318 THE INTENSITY AND DIKECTION OF THE FORCE OF GKAVITY IN INDIA. 



classified as a coast station. It is, however, 100 miles from the coast and is 

 in truth less of a coast station than Kew or Greenwich. It was probably 

 included amongst coast stations because BASEVI obtained there a positive 

 result which accorded with his results at Madras and Bombay. But his 

 positive result will, I think, be found in the future to be due not to 

 Calcutta's proximity to the coast, but to her situation over the long chain of 

 excessive density that is believed to run parallel to the Himalayas from 

 west to east, and that is indicated in fig. 3 of Plate 14 by the position of 

 Station 24.* If we examine the last columns of Tables IVB. and IVc., we 

 see that the deflections are south at Calcutta and Dariapur, but north at 

 Cuttack and Khundabolo. 



(G) If an observer working over the plains of Northern India were to trust only 

 to his eye and his level, lie would record the existence of a great mountain 

 range to the north and of low hills or flat plains to the south ; if, however, 

 he were to disregard the evidence of the eye and of level, and were to believe 

 either his pendulum or plumb-line, he would come to the conclusion that he 

 was standing between two mountain ranges, one of which, visible to the north, 

 was rising abruptly out of the plains, whilst the other, invisible to the south, 

 was slowly gaining in elevation for 300 miles. 



I have taken several instances of abnormal pendulum results from Table I. and 

 have found in each case a direct response from the plumb-lines at neighbouring 

 stations. This conformity could hardly ensue if the variations in density extended to 

 greater depths than 30 or 40 miles. Our results do not justify us in asserting that 

 HO deep-seated variations in density exist, but they do justify the belief that the 

 variations in density which have been discovered are apparently superficial. 



* When I write of the excessive density of the earth's trust, I am judging from local observations only. 

 I mean, therefore, " excessive " compared with surrounding portions of the crust, and not with the mean 



surface density of the earth. 



