300 LIEUT.-COLONEL S. G. BURKAKD ON THE 



hundreds of miles, and it will again become northerly as the Himalayas come into 

 view. 



In spite, therefore, of the fact that the true direction of gravity at any one place 

 cannot be determined with certainty, yet it is possible now to classify deflections of 

 the plumb-line in India by regions. A modification of the spheroid of reference may 

 alter values and may move the regional boundaries, but it will not affect the general 

 correctness of the classification. A change in the assumed value of the direction of 

 gravity at the station of origin will alter all deduced deflections of the plumb-line by 

 the same amount, but it will not affect their differences, nor the mean differences 

 between regions. 



I propose now to show : 



(1) The classification of stations by regions. 



(2) The effects on the classification of changes in the spheroid of reference. 



(3) The effects on the classification of the existence of a deflection at the origin. 



(4) The final values of deflections of gravity, corrected for errors of spheroid and 



origin. 



In Plate 1 5 India has been divided into four regions : 



(1) The Himalayas, (2) the zone of southerly deflections, (3) the Indian Peninsula, 

 (4) North-west India. 



In the following four Tables III A., IIlB., IIIc., IIIo., which correspond to the four 

 regions, the direction of gravity at Kalianpur has been assumed to be coincident 

 with the normal to the spheroid, and has been adopted as the datum. The deflections 

 of gravity are given in the columns headed (A G) ; the symbol A denotes the 

 astronomical or observed value of latitude, G denotes the geodetic value of latitude, 

 which has been calculated through the triangulation extended from the origin over 

 the spheroid. 



