Correspondence — Report of Congress. — Rev. 0. Fisher. 47 



being that "On the Schists of the Lizard District," April, 1890, 

 perhaps the one he likes least. 



As to the points in his letter under his figures 1, 2, 3 and 4, I 

 have no doubt but that Prof. Bonney will in good time demonstrate 

 these assertions ; but in the meanwhile they are only assertions. 

 I will freely and gladly admit the eiTors, both in my observations 

 and inductions, when proofs are forthcoming. I was much amused 

 by General McMahon's letter. I am well aware (pei'haps before 

 the General was) of the apparent sequence of the various rocks laid 

 down by the masterly mind of De la Beche, and also (perhaps) 

 I have seen more of the true dykes in the Lizai'd District than has 

 fallen under the observations of General McMahon. There are 

 dykes, however, that I regard as of contemporaneous or segrega- 

 tion origin. 



Independent of the sequence of the rocks referred to, I think them 

 the product of eruptions of one geological pei'iod, that intermittent 

 action is noticeable, and that there is a decided passage of the main 

 masses into each other, and that the same magma, cooling under 

 different conditions, has given rise to many varieties of rock. My 

 communications were intended to lead up to this point. 



As to my theory of the origin of the " banded structure," let 

 it with the others " sink or swim." I care not which survives. 



As to the close of General McMahon's letter, I much regret having 

 to say, that I think it is quite uncalled for. 



Torquay, 9th December, 1890. Alexk. SomekVAIL. 



EEPORT OF THE INTERNATIONAL GEOLOGICAL CONGRESS. 



Sir, — I am periodically asked by friends who joined the last 

 Geological Congress how it is that the promised report to which 

 each member was said to be entitled has not yet appeared, although 

 some of us paid an additional subscription to expedite its production. 



Ought not the eminent geologists whose names appeared on the 

 circular inviting support to that Meeting to be asked to furnish some 

 explanation for this unaccountable delay ? (B. V)^ 



ON DYNAMO-METAMORPHISM. 

 Sir, — I certainly had no thought of " rolling back the develop- 

 ment of chemical theory a few decades at least," when I wrote of 

 energy taking " the molecular forms of heat and chemical action." 

 Dr. Irving in his criticism of this expression leaves out my reference 

 to heat. I conclude therefore that he has no objection to that part 

 of the statement. As to the assertion that part of the energy, which 

 previously existed in the molar form, was converted into the " mole- 

 cular form of chemical action," I was unable to know whether Dr. 

 Irving's stricture expressed the generally received views upon the 

 subject, owing to my imperfect acquaintance with chemistry. I 

 have, therefore, consulted the highest authority on such questions 

 to whom I could apply and on whose opinion I can place reliance. 

 With respect to Dr. Irving's apparently general statement, that 

 "chemical combination must generate heat," he replies, that, "when 



