46 



Mr. Hopkins on the Structure of the 



it belongs. Thus it may happen that expressions which are strictly calculated to 

 convey perfectly accurate notions of the reasoning employed or the results arrived 

 at, may, when addressed to persons imperfectly acquainted with the language of 

 the subject, convey conceptions either positively erroneous, or at least devoid of 

 that distinctness and precision without which they become comparatively valueless. 

 Such, perhaps, is especially the case in the application of mechanical science to the 

 problems which geology presents to us. In these problems, approximate solutions 

 only can be sought for ; and the sense in which the language of mechanics, as an 

 accurate science, is constantly used, can only be completely understood by those 

 who can understand, from the nature of the problem proposed, the degree of 

 approximation which may be attainable in its solution. In some instances it must 

 be impossible to obviate this difficulty on the part of the reader ; in others it could 

 only be done by a verbal prolixity, which might justly be deemed intolerable in a 

 communication to a scientific body. Under the impression however, that many 

 geologists who have not devoted their attention to mechanical science might feel 

 an interest in these theoretical views on geological elevation, I have ventured, in 

 this memoir, to give such repetitions of former statements and such detailed expla- 

 nations as may tend to render the subject more generally intelligible. Should this 

 object be accomplished, it will be deemed, I trust, a sufficient apology for the want 

 of that greater brevity which it is generally desirable to maintain in original com- 

 munications on scientific subjects. 



TRANSVERSE SECTIONS ACROSS THE WEALDEN DISTRICT. 



16. 



Trotton 

 Common. 



VV. of Hind Head. 



Farnham. 



Crooksbury W. end of 

 HiU. Hog's Back. N. 



17. 



