Water:Miner's Enemy, Streamer's friend.|
All mills, like Tolgus, which were independent of the mines, grew up by rivers and streams so that a supply of water was always to hand.
Tin has a high specific gravity - in other words, it is heavy. The tin particles are heavier than those of the rock in which they are trapped, so their weight will enable them to settle out in a stream of flowing water before the lighter waste particles are washed away - like an ebb tide leaving large stones high up on the beach and small pebbles lower down. This principle, called GRAVITY SEPARATION, was known to the earliest tin streamers, and is still the most efficient way of recovering tin.
...and was equally important as a means of power
An OVERSHOT WATER WHEEL is turned by the weight of water poured on to it at high level.
You will see this kind of wheel powering the Cornish stamps.
The passage of tin through Tolgus Mill
The RAW MATERIAL at Tolgus was sand from the Red River, so-called from the colour of its tin- and iron-laden water, sand which had already undergone considerable processing elsewhere, yet still containing enough tin to be worth re-treating. It was stored in the ORE SHED to be dried out.
Both fresh water and slurry are carried round the Mill by means of open wooden pipes called LAUNDERS.
|History of Tolgus||Stream Tin & Lode Tin||Management & Workers||12-headed Cornish Stamp||Sulpher & Arsenic Waste Disposal.|
|Water Power||The Sand House||The Slime Plant. Assaying.||Smelting||Trevithick Trust|
|TOLGUS Tin streaming at Redruth|