PREFACE. XX111 



if neiiher very elegant nor regular, will be useful 

 and intelligible, and will not produce the great 

 evil of throwing into absolute shade the obser- 

 vations of preceding writers. To submit to bare 

 authority is not one of the characters of an en- 

 quiring age ; and the cultivators of the sciences 

 under review, are far too numerous and too 

 jealous to admit of a despotic and general reform, 

 which, if it may sometimes proceed from asource 

 so respected as that of Brongniart, is more often 

 in danger of being found in hands ambitious of 

 unmerited fame. 



As the present arrangement of rocks is 

 founded on geological principles, it is evident 

 that the geological history of the rocks became 

 an indispensible part of it. Without such des- 

 criptions, indeed, it would have been deficient in 

 one of the circumstances most essential to clear- 

 ness ; as it would have wanted an explanation of 

 the sense in which the terms were used. These 

 descriptions would, it is true, have been super- 

 fluous, if any system of geology had existed to 

 which the author could with safety have referred. 



