Given : Line ABC, AB=1059m, AC=1985m
L= 20m, No error at start, 0.06m too long at B,
0.09m too short
Find : True distance of AC = ?
Solution :
For part AB
L = Length of chain= 20 m
e = Average error in Chain = 0+0.06 /2 = 0.03m
L’ = Incorrect length of chain = L + e = 20 + 0.03 = 20.03 m
( since chain is too Long)
Measured Distance AB = 1059 m
True Distance = (L’/L) X Measured distance
True Distance AB = (20.03/20) X 1059 = 1060.59 m
Similarly,
For part BC
L = Length of chain= 20 m
e = Average error in Chain = 0.06+0.09 /2 = 0.075m
L’ = Incorrect length of chain = L + e = 20 - 0.075 = 19.925 m
( since chain is too Long)
Measured Distance BC = 1985 – 1059 = 926m
True Distance = (L’/L) X Measured distance
True Distance AB = (19.925/20) X 926 = 922.52 m
Total true distance of AC = True distance of (AB + BC)
= 1060.59 m + 922.52 m
= 1983.11 m