PREFACE. xxvii 



though the moft fmgular inftance of warring 

 elements, have been fcarce fo much as fpo- 

 ken of, and we know very little of them ; 

 but what we know is fufficient to recom- 

 mend them to our attention. They are 

 very frequent, as appears by the banks of 

 floating pumice- {tones, met with and noticed 

 by fo many navigators. They have fpent 

 and exerted their power in many places, 

 where new iflands have been accumulated 

 and raifed by their eruptions j and may be. 

 nearer examined in the ocean and on the 

 fhores of thefe iflands by fuch navigators as 

 are Naturalifts ; nay, they may be traced even 

 on the continent, where ancient volcanos are 

 capped by marine ftrata ; which is the cafe in 

 Hefle and in thofe hills of Italy, which Mr. 

 Ferber has noticed as being compofed of 

 alternate volcanic and marine beds. They 

 muft of courfe produce modifications of 

 foflils, which the common volcanic erup- 

 tions above the level of the fea feem never 

 to offer to the obferver. The officinal pu- 

 m ice -(tones, floating in the fea, are un- 

 2 doubtedlv 



