Part III. of the Earth. 



bling therein , is the Caufe of the 

 Shock ; it naturally fleering its courfe 

 that way where it finds the readieft 

 Reception, which is towards thele 

 Caverns ; this being indeed much the 

 cafe of Damps in Mines, whereof more 

 by and by. Befides that thofe Parts of 

 the Earth which abound with Strata 

 of Stone, or Marble, making the 

 ftrongeft Oppofition to this Effort^ are 

 the moft furioufly fhattered, and fuf- 

 fer much more by it than thofe whicfi 

 confift of Gravel, Sand, and the like 

 laxer Matter, which more eafily give 

 way, and make not fb great refiftancej 

 an Event obfervable not only in this^ 

 but all other Explofions w^hateven 

 But, above all, thofe Countries^ which 

 yeild great ftore of Sulphur and Nitre^ 

 are by far the mofl: injured and incom- 

 moded by Earthquakes; thefe Minerals 

 conftituting in the Earth a kind of Na- 

 tural Gunpowder, which, taking fire^ 

 upon this aflfembly and approach of 

 it, occafions that murmuring noife, 

 that fubterranean Thunder (if I may 

 fb fpeak ) which is heard rumbh'ng 

 in the bowels of the Earth during 

 Earthquakes, and, by the afliftance cf 

 its explofive Power, renders the Shock 



