“In this long and winding gallery, fashioned by nature in the marble heart of the mountain, floor, roof, and sides are everywhere intersected by fissures which were formed in the consolidation of the stone. To these fissures and the water which has passed down them, we owe the formation of the cave and its rich furniture of stalactites. The direction of the most marked fissures is almost invariably N.W. and S.E., and when certain of these (which in my geological work I have called master fissures) occur, the roof of the cave is usually more elevated, the sides spread out right and left, and often ribs and pendants of brilliant stalactite, placed at regular distances, convert the rude fissure into a beautiful aisle of primæval architecture. Below most of the smaller fissures hang multitudes of delicate translucent tubules, each giving passage to drops of water. Splitting the rock above, these fissures admit, or formerly admitted, dropping water: continued through the floor, the larger rifts permit, or formerly permitted, water to enter or flow out of the cave. By this passage of water, continued for ages on ages, the original fissure was in the first instance enlarged, through the corrosive action of streams of acidulated water; by the withdrawal of the streams to other fissures, a different process was called into operation. The fissure was bathed by drops instead of streams of water, and these drops, exposed to air currents and evaporation, yielded up the free carbonic acid to the air and the salt of lime to the rock. Every line of drip became the axis of a stalactitical pipe from the roof; every surface bathed by thin films of liquid became a sheet of sparry deposit. The floor grew up under the droppings into fantastic heaps of stalagmite, which, sometimes reaching the pipes, united roof and floor by pillars of exquisite beauty.” At the time of its exploration, the water stood at a considerably higher level inside than at the present time, and formed deep pools. The barrier of dripstone has been cut through, and the water level lowered, and a passage made for a considerable distance. Inside, the old water line, which separated the subaërial from the subaqueous dripstone, is very distinct, the former being deposited in thick bosses, crumpled curtains, drops, straws, pyramids, and other fantastic drip-structures, while the latter is honeycombed, and composed of rounded, grape-like masses. Between them an ice-like coating of stalagmite forms a dividing line, now supported in mid air, but that formerly shot across the surface of the pools that have been drained, or rested on the mud and stones which had been brought down by the stream in ancient times. In some places it still rests on the surface of the pools.