Vol. X, No. 7.] Isostatic Compensation in India. 211 



[N.S.] 



to the distribution of those materials are concerned, they 

 certainly appear to differ from Colonel Lenox-Conyngham's, 

 but I did not attempt to express them in my paper, nor do 1 

 propose to do so here, since the matter is not germane to the 

 real issue, which is the probability or otherwise of the presence 

 of an immense rift along the foot of the Himalaya. I may 

 say, however, that my views are based partly on my own 

 observations and partly on those recorded by geologists and 

 physicists generally. When we realize the highly complex 

 nature of such portions of the crust— extending probably to no 

 greater depth than twenty miles— as the operations of natural 

 forces have laid bare to our observation, few among geologists 

 at any rate would have the temerity to dogmatize with regard 

 to the exact distribution of matter below the surface and 

 stigmatize as impossible the suggestion of the possible occur- 

 rence of conditions other than those that they themselves 

 believe to exist. For mvself , I must confess that I have not 

 the faculty of being able, undeterred by the extreme paucity 

 of the information available, to marshall the component parts 

 of the earth with the meticulous precision of a drill-sergeant. 

 In making the suggestion that the results of my calculations 

 indicated the possibility of isostatic compensation occurring at 

 one depth under India and at another under the United States, 

 I was not unaware of the probable form of an ideal equipoten- 

 tial surface, but I was nob satisfied that in the case of the 

 earth it must of necessity coincide with an ellipsoid of revolu- 

 tion. I hold no brief for the principle of isostasy and am by 

 no means convinced that it will prove, in its more restricted 

 aspect at any rate, to be the panacea for all geodetic ills, but I 

 endeavoured to plead, and do plead still, that it is premature 

 to reject on a partial discussion of the evidence for and against 

 it, while it is still more premature to reject the accepted 

 hypothesis as to the nature of the Indo-Gangetic depression 

 with no discussion of the evidence at all. If isostasy is to be 

 judged by the rigid standard that Colonel Lenox-Conyngham 

 appears to demand, it must fail even for the United States, 

 since I think I am right in saying that Hayford has suggested 

 that there may be local variations in the depth of the surface 

 of compensation under the area that he has dealt with. 



The sum total of what is known as to the distribution of 

 matter at considerable depths beneath the surface is so small 

 that it would require no little hardihood to say what conditions 

 are or are not possible. What one generation of scientific 

 enquirers has declared to be impossible has become to the next 



a household truth. 



pported 



long series of careful investigations merely because it does not 

 fall in with certain views of our own, based on analogy and 

 supported by no direct evidence, is to disregard the experience 

 of past generations ; and the comparatively recent instance of 



