In dAtLoWAir. 



ravines, or precipices, that we are able to examine 

 them. Every geologist knows, that the points ia 

 which we can see and examine the rocks which 

 constitute the crust of our globe, bear hardly any 

 proportion to those from which we are altogether 

 excluded, either by the ocean, or the soil which 

 covers the earth, and, unfortunately for the science 

 of geology, but fortunately for the existence of 

 geologists, renders it a fit habitation for vegetable 

 and animal life. Of the central parts, I believe, 

 it must be confessed, that, in a geological point of 

 view, we know little or nothing. What, then, 

 shall we say of those, who, without having seen 

 or examined one-millionth part of the earth's 

 surface, and certainly none of its central parts, 

 take upon them to affirm, that such and such were 

 the means by which it was brought into its pre- 

 sent state, and that such and such agents exist and 

 act in its central regions ? 



Of all the theorists of this sort, or intellectual 

 adventurers, as we may call them, the late Df 

 HuTTON of Edinburgh, was certainly the boldest^ 

 and the celebrated Werner of Freyberg,. is, I 

 think, the most modest. The former took upon 

 him to account, not only for the present appear- 

 ance of the earth, but for all the revolutions it 

 had undergone in time past, as well as for all 

 those it would undergo in time to come. He as- 

 sumed as a cause, an agent of whose existence 

 he could give no satisfactory proof, and of whose 



p. b 2 



