HER 5606 DESCRIPTION:-

Scheduled Monument Description:-

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 1 metre and 4 metres 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 2 km to the north west of Dark Hill. Titanic Steel Works, built later by Robert Mushet lies 250 metres 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 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 plans 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 tram road, 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 45 metres long and 7 metres 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 metres, which contains an edge runner millstone, 2 metres 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 15 metres by 7 metres, 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 65 metres long and 22 metres wide, held by a massive retaining wall along its south side 4 metre 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 5 metres by 3 metres, lies within a walled enclosure measuring 6 sq metres internally. On the west, within an enclosure measuring 7.5 metres by 4 metres, 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 10 metres by 5 metres, 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 5 metres 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 150 metres 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 1 metre wide by about 2 metres long and 0.1 metre thick, surrounded by large stones, about 1 metre 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.

Assessment of Importance

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 sites 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. {Source Work 2873.}

A cementing furnace was built by David Mushet in 1819 on the site which later developed into the Darkhill Ironworks and Forest Steelworks. Here he produced commercially for the first time many tons of refined iron from a blast furnace without using a refining furnace, by methods which he had evolved experimentally at Forest House SO51SE17. After his death in 1847 and the establishment of the Forest Steelworks, his son Robert Mushet built experimental furnaces at, or adjacent to, the old Darkhill furnaces, probably in the long smith shop shown on a plan of 1866. {Source Work 176.}

A small Bessemer furnace was added in 1856 with which Robert, and his partner S.H. Blackwell of Dudley, revolutionised the method of Bessemer steel production by the addition of spiegel to adjust its carbon-content.

The site of the original Darkhill works probably lies under the broad embankment of the Severn and Wye Valley railway at SO59030878, where the OS 1:63360 map of 1830 marks two large buildings, one on each side of the former Severn and Wye Tramroad. {Source Work 862.}

David Mushet severed his connection with the Whitecliff Furnace in 1818 and built a new furnace at Fetterhill near Coleford, in which he tested the commercial production of 'refined iron' direct from the blast furnace without preliminary decarbonisation in a separate hearth. The Darkhill Iron Co. was founded in 1845 and managed by his son Robert, but on Mushet senior's death two years later the antagonisms which existed between David's three son's resulted in Darkhill furnace being put up for sale, and it was never thereafter in blast.

1818 - David Mushet obtained 6 acres of Crown Land in the Forest Waste at Gorse Hill (now Gorsty Knoll). This land was on the southern slopes of Gorsty Knoll in an area known as Darkhill, just below some brickworks he'd bought earlier. David Mushet built an ironworks here, comprising a couple of small furnaces, a blacksmith's shop, a carpenter's shop, a coke yard, ponds etc, at a cost of £3,800, and later added a big blast furnace. A short connection was run from the nearby tramroad to the works. Mushet was able to continue his iron experiments here. Moses Teague used the cupola furnace at the Darkhill Ironworks for his experiments in making good cheap iron with local Dean raw materials.

NB:Anstits reports that the Darkhill works were built 'just below some brickworks he had bought or built a year or so earlier...', implying that there were already buildings on the site in 1818, or that Mushet himself built the works in two phases.{Source Work 4593, p48}

1845 - David Mushet gave the Darkhill Ironworks and two nearby coal works to his 3 sons. Each had a third share, and his son Robert acted as manager. Robert and his brother David Mushet Jnr began to enlarge and improve the ironworks. They started to rebuild the blast furnace which was intended to be 45 feet high with a volume of 4000 cubic feet, although in the end the height was only c.35 feet, with a proportional decrease in volume.

Nov. 1845 - The three Mushet brothers formalised their joint ownership of the Darkhill Ironworks, creating a firm called the Darkhill Iron Co., also sometimes called Mushet Bros. The company was plagued with financial difficulties.

July 1846 - Boiler of a steam engine blew up, killing two people instantly. Subsequently three more died, and altogether 10 people were injured.

1847 - Following the death of David Mushet Snr, the brothers decided to sell the Darkhill Ironworks by auction on 13th July 1847. The sale did not take place, and by September 1847, the ironworks remained unsold. The brothers dissolved their partnership, although the ironworks remained their joint propoerty.

1864 - Sold to Samuel Morgan.

1874 - Darkhill site was in possession of the Severn & Wye Railway and Canal Co. They sliced off a large part of the south-east corner of the site for the new branch railway line from Parkend to Coleford.

1981 - Great Western Railway (successors to the Severn & Wye Railway) sold the site back to the Crown. {Source Work 4593.}

Recent clearing and excavation of this site close to the disused railway embankment where the minor road to Orepool branches from the B4431, have revealed extensive remains of the furnace buildings. {Source Work 79.}

A full scale excavation was conducted at the site of the Darkhill ironworks. Although supervised by an archaeologist, Mr Philip Isaac, the basic intention of the excavation was not archaeological but to create jobs under the MSC Job Creation Scheme, and the end product should have been a leisure area with an industrial archaeological interest. The functions of the various buildings on the site have been clarified. For example, a room described locally as a foundry has been found to be a forge. Finds from the site include hammers and bottles including small phials perhaps used as test tubes and a couple of small crucibles.

The unrestored 1976-78 excavation by the MSC backfilled most of the site and consolidated some of the above ground structure. Finds were donated to the Historical Metallurgy Society.

On the initiative of the Royal Forest of Dean Rotary Club a job creation was sponsored to excavate and consolidate the upstanding remaining walls of the buildings. Source Work 213.}

Much of the site was excavated during 1975-6 but no report has been published. A rescue stone by stone survey of the blast furnace base was carried out by G.L. Clissold and I.J. Staning during 1981-2. Extensive backfilling of the site was completed by the owner in 1986. The site finds were donated to the Historical Metallurgy Society in 1985 and are in store at Coleford. {Pers. comm. I.J. Standing.}