46 Dr. Mac Culloch on 



department of nature, where it is not applicable, that kind of 

 arrangement which had been found successful in others. 



Though there is no prospect, therefore, of producing a clas- 

 sification of rocks, either natural or artificial, which can be 

 followed in a systematical and descriptive work, there is no 

 reason why we should not attempt to arrange them in some 

 order. Such a classification, could it be perfected, would still 

 have its uses in a scientific view, as it would represent the 

 order of nature, or at least declare the connections, analogies, 

 or relations, of rocks, in a compendious and convenient man- 

 ner. It would also be of use for the mere purposes of descrip- 

 tion and arrangement; because it would be a point from which 

 to depart or deviate, without the risk of straying too far or 

 falling into confusion ; standing as a beacon to indicate such 

 changes as might, from time to time, be made En it. Even if 

 highly imperfect, it would still be useful ; because, by placing 

 the imperfections and difficulties in an obvious light, and by 

 showing those that actually exist, it would lay the first step 

 towards a better system. 



I am very far indeed from presuming that I have discovered 

 an unexceptionable classification ; but if no one will attempt 

 an imperfect one, we are very little likely to succeed in finding 

 one that shall answer the desired ends. It is also true, in 

 every thing, that what an inventor has been unable to accom- 

 plish, is often done in an instant by those who might never 

 have made the original suggestion. 



It seems to me that something like a natural classification 

 may be made on the basis of the materials collected for that 

 System of Geology which I have long since prepared for the 

 press, which has remained these many years dormant in its 

 MS., and may possibly thus remain for ever. The reasons for 

 distinguishing the unstratified from the stratified rocks, in both 

 classes, must long since have been obvious. Those for divid- 

 ing the stratified rocks of the ordinary secondary class into 

 three, are, in my own estimation, satisfactory even as a ques- 

 tion of geological theory ; but being here compelled to crowd 

 what I can into the narrowest possible limits, I dare not attempt 

 to state them. 



I shall only further premise respecting this classification, 



