2 ON THE GENERAL OBJECTS OF 



many inferior branches ; including the history of mi- 

 nerals, of organic fossils,, and of alluvial deposits ; 

 with other matters which it is not here necessary to 

 specify. 



These objects are not merely adapted to the gratifi- 

 cation of speculative curiosity, but are, in many cases, 

 conducive to the wants or luxuries of mankind, to in- 

 numerable uses in the arts of life. Thus it becomes 

 necessary to form accurate records of their places, by 

 means of mineral topography, to indicate the precise 

 circumstances under which they exist, the modes by 

 which they may be best obtained, and the varieties of 

 character which they present : the whole constituting 

 a body of investigations by which geology is raised to 

 the rank of a practical science. 



If now, as in the other branches of natural history, 

 every rock and substance were visible, or could be 

 exhibited by the mere efforts of industry, or if the geo- 

 logical surface of the earth were, like its geographi- 

 cal details, within the reach of actual measurement 

 and examination, time and industry alone would pro- 

 cure for us all the information which could be required, 

 whether for the purposes of curiosity or use. A per- 

 fect accumulation of facts would, as in botany, short- 

 ly form the materials of a science, to which the phi- 

 losopher would superadd those analogies or distinc- 

 tions by which nature has classified or separated all 

 its objects. 



But such is the condition of the earth's surface, and 

 such its structure, that we can make little progress in 

 its study without in some degree inverting this pro- 

 cess. As in geometrical synthesis or in chemical 

 science, we must extend the conclusions and results 

 obtained from the observation of a certain number of 

 facts, to the purpose of discovering others ; and thus 



