Meridian
Meridian is a reference direction with respect to which the direction of lines are mentioned. There are three types of meridian – True Meridian, Magnetic Meridian & Arbitrary Meridian
1 – True Meridian
It is the reference direction of north pole of earth from a given station point. It is also called geographic meridian.
2 – Magnetic Meridian
It is the direction of north pole indicated by magnetic needle.
3 – Arbitrary Meridian
This is any assume direction to a well defined object. It may be useful for small areas. e.g A mosque is taken as reference and location of road will be mentioned with respect to this mosque. Direction of magnetic north with respect to true north is called magnetic direction.
Bearings
Bearing is the angle which a certain line make with a certain a certain meridian. Bearing with respect to true meridian is called true bearings while magnetic bearing is the angle which a line makes with respect to magnetic meridian. There are two ways to represent the bearings,
- Whole circle bearing (W.C.B)
- Reduced Bearing (R.B)
1) Whole Circle Bearing (W.C.B)
It can be taken 0° to 360°. Quadrants are taken clock-wisely and angles are also determined in clockwise direction.
2) Reduced Bearing
Reduced bearing or Quadrantal bearing is the angle which a line makes from North or South Pole whichever may be near. It is value is from 0° to 90°.
Using the above figures you can easily convert the Whole Circle Bearing into Reduced Bearing. Some Examples are given are below.
| Whole Circle Bearing (W.C.B) | Reduced Bearing (R.B) |
|---|---|
| 135° | S45E |
| 37° | N37E |
| 65° | N65E |
| 125° | S55E |
| 215° | S35W |
| 300° | N60W |
