202 



GRAVITATIONAL METHODS 



[Chap. 7 



for Uyz and Uxy 



A'3' = -1.9, a;' 

 -1.8, a;' + A^' 



Chart I, locate - 



Assume, as in the example given on the form, that 

 = -0.1, As = 1.7, and A2 = 0.5. Then A3' - A^' = 

 = -2.0, A3 - A2 = 1.2 and A3 + A2 = 2.2. Using 

 1.8 on the left side of the A3' — A2 axis, go N to +1.2 



on the A3 — A2 axis, thence NE to the intersection with Uxz to find —4.8. 

 Going SE, —1.7 is obtained on the Ua axis. On Chart II, locate —2.0 



Fig. 7-72a. Torsion-balance calculation chart for Ux, and U^ (after Slotnick). 



on the left side of the a'/ + Aj' axis, go N to 2.2 on the A3 + A2' axis, 

 thence SW to +11.8 for Uy, and SE to -0.5 for U^. 



In connection with the form shown in Table 23, a second form is used 

 for the terrain correction, which contains also additional columns fCr 

 far terrain, planetary correction, and calculation of final results (see 

 Table 32). 



The following example is an illustration of calculations made for a 

 station with very large gradients and curvature values, on which records 



