"The ore was roughly broken up by hammers on stone anvils, then reduced to a coarse powder with the pounders used for decorticating rice, the mortars being large blocks of stone with roughly hollowed cavities.
"It was finally ground in stone querns, and washed by women in a stream to remove the earthy matter and foreign minerals with which it was contaminated. The furnace in which the ore was smelted is exactly the same as that used for copper ores, excepting that it is somewhat less in diameter. The ore was charged into it wet, in alternate layers with charcoal, and the process was conducted in precisely the same way as in smelting oxidised copper ores. The tin obtained was laded out of the furnace into moulds of clay."
The furnace employed for copper is also described by Mr. Gowland:--
"An excavation, measuring about 4 feet long, 4 feet wide, and 2 feet deep, is made, and this is filled with dry clay carefully beaten down. In the centre of this bed of clay a shallow, conical-shaped hole is scooped out. The hole is then lined with a layer, about three inches thick, of damp clay mixed with charcoal, and the furnace is complete.
"It has no apertures either for the injection of the blast or for tapping out the metal. A blast of air is supplied to it generally from two bellows, placed behind a wall of wattle well coated with clay, by which they and the men working them are protected from the heat. The blast is led from each bellows by a bamboo tube, terminating in a very long nozzle of clay, which rests on the edge of the furnace cavity."
At Deep Swincombe no bellows were used; the draught probably came in through the hole behind the furnace.
But in the reign of Queen Elizabeth a great revolution in the smelting of tin was wrought by the introduction of German workmen and their improved methods. They brought in the water-wheel. The ruins that are found in such abundance of "blowing-houses," as they are called--one at the least beside every considerable stream--belong, for the most part, to the Elizabethan period. They have their "leats" for carrying water to them, and their pits for tiny wheels that worked the bellows.
The situation of these smelting-houses may be found usually by the mould-stones that lie near them. There is one below the slide or fall of the Yealm, with its moulds in and by it, and another just above the fall. There is one near the megalithic remains at Drizzlecombe, also with its mould-stones. But it is unnecessary to particularise when they are so numerous. I will, however, quote Mr. R. Burnard's description of two in the Walkham valley as typical: