In dressing the ore the miners broke it with hammers, and then "vanned" it on their broad oak shovels. The wind bore away the valueless dust, leaving the metal behind. By the side of the "goyles," or deep workings, may be found "vanning-steads" where this process was conducted. But with the introduction of machinery the crazing-mill was employed, worked by a waterwheel, in which the ore was passed between two grinding-stones. The washing of the dust which took the place of the dry process was this:--
"The streame, after it hath forsaken the mill, is made to fall by certayne degrees" (steps) "one somewhat distant from another, upon each of which at every descent lyeth a green turfe, three or four foote square and one foote thick. On this the tinner layeth a certayne portion of the sandie tinne, and with his shovell softly tosseth the same to and fro, that through this stirring the water, which runneth over it, may wash away the light earth from the tinne, which, of a heavier substance, lyeth fast to the turfe."
After the black tin, or ore, had been thus treated it was conveyed to the blowing-house. The usage on Dartmoor was, when a miner was far from one of these, to tie the ore in a bag marked with his name or sign, and hang it about a dog's neck; the beast then conveyed it to the mill.
Of the "blowing-houses" a great many remain on Dartmoor. There are two on the Yealm, one, very perfect, on the Erme, one very early, before the introduction of the waterwheel, at Deep Swincombe, several on the Dart.
The blowing-house was a small structure of one chamber and a cache, or storeplace, underground. The doorway was rarely high enough to admit a man without stooping double. The walls were of stone without mortar, and, as far as can be judged from their remains, had no window. The furnace was heated with charcoal, and the fire blown by means of a great pair of bellows worked by a tiny waterwheel. The process was so roughly conducted that "divers light sparkles" of tin are said to have lodged in the thatched roof in sufficient quantities to render the burning of the roof once in seven years worth the undertaking. The melted metal ran out into a spoon-shaped hollow in a block of granite, or elvan, and was run into moulds also cut in slabs, many of which remain near the old blowing-houses.
A TIN MOULD
The white tin was then conveyed to a royal smelting-house, where it received a stamp; and no miner was suffered to dispose of his metal till it had thus been marked, and he had paid his due to the Crown for it.
Some of the terms used by tin miners may not prove uninteresting.
Stream-tin when found scattered beneath the surface on a small declivity is called shode, and runs to a depth that varies from one to ten feet. A right to work a certain portion is called a sett. The rubbish thrown out of a mine is called stent; sand or gravel, including tin, is termed gard; the walling on each side of a tye or adit is called stilling; the channels by which superfluous water is let run off are cundards, a corruption of "conduits." Oblong pits for a washing-floor are gounces; the frame of iron bars above is a ruddle.