(Case : 1 When the line of sight is horizontal and staff is held Vertical) Example 2

Example 2

The stadia reading with horizontal sight at a vertical staff held 50 m away from the tacheometer were 1.385 and 2.380. the focal length of the object-glass was 25cm. The distance between the object-glass and trunnion axis of a tacheometer was 15 cm. Calculate the stadia interval.

Ans.=>

            D = KS + C 

D = (f/i) S + (f + d) ........... (1)

    Here D = 50m 

    S = 2.380 – 1.385 = 0.995 

    f = 25cm = 0.25m 

    d = 15cm = 0.15m Put the all value in equation no 1

            50 = ((0.25 x 0.995) / i) + (0.25 + 0.15) 

            i = 0.005 m

         i = 5 mm