Measurement of horizontal angle, Measurement of horizontal angle by repition method,learnwithashiso, learn with ashiso

 To measure the horizontal angle PQR 

• Set the instrument at station Q and level it accurately. 
• Loose all the clamp of instrument and turn the upper plate and lower plate in opposite direction till the vernier scale and main scale at zero(0) and also vertical circle is in left off telescope then clamp the upper plate.
• Turn the instrument towards station P and sight accurately by tangent screw. 
• Now, loose the upper clamp and tight the lower clamp and move the instrument towards station R.
• Bisect the station R with the help of tangent s screw. 
• When upper plate is move main scale and vernier scale read the angle. 
• Main scale read the angle in degree while vernier in minutes and seconds.
• Now, change the face of vertical circle left to right and repeat whole process and read the angles. 
• Find the average of both observation and that is horizontal angle.