36 



A HISTORY OF 



by an undulatory motion, successively affects 

 different regions in its progress ; as the blow 

 given by a stone falling in a lake, is not per- 

 ceived at the shores till some time after the 

 first concussion. 



The shock is sometimes instantaneous, like 

 the explosion of gunpowder; and sometimes 

 tremulous, and continuing for several minutes. 

 The nearer the place where the shock is first 

 given, the more instantaneous and simple it 

 appears. At a greater distance, the earth 

 redoubles the first blow witli a sort of vibra- 

 tory continuation. 



As waters have generally so great a share 

 in producing earthquakes, it is not to be 

 wondered that they should generally follow 

 those breaches made by the force of fire, and 

 appear in the great chasms which the earth- 

 quake has opened. 



These are some of the most remarkable 

 phenomena of earthquakes, presenting a 

 frightful assemblage of the most terrible effects 

 of air, earth, fire, and water. 



Th'> v.dley ofSolfatara, near Naples, seems 

 to exhibit, in a minuter degree, whatever is 

 seen of this horrible kind oa the great theatre 

 of nature. This plain, which is about twelve 

 hundred feet long, and a thousand broad, is 

 embosomed in mountains, and has in the mid- 

 dle of it a lake of noisome blackish water, 

 covered with a bitumen, that floats upon its 



surface. In every part of this plain, caverns 

 appear smoking with sulphur, and often 

 emitting flames. The earth, wherever we 

 walk over it, trembles beneath the feet. 

 Noises of flames, and the hissing of waters, 

 are heard at the bottom. The water some- 

 times spouts up eight or ten feet high. The 

 most noisome fumes, fetid water, and sul- 

 phureous vapours, offend the smell. A stone 

 thrown into any of the caverns, is ejected 

 again with considerable violence. These ap- 

 pearances generally prevail when the sea is 

 any way disturbed ; and the whole seems" to 

 exhibit the appearance of an earthquake in 

 miniature. However, in this smaller scene 

 of wonders, as well as in the greater, there 

 are many appearances for which, perhaps, 

 we shall never account ; and many questions 

 may be asked, which no conjectures can 

 thoroughly resolve. It was the fault of the 

 philosophers of the last age, to be more in- 

 quisitive after the causes of things than 

 after the things themselves. They seemed 

 to think that a confession of ignorance can- 

 celled their claims to wisdom ; they, there- 

 fore, had a solution for every demand. 

 But the present age has grown, if not 

 more inquisitive, at least more modest; and 

 none are now ashamed of that ignorance 

 which labour can neither remedy nor re- 

 move. 



CHAPTER XI. 



OF THE APPEARANCE OF NEW ISLANDS AND TRACTS; AND OF THE 



DISAPPEARING OF OTHERS. 



HITHERTO we have taken a survey only 

 of the evils which are produced by subter- 

 ranean fires, but we have mentioned nothing 

 of the benefits they may possibly produce. 

 They may be of use in warming and cherish- 

 ing the ground, in promoting vegetation, and 

 giving a more exquisite flavour to the pro- 

 ductions of the earth. The imagination of a 

 person who has never been out of our v ovvn 

 mild region, can scarcely reach to that luxu- 

 riant beauty with which all nature appears 



clothed in those very countries that we hare 

 but just now described as desolated by earth- 

 quakes, and undermined by subterranean 

 fires. It must be granted, therefore, that 

 though in those regions they have a greater 

 share in the dangers, they have also a larger 

 proportion in the benefits of nature. 



But there is another advantage arising from 

 subterranean fires, which, though hitherto 

 disregarded by man, yet may one day be- 

 come serviceable to him; I mean, that while 



