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Summary

Building 17: Possible saltpetre crystallising house built in the 19th century at Powder Mills gunpowder factory

Location

Protected Status

• Scheduled Monument 1016635: Gunpowder factory at Powder Mills, a partially enclosed stone hut circle settlement and round cairn

Other References/Statuses

• Old DCC SMR Ref: SX67NW/51/17
• Old SAM Ref: 28718

Monument Type(s) and Dates

• INDUSTRIAL BUILDING (XVIII to XIX - 1800 AD to 1900 AD (Between))

Full description

Ordnance Survey, 1880-1899, First Edition Ordnance 25 inch map (Cartographic). SDV336179.

Long rectangular building with small square addition to the south shown on 19th century map.

Ordnance Survey Archaeology Division, 1979, SX67NW99 (Ordnance Survey Archaeology Division Card). SDV350197.

Pye, A. R. + Robinson, R., 1990, An Archaeological Survey of the Gunpowder Factory at Powdermills Farm, Postbridge, Devon, 35-36, Figure 13, Plate 27 (Report - Survey). SDV254157.

Building 17: possible saltpetre crystallising house at Powder Mills gunpowder factory. Long rectangular structure located at the extreme southern end of the site and aligned north to south. Single-storey with later extension to south. Two, possibly three, phases have been identified:
Phase 1: central part of existing building. Rectangular. Flat roof. Door and two windows through east wall. Water culverted through the building under the floor. Its north wall was probably the dwarf wall which now subdivides it from the extension to the north.
Phase 2: northern extension built, with central doorway through north wall, door and window in east wall. Cartshed added to south end of original building, with gabled roof. Cartshed is square and open towards the east, with central pillar originally supporting roof. All walls apart from south gable end survive to full height. The main (central) portion of the building has south and west walls surviving to full height. North wall largely demolished. Appears to have been either flat roofed, or to have had timber gable ends. Two partially blocked doorways and two windows through the east wall; tall, broad opening midway between the northern of the two entrances and the north-east corner of the building. No openings present in west wall, although its north end has partially collapsed.
The building has two elements:
Unit (a); a square gable-ended building open towards the east with a central pillar originally supporting the roof. All walls, apart from the southern gable, survive to full height. The west wall abuts the south-west corner of the earlier building to the north
Unit (b): the main portion of the single storey building with the southern and western walls surviving to full height. The northern wall has been largely demolished. The south gable was added when Unit (a) was built to the south.
There are two partially blocked doorways through the eastern wall with two windows in between. A broader and taller opening exists in the northern section of the eastern wall.
Dwarf walls in the interior consist of one long spine wall and two side walls. Another dwarf wall runs east to west across the structure from the northernmost door to the east wall. These appear to form a raised floor with water, air or heat circulating beneath. A small, square, stone-lined feature to the west of the south-west corner may be a well, or possibly a pit in which staves were soaked.

Pye, A., 1996, The Gunpowder Factory at Powdermills, 221 (Article in Serial). SDV254160.

Gerrard, S., 1998, 149191 (Un-published). SDV256815.

Saltpetre crystallising house forming part of the gunpowder factory at Powder Mills.

Ordnance Survey, 2012, MasterMap (Cartographic). SDV348725.

Long rectangular building shown on modern mapping. The southern section appears to be vegetated. Map object based on this source and 19th century map.

English Heritage, 9/10/1981, Gunpowder factory at Powder Mills (Schedule Document). SDV350194.

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 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. 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.

Sources / Further Reading

Associated Monuments

Associated Finds: none recorded

Associated Events

• EDV6029 - An Archaeological Survey of the Gunpowder Factory at Powdermills Farm

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