Bull Pit lies in the wood just above this opening, nearer the road. It is a great open abyss, walled on three sides by crags of Limestone nearly a hundred feet high, and with trees growing all round the edges. This, no doubt, is a very ancient swallet that has not been in operation for ages--belongs, perhaps, to the same period as Elden Hole, which opens 200 or 300 feet higher, a mile away, on Elden Hill. A little way on, near Perryfoot, we come in sight of another very ancient cavity, on the side of Gautries Hill. It is a gaping pit about 70 feet deep, with a noble arch inside, spanning the entrance to a broad cave. At present the cave mouth is silted up with sand and clay. All these rocky openings are the lurking-places of beautiful ferns and mosses; the feathery fronds of the Limestone polypody, the late primroses, various saxifrages, and the delicate foliage of herb robert making a brave show. The wilder birds take refuge there. A crow flew out of the hole on Gautries Hill, and one day on approaching Elden Hole I was startled by a dense cloud of jackdaws, more than a hundred, suddenly rushing out. Farther down, from 50 to 100 feet lower, a host of starlings had built their nests on the walls of the chasm. Disturbed, they came flying up in twos and threes, beating the air in painful efforts to wing their way straight up and out of the hole. At Perryfoot a stream is engulfed which M. Martel considers to be the source of Peak's Hole Water, and to be identical with the stream that flows through the inmost passages of Peak Cavern. It now runs into a cleft that is too small to be explored. But at a comparatively recent date it was swallowed in a number of large fissures in a crescent-shaped wall of Limestone 100 yards away. Most of these openings are impracticable, but at the extreme east I had already reconnoitred a promising cleft which we now proceeded to examine thoroughly. This complicated swallet, with the passages behind it, is known locally as "Manifold." Going east for 35 feet, the fissure divides, one passage striking up towards the surface and the other turning south. We soon had to crawl, the passage being very low, narrow, and lined with objectionable stones. After 30 feet more we came to a wider place, with a sort of chimney on one side. Here was the sole mark of humanity that we found in this cave, a stake that had apparently been used to climb into the chimney. Nothing was gained by climbing it, so we squeezed our way along the main passage. Now the tunnel grew into a high but narrow canyon where we could stand upright, then it dwindled to a tunnel again, generally descending, but occasionally rising in what was once a siphon. We passed one or two branches, at the most important of which the principal tunnel curved to the left and descended a little more steeply over some small ledges and basins brimming with water. We began to feel sanguine about the wished-for cavern, but presently the diameter of the tunnel grew so