164 Mr Kenwood on the Phenomena of 



shew how their theory applies to any facts ; or, if a theory we 

 must still have, to modify the existing one so as to embrace 

 them. 



We know, however, as was well stated by Mr Grylls, at 

 Redruth, in remarking on Mr Fox's excellent lecture, that the 

 same phenomena are exhibited in hand specimens, the same ap- 

 parent heaves and slides^ is it contended that these are also me- 

 chanical disturbances ? 



I must conclude this brief notice of the phenomena, with ex- 

 pressing my inability to lay down, or to concur in any diagnos- 

 tic characters of the small veins of this county, which are not 

 equally applicable to our great metalliferous systems. 



We now come to the consideration of the theories which have 

 been propounded for the explanation of the origin of mineral 

 veins, and here I hope I may be permitted to pay my humble 

 tribute of admiration and respect for the illustrious Werner. 

 His views of the origin of many rocks have been rejected, his 

 opinions of the filling of veins have in many cases been aban- 

 doned, but his idea of the veins having originated in fissures has 

 been adopted by all his successors. Strictly speaking, I believe 

 the notion of cracks had its origin as far back as Agricola ; but 

 Werner in geology, like Newton in physical astronomy, com- 

 bined and collected all the beautiful fragments elaborated by 

 his predecessors into a structure, objectionable, perhaps, in some 

 of its arrangements, but in the department of which I am now 

 speaking, so far beyond any thing that I believe, without his la- 

 bours, even the present day would erect, that whether our veins 

 be large or small ; of sudden or progressive formation, of horses 

 and their supports, all the leading views, and all the principal 

 phenomena described by him, have been adopted by successive 

 theorists. 



Fissures being, then, the common postulata of all the theories, 

 excepting of that of the practical men of this county, and which 

 supposes the contemporaneity of the rocks and veins, let us pro- 

 ceed to an examination of the grounds for the assumption. 



Werner, imagining all rocks to have been originally depo- 

 sited from aqueous solutions, says, " the shrinking of the mass of 

 a mountain produced by desiccation, and still more by earth- 

 quakes and other similar causes, may have contributed -to the 



