8. A stout rope not less than twenty feet long with a horse’s girth at the end is necessary for the exploration of vertical fissures, so that the explorer may be let down without any great danger. No large unknown caves should be explored without a rope, or by a party less than three in number. In exploring the caves of Burrington Combe we used a rope sixty feet long. The descent into Helln Pot, described in the second chapter, p. 41, was effected in the following manner. A strong platform of timber was made over the open fissure, and from it a square “cage” or “basket” of the ordinary kind used in mining was let down for the first drop of 198 feet. It was prevented from twisting round by two guide ropes. For the rest of the falls we had two ladders eight feet long, and a rope, without which we should have been unable to reach the bottom. [Illustration: | | a | | --+-----+--------------+-----+-- g | ... | | ... | g | | | | b | e | c d c | e | b | | | | g | ... | | ... | g --+-----+--------------+-----+-- | | a | | ] 9. In the exploration of water-caves, in which there are sometimes sheets of water of considerable size and depth, a raft may be used, such as that devised by Mr. James Parker for the navigation of the great cave of Wookey Hole. It consisted of a platform supported on barrels and built as follows: A frame of stout poles was made; two, _a a_, being eight feet long, with four others, _b_, _c_, lashed firmly across, each four feet in length. The space _d_ was converted into a platform by nailing boards across, and this was buoyed up by a beer-barrel at each end in the interspace _e_. The barrels were attached to the raft by two loops of rope _g_, passing over from _b_ to _c_, and thus kept in place, although they freely twisted and turned in actual use. The ropes had an advantage over iron hoops for the attachment of the barrels, because when they were tightened the platform was raised above the water, when they were loosened it was lowered, and thus the raft could be adjusted to the weight to be carried, to the depth of the water, and the distance of the water-line from the roof. A raft of this kind will bear three persons, and is sufficiently light to be carried over the shallows. With it Mr. Parker made his way for a considerable distance in the Wookey Hole cavern, and subsequently I penetrated as far as the water-line would allow me to get. A long pole is also necessary for punting. Mr. Parker found by experience that a raft made of boards nailed on the top of two beer-barrels was too unstable to be of any use. In making his way across subterranean pools the cave-hunter ought to be prepared for accidents, for the depth is very uncertain, and the water sufficiently cold to cause cramp. For the exploration of ordinary water-caves a