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Post Medieval

1540 to 1900

The period from 1700 to the early part of the twentieth century was the hey-day of Cornish mining. Technical advances in steam pumping marked the Industrial Revolution in Cornish mining. This development in technology made deep mining possible by the end of the eighteenth century.

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Waterwheels provided power for pumps, winding machinery, stamping mills and other appliances. There were hundreds throughout Cornwall's industrial landscape, fed by leats which took water off streams or from purpose built reservoirs.

With the development of large steam engines, purpose-made buildings were needed to contain them and the basic design of the Cornish engine house was established by the early 1800s. Associated structures include boiler houses, chimney stacks and ponds which stored water for the engine condensers and boilers. Nearly 3000 engine houses were built in Cornwall and those that survive have become a distinctive and evocative feature of the Cornish landscape.

Tin ore was crushed and concentrated at the mine site. From the early nineteenth century this became an increasingly mechanical process requiring large areas of land with a sloping gradient and water supply. Ore dressing sites are typically arranged in a 'stepped layout'.

Tin produced in Cornish mines frequently contained arsenic and sulphur. These elements were detrimental to smelted tin and so had to be removed by roasting; this was done in buring houses or calciners. The fumes released into the calciner entered a series of chambers on whose walls they condensed. The chambers were interconnected and the arsenic fumes were forced to follow a zigzag path through them. These structures are known as labyrinths.

The impact of the industry on the landscape was large-scale and the speed of its decline has left a well-preserved relict mining landscape. Its legacy includes thousands of mine shafts, numerous engine houses and the widespread remains of tin and arsenic processing.

The first clay pits were shallow. After removal of the surface soil a supply of water was brought to the site using leats. The water was directed over the exposed clay ground to take off the clay, leaving behind the unwanted rocks in a gully. The waste material left behind had to be removed. In the early days this was done by hand but this was later mechanised, the wastes being hauled up a railed incline and then trammed out along flat-topped finger dumps. These dumps are a characteristic feature of early china clay workings but few survive today.

Processing took place downhill from the pit where the clay slurry flowed through three stepped tanks. The clay was then sllowed to flow into rectangular or circular stone-lined settling pits. The clay slurry was then run off through a sluice in the base of the tank into shallow pans to dry in the open air.

In the early part of the nineteenth century, clay production was a localised small scale industry. After 1820, during the copper mining boom around St Austell, new harbours were built, some connected by rail to the industrial hinterland, and the industry was transformed around 1850 with the adoption of pan kilns to dry the clay. By the turn of the twentieth century more than half a million tonnes of china clay were being produced annually in Cornwall.

The years of increasing china clay production in the second half of the nineteenth century saw a number of changes and improvements in the industry. The old methods were uneconomical. Sky tips were a new form of waste dumping. Waste was hauled out of the pits up steep railed inclines and dumped off the top of the incline which gradually extend upwards as the tip grew. The resulting pyramidal dumps were a distinctive feature of the clay country.

The introduction of mica drags made the process of separating the clay more efficient. Drags consisted of rectangular stone tanks with a shallow gradient and divided into a series of long narrow channels separated by boards. Instead of letting the clay slurry flow into three stepped tanks, it was now directed into the drag.

Industrial granite quarrying was made possible by developments in stone-splitting methods and controlled blasting techniques.

New industrial harbours were constructed to handle the mineral trade. Elsewhere harbours and quays were expanded to cope with the growth in mineral output. Together these form an internationally significant group of eighteenth and early nineteenth century industrial ports. The earliest Cornish railways linked copper mines with mineral ports.

There was a constant movement of miners across the county. Villages such as Pendeen, Lanner and Four Lanes grew up and towns such as Redruth and St Just expanded rapidly. Camborne grew from a small village to one of west Cornwall's major towns.

The majority of those employed in Cornwall's extractive industries lived in towns in terraced houses with only very small gardens or courtyards. Some were housed in rows of cottages with gardens in which food could be grown to supplement incomes. In the late eighteenth century, however, many miners laid out smallholdings; two- or three- roomed cottages with a few acres of land on which to grow vegetables and keep livestock.

Miners' smallholdings typically consist of small rectangular fields and were held under the three lives system. They are sited in areas which were formally upland rough ground. During the eighteenth and nineteenth centuries over 50,000 hectares of upland rough ground were taken into cultivation. The establishment of smallholdings had a significant impact on the landscape which in many areas is still clearly visible.

Under Queen Elizabeth I's reign, the fort at Pendennis was strengthened by adding a bastioned earthwork, and the Star Castle on Scilly was constructed. These fortifications were enhanced during the eighteenth century when many of the nationally important defences on St. Mary's were built.

The threat of invasion by France at the end of the eighteenth century led to the rearming of existing coastal fortifications, the building of a series of redoubts at Maker Heights, and the construction of a new coastal battery on St Anthony Head.

In the second half of the nineteenth century advances in naval technology and the re-emergence of a threat from France led to a major phase of fort construction in Cornwall. These Victorian forts were designed for the defence of the naval base at Plymouth and are known as Palmerston Forts, after Viscount Palmerston, the Foreign Secretary who instigated their construction. 

Palmerston Forts were built around all major British navy dockyards both at home and abroad. They are massive structures with huge fire power. Although the prospect of a war with France evaporated with her defeat in 1870 in the Franco Prussian War, the forts were re-used as bases and the focal points of defences in later conflicts.

Around the turn of the century the coastal defences were further enhanced in the light of the development of fast-moving torpedo boats, which moved too quickly to be targeted by the heavy harbour defence armaments. More heavily fortified batteries, such as those around Plymouth and on St Mary’s in the Isles of Scilly were also built at this time.

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