64 ANGULAR SURVEYING 



forAB, 6.54 -(-.03)= 6.54 + .03= 6.57 

 for EC, - 3.56- (-. 01) = -3.56+.il = -3.55 

 for CD, -6.54 -(-.03) =-6.54 +.03 =-6.51 

 for DA, 3.46 -(-.03)= 3.46 +.03= 3.49 

 These are the corrected values placed in parentheses above 

 the original values. 



Second, determine the corrected longitude ranges. Here 

 the sum of the eastings is 10.41, and that of the westings, 

 - 10.29. Therefore, Sg= 10.41 - 10.29 = .12, and 



Therefore, 



eg for A B = 10.63 X .004 = .04 

 eg i or EC = 4. 10 X .004 = .02 

 c g for CD = 7.69 X .004 = .03 

 CgiorDA = 7. 1 3 X. 004 = .03 



.12 

 The corrected longitude ranges are, 



forAB, 8.38-. 04= 8.34 

 for BC, 2.03 -.02= 2.01 

 for CD, -4.05-.03= -4.08 

 for DA , - 6.24 - .03 = - 6.27 



Third, determine the corrected lengths of the courses. Thus, 

 applying the formula for h, page 63, and substituting the cor- 

 rected ranges, the corrected length of 



AB= \6.S7+8.34* = 10.62 

 BC= V3.55 2 +2.01 = 4.08 

 CD= Ve.51 2 +4.0S 2 = 7.68 

 DA= V3.49 2 +6.27 2 = 7.17 

 Fourth, determine the relative error of closure. Thus. 



-*= A/.003 2 +.004* = V.000025 = .005. 



This error is 5 in 1,000, or 1 in 200. and is greater than would 

 be allowed in any but exceedingly rough work. 



The preceding method of balancing a closed survey is the 

 one that is used for a compass survey, because the errors i 

 the angular measurements are generally considerable. 





