At the extremity furthest from the door was a _cache_ in the thickness of the wall, formed something like a kistvaen, as a place in which to store the metal and tools. The whole structure was banked up with rubble and turf.
Outside to the south still lies a mould-stone, a slab of elvan, in which the mould had been cut, measuring 26 inches long by 12 inches at one end and 15 at the other, and 5 inches deep.
That this is the earliest tin-furnace yet discovered on Dartmoor admits of no doubt. The curious mould-stone is quite different in shape from any others found on the moor. No mortar-stones were discovered, and this also is a token of antiquity.
The earliest smelting arrangements must have been very crude, and much tin was left in the slag. Until recently the Malays threw away their slags, which contained as much as 40 per cent. of tin. As there have been no mortar-stones found at Deep Swincombe, it is to be presumed that the tinners disregarded their slags. These have not, moreover, been found. The reason was this--the sets had been reworked at a later time by the tinners at Gobbetts, further down the river. These later men had stone mortars and a crazing mill, and finding these rich slags, removed them, pounded them up in the hollowed mortar-stones, that may be seen _in situ_ at Gobbetts, and re-smelted them. Deep Swincombe has all the appearance of having been much pulled about by tinners since the first furnace was erected.
[Illustration: TIN-MOULD, DEEP SWINCOMBE.]
The tin running out of the furnace was allowed to flow into holes in the ground, and thence was ladled whilst in a molten condition and poured into the moulds.
Mr. Gowland has given a most interesting account of the manner in which the metals are extracted from their ores in Japan.[12] This shows how that the primitive methods are still in practice there. He says:--
"Although tin ore is found and worked in Japan in several localities, there is but one ancient mine in the country. It is situated in Taniyama, in the province of Satsuma. The excavations of the old miners here are of a most extensive character, the hillsides in places being literally honeycombed by their burrows, indicating the production in past times of large quantities of the metal. No remains, however, have been found to give any clue to the date of the earliest workings. But whatever may have been their date, the processes and appliances of the early smelters could not have been more primitive than those I found in use when I visited the mines in 1883.