K and C are stadia constants, θ is angle of elevation
This equation is used to determine the horizontal distance from the transit to the leveling rod by reading the angle of elevation when a transit is used to read the length of the leveling rod between the upper and lower stadia lines.
Determine the horizontal distance between two points when the length on the leveling rod between the upper and lower stadia lines is 0.865m, and the angle of elevation is θ=+4. Note that K=100 and C=0.
Press 23 FMLA 100 RUN 0.865 RUN 0 RUN 4 RUN (Read-out: S=86.07909397)