32 A HISTORY OF 



duced them : and to this variety of causes, we must, at present, b 

 content to assign those that have happened before we had opportuni- 

 ties for observation. 



CHAPTER VII. 



Or CAVES AND SUBTERRANEOUS PASSAGES, THAT SINK, BUT NOT 

 PERPENDICULARLY, INTO THE EARTH. 



IN surveying the subterranean wonders of the globe, besides those 

 fissures that descend perpendicularly, we frequently find others that de- 

 scend but a litle way, and then spread themselves often to a great ex- 

 tent below the surface. Many of these caverns, it must be confessed, 

 may be the production of art and human industry ; retreats made to 

 protect the oppressed, or shelter the spoiler. The famous labyrinth 

 of Candia, for instance, is supposed to be entirely the work of art. 

 Mr. Tournefort assures us, that it bears the impression of human in- 

 dustry, and that great pains have been bestowed upon its formation. 

 The stone-quarry of Maastricht is evidently made by labour : carts en- 

 ter at its mouth, and load within, then return and discharge their 

 freight into boats that lie on the brink of the river Maese. This quar- 

 ry is so large, that forty thousand people may take shelter in it : and 

 it in general serves for this purpose, when armies march that way ; 

 becoming then an impregnable retreat to the people that live there- 

 about. Nothing can be more beautiful than this cavern, when lighted 

 up with torches ; for there are thousands of square pillars, in large 

 level walks, about twenty feet high ; and all wrought with much neat- 

 ness and regularity. In this vast grotto there is very little rubbish ; 

 which shows both the goodness of the stone, and the carefulness of the 

 workmen. To add to its beauty, there also are, in various parts of it, 

 little pools of water, for the convenience of the men and cattle. It 

 is remarkable also, that no droppings are seen to fall from the roof, 

 nor are the walks any way wet under foot, except in cases of great 

 rains, where the water gets in by the air-shafts. The salt-mines in 

 Poland are still more spacious than these. Some of the catacombs, 

 both in Egypt and Italy, are said to be very extensive. But no part 

 of the world has a greater number of artificial caverns than Spain, 

 which were made to serve as retreats to the Christians against tlte lu- 

 ry of the Moors, when the latter conquered that country. However, 

 an account of the works of art does not properly belong to a natural 

 history. It will be enough to observe, that though caverns be found 

 in every country, far the greatest part of them have been fashioned 

 by the hand of nature only. Their size is found beyond the power 

 of man to have effected, and their forms but ill adapted to the con 

 veniences of a human habitation. In some places, indeed, we find 

 mankind still make use of them as houses ; particularly in those 

 countries where the climate is very severe ;* but in general they are 

 tleserttd by every race of meaner animals, except the bat ; these rtoc- 



Phil. Trans, vol. ii. p 368. 



