CHAIN SURVEYING 



.1 ft. too long, the error is , or .002 ft. in 1 ft. In this case, 



= .002. If the measurement is recorded in chains, and the 

 chain is found to be .1 li. too long, the error is .1 1L, or .001 ch. 

 per chain, and = .001. 



It should be understood that the correction eL expresses 

 the same kind of units as e. If, for instance, e is 1.5 in. per ch., 

 and the length of the line is expressed in chains, its true length 

 is L ch. 1.5 L in. 



If the chain is too long, the distance measured with it will 

 be recorded as too short, and the correction eL should be 

 added; and if the chain is too short, the distance measured 

 will be recorded as too long, and the correction eL should be 

 subtracted. 



EXAMPLE. The length of a line, measured with a 100-ft. 

 chain, was found to be 1,048 ft. It was afterwards found that 

 the chain was .19 ft. too long. What was the true length of 

 the line? 



SOLUTION. If the error is .19 ft. in 100 ft., it is T&T of .19 

 = .0019 ft., or, say, .002 ft. per ft. Then, e = .002, L = 1,048, 

 and, therefore, Lo= 1,048 +.002 XI, 048 = 1,050 ft., nearly. 

 The error is added, because, the chain being too long, the 

 recorded length of the line was too small. 



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Keeping Notes. The notes of a chain survey are usually 

 kent in a transit book. The accompanying illustration shows 



