No one who has eyes in his head, and considers what he sees, if he has been on Dartmoor, can have failed to observe how that every stream-bed has been turned over, and how that every hollow in a hillside is furrowed. The tin-streamers who thus scarred the face of the moor carried on their works far down below where the rivers debouch from the moor on to the lowlands, but there the evidences of their toil have been effaced by culture. The tin found in the detritus of streams is the oxide, and is far purer than tin found in the lode. Mining for tin was pursued on Dartmoor during the Middle Ages to a limited extent only, and solely when the stream tin was exhausted. [Illustration: BLOWING-HOUSE UNDER BLACK TOR] A very interesting excursion may be made from Douseland Station up the Meavy valley to Nosworthy Bridge, above which several old tin-moulds may be seen lying in the track beside the river, and tin-workings are passed. But perhaps the most interesting portion of the walk is that up the Nillacombe that opens on to the Meavy from the right below Kingset. [Illustration: TIN-WORKINGS, NILLACOMBE.] Above this the stream has been turned about and its bed torn up, and rubble heaped in huge piles. Not only so, but the hill-slope to the south is marked as with confluent smallpox, the result of the gropings of miners after tin. They followed up every trickle from the side and dug _costeening_, or _shoding_, pits everywhere in search of metal. The upper waters of the Webburn have in like manner been explored, and some idea of the extent to which the moor was lacerated by the miners may be obtained from the Warren Inn on the road from Post Bridge to Moreton, looking east, when the slopes of Headland Warren and Challacombe will be seen seamed deeply. The remains of the tinners have not been subjected to as full an exploration as they merit, but certain results have nevertheless been reached. One thing is abundantly clear, that all the tin-streaming was done subsequently to the time when men occupied the hut circles. The population living in them knew nothing of tin. Diodorus Siculus, who wrote B.C. 8, says that the dwellers at Belerium, a cape of Britain, mined and smelted tin. "After beating it up into knucklebone shapes they carry it to a certain island lying off Britain, named Ictis, for at ebb tides, the space between drying up, they carry the tin in waggons thither ... and thence the merchants buy it from the inhabitants and carry it over to Gaul, and lastly, travelling by land through Gaul about thirty days, they bring down the loads on horses to the mouth of the Rhine."