Only to judge by the number of climbers that have taken up cave work as a pastime, there must obviously be a natural relation between this sport and rock climbing. Certainly, there are many methods common to the two sports, and the expert cragsman has an immense advantage over others when he takes to cave exploring. But the methods and appliances of the mountaineer are restricted by artificial regulations. There are many things that must not be done, even to enable a climber to ascend an otherwise inaccessible peak or to avoid serious peril. In cave work, on the other hand, the difficulties and dangers are multiplied so formidably by the singular conditions, of which darkness is but one, that such prohibitions would be absurd. When one may be called upon to climb a wall of mud, or a sheet of slippery stalagmite, or to traverse water-swept rocks with an unfathomed pool or swallet underneath, every safeguard must needs be utilised. Any mechanical means of accomplishing, facilitating, or expediting a passage is legitimate in cave work; ropes, pulleys, ladders of rope and wood, windlass, rafts, boats, crowbar, pick, shovel--all these, and an enormous variety of other things, have their place in the cave explorer's equipment. One might write a volume on the equipment of cave explorers. Hardly any other sport requires so formidable a variety. I must limit myself to a few words. The explorer's dress should be a boiler suit, made all in one piece from neck to heel, and with no pockets or buttons to catch in the jagged Limestone, plenty of both being provided inside. He must renounce any hankering after waterproof garments, the proper precaution against the effects of wet being to wear thick woollen underclothing. His boots should be nailed after the manner of those worn by rock climbers. Candles are the best illuminant, much better than any lamp--acetylene, electric, or other. But a supply of magnesium wire should be carried, with waterproofed matches in water-tight boxes; and a powerful limelight, burning ether instead of hydrogen, for the sake of portability, is a useful auxiliary. Boats have been used in some of the caves in the Peak, in Wookey Hole, and in the cavern of Marble Arch, explored by M. Martel, in Ireland. Plenty of rope--not of the Alpine Club material, but hempen--is necessary, and a few rope ladders often come in handy. The only rule of the game that I should like to insist upon is, that no damage should be done to the beautiful features of a cave. It is a rule observed by every cave explorer worthy of the name. The temptation to acquire specimens must be resisted.