been split using a single charge, possibly the result of of testing. To the south west of the gunpowder factory stands an isolated rectangular building in which finished gunpowder was stored prior to transportation. Within the vicinity of the gunpowder works there are four quarries from which material was derived during the construction of the buildings. Parts of the valley bottom contain earthworks related to tin streamworking. A partially enclosed stone hut circle settlement lies adjacent to the leat carrying water from the East Dart and survives as a series of four enclosures associated with at least 13 stone hut circles. The enclosure walls are of rubble bank construction standing up to 0.4m high. The stone hut circles survive as circular or oval walls surrounding an internal area varying between 4 and 50 square metres. A round cairn lies immediately west of the settlement and survives as an 8.7m diameter mound standing up to 0.9m high. Large edge set stones on the north western edge of the mound may suggest the presence of a kerb which survives elsewhere as a buried feature. A pit in the centre of the mound suggests partial early excavation or robbing. Modern post and wire fences, a shed and piles of sand and other materials associated with a consolidation programme are excluded from the scheduling, although the ground beneath them is included.

MAP EXTRACT The site of the monument is shown on the attached map extract. It includes a 2 metre boundary around the archaeological features, considered to be essential for the monument's support and preservation.

Selected Sources

Books and journals
Pye, A, 'The Archaeology of Dartmoor - Perspectives from the 1990's' in The Gunpowder Factory at Powdermills, , Vol. 52, (1996), 221- 20
Other
Devon County Sites and Monuments Register, SX67NW12, (1994)
Devon County Sites and Monuments Register, SX67NW248, (1992)
Devon County Sites and Monuments Register, SX67NW251, (1992)
Devon County Sites and Monuments Register, SX67NW251.2, (1992)
Devon County Sites and Monuments Register, SX67NW266, (1994)
Devon County Sites and Monuments Register, SX67NW267, (1994)
Devon County Sites and Monuments Register, SX67NW304, (1994)
Gerrard, S., English Heritage Book of Dartmoor, 1997, Forthcoming
MPP Fieldwork by S. Gerrard, Gerrard, S., (1998)
MPP Fieldwork by S. Gerrard, Gerrard, S., (1998)
Title: Archaeological survey and evaluation: Powder Mills and Gawler Source Date: 1989 Author: Publisher: Surveyor: 1:10,000 Map
Title: Archaeological survey and evaluation: Powder Mills and Gawler Source Date: 1989 Author: Publisher: Surveyor: 1:10,000 Map

National Grid Reference: SX 62513 76581, SX 62784 76821, SX 63157 77835, SX 63193 77808, SX 63432 77839

Map

Map
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End of official listing