Bearing of Line
It is the horizontal angle which the lines makes with certain reference direction or meridian. Bearing are called magnetic bearing, assume bearing or arbitrary bearing or true bearings according as the meridian is magnetic assumed or arbitrary or true.
Designation of Bearing
There are two systems of representation of bearings.
Whole Circle Bearing of Line
In this angles are always measured in clockwise direction and the angle value lies between 0o to 360o in figure whole circle bearing of AB1 is q1 and AB2is q2 and so on.
Quadrantal Bearing or Reduced Bearing
In this angles are always measured in clockwise or anticlockwise direction from N-direction or S-direction which ever is measured the line toward the east or west. The method is explained in the figure angles values ranges from 0o-90o and the quadrants are denoted by the letters N-E, S-E, N-W, S-W respectively
The disturbing influence due to which magnetic needle deviates from its normal position is known as local attraction. This local attraction is much more in cities then in villages. This disturbing influence may be due to steel structure, rails, electric cables conveying current, iron pipes, railing, iron lamp-posts etc