6 



rocks, or with the structure of the earth, is, doubt* 

 less, an important part of their history ; but as it 

 does not enter into the principles on which they 

 are to be arranged, so it offers no argument for 

 thus extending that system under which they are 

 classed, to the classification of these objects also. 



It will here be readily admitted, that a miner- 

 alogical arrangement of rocks is the best adapted 

 to illustrate the mineral history of the species which 

 are to be ranked under it ; arid that, if we had no 

 other view in studying rocks than to become ac- 

 quainted with their mineral composition, it ought 

 to be preferred. Such an arrangement, could it 

 be perfected, would doubtless facilitate the des- 

 cription of a cabinet of specimens ; but this is an 

 object of very trivial importance. 



The chief end in view in the study of rocks 

 is to inquire respecting the structure of the earth. 

 Hence it becomes our business to investigate their 

 proportions, their gradations, their analogies to 

 each other, their mutual dependence, their order 

 of succession and disposition, and the general 

 relations of all kinds which they bear to each 



