PREFACE. xvii 



ture, in different times, and under different 

 circumftances, by the folvents of water and 

 fire, uniformly produces, and has produced, 

 that variety of foffils, which caps the furface 

 of the earth and fills our mineralogies. The 

 determination of thefe various circumftances, 

 under which Nature produced and depofited 

 them, is, in refpect to the foffils, what the 

 Linnaean Sexual Syftem is to the plants; 

 and {hews not what every foffil is good 

 for, or compofed of but a probable rule, by 

 which to find and to purfue them under 

 ground, and by which we may judge of their 

 origin and antiquity ; advantages, which can 

 never be expected from our mineralogical 

 fyftems, eftablimed merely upon form, co- 

 lour, and chemical aflays j and which will, 

 perhaps, fome day or other, make thefe en- 

 quiries more acceptable and famionable. 

 Much has been done that way, but much is 

 ilill left for pofterity ; for which I refer the 

 reader to Baron Bern's and Ferber's accounts 

 of the Hungarian and Bohemian mines, 

 to my Preface added to them, and to the 

 vaft book of Nature, which lies before us. 



2. The 



