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.
The Linacre smelt mill is a well preserved and undisturbed set of earthworks,
representing the complete layout of an early ore hearth smelting complex. This
degree of preservation is rare nationally. In addition, it is one of the
earliest documented sites in England of which any remains are known to
survive.
Details
The Linacre smelt mill is an early example of an ore hearth lead smelt mill,
surviving as earthworks in woodland on the south side of Linacre Brook.
The west end of the monument is formed by an earthwork dam up to 3m high,
running north-south across the valley floor and breached by the modern course
of Linacre Brook at the north end. An overflow spillway is visible at the
south end. The smelt mill wheelpit is clearly visible as a hollow east of the
south end of the dam, and the site of the smelt mill itself survives as a flat
area immediately north of the wheelpit, with a scatter of building debris.
Slag tips extend east from the building platform, on the north side of a tail-
race (4m wide and up to 2m deep) running east from the wheelpit to re-enter
Linacre Brook.
The smelt mill was first documented in 1596, and last documented in 1613.
MAP EXTRACT
The site of the monument is shown on the attached map extract.
