200 



GRAVITATIONAL METHODS 



[Chap. 7 



By this procedure a linear change of the zero position with time is 

 eliminated. After that the differences ni — no, n2 — no, Us — no and 

 ni ~ no, n2 — no,nz — no (or Ai, A2, A3, and Ai , A2 , and A3) are 



Table 23 

 CALCULATION OF THREE-POSITION TORSION BALANCE RECORD 



Station No. 10 



Location: Fort Bend County, 

 Texas 

 v> = 29° 



Date: July 10, 1935 

 Observer: J. A. S. 

 1st Reading: 9 h., 55 min. 

 Notes: Instr. set due north 



s = 



2 = 



A — A 



2 3 



// / 



A. - A. 



= -1.2 



= +1.8 



+ A3 = +2.2 

 + A," = -2.0 



calculated and averaged. Their sum should equal zero. For three posi- 

 tions the differences A2 — A3 and A2 — A3 , and the sums A2 + A3 and 

 A2' + A3' are then calculated. Their sums and differences are multiplied 



