16 THIRD REPORT — 1833. 



the systems which we have reviewed. Werner expressly tells 

 us, that we are indebted to miners for the theories which he 

 deemed most worthy of acceptation, and he names as such 

 Agricola, Rosier, Henkel, HoiFman, Von Oppel, Charpentier, 

 and Trebra. We may add his own name and that of Dr. Pryce, 

 in our own country, as intimately acquainted with mining. Now 

 all such men would be more acquainted with the metalliferous 

 veins and such as accompany them; and from these they would 

 derive much evidence in favour of the opinions which they ad- 

 vocated ; at least, partaking, as I probably do, in the same pre- 

 judices, so it would appear to me, if by the labour of other 

 inquirers I did not know that there were other facts requiring 

 a different explanation. 



Again, Dr. Hutton and his commentators had largely ob- 

 served veins which may fairly be attributed to injection; they 

 had found dykes of trap passing through coal-beds, and con- 

 verting them into cinder. Such evidence of the effects of heat 

 and of a filling up by matter in fusion is not to be resisted ; but 

 when we look at what is said of the metalliferous veins by some 

 of the writers on this side of the question, we observe great 

 want of practical knowledge and many errors, arising out of 

 the attexnpt to make all bend to a single method of solving the 

 problem. 



For the third hypothesis of contemporaneous formation there 

 is this to be said, — that some veins exist which seem to admit of 

 no other explanation ; and that this being allowed to such as 

 will have but one theory, this is at once the easiest, because it 

 gets rid of many difficulties without further trovible ; but we 

 can hardly be satisfied to adopt it as universal upon experience 

 that has been principally confined to sections in quarries and 

 in cliffs, or to such as are exposed to open view. 



Our present state of knowledge as to the formation of veins 

 should therefore, in my opinion, be allowed to admit that most 

 of the causes which have been stated have operated at various 

 periods and through a long succession of time, some prevailing 

 at one epoch, and some at another, modified by circumstances 

 which we can but imperfectly comprehend or explain. 



In this view we may allow of a classification of veins accord- 

 ing to their probable mode of origin ; and such a classification 

 has been thought of by some of our ablest geologists of the 

 present day, and was indeed propounded in one of our sections 

 at Oxford last year by our present learned President, who ex- 

 pressed his opinion that there were three different sets of veins : 

 — 1. Those which have been plainly mere fissures or cracks, 

 and which have been subsequently filled ; 2. Those of injec- 



