Details

The monument includes a complex of mine features, mostly of 19th century date,
around the Hitchen's Shaft of the Holmbush Mine, north of Kelly Bray near
Callington in south east Cornwall. The Hitchen's Shaft complex was part of the
overall extent of the Holmbush Mine, a copper, lead and arsenic mine operating
mainly during the 19th century but developed from earlier activity, traces of
which are included within this scheduling. The pumping engine house, winding
engine house and their respective boiler house chimneys in this scheduling are
Listed Buildings Grade II.
The earliest mining at Holmbush, recorded from the 17th and 18th centuries,
relates to lead ore extraction from a north-south lode by shallow workings
into uppermost levels of the lode, a phase identified with uneven ground in
this scheduling extending north and west from the 19th century features.
Records indicate further activity in the 1790s and by the 1820s shafts were
being sunk on copper-rich east-west lodes in two areas: that in this
scheduling was called West Holmbush; East Holmbush, beyond this scheduling,
was focussed on a valley 300m to the ESE. By 1826 the shaft at West Holmbush
was served by a 36 inch (91.5cm) pumping engine and a horse-powered winding
drum called a horse-whim. From the early 1830s, investment in progressively
larger steam-powered pumping engines and the replacement of the horse-whim by
steam winding engine allowed Hitchen's Shaft to be deepened to 175 fathoms
(320m) by 1860. From the 1830s to the 1860s, the mine produced large
quantities of copper ore with some lead and associated silver ore. During the
period of peak production, from the 1840s to 1892, Hitchen's Shaft formed the
main pumping, winding and access shaft for the Holmbush Mine, along with its
chief ore-crushing facility and primary waste dump. With those functions it
complemented the mine's service and administrative complex, ancillary shafts,
dressing floors and their waste dumps, all sited beyond this scheduling in the
valley to the east. The mine's workforce and supply needs promoted the growth
of the nearby settlement of Kelly Bray and, from 1872, the siting there of the
East Cornwall Mineral Railway's terminus.
The developing structural complex around Hitchen's Shaft appears on the Stoke
Climsland tithe map of 1841, calling it the `Little Hurldown Mine', but the
shaft-head arrangement shown bears little relationship to the disposition of
surviving structures. By contrast, a sketch of the 1860s shows a shaft-head
complex by then containing several features still extant. These included the
pumping engine house, to the south of the shaft, with walls surviving to full
height though incorporating subsequent modifications when later engines were
installed: by 1876 the engine house contained an 80 inch (2m) beam engine
whose granite bedstones remain in the engine house.
North of the pumping engine house, the mouth of Hitchen's Shaft itself has
been covered by a low mound and is no longer visible. Immediately west of the
shaft is a tall balance bob slot, 1m wide, in which a heavy balance bob was
pivoted from the upper end of the pump rods to counter-balance their weight.
The unusual 3.4m height of the slot walls reflects its function also as a
plinth to support a water tank serving either the pumping engine's condensing
needs or to power a water wheel sited to the west.
To the west of the pumping engine house, its boiler house, shown on the 1860's
sketch as a two-gabled building, survives with a rectangular sunken interior
defined by extensive lengths of its lower walling; in its southern half are
three elongated low mounds which steadied the three boilers. At the boiler
house's south west corner its chimney survives to about 15m high, built of
local rubble but with a brick upper section now partly collapsed.
The 1860's sketch also shows some structures removed during later decades of
the mine's operation, including a winding engine house with its winding drum,
boiler house and detached chimney located east of Hitchen's Shaft in an area
now covered by the southern lobe of the mine's later spoil dumps. A building
shown west of the pumping engine boiler house may be a copper crusher house,
later replaced by a larger crusher building still extant on the site.
In 1876, the Holmbush Mining Company was formed to extract arsenic ore which,
by the early 1880s, had joined copper ore as the mine's chief profitable
products. The 1883 Ordnance Survey map shows the mine in this phase,
confirming the presence of further features surviving in the Hitchen's Shaft
complex. North west of the pumping engine boiler house is a water wheel pit,
7m long by 1m wide, with massive side-walls. Against its southern wall is a
pit for the pitwheel taking the drive from the water wheel. To the south, the
map shows a building, now gone, perhaps the copper crusher on the 1860's
sketch. In addition to powering that copper crusher, the water wheel at this
stage may have driven the Hitchen's Shaft winding gear as enlarged dumps had
supplanted the winding engine east of the shaft by 1883 with no replacement
evident. The water wheel was fed from a reservoir to its north west, shown in
1883 as rectangular, subdivided by a bank partitioning its western third,
arrangement visible in the now dry reservoir ponds.
After the arrangement shown on the 1883 map, further developments are evident
from historical sources and the disposition of surviving remains. By 1884
three rock drills were in use and in the following year the mine achieved its
highest annual production of copper ore, though falling ore prices severely
diminished its value and greater profits were gained from arsenic production.
The increased production reflects the addition, in the mid-1880s, of a winding
engine house sited 60m west of the shaft and survivng with walls to full
height, accompanied by masonry loadings of its crank pit and winding cage on
the east. Along the north side of the engine house and extending to its west
is its boiler house, its south wall surviving to 3m high but with its north
wall partly collapsed. To the west of the boiler house, its chimney survives
to full height, about 14m, of local rubble on brick lower courses and with a
brick upper section. A rectangular reservoir was also added across the north
of the earlier two, a pattern shown on the 1906 map and still clearly visible
on the ground. Broadly contemporary with these changes, a larger copper
crusher house was built west of the pumping engine bolier house, its walling
now partly collapsed but with its south wall surviving to full height.
In the later 1880s the mine became increasingly uneconomic against cheaper
ores available from overseas; shaft-mining operations eventually ended in
1892, followed by limited and intermittent activity during the first half of
the 20th century which included reworking parts of the mine's dumps.
The monument includes a 2m margin considered essential for the monument's
support and preservation where the mine buildings directly abut the modern
field adjacent to the south.
All modern fences, gates and posts, the water main and its trench, and the
electricity supply cables and their posts are excluded from the scheduling,
although the ground beneath all these features is included.

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

Source: Historic England

Reasons for Scheduling

For several millennia the south west peninsula has been one of the major areas
of non-ferrous metal mining in England, its more important and prolific
products including copper and tin along with a range of minor metals and other
materials, notably arsenic, which occur in the same ore bodies. Before the
16th century, exploitation of this region's non-ferrous metal resources almost
exclusively involved tin. Extraction focussed along valley floors and
hillslopes on and around the granite uplands of the south west where tin ore
had accumulated after natural erosion from the parent lodes. These
accumulations were exploited by streamworks, using carefully controlled flows
of water to expose and then concentrate the ore, leaving behind distinctively
deepened valley floors with various patterns of spoil heaps.
By the early post-medieval period, most substantial deposits susceptible to
streamworking had been exhausted and exploitation transferred to the
mineralised lodes themselves, a change which marks the appearance of copper as
an important product of the south western mining industry. The early
post-medieval exploitation of the lodes was restricted by the ability to drain
the cut, resulting in relatively shallow workings directly into lode exposures
at the bedrock surface, often by pits called lode-back pits and sometimes
enlarged to form longer openworks along the lodes.
By the 18th century, ore extraction and processing rapidly expanded to meet
growing demands, aided and promoted by technological development. Surface
workings became larger and more extensive, and deeper extraction was achieved
from shafts, the water pumped from larger mines by early steam engines or
drained through near-horizontal tunnels called adits which also served to
access the lodes. Horse-powered winding engines lifted ore from the shafts
while larger and more efficient water wheels served ore-processing areas. By
such means, west Cornwall became England's main producer of copper ore in the
18th to early 19th century.
Intensification accelerated in the late 18th to early 19th century with more
efficient steam-powered pumping engines allowing deeper shafts from which
extensive underground workings spread out. By the mid-19th century, steam also
powered winding and ore-processing operations, the engines, boilers and
ancillary machinery housed in distinctive masonry buildings grouped around the
main shafts and dressing areas. Later in the century, compressed air was used
for underground extraction equipment, fed from steam-powered compressors on
the surface. Ore-processing became increasingly mechanised, along with the
development of more effective methods of separating and retaining different
ores, particularly in the production of arsenic which became a major saleable
product in the 19th century, adding a further range of distinctive processing
and refining components to some mines. With these advances, east Cornwall and
west Devon became one of the world's main sources of copper and arsenic ore
until the later 19th century, while in west Cornwall, copper ores became
exhausted and replaced as that area's main product by the tin ores present at
deeper levels.
From the 1860s, the south western mining industries began to decline in
competition with cheaper sources of copper and tin ore overseas, especially
from South America, leading to a major economic collapse and widespread mine
closures in the 1880s, though limited ore-extraction and spoil reprocessing
continued into the 20th century.

The Hitchen's Shaft complex at the Holmbush Mine survives well as a very good
example of the range of features and structures grouped to serve the needs of
a mid- to later 19th century shaft head in a non-ferrous metals mine. Within
that grouping, the survival of a copper crusher house is rare, despite some
collapse of its walling, while the enlargement of the balance bob slot to
support a water tank is unusual and shows the ingenuity employed in resolving
such difficulties as maintaining the mine's adequate water supplies. The good
body of supporting documentation allows the development of the complex to be
understood and shows well how that development reflected the mine's economic
fortunes and its wider context in the world market for its products. The good
survival of this complex also provides a highly visible and tangible reminder
of the ongoing impact of the 19th century mining boom on settlement patterns,
accounting for the development of Kelly Bray which remains a substantial
settlement in the local landscape.

Source: Historic England

Sources

Books and journals
Barton, D B , A Historical Survey of the Mines and Mineral Railways of East Cornwall and West Devon, (1964)
Booker, F, Industrial Archaeology of the Tamar Valley, (1971)
Todd, , Laws, , Industrial Archaeology of Cornwall, (1972)
Other
CAU Report to Cornwall County Council, Buck, C, Holmbush Mine Archaeological Assessment, CAU , (1998)
Title: 1:10000 Ordnance Survey Map SX 37 SE
Source Date:
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Source: Historic England