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 smeltmills and related features at Langley represent a complex lead works
of two separate, but interdependent smeltmills. These mills, which were
individually large and elaborate, were focussed on a small area and have a
complex history spanning over a century. The site is well documented in
contemporary accounts and all the major mining companies in the North Pennine
lead industry were involved in the site at various times: Greenwich Hospital,
the London Lead Company, WB Lead and the Hudgill Mining Company. The changing
fortunes of the lead industry left a series of distinct impressions on the
site, and the monument is a very good example of how economic, technological
and social factors shaped industrial sites in the late 18th and 19th
centuries. The entire layout of Langley Mill survives as earthworks which will
retain evidence for the development of the site and the technologies
employed. Langley was also an important early site for zinc smelting and
archaeological remains related to this process are also believed to survive.
The standing and earthwork remains of ancillary buildings will all add to the
understanding of the working of the site. The flue, which was extended and
modified several times, retains rare surviving evidence of a steam powered
condenser together with features related to the washing and lead recovering
system.
Details
The monument is situated towards the top of the hillside rising from the South
Tyne up to Stublick Moor. It includes the buried remains of a closely
associated pair of smeltmills, with the standing and earthwork remains of a
shared flue system which leads to an intact chimney.
The estates of the Earl of Derwentwater were forfeited to the Crown after his
part in the 1715 Jacobite Rebellion. These lands, which included the mineral
rich area of Alston Moor, were assigned to the Greenwich Hospital in 1735. The
London Lead Company took most of the mineral leases and paid Greenwich
Hospital a rent in the form of duty ore. Initially this ore was sold back to
the London Lead Company who smelted it at their smeltmill at Nenthead, but in
1768 Greenwich Hospital built their own smeltmill at Langley and started
smelting the ore themselves. The mill was further expanded in the 1770s and
the mill, in addition to the ore hearths, included two refining furnaces (for
extracting silver from the lead ore), a reducing furnace (used to convert the
lead litharge, which was left after the silver had been extracted, into
metallic lead), and a slag hearth (for resmelting the waste slag from the ore
hearths). In the 1780s the Greenwich Hospital built a second smeltmill next
to, and downhill from Langley Mill which was leased to one of the smaller
mining companies. This mill, known as Blagill Mill, used the tailrace water
from Langley Mill and later shared the same flue system. In 1801-1803, the
first section of horizontal flue was constructed, which extended 70m to 75m
uphill from Langley Mill. By 1805, each had three ore hearths, a double
refining furnace, a slag hearth, and roasting and reducing furnaces. The
complexes each had a water powered stamp mill (for breaking the slag into
smaller pieces prior to reprocessing), in addition to a number of store rooms
for the different sorts of fuel used by the various processes and for lead at
various stages in production. By around 1817 zinc was also being smelted at
Langley. This was initially very successful, but due to competition from
Germany, the zinc works closed around 1822. By this date, Langley Mill had
increased to seven ore hearths and the Blagill Mill was leased by another
company, the Hudgill Burn Mining Company. Between 1845 and 1860 the flue
system was extended further by approximately 580m with a steam powered
condenser installed before 1865. From cartographic evidence most of Blagill
Mill had been demolished c.1860, leaving the reducing and refining house which
was then converted into cottages. The last 500m section of flue leading to the
chimney was built after the first edition 25 inch Ordnance Survey map and was
complete by 1882. The mills finally closed in 1887 and much of the remaining
works had been demolished by 1896.
The building range known as Sawmill Cottages, which includes a two storey
house at the east end of a row of three cottages, is excluded from the
scheduling, although the ground beneath it and the flue which exits the
building through the south wall are included. The 1805 plan of Blagill Mill
shows this range of buildings to be the reducing and refining house.
Across the trackway to the west of the cottage conversions there is another
range of buildings, mostly surviving as wall footings with the easternmost
single storey lean-to building still roofed and used as a garage. This
building range is considered to have comprised ancillary buildings (such as
store-rooms and workshops) and will retain buried deposits that will allow the
identification of their functions. The remains of the range of buildings is
included within the scheduling. To the east of the cottages
there are a series of small gardens belonging to the currently occupied
terrace. The revetment wall to the south of the gardens is thought to contain
features from the original smeltmill or even to have once been part of it. To
the south of this wall and the trackway that runs along the north side of the
cottages, the land surface rises to a trackway that runs along the foot of the
reservoir's dam. This area contains a number of terraces that include
earthworks up to 0.75m high which are the remains of Langley Mill with
associated ancillary buildings related to both mills. The entire layout of
Langley Mill is believed to survive with in situ deposits of process residues
which will retain important technological information about lead smelting from
1770 onwards as well as early 19th century zinc smelting. One nearly complete
building survives at the east end of the area, 60m east of the cottages, which
has been interpreted as a coal and lime house dating to before 1805. This twin
celled, two storey stone building built into the rising ground, retains some
flooring and more than half of its stone slab roofing. Across the trackway
behind this building there is the approximately 2m high earthwork dam for the
reservoir (which still holds water). This reservoir was part of a complex
water management system which supplied water to both mills. The original
reservoir was extended eastwards sometime after 1805 to triple the size shown
on the 1805 plan. It was supplied from a second larger reservoir (Langley Dam)
built around 1805, 0.4km to the south west. The embankment of the dam adjacent
to the smeltmills has been altered in places to provide platforms for anglers
and the north eastern end of the dam is not included in the scheduling.
The section of dam included in the scheduling retains at least three different
construction styles. The southern end of the dam incorporates the earliest
section of the flue built in 1805. In front of the section of walling is
an in situ iron valve assembly which is interpreted as part of the water
control mechanism for the smeltmills. To the west of the dam are the
foundations of another building dating to before 1860 with further earthworks
to the rear standing up to 0.2m high which, from cartographic evidence, are
thought to be early bingsteads (storage bays for unsmelted ore). Remains of
further bingsteads are thought to survive along the flue where it forms part
of the dam.
The flue was extended after 1805 and zig zags up the hillside. It is thought
to have been constructed as a stone lined trench about 1.5m wide which was
arched over with a single thickness of pitched stones and then covered with
the earth excavated from the trench, thus stabilising the construction. For
most of its length the flue survives as an earthwork averaging 1m high and 6m-
7m wide with a hollow running along its top where the stone arching has
collapsed. The flue was modified in the 1860s to allow the construction of the
Hexham to Allendale railway, with a stone bridge being built to carry the flue
across the railway cutting.
Langley Mill actively tried to recover lead from the fumes of the furnaces and
the earthwork remains of the steam powered condenser and associated features
such as low mounds of boiler waste, are included in the scheduling. Just
downhill from these earthworks on either side of the flue are the earthworks
of a pair of small reservoirs. One is thought to have provided water for the
steam engine's boiler which powered the fan in the condensor, but both are
thought to have been part of the washing system for the flue. It is thought
that periodically workmen entered the flue (via a number of access points
along its length) to scrape the deposited material off the walls. Water was
then allowed into the flue to wash the material down its length and into
settling tanks where the water was allowed to evaporate off, leaving a lead
rich mud which was then resmelted. Maintenance access points can be identified
at several points along the flue's length retaining its side walling through
the bank of the flue, the others as earthwork features considered to retain
buried walling. A third small reservoir is located immediately on the west
side of flue between these two of the access points. Three settling tanks have
also been identified. The first (NY 8334 6230) is a 1.5m deep depression
located at the bottom of the steepest section of flue whilst the second is
approximately 120m to the south west. The last lies on the south side of the
disused railway line, measures 8m by 8m with a 1m high embankment, with
another level area served by a trackway immediately to the east. All of these
features identified as being part of the washing system for the flue are
included within the scheduling.
In the 1860s the flue was extended an additional 0.5km beyond the steam
powered condensor to end at a chimney on Stublick Moor. This section of flue
was slightly wider and, for most of its length, was buried deeper. A small
collapsed section, just north of the road, shows that it was 2m wide and 2m
high internally, with an arched roof formed by a single thickness of pitched
stone. The top of the arch was level with the surrounding land surface and was
covered by 0.5m of earth forming the 6m to 7m wide mound that can be seen
running across the fields. It is thought that the flue is intact underneath
the B6305, and so this section has also been included in the scheduling. At
the end of the flue is the chimney which is mostly built in rough ashlar
masonry, with the upper third in brick.
A number of features are excluded from the scheduling; these are the surface
foundations of the B6305 road, modern metalled trackways, the small modern
concrete building at NY 8294 6149, Sawmill Cottages, the building west of the
dam and all fencing and drystone walls; although the ground beneath all these
features is included.
MAP EXTRACT
The site of the monument is shown on the attached map extract.
