INTENSITY AND DIRECTION OF THE FORCE OF GRAVITY IN INDIA. 315 



The southerly deflection at Kalianpur of G"'4. which has been deduced from 

 plumb-line observations, is to a certain extent corroborated by the section drawn in 

 Plate 14, fig. 3, from pendulum observations ; if we assume that the errors in BASEVI'S 

 pendulum results will be found constant, the section will be raised with reference to 

 the sea-level, but will not be otherwise affected ; and if we regard the distribution of 

 mass exhibited by this section, and calculate the deflection at Kalidnpur by means of 

 CLARKE'S formula (' Geodesy,' p. 298), 



f /' l\<i&nW /,,\ciu2<7 /7/\2A-| 



A = P log. {(I) . (y . (~) \+2p{c'<j>' sin 2 c/-c4, sin' cr}, 



we obtain a value of +5"'!.* 



In Tables IVA., IVu., IVc., IVD., IVE., in the columns headed " Referred to 

 Kalidnpur as 4-6"," the values of deflections have been exhibited on the assumption 

 always that the plumb-line at Kalidnpur is deflected G" towards the south. 



(7.) Summary. 



A comparison of the two values given to each deflection in Tables IVA., IVs., IVc., 

 IVD., and IVE. will illustrate the effects of the adoption of the corrected datum ; the 

 large Himalayan deflections, it will be seen, have been slightly decreased ; they amount 

 now to about half the theoretical values derived from an application of the law of 

 gravitation to the visible mountain masses ; the sudden diminution of the large 

 deflections at the foot of the mountains is still very remarkable. 



The great zone of southerly deflection has been expanded both to the north and to 

 the south, and it now includes many of the stations classified in the first and third 

 regions; for instance, in the sub-Himalayan region (Table IVA.), the stations of 

 Kaliana, Bansgopal, Jarura, and Jalpaiguri exhibit southerly deflections when the 

 corrected datum is used; in the Indian Peninsula (Table IVc.) the positive zone has 

 been extended southwards to Thikri, Ladi, Hathbena, and Chandipur ; in North-west 

 India (Table IVo.) every station now presents a marked southerly deflection; and the 

 positive character of the deflections in the positive zone itself (Table IVs.) has been 

 strongly accentuated. 



To the north of the second and fourth regions stand the mountain masses of 

 Central Asia, but throughout those regions the direction of gravity is systematically 

 deflected towards the south. That the direction of gravity should be deflected 

 everywhere towards the south with a mean inclination of 8" throughout an area of 

 half a million square miles (Tables IVB. and IVo.) is an extraordinary phenomenon 

 of nature, and this phenomenon has been observed on flat low-lying plains bounded 



* Attraction at Station 24 of mass lying north of Station 38= 1" - 61 

 24 south 38 = 6" -67 



5" -06 



2 S 



