Details

The monument includes a C19 and early-C20 water powered tin mine and
openwork, together with an early post-medieval lodeback tinwork situated on
the east and south-facing slopes of Hobbs Hill, overlooking the valley of the
St Neot River or River Loveny. The C19 Hobbs Hill tin mine was established
in 1844 and by 1846 an adit, together with a 36 fathom deep shaft, had been
excavated. Adverse geological conditions meant that the mine was abandoned in
1849 and it is not known whether any tin was produced. Many of the surviving
buildings and structures date to this abortive operation. The substantial
adit complete with dumps and associated shaft survive to the south and south
west of the processing floors and other mine buildings. The stamping
machinery, associated wheelpits, dressing floor and various ancillary
buildings are situated on terraces cut into the steep east-facing slope and
are reached by a series of trackways. The stamps were powered by water
wheels situated over 40m to the north with the power being transferred using
flat rods. The surviving stamps probably date to the later C19 period of
working, but are likely to be on the site of the original machinery. The
dressing floor is situated immediately downslope of the stamps and includes
at least three circular buddles and several bases upon which timber dressing
apparatus once sat. Scattered around the edges of the dressing floors are a
series of drystone built structures which represent the site of buildings
associated with the mine.
The mine re-opened in 1872, but this time a mineralised elvan dyke north of
the processing area was exploited using an opencast quarry known as an
openwork. There are at least seven separate stopes (or steps) within this
openwork, each represented by a steep cliff. Between 1872 and 1874 a total
of 15 tons of black tin was produced. The stamps, dressing floors and many of
the buildings would have been refurbished during this extraction period and
the settling pit adjacent to the earlier adit may have been built at this
time. A small building situated some 80m north of the openwork adjacent to
the mine leat probably represents the remains of the magazine house in which
explosives used in the openwork were stored.
The final phase of activity at the mine was in the early part of the C20 when
a total of 13 miners were employed by Kingsway Syndicate Ltd. The small
hydro-electric power station built next to the Loveny River probably dates to
this period. Water was carried to the turbine in a pipe from a small
triangular concrete reservoir. The line of this pipeline can still be traced
where it cut through a dump from the earlier openwork and was carried on a
raised platform and finally where it was supported above the ground on stone
built piers. Electricity from the power station would have been used to power
crushing and dressing machinery.
West of the later mine are the remains of a much earlier lodeback tinwork
which may be identified as Hobbys Worke which was in existence by at least
1516. A series of pits excavated onto the back of a lode represent the
remains of early shallow shaft mining. Further lines of smaller holes are
the remains of prospecting pits. Two small rectangular buildings, one of
which is excavated within an earlier pit represent tinners' shelters. Of
particular significance is the survival of a contemporary leat carrying water
towards the deepest lodeback pit. The height of the leat relative to the pit
strongly suggests that a wheel similar in character to those depicted in 16th
century German engravings existed at this site. It is therefore possible that
pumping and or lifting machinery may have been employed at this tinwork.
Low rubble walls surviving within the monument represent the remains of a
probable prehistoric field system and a large leat leading between the C19
openwork and the lodeback tinwork was originally cut in 1846 to carry water
from West Colliford to Wheal Friendship on Goonzion Downs.

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

Source: Historic England

Reasons for Scheduling

Hobbs Hill tin mine, openwork and lodeback tinwork 530m east and 160m north
east of Chyseger Farm survive very well and together they contain a wide
variety of information concerning the character of early mining technology.
The comprehensive range of surviving structures and buildings associated with
the mine provide a clear insight into the character of a small water-powered
C19 tin mine. The dressing floors are intact and will contain important
information concerning the efficiency and character of the processes
employed. The openwork is unusually late in date, is impressive in character
and has a series of well preserved stopes. The survival of a small
hydro-electric power station built to serve the final period of working is
almost certainly unique and certainly enhances the significance of an already
important complex.
The lodeback tinwork at Hobbs Hill was the first of its type to be recognised
and archaeologically recorded in detail. Of particular significance is the
contemporary relationship between a leat and the deepest pit which suggests
that a wheel once rotated above the pit. This wheel could have been used to
either power lifting or pumping machinery. Wheels of this type are known from
C16 German literature, but this is the only instance in the South West of
England where archaeological evidence has been found to support their use in
a C16 tinwork.

Source: Historic England

Sources

Books and journals
Gerrard, S, The Early British Tin Industry, (2000), 85
Other
Cornwall HES, National Mapping Programme - Cornwall,
Fieldwork at Hobbs Hill, Gerrard, S., (1983)
Gerrard, S., Hobbs Hill Mine, 1986, Unpublished plan held by Cornwall HES

Source: Historic England