278 Journal of the Asiatic Society of Bengal. [July, 1914. 



the discovery of the properties of the radio-active minerals and 

 consequent vindication of the claims of historical geology to an 

 age for the earth which was asserted by a certain section of the 

 scientific world to be impossible, emphasizes the danger of 

 claiming to possess the one and only true view as to the physi- 

 cal constitution of the earth. I am still disposed to agree 

 with Major Crosthwait, who is not only a geodesist but a 

 geologist also, that the difference in geological age between 

 most of the tectonic features of the United States and the 

 Himalaya should lead us to expect some difference in their 

 respective conditions of equilibrium. 



Colonel Lenox-Conyngham rightly points out that a table 

 by means of which I attempted to compare the effects of 

 isostatic compensation in adjacent areas at different depths is 

 of no real significance. He omits to mention, however, that 

 we had some considerable correspondence on this as well as on 

 most of the other points with which he deals, and that I 

 agreed with him that the table in question, as it stood, 

 involved a fallacy, a fact which had already been pointed out 

 to me by Mr. R. D. Oldham, immediately after the publication 

 of my paper. The elimination of this table, however, has no 

 effect on the general conclusion at which I arrived, namelv that 

 the application of the principle of isostasy to India had not 

 been so exhaustive as to justify its wholesale condemnation. 

 Nor would the omission of the table in any way affect the 

 validity or otherwise of the prevailing hypothesis as to the 

 nature of the Indo-Gangetic depression. Whether we assume 

 isostatic compensation to take place at a depth of 113-7 km. or 

 not to be operative at all, the anomalies in the observed force 

 of gravity at a number of stations on the alluvium— at all 

 those with which I had the opportunity of dealing— entirely 

 support that hypothesis, based on geological observations, as 

 to the form of the depression. I gave in my paper certain 

 figures, deduced in two separate ways, for the depth of the 

 alluvium : these figures were based on calculations for which 

 some of the data were derived from the published work of Colo- 

 nel Lenox-Conyngham himself, but lest I should be suspected 

 of a design to imply that he agrees with the results observed, 

 1 hasten to add that I have no reason to suppose that he does 

 agree. In his note he has not made any reference to this 

 aspect of the question, presumably therefore he is not prepared 

 to show that my results are incorrect, I should mention, 

 However, that from the correspondence to which I have al- 

 ready referred, I gather that he is not satisfied with the figure 



feel that I owe mm an apology for mentioning this fact without 

 nis permission ; I must plead as my excuse the improbability 

 ot my being able to receive answers to correspondence during 

 the next five months. 





