There is a fascination in exploration work such as that at Eastwater, where corridors, hitherto untrodden by the foot of man, open up all around as you make your way ever downwards into the heart of the hills; and even now there are many accessible passages into which as yet no one has penetrated. Reference to the section annexed will show an upper way, which terminates abruptly in a choke of stones and gravel, holding up a little water, whilst allowing a considerable quantity to pass. It is a remarkable fact that in all the labyrinths of galleries which we have explored in the profound depths of this cavern we have not yet alighted upon any portion which gives access to the continuation of this channel. There, rendered inaccessible by the barrier of débris, is, without doubt, a cavern as extensive as that which we have proved to exist in the sister watercourse hard by; and these two channels, starting from practically the same point, must diverge widely, and certainly do not unite again before the depth of 500 feet is attained. Farther eastward in Mendip, too, are similar swallet caverns. Not far to the north-west of Stoke Lane is an interesting cavern locally known as Cox's Hole. It is situated in the Limestone forming the southern edge of the great basin in which lies the Radstock Coalfield. Owing to the existence of this coalfield, there are no deep caves accessible in this part of Mendip. Yet a good deal of water must be absorbed through the innumerable fissures into the depths of the Carboniferous Limestone underlying the coalfield, and it is by no means unlikely that this water, heated to a high point by the subterranean temperature, gives rise to the hot springs at Bath. Cox's Hole was at a remote period, when the form of the hill was very different from that presented now, an active water-channel, evidently draining towards St. Dunstan's Well. It has two distinct entrances, one, the more westerly, being a cavity of considerable size. For about 100 feet the cavern consists of a roomy gallery running more or less horizontally. Then it pinches in, until the height is less than a foot, and only those can get along who are able to compress themselves into small compass. In a few feet, however, it widens out into a good-sized passage, with fine stalactites here and there, especially at a point on the northern side where an aven opens into a chamber more than 30 feet high. Now roomy and now contracted, the passage leads on until, at a distance of 100 yards from the entrance, it becomes so small that there is considerable difficulty in proceeding. Beyond this point the cavern becomes a simple water-tunnel, of a type common in Yorkshire. At 130 yards there is a sharp descent, the floor is littered with boulders, and 20 yards farther the passage is choked with silt. A very small passage, which had water in it when I was there, is said to be passable at times, though I am inclined to doubt this.