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Post-Medieval period, 1500-1700
By the early sixteenth century many tin streams
were becoming exhausted and miners were turning to the
exploitation of tin and copper lodes that outcropped in cliffs and
other places where hard-rock was close to the surface.
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Goffen works
Much of this early mining was in the form of open-cast
trenches up to 20m deep; known as ‘goffen works’. The next step
was to sink shafts and drive horizontal levels through the
ore-ground which occurred in fissures or veins. Once the shallow
ore had been mined the only way to go was deeper, progress only
being possible if the workings were free of water. Workings were
drained by adits and primitive pumps. The pumps were operated by
perhaps five times more pump-men than miners. From the
late-seventeenth century miners used water power to drain their
shafts. Waterwheel pumps were built wherever there was sufficient
surface water to drive them. Man-made watercourses (leats) often
brought water several kilometres to drive pumps and tin stamping
machinery.
Copper mining
The earliest recorded attempts to mine Cornwall’s copper ores
had been in the 1580s by The Society of Mines Royal (which had
first worked the Keswick deposits in Cumbria on a large scale).
The Cornish mining operations took place in St Just, St Agnes,
Perranzabuloe, Illogan, Marazion and St Hilary. Ulrich Fosse (a
German mining expert) was sent to Cornwall to manage operations
and under his direction a small smelting works was also set up at
Neath in South Wales. This smelter operated under German
management and copper ore was received from mines near St Ives and
St Just. Carew in his Survey of Cornwall (1602) mentions
the shipment of copper ore from St Ives to be refined in Wales:
the beginnings of a long-standing relationship between Cornwall
and South Wales.
These early copper mines were unsuccessful and
significant exploitation did not begin until the passing of the
Mines Royal Acts of 1689 and 1693. During the last years of the
seventeenth century, copper production largely progressed as a
result of the efforts of a copper smelter named John Coster who
had established works on the River Wye, Herefordshire in 1680. He
was a metallurgist and engineer who also helped to further develop
adit drainage, to make significant advances in assaying and
dressing copper ore, erected one of the first horse-whims in
Cornwall and developed its first true copper mine at Chacewater in
the early 1700s.
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Gunpowder
In 1689 the Godolphins asked Thomas Epsley, who
had learnt the art of ‘shooting the rocks’ in the Mines Royal in
Somerset, to come and demonstrate the use of gunpowder to their
miners in the Breage district. Thomas Epsley died at Godophin Ball
six months later but the import was quickly adopted in other
districts such as the cluster of tin mines around St Agnes Beacon. The time, labour and capital required to drive adit levels
and crosscuts was reduced significantly by the use of gunpowder.
As a result, ore-ground could be opened up much more quickly.
Sir Francis Godolphin was highly successful with
his innovations at Great Work mine and his services as a mining
engineer were sought by the owners of the lead mines in
Cardiganshire in Wales.
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Adit drainage
Drainage tunnels (adits) had been used for
centuries to drain water out of mines (e.g. the thirteenth-century
Bere silver mines). They were driven from the lowest convenient
point the topography allowed, such as a river, the base of a cliff
or a valley bottom.
These tunnels lowered the natural water table and
presented a new datum to which water could be pumped up from
below. However the depth at which this could be done was still
limited by the primitive design of early pumps, such as the ‘rag
and chain’ pump.
Gunpowder made it possible to drive
adits much more rapidly along a known or towards a surmised lode.
Such undertakings were costly and could take tens of years to
accomplish so were often financed by mineral lords or other
adventurers with significant capital. In addition to mineral
revenue, further rewards were often reaped by leasing the use of
the adits to other mine operators for transferring water. |
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