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



limestone districts, while it offers no rational explanation of 

 a single phaenomenon they present to us, can scarcely be ex- 

 pected, I conceive, even by its warmest advocates. I wish 

 Dr. Boase had stated more distinctly the extent to which he 

 conceived it applicable. Perhaps he will leave me quiet 

 possession of the limestone districts and entrench himself 

 within the Cornish veins, not allowing that the phaenomena 

 above mentioned are to be distinctly recognised in them. If, 

 however, we consult for a moment the map published by 

 Mr. Thomas of the Camborne and Chacewater district, and 

 that by Mr. Carne of the district of St. Just, we recognise im- 

 mediately a system of veins and of cross-courses such as has 

 been mentioned above. The irregular width also of the cross- 

 courses is universally recognised ; and though I am not dis- 

 posed to place implicit reliance on all that has been advanced 

 respecting the heaves and shifts of Cornish veins, I should 

 regard any one as a bold theorist who, for the sake of his 

 theory, would set aside some of the facts of this kind which 

 have been adduced. Whether the other phaenomena above 

 stated under the heads (2.), (5.), and (6.) exist in many Cor- 

 nish veins it is impossible to say, because evidence of them can 

 only be obtained where veins occur in masses so stratified as 

 to enable us to identify some particular stratum on opposite 

 sides of the vein. But leaving these out of the question, does 

 the theory of contemporaneous formation offer the smallest 

 explanation of the other phaenomena? 



It appears to me difficult to conceive a theory in a more 

 perfectly unsatisfactory state than the one of which I am 

 speaking ; and, indeed, I scarcely understand what claim that 

 which affords no intelligible explanation of anything can 

 have to the title of theory. It seems mere hypothesis, with- 

 out any direct support from physical facts or physical reason- 

 ing, — a negative of other theories rather than a theory itself; 

 and the only foundation on which it appears to me to rest is 

 the assumed insufficiency of more definite theories to account 

 for some of the appearances presented by certain veins. 

 Whether the two theories I have discussed will hereafter be 

 deemed sufficient by geologists when careful observation shall 

 have been made imth direct reference to them, I pretend not to 

 say, but I am quite certain that the theory of contemporaneous 

 formation must rest on foundations very different from those on 

 which it now stands before it can be admitted as affording 

 any explanation of the formation of veins in general. 



One of Dr. Boase's objections is founded on the want of 

 sufficient coincidence between the Cornish veins and joints. 

 At the same time it will be observed that he fully allows as a 



