INTENSITY AND DIRECTION OF THE FORCE OF GRAVITY IN INDIA. 295 



THE Force of Gravity in Dynes as observed by 



LENOX CONYNGHAM'S observations confirm Professor HELMERT'S prediction that 

 BASEVI and HEAVISIDE'S results would be found too small. The sections in figs. 2 

 and 3 of Plate 14 of this paper have been based on their results, and it may be asked 

 what purpose has been served by the construction of sections from impugned data ? 

 The answer to this question is that BASEVI'S results have been accepted by geodesists 

 and have formed the basis of controversies and theories ; they have, too, been 

 rendered historic by the difficulties and death of the observer at More", and by the 

 great light they undoubtedly threw upon Himalayan formation. Now that pendulum 

 observations are being re-opened, I have thought it advisable in an historical 

 retrospect to give a graphical summary of the results that were formerly obtained, 

 and that have so profoundly influenced the ideas of geodesists. 



In figs. 2 and 3 the deficiency underlying Dehra Dun (38) will be reduced by 

 almost one-half if LENOX CONYNGHAM'S value be substituted for BASEVI'S. Similarly 

 the height of Mussooree (41) in fig. 3 will be almost doubled. 



In the near future BASEVI'S other stations will possibly be visited ; it seems certain 

 that his results will everywhere be found too small, that throughout fig. 2 the curve 

 of deficiency will have to be raised, and that in fig. 3 the line of sea-level will have to 

 be lowered. 



From LENOX CONYNGHAM'S observations at Bombay and Dehra Dim, it appears 

 that BASEVI'S and HEAVISIDE'S results are not in error by any constant quantity, and 

 that the error of each will have to be separately determined ; it is not easy to account 

 for the variation in the magnitudes of their errors ; their observations were taken 

 with a care that it is difficult for us to equal ; in assuming that flexure could be 

 prevented by the employment of a rigid stand, the old observers were following the 

 highest authorities of their time ; the only faults that have been found with their 

 work are such as would tend to produce constant error. That their errors vary so 

 largely can only, I think, be explained on the supposition that the flexure of the 

 wooden stand of the Eoyal Society's apparatus was influenced by temperature and 

 humidity. 



The idea that gravity is exceptionally weak throughout India as compared to 



