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



Burrard in his paper, but was tacitly dismissed in favour of his 

 new theory of a deep rift, a theory based on the fact that 

 certain anomalies had been observed in the deflection of the 

 plumb-line and in the attraction of gravity, which could not be 

 accounted for on the assumption that isostatic compensation 

 occurred at a depth of 113*7 kilometres everywhere beneath 

 India and the Himalaya, while the postulated rift was regarded 

 as capable of producing these anomalies. 



The summary rejection of the generally accepted hypo- 

 thesis without any attempt to discuss or combat the results 

 derived from the extensive work of some of the foremost 

 geologists of the nineteenth century, led me to examine the 

 results on which such rejection was based, although it must be 

 admitted that they had no apparent connection with the 

 hypothesis itself. The results in question were those obtained 

 by Major H. L. Crosthwait from the application of a certain 

 aspect of the principle of isostatic compensation to India. 

 Major Crosthwait confined himself to the assumption that such 

 compensation occurred at a depth of 113-7 km., an assumption 

 which had been found to eliminate most of the geodetic anoma- 

 lies in the United States, when applied to observation made in 

 that country. It seemed to me that the condemnation of the 

 hypothesis of isostatic compensation on the mere ground that 

 the assumption of its occurrence at a depth of 1137 km. 

 beneath India failed to explain observed geodetic anomalies 

 was not justifiable and savoured of that commonest of all 

 fallacies, the deduction of the universal from the particular. I 

 made an attempt therefore to investigate the effects for depths 

 other than 11 37 km., as had been done by Messrs Hayford 

 and Bowie in America. In publishing the results I pointed 

 out that they were on the whole more favourable for other 

 depths than for 113*7 km. and that, therefore, if the occurrence 

 or otherwise of isostatic compensation is under investigation, 

 it is not fair to dismiss the hypothesis merely because it 

 happens to be found inadequate if compensation be assumed to 

 occur at one particular depth. To this suggestion Colonel 

 Lenox-Conyngham appears to take exception on the ground that 

 the depth of compensation must be one and the same every- 

 where ; he regards my conclusions as based on a misconception 

 of the theory of isostasy generally and as resting on no " con- 

 sistent ^ theory of the distribution of matter in the earth's 

 crust/ ■ With regard to the first criticism, I can only say that 

 my conception of the theory of isostasy is based on the 

 original idea as enunciated by its author, Dutton, and that any 

 difference in our respective points of view may be due to the 

 fact that Colonel Lenox-Conyngham has restricted his consi- 

 deration of the question to one particular aspect, circumscribed 

 by his own convictions as to a suitable arrangement of the 

 materials composing the earth. So far as my own views as 



