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.
The Wheal Prosper engine house 210m south of Eastcliff Farm survives well
in a prominent location on the coastal footpath between Praa Sands and
Porthleven. The design, while typical overall of a Cornish engine house,
has the unusual feature of an additional pair of girder pockets located
immediately above the bottom chamber windows. The presence of the Wheal
Trewavas engine houses nearby to the south east demonstrates well the
grouping of mines working extensions of the same mineral lodes.
Details
The monument includes the Wheal Prosper pumping engine house south of
Rinsey. Wheal Prosper was a short-lived tin and copper mine that was in
operation between 1860 and 1866 on the cliffs above Porthcew. Its engine
house was constructed at the commencement of mining operations and housed
a 30-inch steam engine in order to pump water from the adjacent engine
shaft. The engine house is a Listed Building Grade II.
The engine house is constructed on a rectangular slate-stone plinth and
has a circular chimney adjoining. Built in the typical Cornish style of
three floors and a cataract pit, the fabric is of uncoursed slate-stone
rubble incorporating some granite blocks, with dressed granite quoins for
the wall corners and openings. Parallel timber and concrete lintels are
used to head the wall openings and the house has the unusual feature of an
additional pair of girder pockets located immediately above the bottom
chamber windows. The machinery, floors and roof structure of the engine
house have been removed. The engine boiler house has been largely removed
but its position is indicated by some wall footings adjacent to the north
western corner of the engine house, but is not included in the scheduling.
The chimney is constructed of slate-stone rubble rising to red brick over
its upper third and collar.
The adjacent coastline from Rinsey Head to Trequean Cliff experienced much
mining activity during the 19th century leaving a variety of scattered
earthwork and built remains including two other engine houses on the cliff
top at Wheal Trewavas, 750m to the south east.
MAP EXTRACT
The site of the monument is shown on the attached map extract.
It includes a 2 metre boundary around the archaeological features,
considered to be essential for the monument's support and preservation.
