Write down the procedure for determination of tacheometric constants.

Method of determining tacheometric constants in the field1) A fairly level ground is selected. The tacheometer is set up at O and pegs are fixed at A, B & C, known distances apart.

2) The staff intercepts (stadia hair readings) are noted at each of the pegs. Let these intercepts be S1, S2 & S3.

3) The horizontal distances of the pegs from O are actually measured. Let these distances be D1, D2 & D3.

4) By substituting the values of D1, D2, D3 and S1, S2, S3 in general equation

D = (f/i) S + (f+d)

We get a number of equations, as follows

D1 = (f/i) S1 + (f+d)

D2 = (f/i) S2 + (f+d) and so on.

5) By solving the equations in pairs, find tacheometric constants (f/i) and (f+d)