Mr. Hopkins's Reply to Dr. Boase's Remarks. 367 



perienced various degrees of diversion, being either partially 

 or altogether involved in the impetus of their stronger oppo- 

 nents." 



Now it appears to me that all we can conclude from the 

 above reasoning (and I am not aware that it has been put by 

 any one in a better form) is this, — that it is not impossible that 

 veins may have been the effect of certain electric currents 

 which, it is possible, may have existed. The theory rests, not 

 on our knowledge, but entirely on our ignorance. We know 

 not that these electric currents could be produced as above 

 supposed, and we know not whether if they did exist they 

 could produce the effects assigned to them. Let any one 

 consider whether by any reasoning like the above he could 

 give any rational account of such pheenomena as the follow- 

 ing: 



1. The approximate rectilinearity and parallelism of veins. 



2. The relations which their directions usually bear in stra- 



tified masses to the dip and strike of the beds. 



3. Their division into two principal systems, approximately 



perpendicular to each other. 



4. The irregularity of the cross courses in width, as com- 



pared with the beai'ing veins. 



5. The th-ovo of a vein, or the difference of level of the 



same stratified bed in the opposite walls of the vein. 



6. The general relation between the throvo and the hade, 



or inclination of the vein to the vertical. 



7. The numerous appearances of heaves and shifts in veins. 

 These are some of the most obvious and general characters 



which mineral veins present to us ; and yet I am not aware 

 that the advocates of contemporaneous formation have made 

 even an attempt (for as such we cannot regard the second 

 paragraph of the above quotation) to account for one of these 

 phaenomena as a necessary or probable consequence of any 

 definite physical cause connected with their theory, while all 

 of them are, I conceive, perfectly accounted for on the hypo- 

 thesis of an elevatory force, considered either as the original 

 cause of fissures, or as modifying them when previously pro- 

 duced by joints. In the present imperfect state of our know- 

 ledge of geological causation, I would not positively reject 

 any hypothesis carrying with it the most remote plausibility, 

 provided it could be received without giving up others of 

 stronger claims to our notice ; and therefore I would not ab- 

 solutely reject this hypothesis of contemporaneous formation 

 as possibly applicable to certain veins, though I must still 

 regard the process as an inconceivable one ; but that we 

 should adopt it with reference at least to the veins of our 



