CAVERN OF ADLESBERG.— SPEEDWELL MINE CAVERN. 301 



chased by beasts of prey, they may fall in whole droves. Their 

 bones may either stick fast in the fissures, and be afterwards inclosed 

 in calcareous stalactites, or they may be carried by subterranean 

 currents into caverns which have no communication with the surface. 

 Such was the cavern at the Bull's Eye mine, near Worksworth, in 

 Derbyshire, which was opened by mining operations in the year 

 1663, and contained the entire skeleton of an elephant. 



There is a considerable river, called the Pinka, in the cavern at 

 Adlesberg, in Carniola, which forms a subterranean lake, where it 

 appears to be lost ; but it emerges again on the north side, and takes 

 the name of the Renz. This cavern is one of the largest in Eu- 

 rope ; it extends for several leagues into a calcareous mountain, sit- 

 uated between Laybach and Trieste, and contains the bones of bears 

 and other animals, in the mud that forms the floor of the cavern, or 

 rather series of caverns, that are connected by passages with each 

 other*. 



There are numerous caverns and grottoes in the vicinity of Adles- 

 berg, and the surface of the country is, in various parts, broken by 

 depressions from the subsidence of the roofs of these caverns. 

 There are doubtless, in all these caverns, subterranean rivulets, which 

 are continually in action, and are undermining and wearing down the 

 rocks that support the strata above them. In Derbyshire, and the 

 district called Craven, in Yorkshire, beside the subterranean rivulets 

 before mentioned, there are currents of water incessantly in action, 

 which are discovered only by mining operations. 



The Speedwell mine, near Casdeton, in Derbyshire, is a subter- 

 ranean tunnel and canal, nearly half a mile in length, penetrating into 

 the centre of a mountain, composed of metalliferous limestone : the 

 descent to the canal is by a flight of steps, about forty yards in depth. 

 The mountain is intersected by numerous metallic veins, and the 

 proprietors of the mine intended to carry the tunnel and canal through 

 the whole extent, in order to discover the veins, and have ready ac- 

 cess to work them, to bring out the ore. It was necessary to exca- 

 vate the stone by blasting, and before every explosion the miners re- 

 tired for safety to a considerable distance in the tunnel. When 

 they had proceeded in this manner about eight hundred yards, 

 they were greatly alarmed after a blast, to hear the tremendous roar- 

 ing of a torrent, and fled towards the entrance of the tunnel. A 

 miner, who was working there at the time, informed the author, thai 

 he thought there was no chance of their escaping immediate destruc- 

 tion ; however, when they had retreated a considerable distance, 

 they perceived the rushing sound to grow less alarming; they tlieii 

 halted awhile, and took courage to return, when they discovered that 

 the last blast had made an opening into a spacious cavern, and that a 

 torrent of water was falling from a considerable height into a vast 

 chasm on one side of it. The loud roaring of the water was greatly 

 increased by the echoes of the cavern ; for in the roof of this cav- 



