While using a theodolite, how to change the reading on the horizontal circle while measuring an horizontal angle?
While using a theodolite, how to change the reading on the horizontal circle while measuring an horizontal angle? Correct Answer upper clamp is loosened and lower clamp is tightened.
Lower Plate is a horizontal circular plate that provides the main scale reading of a horizontal angle and a means to fix or unfix the whole instrument.
Upper Plate is a horizontal circular plate having two diametrically opposite vernier scales and it provides a means to fix or unfix the upper plate of the instrument with its lower plate.
To change the reading on the circle while measuring an angle following procedure is adopted
Tighten the lower clamp ⇒ Loosen the upper clamp ⇒ Turn the instrument and direct the telescope towards the target to bisect it accurately with the use of tangent screw ⇒ Read the Vernier and record the readings
∴ To change the reading on the circle while measuring an angle, upper clamp is loosened and lower clamp is tightened is correct statement.