A circle was described in the grass, in diameter from 6 feet to 9 feet. Then a second circle, concentric, 3 feet beyond the first, that is to say, with a diameter 12 feet to 15 feet. Stones were set up on end in the ground where these circles had been described, and walls of horizontal slabs were laid between and on these uprights, their interstices filled in with moss and turf. After the walls had been carried to the height of four feet, the horizontal courses were drawn together inwards, so as to form a dome of overlapping slabs, and in the centre an opening was left to admit light and to serve as a smoke-hole, but sufficiently small to be easily closed with a stone or a wad of turf. On the south side of this bee-hive habitation a door was contrived by planting two jambs in the soil at right angles to the walls, standing about 2 feet 6 inches high, and placing over these a broad flat slab as lintel, on which the structure of the dome could be continued, and could rest. There are several of these huts still in existence as perfect as when first made. One is on the Erme on Dartmoor; it is almost buried in heather, and might be passed without observation as a mere mound. The door remains, and it will serve the pedestrian, as it has served many a shepherd, as a place of refuge from a shower. There are three or four under and on Brown Willy, the highest peak of the Cornish moors. Connected with one of these is a smaller hut of similar structure that served apparently as a store chamber. Comparatively few are perfect. The vast majority have fallen in. All were not originally domed over with stones, some--the majority--were roofed over by planting sticks in the walls and gathering them together in the centre, and then thatching them with reed, or packing turf round the beams. This we judge from the ruins. Some give evidence of having been domed, by the amount of stone that has fallen within the circle of the foundations; others, on the other hand, are deep in turf and peat, and show no fallen stones within the ring. [Illustration: _Fig. 14._--GRIMSPOUND, DARTMOOR.] Very often clusters of these circular hovels are enclosed within a circular wall of defence. The villages were, in a word, defended against assault. At Grimspound on Dartmoor is such a walled village. The pound contains four acres; a stream is ingeniously diverted from its course and brought within the enclosure. There remain the ruins of about twenty-five huts, but there are scattered heaps that indicate the former existence of other habitations which have been destroyed. Near Post Bridge, in the heart of Dartmoor, are the remains of something like fourteen village enclosures, whereof one contains about forty of these huts.[14] An account of a very numerous and remarkable group within fortifications, near Holyhead, was published by the Hon. W. O. Stanley in 1871. He explored the settlement with the spade.