Chap. 7] 



GRAVITATIONAL METHODS 



201 



by factors o, p, q, and r, which gives gradients and curvatures, assuming 

 that the factors s and t are equal to 1. When there are rapid changes of 

 zero position with time, deflections are calculated by leaving out one in 

 each set of deflections, 



— As As 



Ai — As 



Ai A2 — , 



Fig. 7-71. Evaluation of torsion-balance readings (small Suess balance). 



and completing the vacant spaces from 



(— ) + A2 + As =0 



Ai + (— ) + As = 



Ai -F A2 + (— ) = 0. 



Several short cuts to calculations of torsion-balance quantities from 

 records and readings have been suggested. One method uses nomo- 

 graphs^" and another" employs charts for calculating gradients and 

 curvatures from the differences A2 — A3 and the sums A2 + A3. Fig. 7-72 

 shows such charts calculated for a balance with the coefficients = 1.59, 

 p = 2.75, q = 2.93 and r/2 = 2.56. Chart I is for IJ^z and IJ ^, Chart II 



•0 A. Stepanoff and W. Ayvazoglou, U.S. Bur. Mines I. C, 6306 (July, 1930). 

 »i M. M. Slotnick, Physics, 2(3), 131-133 (March, 1932). 



