54 A HISTORY OF 



A jumbling sound before the earthquake. This proceeds from the 

 air or fire> or both, forcing their way through the chasms of the earth, 

 and endeavouring to get free, which is also heard in volcanoes. 



A violent agitation or heaving of the sea, sometimes before and 

 sometimes after that at land. This agitation is only a similar effect 

 produced on the waters with that at land, and may be called, for the 

 sake of perspicuity, a seaquake ; and this also is produced by volca- 

 noes. 



A spouting up of waters to great heights. It is not easy to describe 

 the manner in which this is performed ; but volcanoes also perform 

 the same : Vesuvius being known frequently to eject a vast body 

 of water. 



A rocking of the earth to and fro, and sometimes a perpendicular 

 bouncing, if it may be so called, of the same. This difference chiefly 

 arises from the situation of the place with respect to the subterranean 

 fire. Directly under, it lifts ; at a farther distance, it rocks. 



Some earthquakes seem to travel onward, and are felt in different 

 countries at different hours the same day. This arises from the great 

 shock being given to the earth at one place, and that, being commu- 

 nicated onward by an undulatory motion, successively affects different 

 regions in its progress. As the blow given by a stone falling in a 

 lake, is not perceived at the shores till some time after the first con- 

 cussion. 



The shock is sometimes instantaneous, like the explosion of gun- 

 powder ; and sometimes tremulous, and continuing for several minutes. 

 The nearer the place where the shock is first given, the more instan- 

 taneous and simple it appears. At a greater distance, the earth re- 

 doubles the first blow with a sort of vibratory continuation. 



As waters have generally so great a share in producing earthquakes, 

 it is not to be wondered that they should generally follow those breach- 

 es made by the force of fire, and appear in the great chasms which the 

 earthquake 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. 



The valley of Solfatara, near Naples, seems to exhibit, in a minuter 

 degree, whatever is seen of this horrible kind on 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 middle 

 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 sometimes 

 spouts up eight or ten feet high. The most noisome fumes, fetid 

 water, and sulphureous vapours, offend the smell. A stone thrown 

 into any of the caverns, is ejected again with considerable violence. 

 These appearances generally prevail when the sea is any way dis 

 lurbed ; and the whole seems to exhibit the appearance of an earth- 

 quake in miniature. However, in this smaller scene of wonders, a* 

 well as in the greater, there aie many appearances for which, perhaps 



