Reasons for Designation
For several millennia the western part of the South West Peninsula, namely
Cornwall and West Devon, has been one of the major areas of non-ferrous
metal mining in England. It is defined here as prospecting, extraction,
ore processing and primary smelting/refining, and its more important and
prolific products include copper, tin and arsenic, along with a range of
other materials which occur in the same ore bodies. Throughout much of the
medieval period most of the tin was extracted from streamworks, whilst the
other minerals were derived from relatively shallow openworks or shafts.
Geographically, Dartmoor was at the peak of its importance in this early
period.
During the post-medieval period, with the depletion of surface deposits,
streamworking gradually gave way to shaft mining as the companion to
openworking methods. Whilst mining technology itself altered little, there
were major advances in ore processing and smelting technologies. The 18th
century saw technological advances turning to the mining operations
themselves. During this period, Cornish-mined copper dominated the market,
although it was by then sent out of the region for smelting. The
development of steam power for pumping, winding and ore processing in the
earlier 19th century saw a rapid increase in scale and depth of mine
shafts. As the shallower copper-bearing ores became exhausted, so the mid
to late 19th century saw the flourish of tin mining operations, resulting
in the characteristic West Cornish mining complex of engine houses and
associated structures which is so clearly identifiable around the world.
Correspondingly, ore processing increased in scale, resulting in extensive
dressing floors and mills by late in the 19th century. Technological
innovation is especially characteristic of both mining and processing
towards the end of the century. In West Cornwall, these innovations relate
chiefly to tin production, in East Cornwall and West Devon to copper.
Arsenic extraction also evolved rapidly during the 19th century, adding a
further range of distinctive processing and refining components at some
mines; the South West became the world's main producer in the late 19th
century.
From the 1860s, the South West mining industries began to decline due to
competition with cheaper sources of copper and tin ore from overseas,
leading to a major economic collapse and widespread mine closures in the
1880s, although limited ore-extraction and spoil reprocessing continued
into the 20th century.
A sample of the better preserved sites, illustrating the technological and
chronological range, as well as regional variations, of non-ferrous metal
mining and processing sites, together with rare individual component
features, are considered to merit protection.
Despite limited disturbance, the remains of Wheal Busy survive well. The
complex of earthworks in the eastern area of the monument, and the Brunton
calciner, are particularly well preserved. The various structures and
earthworks represent well the range of mining activity here, and its
development over time. The eastern complex is of outstanding importance for
its visual impact and significance as a mining landscape; the pits and shafts
illustrating the scale and methods of 18th century mining, and the reservoirs
and leats showing the lasting importance and management of surface water
resources. There is also great potential for buried remains associated with
pioneering water, horse, and steam powered engines; the earliest of the
series of major steam engines employed on the mine being sited within the
monument. Overall, Wheal Busy provides an excellent example of a larger
Cornish copper mine, which had a prolonged impact on settlement and transport
patterns in the area.
Details
The monument includes the remains of the copper and tin mine Wheal Busy, also
known as Chacewater Mine and Great Wheal Busy, situated west of Chacewater on
a tract of fairly high and flat country extending west from here through
Scorrier. The location comprises level ground and slight slopes around the
head of a shallow dry valley falling away to the south. Also included in the
scheduling are traces of World War II military activity. The mining remains
in this monument are associated with others nearby. The arsenic works is also
a listed building, Grade II. The monument is divided into three separate
areas of protection.
The history of Wheal Busy is long and varied. Contemporary accounts, maps,
and other documents significantly enhance our understanding of the site.
These sources show that this was the most productive of the Scorrier copper
mines. In the 18th century in particular it was large and intensive, and its
development is marked by the adoption of new pumping engine technologies.
These innovations were necessitated by the lack of surface water for power,
which led to a notorious conflict with another mine in 1811, and by
particularly wet conditions underground. They were made economically viable
by the richness of the lodes.
The area is crossed by mineral lodes running roughly east-west. Small-scale
tin mines are thought to have been active here in the 17th century, when the
ground was largely open downs and around the turn of that century, copper was
found as the ore bodies were worked at greater depths. By the 1720s the mine
incorporated several earlier works, with most leased by John Coster and his
son of the same name. The Coster's introduced or adapted large waterwheels
and horse-powered whims or winding engines to Cornish mines to improve the
drainage critical to their development at this time. Around 1710 a new water
driven rag-and-chain type pump was introduced here, on the edge of the
Pittslouarn or Wheal Busy section, thought to lie in the eastern area of
protection. Again in this area, around 1725, one of Cornwall's first Newcomen
atmospheric or true steam powered pumping engines was erected by Joseph
Hornblower. Another such engine was working nearby by the mid-18th century.
In the 1770s the mine acquired a Smeaton improved atmospheric engine and
Cornwall's first Boulton and Watt condensing engine, both exceptionally
powerful.
Through most of the early 19th century the mine prospered, tin becoming an
important product around 1857. The name Wheal Busy was extended to the whole
mine around 1823. In 1856 the engine house in the north-western area of the
monument was built for a Harvey's engine. Mine plans show dressing floors for
ore processing in the west part of the main area of the monument, and later,
near its south-west area. They also mark the mine count house or office and
other service buildings, near the smithy. The smithy building is a listed
building and is not included in the scheduling. For some years around 1860
the mine incorporated several others to the north-west, as Great Wheal Busy.
Growth was halted in 1866 by the collapse of copper prices.
The mine was rich in arsenic, and was reopened for this in several phases
until closure in 1928. In 1909 another engine was placed in the 1856 house;
the secondary boiler house (which does not form part of this monument) was
also built at this time. The two successive arsenic works were sited south of
the core of the mine to reduce the nuisance from their fumes. After
extraction ended, some spoil was reprocessed for arsenic and wolfram.
The historical sources show that the underground development of the mine was
pursued systematically from the time of the Coster's with the driving of
slightly inclined tunnels known as adits, to drain water as well as providing
ventilation and access to the lodes. Numerous shafts were sunk, some designed
to allow connecting adits to be driven from several points at once. In 1778
the workings were linked to the Great County Adit (Cornwall's most extensive
drainage tunnel network) discharging some 3.5km south east. At the end of the
18th century the main lodes were exploited throughout the length of the mine.
Shaft names changed frequently, reflecting the growth and evolution of the
mine.
In its prime, Wheal Busy was a major Cornish employer, requiring many surface
workers for the hand breaking and sorting of copper ore, as well as miners.
The mine contributed greatly to the development of the village, and new
parish, of Chacewater. It also influenced regional transport networks, for
example, sending ore to be shipped for smelting by road to both coasts of
Cornwall in the 18th century, then using a pioneering horse drawn tramroad to
the north coast.
The eastern part of the monument survives as a complex palimpsest of
earthworks, some superimposed, developed over several centuries. It is
characterised by numerous early post-medieval lode back pits, which are
shallow shafts accessing the upper part of a lode; aerial photographs show
how they form lines following the ore lodes. Deeper shafts with adjacent
spoil heaps are visible towards the centre, south, and west. Those in the
centre are associated with the name Pittslouarn and with early steam engine
sites, and remains of an engine house, possibly of 1868, are visible here. At
least one shaft has an adjoining horse whim platform. Earthworks for managing
water are another feature of this area. Reservoirs, retained by dams or fully
enclosed by banks, are connected to leats, some diverted around pre-existing
earthworks. These will have provided water power, or supplied steam engines.
On the north-west of the area is a cluster of pools for different functions,
built up over time. This group seems to have expanded over dressing floors,
remains of which can be expected to survive below ground level. Also in the
area, on its south-west, are traces of the flue and chimney of the earlier
arsenic works.
The area on the north-west of the core area of the monument includes the 1856
pumping engine house, with the site of its first boiler house on its east
side, and the shaft it served, Engine Shaft, on its south side. The engine
house stands to roof level, retaining the wall openings, internal ledges,
bedstone, and other features designed to admit and support the steam engine
with its cylinder and rocking beam. Its fabric is local slate stone, with
granite at load bearing points, and brick details. The detached chimney is of
early telescope-like form and is built of stone and brick. The original
boiler house is visible as an earthwork (its stone was probably reused for
its successor). Engine Shaft itself is typical of pre-20th century shafts in
that it descends at an angle, slanting to the north along the tilt of the
lode so that it passes under the engine house. It extends to the maximum
depth of the mine.
The 1900's arsenic works is in the south-west area of the monument. A Brunton
calciner for roasting ore to produce arsenical vapour stands to roof level.
The structure is of massive granites bound by iron ties, with a brick front
retaining iron door fittings. The revolving ore bed and other machinery
survive within. West of this are substantial remains of a second, shaft type
furnace and beyond, a double labyrinth where arsenic was recovered from the
vapour, with much of the stone walling forming its multiple condensing
chambers visible. Beyond this are a final scrubbing chamber, and the near
intact tall chimney of stone and brick which vented the waste fumes. Much of
the ground in the arsenic complex is raised and will contain associated
deposits.
In World War II a large temporary US army camp was sited in the centre of
Wheal Busy. Aerial photographs show trenches and vehicle tracks of this
period in the eastern area of protection, probably used for training by the
troops.
All modern fencing and safety barriers, gates and gate fittings, waymarkers,
and vehicular access blocking rocks, are excluded from the scheduling,
although the ground beneath these features is included.
MAP EXTRACT
The site of the monument is shown on the attached map extract.
