The Wealden iron industry was located in the Weald of south-eastern England. It was formerly an important industry, producing a large proportion of the bar iron made in England in the 16th century and most British cannon until about 1770. Ironmaking in the Weald used ironstone from various clay beds, and was fuelled by charcoal made from trees in the heavily wooded landscape. The industry in the Weald declined when ironmaking began to be fuelled by coke made from coal, which does not occur accessibly in the area.
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Iron ore in the form of siderite, commonly known as iron stone or historically as mine, occurs in patches or bands in the Cretaceous clays of the Weald. Differing qualities of ore were extracted and mixed by experienced smelters to give the best results. Sites of opencast quarries survive from the pre-Roman and Roman eras, but medieval ore extraction was mainly done by digging a series of minepits about five metres in diameter and up to twelve metres deep with material being winched up in baskets suspended from a wooden tripod. This was less destructive of the land as spoil from one pit was used to backfill the previous pit allowing continued land use. The fuel for smelting was charcoal, which needed to be produced as close as possible to the smelting sites because it would crumble to dust if transported far by cart over rough tracks. Wood was also needed for pre-roasting the ore on open fires, a process which broke down the lumps or nodules and converted the carbonate into oxide. Large areas of woodland were available in the Weald and coppicing woodlands could provide a sustainable source of wood. Sustainable charcoal production for a post-medieval blast furnace required the timber production from a 3-mile (4.8 km) radius of a furnace in a landscape that was a quarter to a third wooded. Forging and finishing of the iron from bloomeries and blast furnaces also required large quantities of charcoal and was usually carried out at a separate site.
Water power became important with the introduction of blast furnaces and finery forges in the late medieval period. Blast furnaces needed to operate continuously for as long as possible and a series of ponds were often created in a valley to give a sustainable flow for the waterwheel. A campaign, as the production run was known, usually ran from October through to late spring when streams began to dry up, although Lamberhurst Furnace driven by the River Teise ran continuously for more than three years in the 1740s. Finery forges with three or four waterwheels to drive bellows and hammers needed more water than a furnace at times, although continuity was not as important. They tended to be sited downstream from a furnace if they were in the same valley. Ponds were created by building a dam known as a pond bay, which often served as a road, across one of the many valleys in the undulating Wealden landscape. In 1754 one furnace was so drought-stricken that its manager considered hiring workmen to turn the wheel as a treadmill. This need for continuous water power was an incentive in the development of the water-returning engine, a waterwheel driven by water raised by a steam engine pump.
Prehistoric ironmaking So far only about two dozen sites have been identified where iron was made before the Roman invasion, mostly scattered across East Sussex and the Vale of Kent. A large site at Broadfield, Crawley is the westernmost place where smelting has been ascertained, although there is a possible site associated with an Iron Age enclosure at Piper's Copse near Northchapel in the western Weald. Continuity of pottery styles from the Iron Age into the early Roman period makes precise dating of many sites to before or after the Roman conquest difficult. Carbon dating has identified a site at Cullinghurst Wood, Hartfield to between 350 and 750 BC. During his invasions of Britain in 55 and 54 BC Julius Caesar noted iron production near the coast, possibly at known sites at Sedlescombe and Crowhurst Park near Hastings.
Roman ironmaking
Beauport Park, where evidence has been found of probably the third largest iron works in the whole Roman Empire. The Romans made full use of the brown- and ochre-coloured stone in the Weald, and many of their roads there are the means of transport for the ore, and were extensively metalled with slag from iron smelting. The sites of about 113 bloomeries have been identified as Roman, mainly in East Sussex. The Weald was in this period one of the most important iron-producing regions in Roman Britain. Excavations at a few sites have produced tiles of the Classis Britannica, suggesting that they were actually run by, or were supplying iron to this Roman fleet. Total iron production has been estimated at 750 tons per year, but under 200 tons per year after 250 AD.
Medieval The invasion and settlement of the Weald by Anglo-Saxons seems to have brought a complete end to the Romano-British iron industry. No evidence of iron smelting has been found after the end of Roman rule until the ninth century when a primitive bloomery was built at Millbrook on Ashdown Forest, with a small hearth for reheating the blooms nearby. The date of this site has been established by radiocarbon and archaeomagnetic methods. The technology used there was similar to a slightly earlier furnace excavated in the eastern Netherlands, indicating that knowledge of Romano-British methods had been completely lost and replaced by the Saxons' own method. Evidence of forging of iron blooms in settlements close to the South Downs does indicate that smelting may have been going on at other undiscovered sites. It was usual for settlements concentrated along the Downs to have outlying parcels of land in the Weald for summer grazing. It is likely that smelting was carried out during the summer and the iron blooms taken back to the main settlement to work on in the winter. In all some 30 unpowered medieval bloomery sites are known in the Weald, but most of these remain undated. Accounts survive of the operation of just one, at Tudeley near Tonbridge in the mid-14th century.
Powered bloomeries From about the 14th century, water-power began to be applied to bloomeries, but fewer than ten such sites are suspected.
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