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: "The first is about 250 yards above Merrivale Bridge, on the left bank of the river. One jamb is erect, and, like most of the doorways of Dartmoor blowing-houses, was low, and to be entered necessitated an almost all-fours posture. Very little of the walls is standing, but what remains is composed of large moor-stones, dry laid. Near the entrance is a stone, 3 feet long and 2½ feet wide, containing a mould, which at the top is 18 inches long, 13 inches wide, and 6 inches deep. The sides are bevelled, so that the bottom length is 12½ inches, with a width of 7 inches at one end and 8 inches at the other. One end of the mould has a narrow gutter leading from the top to halfway down the mould. This was probably used for the insertion of a piece of iron prior to the metal being run in, thus permitting the easy withdrawal of the block of tin when cool from the mould. This stone also contains a small bevelled ingot or sample mould, 4 inches long, 2 inches wide, and 1¼ inches deep. "A water-wheel probably stood in the eastern recess of the house, for there is a covered drain leading from here right under the house and out at the western end, where the water was discharged into the river. Traces of the leat which supplied the motive power to this wheel may also be seen. "What appear to be the remains of the furnace, consisting of massive stones placed vertically, and inclosing a small rectangular space, are plainly visible. In this place, lying askew, as if it had been thrown out of position, is a large stone containing a long, shallow cavity, which may have been the bottom of the furnace or 'float,' _i.e._ the cavity in which the molten tin collected before being ladled into the mould. "This ruin lies at the nether end of deep, open cuttings, which start from near Rundlestone Corner, and are continued right down to the Walkham.