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HER Number:MDV6170
Name:Blowing mill at Outer Down, Chagford


A well preserved blowing mill with a wheel pit and possible furnace structure and walled yard at Outer Down, Chagford. At Outer Down, south of the house (at each corner of the garden path) are the remains of a mortarstone and an unbroken mouldstone.


Grid Reference:SX 682 865
Map Sheet:SX68NE
Admin AreaDartmoor National Park
Civil ParishChagford
DistrictWest Devon
Ecclesiastical ParishCHAGFORD

Protected Status

Other References/Statuses

  • National Monuments Record: 443644
  • Old DCC SMR Ref: SX68NE/45
  • SHINE Candidate (Yes)

Monument Type(s) and Dates

  • TIN MILL (Early Medieval to Post Medieval - 1066 AD to 1750 AD (Between))

Full description

1840, Tithe Map (Cartographic). SDV339770.

Tithe apportionment lists 523: copse, 525: Twicky stones.

Worth, R. H., 1927, A blowing house in the parish of Chagford, 343-4 (Article in Serial). SDV275194.

Outer Down blowing mill/stamping mill? building divided into two compartments, separated partially by a wall, through which there is an opening, 0.63 meters wide, a greater thickness than the outer walls. Furnace may have been placed here. Well marked leat, which still carries water to another site. Wheel may have been 3.05 meters in diameter and 0.4 meters breast. A broken mouldstone was found, cavity at the bottom. Another mouldstone from this house has been removed to the grounds of Outer Down. It would contain 171 kilograms of tin when filled. There is also a mortar, diameter 0.28 meters, depth 0.19 meters also taken to Outer Down grounds. The broken mouldstone was built into the outer wall of the building. Other details: Plate 12-13, Figure 1.

Worth, R. H., 1940, The Dartmoor Blowing House, 212-3 (Article in Serial). SDV154693.

Ordnance Survey Archaeology Division, 1978, SX68NE59 (Ordnance Survey Archaeology Division Card). SDV275193.

The blowing-house at 'Outer Down' is in a ruinous condition. The outer wall, 0.8 meters to 0.9 meters thick, varies in height up to a maximum of 1.7 meters, and consists of massive roughly-squared blocks of stone. The leat was on the west side but its course into the building cannot be traced. An interior wall at right angles to the long side divides the building into two chambers of unequel size. The wheel pit is visible in the south west corner and is 0.3 meters deep. A broken mould stone is set in the wall on the west side of the entrance in the north wall.
About 5.0 meters south of the house, at each corner of a garden path, are an unbroken mould-stone measuring 0.8 meters by 0.7 meters with a cavity 0.4 meters by 0.3 meters by 0.15 meters deep, and a mortar-stone measuring 0.9 meters by 0.5 meters, with a mortar-hole 0.3 meters by 0.3 meters by 0.2 meters deep. Other details: Plan.

Greeves, T. A. P., 1981, List of Known Devon Tin Mills c1450 - c1750 (Report - non-specific). SDV319826.

Mould stones still visible. Blowing/stamping? mill (undocumented) field evidence. Documented mill at Hole and Collaton may be identified with this mill. Other details: no 37, 65.

Greeves, T. A. P., 1981, Medieval Industry, 92 (Article in Serial). SDV275197.

Analysis of slag gave results of 13.5% tin. This indicates very poor smelting conditions. This is listed as a pre-1700 tin-mill.

Greeves, T. A. P., 1990, An Assessment of Dartmoor Tinworking, 39 (Report - Assessment). SDV343684.

Cranstone, D. + Hedley, I., 1995, The Tin Industry, Step 3 Site Assessments: Devon, 59,61 (Report - Assessment). SDV346887.

A well preserved blowing mill with a wheel pit and possible furnace structure and walled yard.

Ordnance Survey, 2011, MasterMap (Cartographic). SDV346129.

'Blowing House' depicted on the modern mapping.

English Heritage, 2013, National Heritage List for England (National Heritage List for England). SDV350785.

An early post-medieval tin blowing mill, terraced into a west-facing slope within the valley of the South Teign River. It is situated in the gardens to the west of Outer Down, an early-C20 country house (Grade II).
The blowing mill at Outer Down is scheduled for the following principal reasons: * Archaeological interest: the site is an early post-medieval blowing mill which is of national importance for the understanding of tin smelting; * Survival: the blowing mill has been identified as one of the best surviving blowing mills on Dartmoor; * Potential: the site has not been excavated and will contain important archaeological and metallurgical information concerning the character and technology of early tin smelting.
From the medieval period until the early C19 black tin (cassiterite) extracted from streamworks and mines was taken to blowing mills (also known as blowing houses) to be smelted. At the blowing mill the cassiterite may have been washed a final time before being put in the furnace together with charcoal. To smelt tin the temperature within the furnace had to reach 1150°C. This was achieved by blowing air through the furnace using water-powered bellows. Once the tin had become molten, it flowed from the furnace into a float stone and was ladled into the mould stone, in which it cooled to form an ingot of white tin.
Blowing mills are typically rectangular drystone buildings served by one or more leats and internally are characterised by the presence of granite blocks with moulds cut into them – bevelled rectangular troughs known as mould stones – and on occasion by the survival of the square or rectangular stone-built base of the furnace itself.
The original number of blowing mills on Dartmoor is unknown but at least 26 are believed to survive, whilst a further 41 are known only from stray finds and documentary sources. This blowing mill at Outer Down is considered to be of early post-medieval date and is located 250 metres to the west of the hamlet of Thorn. It is depicted on the current Ordnance Survey map as well as the second edition OS map published in 1905.
In 1927, a measured survey of the blowing house was undertaken by R H Worth. In the late C20 an analysis of slag recovered from the vicinity of the mill revealed that it contained 13.5% tin. This high proportion of tin indicates poor smelting efficiency and would, therefore, suggest a relatively early date for the operation of this blowing mill.
The blowing mill which is probably early post-medieval in date, survives as a roofless ruin. It is built of granite blocks and is rectangular in plan. The interior is divided into two rooms, the smaller of which contains a wheel pit against the southern wall.
The blowing mill is terraced into a west-facing slope within the valley of the South Teign River. It survives as a ruinous, rectangular building; the walls standing up to 1.7m high. The interior of the mill is divided into two rooms. The smaller, western, room measures 4.9m long by 3m wide and contains a wheel pit built against the southern wall. The eastern room measures 7.4 m long by 4.9m wide and is filled with rubble. The internal dividing wall has a 1m wide opening at its north end. Although there is no visible evidence for the furnace, the dividing wall is of a greater thickness (1.5m) than the external walls which may indicate that this is the position of the furnace. Buried archaeological deposits associated with the furnace may survive in the vicinity of this internal wall. A broken mould stone has been incorporated into the north wall of the structure. The scheduled area occupies a roughly rectangular area measuring approximately 15m by 6m.
The mortar stone and mould stone within the garden of Outer Down, that lie some distance from the scheduled monument, are not included in the scheduling.

Sources / Further Reading

SDV154693Article in Serial: Worth, R. H.. 1940. The Dartmoor Blowing House. Transactions of the Devonshire Association. 72. 212-3.
SDV275193Ordnance Survey Archaeology Division Card: Ordnance Survey Archaeology Division. 1978. SX68NE59. Ordnance Survey Archaeology Division Card. Card Index.
SDV275194Article in Serial: Worth, R. H.. 1927. A blowing house in the parish of Chagford. Transactions of the Devonshire Association. 59. Unknown. 343-4.
SDV275197Article in Serial: Greeves, T. A. P.. 1981. Medieval Industry. Council for British Archaeology Research Report. 40. Unknown. 92.
SDV319826Report - non-specific: Greeves, T. A. P.. 1981. List of Known Devon Tin Mills c1450 - c1750. List of Known Devon Tin Mills c1450 - c1750. 35. Unknown.
SDV339770Cartographic: 1840. Tithe Map. Tithe Map and Apportionment. Map (Paper).
SDV343684Report - Assessment: Greeves, T. A. P.. 1990. An Assessment of Dartmoor Tinworking. Digital. 39.
SDV346129Cartographic: Ordnance Survey. 2011. MasterMap. Ordnance Survey. Map (Digital). [Mapped feature: #96851 ]
SDV346887Report - Assessment: Cranstone, D. + Hedley, I.. 1995. The Tin Industry, Step 3 Site Assessments: Devon. English Heritage Report. Unknown. 59,61.
SDV350785National Heritage List for England: English Heritage. 2013. National Heritage List for England. Historic Houses Register. Digital.

Associated Monuments

MDV54522Related to: Clampitt Leat, Chagford (Monument)
MDV30884Related to: Slag from Outer Down blowing mill, Chagford (Monument)
MDV30885Related to: Slag from Outer Down blowing mill, Chagford (Monument)
MDV30886Related to: Slag from Outer Down blowing mill, Chagford (Monument)
MDV30887Related to: Slag from Outer Down blowing mill, Chagford (Monument)

Associated Finds: none recorded

Associated Events: none recorded

Date Last Edited:Oct 4 2013 10:14AM