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1. Suppose A and B are two points on the opposite banks of a river. The level is set up very near A and after proper temporary adjustment, staff readings are taken at A and B . Suppose the readings are a1 and b1 .2. The level is shifted and set up very near B and after proper adjustment, staff readings are taken at A and B. Technical Data used in the field explained in civil surveyor course in rawalpindi.  Suppose the readings are a1 and b1.3. Let h= true difference of level between A and B.e= combined error due to curvature, refraction and collimation ( The error may be positive or negative, here the error is assumed positive)

In first case; Correct staff reading at A =a1   (as the level is very near A).Correct staff reading at B=b1-e.True difference of level between A and B,H=a1-(b1)(fall from B to A)(1) Some more details of civil surveyor course in rawalpindi are as under.  .In the second case, Correct staff reading at B=b2    (as level is near B)Correct staff reading at B=a2-e.So, true difference of level h = (a2-e) –b2(2)From (1) and (2),2h = a1 – (b1-e) + (-e) - b2 =a1-b1+e+a2-b2= (a1 – b1) + (a2 – b2)h =(a1 – b1) + (a2 –b2)/2It may be observed that the error is eliminated and that the true difference equal to the mean of the two apparent differences of level between A and B.

3.7 PROBLEMS ON RECIPROCAL LEVELLING; Problem 1

In an operation involving reciprocal leveling, two points A and B are taken on opposite banks of a river. When the level was set up near A, the staff readings on A and B were 2.245 and 3.375 respectively. When the level was set up near B, the respective staff readings were 1.955 and 3.055. Find the true difference of level between A and B. What is the RL of B, if that of A is 125.550? Solution In the first setting, Apparent difference of level between A and B = 3.375 – 2.245 = 1.130m (Fall from A to B). . TSK Training for Skills and Knowledge is the best institute in Rawalpindi Islamabad for Pakistani Students who wants to join civil surveyor course in islamabad.