Measurement of Magnetic bearing of a line by theodolite, In order to measure the magnetic bearing of a line, the theodolite should be provided with, How to measure magnetic bearing of a line by theodolite.

 

• Attach trough compass to the theodolite at the place provided. 

• Set up the instrument over station P and level it accurately. 

• Set the vernier A to 0° of the horizontal circle. 

• Unclamped the lower plate and release the magnetic needle. Rotate the instrument about its outer axis until the magnetic needle shows N & S directions exactly. 

• Now loose the upper plate turn the telescope and bisect the stations B exactly by using upper clamp screw and upper tangent screw. 

• Note the reading from both vernier which gives magnetic bearing of line AB.