470 APPENDIX. 



tomize the rocks beneath the surface, by the penetra- 

 ting eye of science. In hilly countries, investigation 

 is comparatively easy ; as the cliffs of mountains and 

 of sea coasts often display, not only the rocks them- 

 selves, but their order of succession and their minuter 

 circumstances ; teaching us also to construct sections, 

 or serving to check those which we have inferred from 

 more difficult comparisons of the surface. He who 

 can commence from such a point, has often gained a 

 firm foundation for his work ; since he can thus ex- 

 tend the same conclusions to places of greater obscurity. 

 Mountains which exhibit no precipices demand more 

 attention : yet, by giving passage to streams, they often 

 display enough of their structures ; though patient in- 

 vestigation is here especially required, since true de- 

 ductions can only be made by the comparison of many 

 observations on the nature and positions of the rocks; 

 while the geologist must add all his preliminary know- 

 ledge to industry and acuteness. And here also must 

 he carefully record observations ; since the truth is 

 generally to be obtained but by a distant and final com- 

 parison. And though deficient in streams, protruding 

 rocks often convey sufficient indications of the internal 

 structure: although the student must be careful not to 

 mistake transported for fixed ones ; while, if the sound 

 on being struck, and an irregularity of position in stra- 

 tified ones, offer criterions, there are other circumstan- 

 ces which words can scarcely convey, but which ex- 

 perferice will give; forming him to that tact so well 

 illustrated in 6C Zadig." If superficial observers have 

 too often trusted to the stones deposited by rivers, they 

 teach little or nothing: while, being often derived from 

 antient alluvia, they cannot even indicate their birth 

 places; as, in no case, can they instruct us respecting 

 the successions or positions of any rocks. 



