312 



LIEUT.-COLONEL S. G. BUERARD ON THE 



TABLE 

 Summary of the four preceding tables. 



We can now judge of the effects of the substitution of the Clarke-Bessel spheroid 

 for EVEREST'S by comparing the values given in the columns of Tables IVA., IVB., IVc., 

 IVc., headed "Eeferred to Kalidnpur as zero," with the values given in Tables IIlA., 

 IIlB., IIIc., HID. It will be seen that the large Himalayan deflections are slightly 

 decreased, and that the positive tendency of the second region has been accentuated. 



There is a marked difference between the values of Table IIIc. and the values 

 "Referred to Kalianpur as zero" in Table IVc. The progressive decrease in the 

 observed deflections, from latitude 24 to latitude 8, as exhibited on the spheroids of 

 EVEREST and of CLARKE, had led me to believe that the direction of gravity 

 throughout Peninsular India was being influenced by some external excess or 

 deficiency of mass, such as the Himalayas or the Indian Ocean.* The southerly 

 deflections, shown in Table IIIc., at the extreme south of India, were attributed by 

 General WALKER to the condensation of submarine strata, t The introduction of the 

 Clarke-Bessel spheroid eliminates at once both the progressive decrease and the 

 supposed southerly deflections in South India, and substitutes for them throughout 

 the peninsula a large apparent northerly deflection averaging G". The introduction 

 of the Clarke-Bessel spheroid shows that the progressive change exhibited by 

 Table IIIc. in the inclination of the level to the spheroidal surface from latitude 24 

 to latitude 8 was due, not, as I had supposed, to the deformation of the level surface, 

 but to the abnormal curvature of the surface of EVEREST'S spheroid. 



* Professional Paper No. 5 of 1901, "Survey of India;" Monthly Notices, 'Royal Astronomical 

 Society,' January, 1902. 



t 'Phil. Trans. Roy. Soc.,' vol. 186, 1895. 



