shown in the sketches opposite, showing a plan of the summits and a section through them to explain how accurately the two coincide in their slope with that of the original plateau. Every year the frost loosens the rock on the northern precipices, every heavy rain washes down earth from the ridge, while the gentler showers and mists penetrate the soil to the rock surface, which they slowly decompose. Thus, year by year, the flat portion of the summits becomes smaller, and a few thousand years will probably suffice to eat them away altogether, and leave rocky peaks more like that of Snowdon. The formation, as we now find it, is, in my experience, unique —that is, a mountain-top presenting two small patches of almost level ground, evidently being the last remnant of the great rolling plateau, out of which the whole range has been excavated. Double-headed mountains are by no means uncommon, but they are usually peaked or irregular, and carved out of inclined or twisted strata. The peculiarity of the Beacons consists in the strata being nearly horizontal and undisturbed, while the rock formation is not such as usually to break away into vertical precipices. The original surface must have had a very easy slope, while there were no meteorological conditions leading to great inequalities of weathering. The thick covering of peat has also aided in the result by preserving the original surface from being scored into gullies, and thus more rapidly denuded. After we had completed most of our work at Trallong we had to go further up the valley to Devynock. This is an enormous parish of more than twenty thousand acres, divided into four townships or chapelries, the two eastern of which, Maescar and Senni, we had to survey. In these mountain districts, however, we only surveyed those small portions where the new roads or new enclosures had been made, the older maps being accepted as sufficiently accurate for the large unenclosed areas of mountain land. We first went to Senni Bridge, where both districts terminate in the Usk valley; but after a short time I went to stay in a little publichouse at Senni in the midst of my work, while my brother stayed at Devynock or at Trallong, which latter was quite as near for half the work. On the other side of the river Usk there was a fine wooded rocky slope in which paths had been made near and above the river by some former resident owner, and this was a favourite walk on holidays. In the farmhouse adjacent a relative of the owner, a middle-aged man, who was apparently on the verge between eccentricity and madness, lived în retirement, and we heard a good deal of his strange ways, though they said he was quite harmless. He used to walk about a good deal with a pipe in his mouth and dressed in a gamekeeper style, and he always stopped to make some remark, and then walked on without waiting for an answer. My brother made a rough pen-and-ink sketch of him, which has fortunately been preserved, and which is here reproduced, as it well represents his appearance and manner when meeting any one. Some of his sayings were not only wild but exceedingly coarse, others merely abrupt and strange. One day he would say, "Where's your pipe? Don't smoke? Then go home and begin if you want to be happy." Another time something like this, "Who are you? Come to look after me? They say I'm mad, but I ain't. I'm here to enjoy myself. Do as I like." One time when he met my brother, after some such rigmarole as the above, he ended with, "Shave your head and keep your toe-nails cut, and you'll be all right." When I went up to Senni Street (Heol Senni, as it is called in Welsh) I greatly enjoyed wandering over the pretty valley which extended a long way into the mountains, flowing over nearly level meadows and with an unusually twisted course. This I found was so erroneously mapped, the numerous bends having been inserted at random as if of no importance, that I had to survey its course afresh. Above the village there were several lateral tributaries descending in deep woody dingles, often very picturesque, and these had usually one or more waterfalls in their course, or deep rocky chasms; and as these came upon me unexpectedly, and |