Cobscar Mill ore hearth lead smeltmill, flue and chimney


Heritage Category: Scheduled Monument

List Entry Number: 1015822

Date first listed: 17-Apr-1997


Ordnance survey map of Cobscar Mill ore hearth lead smeltmill, flue and chimney
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The building or site itself may lie within the boundary of more than one authority.

County: North Yorkshire

District: Richmondshire (District Authority)

Parish: Redmire

National Grid Reference: SE 05861 93119


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

Reasons for Designation

Approximately 10,000 lead industry sites are estimated to survive in England, spanning nearly three millennia of mining history from the later Bronze Age (c.1000 BC) until the present day, though before the Roman period it is likely to have been on a small scale. Two hundred and fifty one lead industry sites, representing approximately 2.5% of the estimated national archaeological resource for the industry, have been identified as being of national importance. This selection of nationally important monuments, compiled and assessed through a comprehensive survey of the lead industry, is designed to represent the industry's chronological depth, technological breadth and regional diversity. Ore hearth smelt mills were introduced in the 16th century and continued to develop until the late 19th century. They were the normal type of lead smelter until the 18th century, when they were partially replaced by the reverberatory smelt mill. The ore hearth itself consisted of a low open hearth, in which lead ore was mixed with fuel (initially dried wood, later a mixture of peat and coal). An air blast was supplied by bellows, normally operated by a waterwheel; more sophisticated arrangements were used at some 19th century sites. The slags from the ore hearth still contained some lead. This was extracted by resmelting the slags at a higher temperature using charcoal or (later) coke fuel, normally in a separate slag hearth. This was typically within the ore hearth smelt mill, though separate slag mills are known. Early sites were typically small and simple buildings with one or two hearths, whereas late 18th and 19th century smelt mills were often large complexes containing several ore and slag hearths, roasting furnaces for preparing the ore, refining furnaces for extracting silver from the lead by a process known as cupellation, and reducing furnaces for recovering lead from the residue or litharge produced by cupellation, together with sometimes complex systems of flues, condensers and chimneys for recovering lead from the fumes given off by the various hearths and furnaces. The ore hearth smelt mill site will also contain fuel stores and other ancillary buildings. Ore hearth smelt mills have existed in and near all the lead mining fields of England, though late 18th and 19th century examples were virtually confined to the Pennines from Yorkshire northwards (and surviving evidence is strongly concentrated in North Yorkshire). It is believed that several hundred examples existed nationally. The sample identified as meriting protection includes: all sites with surviving evidence of hearths; sites with intact slag tips of importance for understanding the development of smelting technology; all 16th- 17th century sites with appreciable standing structural remains; 16th-17th century sites with well preserved earthwork remains; and a more selective sample of 18th and 19th century sites to include the best surviving evidence for smelt mill structures, and flue/condenser/chimney systems.

Despite its ruined state, Cobscar smeltmill retains rare visible furnace structures, and further intact stratigraphy of both furnace structures and process residues will survive hidden below the debris. The smeltmill was active for 130 years and was altered at least once during its lifetime. Archaeological evidence for this and other modifications made to the site during its working life are believed to survive, which together with a collection of rare contemporary photographs, will contribute to the understanding of the smeltmill's opperation. The site also includes an in situ slag heap which will retain important technological information about the efficiency of the mill's processes, and the development of smelting techniques over time. The intact chimney is also a local landscape feature.


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


The monument includes the standing, earthwork and buried remains of an ore hearth lead smeltmill, fuel store, and associated buildings, with the remains of a flue system leading to an intact chimney. It also includes a short length of flue from Keld Heads Mill and deposits of slag to the south. It lies within an area of open moorland within a wider lead and coal mining landscape. The monument includes the ruined remains of a waterpowered smeltmill built in 1762 to smelt ore from Cobscar Rake (upon which it is situated) and Cranehow Bottom Mine 0.8km to the north east. The smeltmill was divided into into three bays with a waterwheel (of c.6m diameter) powering a single set of bellows in the central bay, blowing two ore hearths to the south and a slag hearth in the remaining bay to the north. The building is choked with rubble following the part demolition by the army in the late 1940s, but walling typically survives to 2m, with one section surviving to a maximum of 4m. Photographs of the buildings, prior to the part demolition, provide evidence of the internal features of these structures. The bases of the hearths, settings for bellows and other remains are thought to survive beneath the rubble. Features that can be identified above the rubble include some of the iron strappings for the ore hearths and the arched opening through an internal wall for the bellows. Adjoining the north side of the smeltmill are the ruins of the roasting furnace building added in 1848. It includes part of the roasting furnace itself, which now stands to c.0.75m, retaining dressed stonework and iron tie bars. From the west wall of the smeltmill, two flues run uphill, merging after a few metres, to be joined in turn by the 2.5km long flue built in 1855 for Keld Heads Mill to the south east, of which a c.100m length is included in the scheduling. The flues, which have lost most of their capping stones, are typically c.2.5m wide, with occasional narrow openings on either side for maintenance access. The merged flue terminates at a chimney of a plain rubble stone construction, c.3.5m square and 9m tall, with a single drip course immediately below the coping stones. To the south of the mill there is a small slag heap which will retain important technological information about the smelting on the site. Extending to the east side of the roasting furnace building there are the footings and rear wall of a set of fuel and other storage buildings. To the south of these there is a small courtyard, footings of another store house and a pair of bingsteads (storage bays used for holding the unsmelted lead ore). The smeltmill ceased work around 1890, but remained largely intact with in situ machinery until the 1940s.

MAP EXTRACT The site of the monument is shown on the attached map extract.


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

Legacy System number: 29004

Legacy System: RSM


Books and journals
Clough, R T, The Lead Smelting Mills of the Yorkshire Dales, (1980), Indexed
Raistrick, A, 'The Smelting Mills' in The Lead Industry of Wensleydale and Swaledale, , Vol. 2, (1975), Indexed

End of official listing