242 



To attempt to overthrow opinions erected on so broad a basis, as 

 the vast portion of- chemical and mineralogical knowledge which 

 Mr. Kirwan possesses, cannot but, at first sight, appear to be an act 

 too presumptive to promise the least success. But when even the 

 most wise and intelligent loosen the reins, and lessen those restraints 

 which their judgment, in general, places on their imagination, he 

 who first notices any unwarrantable deviation from established 

 principles may, without fearing censure for his interference, boldly 

 venture to point it out. 



The disposition of the various substances, of which the earth is 

 composed, yields us so little satisfactory information; and the data 

 we thus obtain are so few, and so unconnected, as to render the aid 

 of conjecture indispensably necessary. Hence, on the subject of 

 the formation of this globe, and of the various revolutions it has 

 suffered, the wisest men have formed the most extraordinary and 

 romantic conclusions. Nor can this occasion surprise, when it 

 is considered, that to point out the operations of nature, by which 

 the various substances which constitute the earth obtained their 

 present figure and arrangement, is, in fact, an attempt to form a 

 history of the most remote periods, with the scantiest stock of ma- 

 terials possible. In such a performance, success cannot frequently 

 be expected ; it must resemble the bold sketch of a master, who. 

 whilst depicting scenes which have originated in his own rich fancy, 

 strives, but, perhaps, ineffectually, so to correct them by his judg- 

 ment, as to make them accord exactly with nature. To approach 

 near to the completion of such an undertaking requires a consi- 

 derable portion of genius, the efforts of which must be directed by 

 a mature and correct judgment ; whilst very inferior abilities indeed 

 may be sufficient, to enable any one to point out an instance or two 

 of disagreement, between the conjectures which are offered, and the 

 circumstances they are intended to explain. This 1 shall therefore 

 attempt. 



