Scheduled Monument: STONE EDGE SMELT MILL AT MOSS FARM (1020718)

REASONS FOR DESIGNATION Approximately 10,000 lead industry sites are estimated to survive in England, spanning nearly three millennia of mining history from the later Bronze Age (c.1000 BC) until the present day, though before the Roman period it is likely to have been on a small scale. Two hundred and fifty one lead industry sites, representing approximately 2.5% of the estimated national archaeological resource for the industry, have been identified as being of national importance. This selection of nationally important monuments, compiled and assessed through a comprehensive survey of the lead industry, is designed to represent the industry's chronological depth, technological breadth and regional diversity. The reverberatory lead smelt mill was developed in the late 17th century, and marked an important stage in the development of the switch from wood to coal fuel which rendered the Industrial Revolution possible. The reverberatory smelt mill was a rectangular enclosed structure of stone or firebrick held by iron strapping, within which ore was smelted by the heat of flames from a separate coal fire in one end, reflected down onto the ore by an arched roof. The separation of fuel from ore made the use of coal possible. A chimney (or flue to a separate chimney) at the far end from the fire provided the draught to draw the flames over the ore; no air blast was used and, consequently, water power was not required. Early reverberatory lead smelt mills consisted simply of a large barn-like building containing the furnaces, with chimneys projecting from the outer wall. Late 18th and 19th century smelt mills were often large complexes containing several smelting furnaces, together with slag hearths for extracting lead from the slags, roasting furnaces for preparing the ore, refining furnaces for extracting silver from the lead by a process known as cupellation, and reducing furnaces for recovering lead from the residue or litharge produced by cupellation, together with sometimes complex systems of flues, condensers and chimneys for recovering lead from the fumes given off by the various hearths and furnaces. Reverberatory smelt mill sites will also contain fuel stores and other ancillary buildings. Many of the later sites used water power to provide the air blast for the slag hearths. Reverberatory smelt mills existed in all the lead mining fields of England, and also in some coastal areas, using imported ores; about 100 sites are believed to have existed. Since both the buildings and the sites of reverberatory smelt mills were more easily reused than those of ore hearth smelt mills, examples surviving as well preserved field monuments are very rare nationally. All early sites with any structural or earthwork remains, and all later sites retaining a range of structural and/or earthwork features, together with any sites believed to retain the remains of furnaces, whether as exposed ruins or as buried stratigraphy, will merit protection. Stone Edge smelt mill is one of the best preserved examples in England of a reverberatory smelt mill, retaining the overall layout of smelt mill, slag hearth, condensing flue and chimney, and slag-washing area. The site demonstrates the development of a large smelt mill complex through the later 18th and earlier 19th centuries, and is expected to retain considerable below ground stratigraphic remains of its early phases. The chimney is thought to be the earliest free standing industrial chimney in England. The site is of amenity value since it lies in a prominent location beside a road and is crossed by a public footpath. The chimney is a prominent landmark. DETAILS Stone Edge lead smelt mill is a well-preserved example of a reverberatory or `cupola' smelt mill. The monument includes the smelt mill itself, a condensing flue and chimney (for recovering lead fumes), and a millpond to supply water to power the bellows for the slag hearth of the smelt mill. The smelt mill used reverberatory or `cupola' furnaces to smelt the lead ore. These heated the ore from a separate fire within the furnace, and used natural draught for their airflow instead of relying on mechanical blast. The slags from the furnaces contained appreciable quantities of lead which was extracted by crushing and washing, followed by resmelting in a slag hearth (a shaft furnace fuelled by coke and blown by water power. The southernmost feature of the site is a millpond and dam, which held water to power the bellows of the slag hearth. To the north west of this stands the square chimney, which is perhaps the oldest surviving industrial chimney in England and is included in the scheduling. Around the chimney lies a complex system of flues, surviving as underground tunnels. The extensive ruins of the smelt mill itself lie east and north east of these features; it is known that the smelt mill was rebuilt at least once. A masonry-revetted mound, approached by a ramp from the west, formed the loading ramp for a `Spanish' slag hearth (an improved type of shaft furnace). To the north of these features, the remainder of the site is occupied by tips of slag and the earthworks of tanks, forming the remains of the washing floor where slags were crushed and washed to extract entrapped lead. The smelt mill was built around 1770, and a slag hearth was added in the early 19th century. A Spanish slag hearth added by 1850 was the earliest in England. The smelt mill closed around 1860. The scheduling excludes all modern boundary walls and a modern track across the northern part of the site, but the ground beneath these features is included. SELECTED SOURCES Book Reference - Author: Willies, L - Title: Problems in the Interpretation of Cupola Lead Smelting Sites - Date: 1992 - Journal Title: Boles and Smeltmills - Page References: 40-42 - Type: DESC TEXT Article Reference - Author: Williams, C J, and Willies, L - Title: Stone Edge Cupola - Date: 1968 - Journal Title: Bulletin of the Peak District Mines Historical Society - Volume: Vol 6 - Page References: 315-322 - Type: DESC TEXT Article Reference - Author: Willies, L - Title: Derbyshire Lead Smelting in the 18th and 19th Centuries - Date: 1990 - Journal Title: Bulletin of the Peak District Mines Historical Society - Volume: Vol 11 - Page References: 1-19 - Type: DESC TEXT