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.
Lumb Clough smeltmill is a good example of the small, simple ore hearth
smeltmill typical of the 17th and early 18th centuries. The rare preservation
of a complete layout survives with reservoir, wheelpit and tailrace in
addition to the smeltmill itself with its remains of the hearth and settings
for the bellows. The wood drying kiln, which also survivies in good condition
is also a rare structure nationally. The smeltmill was excavated to floor
level in 1973, but intact archaeological stratigraphy will survive, especially
to the north and east of the mill building where stratified deposits of slag
and fuel retaining important information about the development of smelting
technology are believed to remain in situ.
Details
The monument lies to the west of a confluence of two streams in the base of a
narrow wooded valley. It includes the buried and standing remains of a small
water-powered lead smeltmill, together with its associated reservoir and
wheelpit. The site also includes the standing remains of a small wood drying
kiln.
Investigated and partly excavated to floor level by the Northern Mine
Research Society in 1973, Lumb Clough smeltmill is an example of a simple ore
hearth smeltmill. Water, taken directly from Lumb Clough Beck, filled a small,
now silted reservoir originally 10m by 30m which is terraced into the valley
side, to power an overshot or high breastshot waterwheel to the dam before
returning to the beck via a culverted tailrace, which is also included in the
scheduling. The smeltmill, measuring 5.5m north-south by 4.6m wide, is
visible as wall footings and retains in situ settings for a pair of bellows
(originally powered by the waterwheel) just to the south of the stone
foundations of the ore hearth. The hearth is flanked by a pair of 0.9m high
gritstone `keeper stones'.
The 1973 excavation of the wheelpit, which lies on the east side of the
smeltmill, showed it to be 6.7m by 0.45m by 2.1m deep with a stone flagged
floor, with a partly collapsed tailrace chamber at its north end. It has since
been partly infilled, although the low arched (0.3m) end of the tailrace
culvert c.20m to the north of the smeltmill remains visible and is still
issuing water. Approximately 15m north east of the ore hearth a well preserved
drystone structure is built into the bank of a former steam course. Key-hole
shaped in plan, it measures 1.4m in diameter and 1.8m deep, tapering towards
the base. This is believed to be the remains of a wood drying kiln used to dry
wood to produce `white coal' which was often mixed with peat and coal, and
used as fuel in ore hearths.
The surrounding area retains small quantities of scattered slag; both vitreous
(black) slag and grey slag are visible. This material, typical for smeltmill
sites, retains important technological information, and is included in the
scheduling.
MAP EXTRACT
The site of the monument is shown on the attached map extract.
