What was arsenic used for?

In the 1870s a handful of mines in Cornwall produced over half the world’s arsenic. 

The principal market for arsenic was the expanding Lancashire cotton industry, which used it in pigments and dyes. Arsenic was also used by other industries such as glass manufacture (as a decolouriser), in the production of lead-shot, in leather tanning and in wallpaper manufacture (to create green and yellow print).

Despite its toxicity, it had a number of beneficial medicinal uses so was also sought after by the burgeoning pharmaceutical industry. It was also widely used in agriculture for sheep dips. From the 1870s, arsenic was used as a pesticide to control the Colorado beetle which devastated potato, tobacco and other crops in America during the late 19th century.

Using calciners to extract arsenic

Calciners were an essential part of most 19th century Cornish tin mines whose ores contained contaminating arsenic and sulphur. These had to be removed by roasting as they made the smelted tin brittle and reduced its value.

Arsenic is highly toxic, and surface workers risked arsenic poisoning through continued exposure.

Brunton calciners became the most commonly used type and these were often tended by women or girls. The contaminated ores were fed into the furnace through the hopper located above its rotating hearth.

How arsenic helped boost the mining industry

Arsenic helped control the Colorado beetle, which devastated potato crops and tobacco across America.

For some flagging copper mines, extracting arsenic provided several more years of profitable work – and in some cases became their principal output. The English Arsenic Company established substantial works at Roseworthy, Gwithian and at Greenhill near Gunnislake, but the largest in the region was at Devon Great Consols, which at its peak produced 3,000 tons of refined arsenic a year. In the 1870s a handful of mines in Cornwall produced over half the world’s arsenic. Arsenic is highly toxic, and surface workers risked arsenic poisoning through continued exposure.

During the 18th century, most of the ore dressing (or processing) was done by hand. From the early 19th century, it became much more mechanised but female and child labour remained particularly important especially in relation to copper mines.

Miners’ children started work by the age of eight or nine – shovelling and hauling ore, or tending the dressing floors.

Women and girls in mining

Although they didn’t work below ground, women and girls played a big part in the Cornish mining industry.  Known as ‘bal maidens’, (the word ‘bal’ is Cornish for ‘mining place’) they dressed the ore brought up from underground. It was hard, physical work which soon took a toll on their health and appearance. While they tried to protect their faces from the sun, wearing cardboard  hoods (‘gooks’) to shade their complexions, accounts from the time often mention their rough, chapped hands. 

Fancy gloves bought from the chapman weren't a luxury for these women, but a way of trying to stay young and attractive. 

Teams of women and girls were also employed in barrowing ore around the dressing floors. They worked in pairs using hand barrows, often carrying over 68kg (more than the weight of an average man) between them.

Copper was by far the most valuable mineral produced in Cornwall and west Devon during the 18th and 19th centuries (the period to which our World Heritage Site inscription applies), giving around five times more profit on average.

Processing copper

Copper ore was dressed somewhat differently than tin and was usually sorted and crushed by hand. Copper dressing relied extensively on manual labour throughout the 18th and 19th centuries, though mechanisation did play a part. Copper crushers (‘Cornish rolls’) were introduced in the early 19th century and low grade or otherwise difficult ores were also stamped at some mines.

1.    Copper ore was spalled in the same way as with tin.

2.    The younger girls washed and sorted the ore. This was a skilled but wet and dirty job which took knowledge and considerable concentration. 

3.    ‘Cobbers’ broke the picked ore into pebble-sized pieces using short handled hammers.

4.    ‘Buckers’ used flat-faced hammers to grind the cobbed ore into fine powder. Cobbing and bucking were both strenuous jobs that only the strongest women could do.

5.    Mechanical ‘jigging’ used water to sift out the heavier particles of ore from the lighter waste (‘gangue’).

Processing tin

Tin ore was initially crushed and concentrated at the mine and underwent a variety of processes which, to a degree, differed from site to site. The product (cassiterite or ‘black tin’) was always smelted in Cornwall up until 1838, due to Stannary requirements, with the last works surviving until the 1930s – ‘Seleggan’ at Carnkie closing in 1931.

1.    Once the ore was brought to the surface, it was usually broken up initially by male labourers

2.    Spalling was the next part of the process.  The ore was broken up into smaller pieces by women and girls using long handled hammers.

3.    Stamping - using steam powered machines called stamps to crush the ore with water.

4.    When crushed the finest material suspended in water (known as ‘pulp’) was sent to settling strips or buddles, where water flow and gravity separated the heavy tin ore from the lighter waste (‘gangue’) minerals. Children were often employed at this stage.

5.    The part-processed ore was sent on to be put through the trunks and kieves.

6.    Next, the ore was passed through the tin frames.

7.    The final stage of the process was the jigging (sieving) of the heavier particles, which was done by stronger boys or women by hand, or by boys or girls using semi-mechanised jigging boxes.

Processing arsenic

Arsenic was a contaminant of tin ore particularly which had to be removed by heating or ‘calcining’ (it made the tin metal brittle and reduced its value). Purpose-built calciners were used for this with by far the most common model being the Brunton, though the Merton and Oxland types also saw limited use.

Arsenic became a marketable commodity in the latter 19th century with eventual uses in dye and pigment manufacture, as an insecticide, and in medicines. Elaborate stone chambers were subsequently constructed adjoining the calciners to condense the cooling arsenic gasses as arsenic oxide. This was later refined either at the mine or in special refineries built in the arsenic-producing districts.

Key stages of transporting ore

A mine was usually made up of many underground levels (tunnels) linking the productive ore galleries, the stopes. Ore was transported to the surface in stages, depending on how big the mine was and how far the working stopes were from the surface.

1.    Miners loaded the ore into hand barrows or tram wagons and transferred it to the shaft, to await haulage to surface, or to a central collection point via underground interconnecting shafts known as ore passes.  This made ore handling easier as haulage was limited to being from only one point in the mine. Tramways ran along levels (tunnels) driven with a slight incline towards the shafts. Constructed in this manner to aid natural drainage, this also made it slightly easier to transport larger loads of ore.

2.    The ore was transferred into kibbles (large egg-shaped iron containers used for haulage).

3.    The kibbles were hauled up the shaft to the surface using a winding device, perhaps a horse whim, or other winder driven by a water wheel or steam engine.

4.    Once the ore reached the surface, it was unloaded and transported to the dressing floors, either using hand barrows, or by hand, horse-drawn or steam hauled tram wagons.

Winding devices (horse and steam whims)

Horses were important to the mining industry, helping to haul ore to the surface (horse whims) and to move ore around mine sites and to the mineral ports for transshipment.

While miners could ascend and descend using ladders, the ore was too heavy to be transported in this way. One of the most commonly used ways of bringing it to the surface was by using a winding device called a whim to haul it up the shaft. There were several types of whims, which used ropes, chains or steel cables connected to a large winding drum. Capstans were also used for haulage but usually specifically to service heavy pit work located in pumping shafts. As the rope was wound around the drum, it winched up a kibble full of ore while perhaps lowering an empty one. A whim could be powered by a waterwheel, a horse walking round a circular platform (a horse whim) or by steam. 

Beam engines and horizontal engines

As Cornish mines grew deeper, the methods for getting the ore out of the mine had to improve. The development of steam power transformed the mining process, allowing this to be done much more quickly and efficiently. A beam engine was a steam engine used in Cornish mines for pumping water, as well as hauling from the shafts and crushing ores before being dressed (refined).

Beam engines today

Four Cornish beam engines are on public display in Cornwall which survive in their original engine houses. There is a winding (hoisting) engine at Levant Mine, St Just Mining District, winding and pumping engines at East Pool Mine and a pumping engine at South Crofty Mine (both in Camborne and Redruth Mining District). Poldark Mine, Wendron, also displays the Greensplat Engine which was the last Cornish beam engine to pump commercially in Cornwall.

Getting the valuable copper or tin ore out of the rock was a difficult and often hazardous process. The rock had to be broken, either by hand, gunpowder, or later with dynamite or other high explosive. As Cornish mines became deeper, the mine worker’s job became more dangerous – with an increased risk of falling from the many ladders in use, collapsing rock, or flooding. 

Separating the ore from the rock

Mining today owes much to 19th century Cornish miners, who pioneered new tools and methods for extracting ore.

Miners used a variety of tools to extract the ore, including hammers, borers (chisels) and gads (wedges).  From the 1880s, they also used air-powered rock drills to increasing effect.

The productive area of the lode being exploited is known as the stope. The most effective way of extracting the ore was to drill holes, called ‘shot holes’, into the rock and introduce gunpowder (or another explosive) into the hole. When suitably stemmed (packed) a safety fuse would be inserted then lit, and the resulting explosion would break the rock apart. The fuses would be lit in sequence, if driving a level (tunnel), to ensure the rock would break out to the full width and height required.

Blasting was usually done at the end of a shift, so that the fumes had chance to clear before the next gang arrived to load the ore ready for hoisting to surface.  Over-sized ore would be broken manually to a size suitable for loading into kibbles and later skips, used for hauling. Once above ground, surface workers started the process of dressing the ore.

There were six main stages in the Cornish mining process:

1.    Prospecting/Surveying

Skilled workers with geological knowledge could identify an area where a particular ore was likely to be present by analysing the composition of the rock in the area and surface mining activity such as streamworks nearby.  If it looked promising, small-scale exploratory shafts might be sunk to confirm the area’s promise.  Setting up a new mine was an expensive business, so skill and experience were important to maximise the chances of striking a profitable ore body.

2.    Reaching the ore

While ore could sometimes be found on the surface in small amounts, larger lodes – or veins of metal ore in the rock – were found deep underground.  To reach them, miners had to dig levels (tunnels) and sink shafts into the ground. 

3.    Breaking the ore underground

Extracting the ore from the rock was an arduous and sometimes dangerous process. Miners used a variety of hand tools – including hammers, borers (chisels) and gads (wedges) – as well as gunpowder, and later dynamite or other high explosives, to break the rock up and free the ore.

4.    Bringing the ore to the surface

Depending on the extent of the mine, and where the ore was located, ore could be brought up to the surface using a hand operated windlass (winch) or by using a more mechanised winding device such as a horse whim (winch) or that driven by a water wheel. As mining technology developed, steam powered beam whims were constructed to do this, later to be superseded by horizontal steam winders.

5.    Dressing the ore

Once the ore had been brought up from underground, it needed to be dressed, or processed ready for smelting. Women (known as ‘bal maidens’) and children did the majority of this work, particularly on copper mines, but men were also employed to perform some of the heavier ore dressing tasks.

6.    Smelting the ore

To extract the metal from the ore, it needed to be smelted.  Most ores are a chemical compound of metal with other elements, like oxygen or sulphur. Smelting uses heat and a reducing agent, like charcoal, to remove these other elements from the metal.

ADIT    

A level tunnel (usually driven into a hillside) giving access to a mine and used for drainage or the hauling of broken ore. Deeper adits did not necessarily connect to surface, and were used to carry water back from distant workings to a pumping shaft.

ALLUVIAL DEPOSITS (tin)

Detrital ores which have been eroded and transported from the originating mineral lode by water action and re-deposited in the beds of water courses – thereby forming the concentrated tin ground. This was then worked by TIN STREAMING.

ANGLE BOB

A simple lever-based device. When using it, the direction of a reciprocal motion (e.g. of pump rods, flat rods) could be changed (e.g. from horizontal to vertical).

ARSENIC

A chemical element contained in many minerals, usually found with sulphur or metals. Arsenic has many industrial and agricultural uses. It is highly toxic and many mine workers suffered from arsenic poisoning.

ASSAY HOUSE

The mine laboratory, where samples or ore were analysed for their mineral content.

BAL or BALL    

From Cornish ‘Pal’; a shovel, and hence ‘a digging’ = a mine. Generally applied to earlier mines. See also WHEAL.

BALANCE BOB    

A large counterweighted lever attached to the shaft pump rods and used to offset their weight and so reduce the work of a pumping engine to lifting water alone. A surface balance bob would be mounted adjacent to the shaft on a pair of plinths or on a masonry support at ground level (balance bob mounting), with the attached counterweight – a large box filled with scrap iron or rocks – working in an adjacent stone-lined pit. Other balance bobs would be installed in chambers cut into the rock adjacent to the shaft wall as needed to counterbalance the weight of the pump rods, especially on a deep shaft.

BAL MAID

A woman or girl employed at the surface of a mine, generally in the dressing of ore.

BEAM ENGINE    

A type of steam engine much favoured in Cornwall for use in pumping, winding and providing the power to crush ores ready for dressing. The power from a large cylinder set vertically in an engine-house was transferred via a massive rocking beam or bob to the pumps in the shaft outside. For winding and crushing, the bob was instead attached to a flywheel and crank on a LOADING next to the BOB-WALL (or, in the case of all indoor engines, the side wall). In most cases, the engine house formed an integral part of the framing of the engine.

BEDSTONE    

The granite slab that formed the foundation for the cylinder of a Cornish Engine.

BLOWING-HOUSE    

An early form of tin smelting furnace, small in scale and using charcoal as a fuel.

BOILER HOUSE    

A generally lightly-built structure attached to an engine house, and designed to contain the horizontal boilers for a steam engine. The associated chimney stack could be attached to this structure, or built into one corner of the engine house.

BRATTICING    

Timber partition work in a mine, for instance the LAGGING BOARDS which lined the upper section of a shaft where it ran through soft ground.

BUCKING    

The breaking down of copper ore on an anvil to about 10mm in diameter by bal maids using small hammers, after which the ore was separated from the waste by hand. This process followed COBBING, in which it had been broken down to about 25mm in diameter, the waste again being hand removed. These processes, through which the majority of the highest quality copper ore was recovered, took place within roofed structures called bucking houses.

BUDDLE    

A device for concentrating tin ore. In the mid-19th century, these usually took the form of a circular pit with rotating brushes. The tin from the stamps was fed into the centre or side of the pit and graded by gravity, concentrating the heavy ore near the inlet point. These were often mechanically worked. Earlier buddles were trapezoidal in shape, and manually operated. A variation used in TAILINGS works to treat sands and slimes was the ROUND FRAME – a free-standing, all wooden, mechanically-actuated buddle. A further variation was the dumb buddle or dumb pit, which were not mechanically operated.

CALCINER    

A furnace and heating chamber in which ores were roasted to drive off impurities such as sulphur and arsenic. These were also known as Burning Houses, with some later designs being REVERBERATORY. The Brunton pattern calciner, introduced in the mid-19th century, was mechanically powered and operated on a continuous basis (unlike earlier designs). Other patterns of calciner were also devised, most being named after their designers (eg Oxland, Hocking and Loam).

CAPSTAN    

A manually or steam-operated winding drum, usually installed on a mine to raise pitwork from the shaft for maintenance or repair.

CATARACT PIT (or cock pit)

An under-floor area within the foundation levels of an Engine House between the CYLINDER PLAT and the Bob Wall, containing the regulating apparatus and giving access to cylinder hold-down bolts.

CILL    

The base of a window or other wall opening.

COBBING

Part of the ore dressing process. The breaking off of waste from ore fragments using special long-headed hammers.

COFFIN or GOFFEN

The narrow excavation resulting from stoping on a lode being carried to or from surface on part or all of a lode. See also GUNNIS, STOPE, OPENWORK

CONSOLS

A shortened form of the term ‘consolidated’, used where a number of mines were brought together and worked under a common management eg. Devon Greater Consols

CONDENSER    

The cast-iron cylinder set in a tank of cold water immediately in front of the bob wall of an engine house in which the exhaust steam was condensed, creating a vacuum which greatly increased the efficiency of a steam engine. For a pumping engine, this equipment was often contained within a pair of masonry walls projecting from the bob wall towards the shaft.

COUNT HOUSE    

A commonly used shortened version of the proper name ACCOUNT HOUSE. The mine office, sometimes incorporating accommodation.

CRUSHING

Part of the ore dressing process. Ore was crushed, either by hand or using a mechanical crusher to break it up.

CULVERT

A small tunnel built to carry a channel of water.

CYLINDER OPENING    

The often large, arched opening in the rear wall of an engine through which the steam cylinder was brought into an engine house during the erection of the engine. This opening was generally then closed off with a timber partition and usually incorporated the principal doorway into the engine house.

CYLINDER PLAT    

The massive masonry base on which the cylinder of a Cornish Engine was bolted down (see also BEDSTONE).

DRESSING    

The concentration of the tin (copper or other ores) contained in the rock excavated from the STOPES of a mine. Carried out on DRESSING FLOORS.

DRESSING FLOORS    

An (often extensive) area at the surface of a mine where the various processes of concentration of ore took place. These consisted of crushing or stamping to attain a uniform size range; sizing (particularly on later mines); separation of waste rock; concentration (generally mechanically and hydraulically on tin mines, manually on copper mines); the removal of contaminant minerals (by calcination, flotation, magnetic separation); and finally drying and bagging for transportation to the smelter.

Tin floors in particular were generally laid out down a slope to reduce mechanical or manual handling between stages in the process.

DRIVE (alternatively LODE DRIVE or HEADING)    

A tunnel excavated on the line of a lode as the first stage of the development of a STOPE.

DRY or CHANGE HOUSE (earlier MOOR HOUSE)    

The building in which miners changed their clothes before and after going underground. Some were heated by steam pipes connected to the engine boilers. Where there were large numbers of women or children employed on a mine, there might be two drys – one for men, the other for women and children. The pithead baths or showers found in collieries were rarely found in Cornwall.

DUMP or BURROW (alternatively SPOIL DUMP, SPOIL TIP).    

A pile of waste material, usually from a mine or quarry. Could contain primary waste (where this could not be disposed of underground) or waste from various stages in the dressing process. TAILINGS LAGOONS stored the extensive slimes from the final stages in the process – in earlier mines these were flushed over cliffs or allowed to wash away in streams or rivers.

EDUCTION PIPE    

The large diameter pipe through which exhaust steam was drawn into the condenser set outside the bob wall.

ENGINE HOUSE

A building designed to contain steam, gas, oil or electric engines on a mine or other works. When forming part of the framework of a beam engine these were particularly strongly constructed.

FINGER DUMP    

A linear dump of waste material from a mine or quarry; flat-topped to allow material to be barrowed or trammed along it and often equipped with a temporary tramway track.

FLAT RODS    

Reciprocating (or very occasionally rotative) iron rods, used to transfer power from a steam-engine or water-wheel to a remote location.

FLUE    

A stone tunnel or conduit connecting a furnace to a chimney stack.

FOUNDRY

A manufacturing site where metals were cast or formed to create machine parts, tools and civic or domestic ironwork.

GIRDER

The massive timber beam set across an ENGINE HOUSE just below top floor level, to which the parallel motion was attached and on which the spring beams sat.

GRIST

Grain or quantity of grain for grinding into wheat or corn.

GUNNIS

A narrow linear excavation left where a lode has been worked, most commonly used when open to surface. See COFFEN

HEAD or CROP

The richest part of material in a BUDDLE - nearest its feed point.

HEADFRAME

The tall construction set over a winding shaft which carried the sheave wheels over which the winding ropes ran. Headframes usually contained ore bins or ore chutes to allow the broken rock in the skips or kibbles to be tipped into trams at surface.

HORIZONTAL ENGINE

A steam engine where the cylinder(s) are set on a horizontal bed and the piston rods are attached via a cross-head to a crank and flywheel.

HORSE WHIM

Similar to a CAPSTAN, but in this case power supplied by a horse walking around a circular platform (PLAT) was applied to an overhead winding drum. Frequently used for winding from small shafts on Cornish mines, especially during exploratory work and shaft sinking. The smaller under-gear whims found in some 19th century farms were rarely used on mines.

JIG/JIGGING BOX

A large mechanically or hand-operated sieve set in a tank of water, used to separate ore by waste. Sometimes constructed in groups within jigging houses.

KIBBLE

A large, strongly-constructed, egg-shaped iron container used for ore and rock haulage in earlier shafts. Superseded by SKIPS.

KIEVE

Wooden tub used in the ore dressing process for tin. Ore was put into the kieve with water and stirred up so that heavy metallic particles sank to the bottom while the waste materials rose to the top.

LAGGING BOARDS

The timber planks lining the upper part of a shaft, or where it ran through soft ground.

LAUNDER    

A wooden or steel trough used to carry water or other liquids. Often used to feed water or finely-divided material in suspension around a dressing floor.

LABYRINTH (colloquially "lambreth")    

A line of interconnected stone chambers, on whose walls the arsenic vapourised in a calciner or arsenic furnace was condensed out. The gas followed a zig-zag path through the chambers, and one end of each chamber would be closed off with a door through which the condensed arsenic could be collected.

LEAT    

An artificial water-course, built to carry a supply of water to a mine.

LINTEL    

The horizontal timber or stone support above an opening in a wall or structure.

LOADING    

The stone platform in front of an engine-house (or elsewhere on a mine) on which machinery such as cranks, flywheels or winding drums were mounted. The reciprocal motion of the sweep rod attached to the beam was turned into a rotative motion on the loading.

LOBBY    

The excavated cutting running up to an ADIT portal.

LODE

 A linear area of mineralisation underground. Known in other parts of Britain as a VEIN or SEAM. Generally vertical or near-vertical, and often extending for considerable distances along its strike.

LODE-BACK PIT    

A shallow shaft dug from surface into shoad or the upper part (backs) of a lode, from which ore could be extracted from shallow STOPES to the depth of the water table or just below. Waste material was generally dumped next to the shaft mouth.

MAGAZINE  

Small strongly built store containing explosives (gunpowder or dynamite); often circular, sometimes with additional enclosing walls to contain the blast of an accidental explosion.

MELLIOR STONE    

The granite bearing stone in which the upright shaft of a HORSE WHIM ran.

MIDDLES    

The material in a BUDDLE found between the crop and the TAILINGS, this generally contained enough ore to warrant its re-treatment.

OPEN-CAST

An excavation where the mineral LODE or lodes are opened to the surface and exploited directly – similar to stone quarrying.

OPENWORK or BEAM

A mineral extraction site open to the surface – similar to a quarry but usually distinguished by its elongated shape and steep sides. Generally applied to features broader in extent than a GUNNIS or COFFIN. A variation is a STOCKWORKS, where an area of ground containing a large number of small parallel LODES was removed wholesale.

ORE

A mineral or mixture of minerals which could be worked for sale.

OVERBURDEN

The topsoil and subsoil removed in the process of opening or extending a quarry, streamworks or mine.

PELTON WHEEL    

A small enclosed water turbine, working at high pressure and rotational speeds. In use from the later 19th century.

PITWORK    

The term used to describe the pump rods, rising main, shaft guides (buntings) etc. within a shaft.

PORTAL    

The entrance to an ADIT beyond its LOBBY. Often timbered or stone vaulted.

PROSPECTING PIT FOSSICKING PIT or COSTEANING PIT    

A small pit dug in search of minerals, and almost always found in linear groups – often arranged cross-contour or at right angles to the projected strike of known lodes or deposits of shoad. A COSTEANING TRENCH is a linear excavation cut for prospecting purposes.

RAG FRAME or RACK FRAME    

A mechanically vibrated inclined table-like surface on which very fine slimes in slurry form were treated to recover their tin. Large mines would have hundreds of such frames arranged in groups.

REVERBERATORY KILN    

A design of furnace in which there was indirect contact between the heat from a hearth and ore to be roasted, usually by incorporating a baffle flue.

ROSE    

The cast-iron strainer attached to the bottom lift of pumps.

ROTATIVE ENGINE    

A beam engine in which the reciprocating motion of the beam was converted to rotary motion via a sweep rod, crank, and flywheel.

SCORIA

A dark-coloured slag formed as a waste by-product of the copper smelting process. Scoria saw limited use in the early 1800a as a building material when cast as blocks eg. the Black Bridge, Hayle.

SETT

The legal boundary within which a mine could extract minerals.

SETT

One of a series of stone supports for a tramway, performing the same function as sleepers.

SETT

One of the components of timber framing of an adit where it ran through loose ground; also the timber framing of a shaft to which the shaft guides and LAGGING BOARDS were attached.

SHAFT    

A vertical or near-vertical tunnel sunk to give access to the extractive areas of a mine.

SHAKING TABLE  

An inclined, mechanically vibrated table on which fine tin (as sands or slimes) in suspension in water was concentrated by relative density.

SHEARS or shear legs.    

A tall timber frame carrying a pulley or sheave wheel erected in front of an ENGINE HOUSE over a shaft and used for the installation and maintenance of PITWORK.

SHOAD or SHODE    

Ore weathered from the LODE and moved (in geological time) downslope under the force of gravity. Material reaching a river valley would be to some degree concentrated before redeposition in horizontal beds. These beds of detrital material (placer deposits) were exploited in STREAMWORKS.

SKIP    

A (generally elongated) iron or steel container equipped with small wheels or brackets running on the shaft guides (buntings) and used for rock and ore haulage in later mines.

SMALLHOLDINGS

Small plots of land, usually around 3-5 acres (1-2 hectares), which were leased to mine workers and others to build cottages and lay outfields for growing their own food.

SMELTING

The process in which mineral ores are subjected to heat combined with chemical reducing agents in a furnace, to liberate base or precious metals for sale.

SPALLING

Breaking the ore into smaller pieces by hand. Part of the ore dressing process, usually done by young girls.

SPRING BEAMS

The pair of longitudinal timbers extending from the rear of an ENGINE HOUSE parallel to and on either side of the BEAM at top floor level. These stopped any unwanted excess indoor motion of the beam via catches set onto its rear and were extended out from the front of the house to form the foundation for the

BOB-PLAT (the timber platform from which the bearings on the outdoor section of the beam could be serviced).

STACK

A chimney on an industrial site, used to carry away smoke or fumes from boilers, furnaces and calciners. Often situated at the end of a FLUE.

STAMPS

A mechanical device for crushing ore-bearing rock to a fine sand. Heavy vertically-mounted beams (or later iron rods) carrying cast or forged iron heads were lifted and dropped onto the prepared ore beneath them by a series of cams mounted on a rotating drum. This was usually driven by a water-wheel or rotative steam engine.

STOPE    

Excavated area produced during the extraction of ore-bearing rock. Often narrow, deep and elongated, reflecting the former position of the lode. Where open to the surface, these form GUNNISES or COFFINS.

STREAMWORKS    

An area worked for detrital (redeposited) tin deposits by shallow excavation. Often characterised by linear dumps, river diversion and evidence for leats. Some streamworks (dryworks) exploited deposits of SHOAD in now dry valleys and on hillsides, where concentrations of this material were economically workable. LEATS and reservoirs were necessary to work these sites, and are characteristic of them.

STRIPS (settling strips)    

Elongated shallow tanks in which the primary settlement and subsequent separation of tin ore from waste took place after it had been STAMPED.

SWEEP ROD    

The elongated iron rod which connected the beam of a Cornish engine to a crank and fly wheel.

TAILINGS    

The waste sand and slime from a mine dressing floor, not containing workable quantities of mineral.

TAILRACE    

The channel along which water flows after passing over or under a water-wheel before returning to the water course.

TIN STREAMING (streamwork)

An area worked for detrital (re-deposited) tin deposits by shallow excavation; often characterised by linear dumps, river diversion, and evidence for LEATS. Some such works (dryworks) exploited deposits of SHOAD in now dry valleys and on hillsides, where concentrations of this material were economically workable. LEATS and reservoirs were necessary to work these sites and often characterise them. This term is often applied to tin recovery works where tin ore lost with waste discharge from mine DRESSING FLOORS is recovered for sale by third parties.

TRAMWAY

A method of transportation for ore and materials at surface using iron plate or rails; similar to a modern railway and operated using either horse or locomotive power; also known as tramroads.

TRIBUTE

A system of payment in which groups of miners bid against each other for contracts to work sections of the mine for a percentage of the value of the ore raised from that area.

TUTWORK

A system of payment where groups of miners contracted to work on a "payment by results" system at previously-agreed rates, usually for shaft sinking or driving levels.

VANNER

A mechanically-driven, laterally vibrated, inclined rotating belt on which fine tin-containing material in suspension in water was treated by relative density. A VANNING SHOVEL was used to test the relative concentration of ore in a sample of finely crushed ore or partially dressed ore.

WATERWHEEL    

Wheel fitted with buckets or paddles around its periphery, and driven by the weight or force of a stream of water directed onto them.

WHEAL also WHELE, WHILE, HUEL.    

A mine.

WHEELPIT    

A structure built to house a water-wheel, often excavated and stone-lined, but sometimes free-standing.

WHIM PLATFORM    

The level – and usually circular –platform on which a horse-whim was sited.

WHIM    

The winding gear used for hauling from a shaft; consists of a power source and a winding drum. See HORSE-WHIM.