APPENDIX. 



479 



plete; as have many other matters, often of great mo- 

 ment, been rectified or determinedby these means alone. 

 And, of all this, whatever yet remains, is reserved for 

 him whose eye of knowledge is quickened to the ap- 

 prehension of distinctions which escape an unprepared 

 and careless observer. 



It is a sufficient reason for the study of zoology and 

 botany, that the organic remains of former worlds con- 

 stitute one of the most interesting branches of their 

 history. The subject is however so extensive, that it 

 is too much to demand from the geologist an intimate 

 acquaintance with it; though, without some attain- 

 ments, in at least certain departments, he will often be 

 obliged to resort to those who have bestowed undivided 

 attention on these branches of natural history. Yet if 

 this is an inconvenience, it is perhaps best as it is; since 

 it is compensated by the greater accuracy arising from 

 the division of labour. Yet let me still caution stu- 

 dents against believing that the collection and arrange- 

 ment of fossil remai ns constitute geology, or that a theory 

 of the earth can be constructed from materials, which, 

 though evidential of some parts of its history, are, with 

 the sole exception of limestone, but incidental to its 

 nature and progress as a planetary globe. 



So entirely is geology dependant on chemical prin- 

 ciples, that scarcely a step can be made in geological 

 reasoning without their aid. All the theories of the 

 earth are questions of chemistry ; and had that science 

 been understood by their propounders, geology would 

 have escaped the censure due to those who have thus 

 obtruded their ignorant speculations to enthral the 

 minds of the equally ignorant. Without chemistry, 

 the origin, nature, and effects of the igneous rocks, in 

 particular, would never have been understood ; as the 

 labours of chemists have already materially elucidated 



