Observing the Bearing:

Once the compass is centered over the station and levelled, the process of bearing measurement can start. Let AB be the survey line as shown in Figure (a), the bearing of which is required to be measured. The instrument is set at A and a ranging rod is fixed at B.

The compass is turned so that line of sight is aligned in the direction of AB by making eye slit of observation vane, vertical hair of object vane and ranging rod at B in same horizontal line. Wait for oscillation of graduation ring to dampen, along with the use of brake pin if essential. The viewing prism is focused by moving it vertically with the help of focusing stud. The reading of the image of hair line as observed through prism is noted indicating the whole circle bearing of survey line. The process is repeated to check the repeatability of measurements. This bearing is called fore bearing of line AB.

(a) Survey Line AB  (b) Compass Set at A

(c) Reading on Compass

Figure: Recording of Bearing