Reasons for Designation
Iron has been produced in England from at least 500 BC. The iron industry,
spurred on by a succession of technological developments, has played a major
part in the history of the country, its production and overall importance
peaking with the Industrial Revolution. Iron ores occur in a variety of forms
across England, giving rise to several different extraction techniques,
including open casting, seam-based mining similar to coal mining, and
underground quarrying, and resulting in a range of different structures and
features at extraction sites. Ore was originally smelted into iron in small,
relatively low-temperature furnaces known as bloomeries. These were replaced
from the 16th century by blast furnaces which were larger and operated at a
higher temperature to produce molten metal for cast iron. Cast iron is
brittle, and to convert it into malleable wrought iron or steel it needs to be
remelted. This was originally conducted in an open hearth in a finery forge,
but technological developments, especially with steel production, gave rise to
more sophisticated types of furnaces. A comprehensive survey of the iron and
steel industry has been conducted to identify a sample of sites of national
importance that represent the industry's chronological range, technological
breadth and regional diversity.
Despite having been partially excavated, the brickworks and iron works at Dark
Hill survive well. The site is associated with the Mushet family who were
amongst the foremost pioneers in the development of iron and steel technology
in England in the century. Their achievements include the first
commercially produced refined iron from a blast furnace without the use of a
refining furnace, and the production of the first steel rail for railways. A
number of locations at the Dark Hill site are associated with specific
developments in the industry. Kilns at the brickworks site were used for
small-scale experimental work on new materials, and it was also the site of a
Bessemer furnace in which, by the addition of spiegel and the adjustment of
the carbon content, Mushet revolutionised the method of steel production. In
addition, the site displays the elements of a complete 19th century iron works
including a tramway track for the movement of goods. An example of the
production of the works is found in the `Bear', which lies some distance away
from the main site, and which is thought to be the fused residue of the
contents of the blast furnace after one of Mushet's experiments.
The site will retain archaeological information and environmental evidence
relating to the industrial activity on site, and will preserve a record of the
long series of experimental operations that took place under the Mushet's from
1819 to 1862.
David Mushet at one time owned the brickworks, and the site is integral to the
events which formed the sequence of development of the iron works and Robert
Mushet's Forest Steelworks. The brickworks site preserves the layout and
processes of a 19th century example of this type of industry and the tram
road, which abuts the site, completes the contemporary industrial landscape.
As a site which is open to the public, it is also a valuable educational
amenity.
Details
The monument includes the standing and buried remains of an iron works,
brickworks, part of a tramway and a `Bear' lying on the southern slope of
Dark Hill in the Forest of Dean. It lies in two areas of protection. The
standing remains of the walls of the ironworks and brickworks have been
consolidated and stand to between 1m and 4m high.
The works were owned by both David Mushet, a figure important in the
development of both iron and steel working technology, and his son Robert,
who carried on the work of his father. David Mushet first arrived in the area
in 1809 when he moved to Coleford, managing the iron works at Whitecliff (the
subject of a separate scheduling) about 2km to the north west of Dark Hill.
Titanic Steel Works, built later by Robert Mushet lies 250m to the north
west and is the subject of a separate scheduling (SM28879). The brickworks
were established some time before 1818, and were owned by David Mushet in 1841
After David's death in 1847, the furnaces at the smithy in the brickworks were
used by Robert for experimental work on new metals to discover their
properties. Robert Mushet carried out much of his secret experimental work
near his home, but larger scale experimentation was done at the furnaces by
the Smithy. The lessons learned here were put into practice when the nearby
`Titanic Steel and Iron Co Ltd.' works were built in 1862. In his will dated
to April 1847, David Mushet left the brickworks to three trustees. In July of
the same year the premises were advertised for sale, and when it was sold
again in 1857, it was in need of repair. Later the site of the brickworks
became a Colour works for processing ochre which is the yellow or brown
hydrated oxide of iron (ferric oxide). `Colour' or `oxide' is suitable for
pigment.
David Mushet built his first iron working furnace at Dark Hill in late 1818 or
1819. It is thought that the iron works at Dark Hill were developed mainly as
an experimental site, although small-scale production appears to have been
carried out. In 1845 David Mushet conveyed Dark Hill iron works to his three
sons, and in November of that year, the Dark Hill Iron Co. styled `Robert
Mushet and Co.' was formed, with Robert Forester Mushet, David's younger son,
as the sole manager. In June of 1847 David Mushet senior died, and in July of
that year Dark Hill iron works was auctioned, but not sold. In September of
1847 there was a deed of dissolution of agreement under conveyance of 1845,
and the furnace was probably never again in blast.
No contemporary plan has been found, and therefore the interpretation of
successive uses to which different buildings were given is based on expert
opinion.
The complex of tramway, brickworks and ironworks lie on a series of terraces
above one another on the hillside. At the north end of the complex, on the
high ground above the brickworks, is the Milkwall branch of the Severn and Wye
tramroad, some of the stone tram road blocks of which are still visible. In
1819 instructions were given to extend the branch tram road to serve the new
furnace at Dark Hill, thus a second branch of the tram road from the west
enters the site above the furnaces and below the brickworks area.
Just below the upper tram road is the brickworks, which lie above the iron
works on the slope. At the north west corner of the brickworks is a kiln, with
another at the north east corner, shown by its semicircular brick floor.
These are linked by a long building which served as the brick drying sheds,
some 45m long and 7m wide. This building had brick pillars under the floor
enabling heat from stoves to circulate around the stacked bricks allowing them
to dry. To the south of the drying sheds, on the west side, is an edge mill
room, measuring 10 sq m, which contains an edge runner millstone, 2m in
diameter, lying on its side. In its original upright position it would have
been rotated around a trough by a pony harnessed to a beam. At the centre of
the room is a posthole lined with five wedge-shaped packing stones, although
originally there were six, which mark the point of the central pivot post
around which the millstone was rotated. The millstone is thought to have
been used for crushing dried clay to powder, or alternatively may have been
used to crush ore for the iron works.
At the same level as the edge mill room of the brickworks is the Smith's Shop,
which is quite extensive, measuring 15m by 7m, and two large blacksmiths
hearths, with four brick-lined crucibles. The Smith's Shop building is thought
to be the site of Robert Mushet's spiegal experiments of 1847. In September of
1847 Robert entered into partnership with Thomas Daykin Clare and formed the
small experimental steelworks called `R Mushet and Co.' Forest Steel Works,
with premises which lay `a few hundred yards to the north west of Dark Hill',
was probably situated within the brickworks site. The kiln base on the east
side of the Smith's Shop is thought to be the site of the 1856 Bessemer
Furnace, with which Robert, and his then partner, S H Blackwell of Dudley,
revolutionised the method of steel production by the addition of spiegel to
adjust the carbon content of the metal. Spiegel is pig iron which contains
high concentrations of manganese and carbon, which, when added to steel
adjusts its final composition.
Downslope from the Smith's Shop is the loading area, and the charge
preparation area for the iron works, below which is the charge incline. The
loading and unloading area is an artificially raised platform, some 65m long
and 22m wide, held by a massive retaining wall along its south side 4m high.
On top of the wall above the furnace complex is the charge preparation area,
which is made up of the weigh batching room and the coking area. Iron ore and
other materials would be barrowed out to the blast furnace, which lay directly
downslope from the charge preparation area, via a charging bridge. The
furnace, measuring 5m by 3m, lies within a walled enclosure measuring 6 sq m
internally. On the west, within an enclosure measuring 7.5m by 4m, is the site
of the hot air blast furnace dating to 1845-6, and on the east is a boiler
room. A brick arch still stands behind the blast furnace area. On the east
side of the furnace, beyond the boiler room, are the remains of the area
thought to have contained the steam powered beam blowing engine for the
furnace. The engine house is 10m by 5m, and sub-divided internally. In front
of the arch, at the lowest level, is a horseshoe shaped hearth, which was
never fired.
At the very southern end of the site is the railway embankment, built in 1874,
which covers the area where the `Puddling' sheds stood. The embankment stands
to about 5m high, and it is thought that it also covers the remains of an
earlier part of the iron works including the sand floor and the casting house
of the 1819 furnace site.
Approximately 150m to the north east of the iron works is a mass of solidified
impurities, known as a `Bear', which consists of the scum which is removed
from the metal before it is tapped. The `Bear' is about 1m wide by about 2m
long and 0.1m thick, surrounded by large stones, about 1m diameter, which had
hidden it until some of the stones had rolled down the slope. It is thought
that the Bear had been deliberately hidden to conceal the secret of the
contents of the blast furnace.
A number of accidents occurred at the iron works; most notably in August 1846
when a steam engine exploded causing five deaths and seven injuries. The site
was abandoned, probably around 1862, when Robert built the Titanic Steel Works
nearby. Following the building of the Severn and Wye Valley railway embankment
across the south east corner of the iron works in 1874, the site lay
undisturbed until partial excavation in 1977. The excavation was carried out
under the MSC Job Creation Scheme, although supervised by an archaeologist.
Finds from the site included mainly hammers, some bottles and two small
crucibles.
The post and wire fence, which surrounds the site, is excluded from the
scheduling, although the ground beneath it is included.
MAP EXTRACT
The site of the monument is shown on the attached map extract.
