“Cone-in-Cone.”

CONE-IN-CONE."SIR,-I am glad to observe in the short article on "Cone-in-cone," by Professor Newherry, M.D., in the December Number of the GEOLOGICAL MAGAZINE for 1885, that he at one time was inclined to look upon that structure as due to "the escape of gases through a pasty medium."I think that if he had the opportunity of studying the large series of specimens that I have now assembled, and the transparent sections of the cone structure that I have prepared, he would still be inclined to favour that view as an explanation of the phenomena that they present, rather than the one he now adopts, •viz." an imperfect crystallization" of the deposit in which it is found.Professor Newberry, after referring to a number of cases of cone-in-cone structure that had come under his observation (some of which apparently differ from what I have described), concludes by stating that these examples " seem to me to be incompatible with the theory that cone-in-cone is caused by pressure, or the escape of gases, and appear rather to confirm the conclusion that it is due to an impeded tendency to crystallization."He, however, in the article in question, offers no evidence in support of this crystallization theory, nor does he explain in any way the peculiar structure and arrangement of the cone layers.Those supporting a crystallization theory have not referred to any known law of crystallization, which would account for a structure agreeing with what is seen in the bestpreserved specimens of our Scottish cone-in-cone, or which would satisfactorily explain all that is represented in the external structure of the cones, and their terminations on the surface of the bed, as is briefly noted in the short abstract of the paper I read to our Glasgow Geol.Soc, and printed in the June Number of the GEOL.MAG. for 1885.In the abstract, to which I would refer your readers, I have endeavoured to indicate what is seen in both the internal and external structure of the cones, but which I explain more fully in my paper, and I do not think that in either I have ventured to hazard any explanation that is not fully warranted by what the specimens reveal.During the progress of my investigations, I have not wholly relied upon my own judgment in coming to the conclusion that the cone-in-cone structure was due to the escape of gases generated in the sediment, but that from time to time I have had the opportunity of submitting specimens and sections of the structure to Dr. Young, Prof, of Geology; Prof. Sir William Thomson, President of the Glasgow Geol.Soc, and his brother Prof. James Thomson, who has paid some attention to rock structures; likewise to Mr. Ferguson, Prof, of Chemistry in this University, and to others, on whose opinion I could rely, and I am pleased to be able to state, that they are all inclined-so far as the specimens noticed in my paper are concerned-to agree to the explanation I have given as to the probable origin of the structure.They also agree with me