In the field of compass surveying the direction and orientation of survey line measured by a compass and also their lengths by chaining or taping directly on the surface of the earth, is defined as Compass surveying.
Generally Surveying Compass are two types,
- Prismatic Compass
The different parts of prismatic compass are as follows.
- Compass box
- Lifting Lever
This single needle is of edge bar type and it also acts as an index marker.
- Agate Cap
- Glass Cover
- Eye vane
- Focussing stud
- Brake pin
- Spring brake
- Lifting Pin
- Objective vane
The vanes is consists of metal vane with a vertical hair line.
- Adjustable mirror
- Prism Cap
- Graduated ring
This ring is attached to the box and not to the needle. This graduated ring rotates along with the line of sight. The graduations are in Q.B system having 0o at North and South and 90o at East and West are interchangeable.
The compass reading are taken directly by seeing through the top of the glass .Slighting and reading cannot be done simultaneously from one position of the observer. The instrument must be used with tripod.
- Surveyor Compass
The different parts of Surveyor compass are as follows.
- Lifting lever
- Circular Graduated arc This ring is attached to the box and not to the needle. This graduated ring rotates along with the line of sight. The graduations are in W.C.B system having 0o at South , 90o at West , 180o North and 270o
- Glass top
- Sight vanes
The object vanes consists of a metal vane with a vertical hair line. The eye vane consists of a metal vane with a slit.
- Jewel bearings
- Lifting pin
- Magnetic needle
The needle is broad type of needle and does not act as an index.
- Metal pin
The readings are taken with the help of prism and eye slit. The slighting and reading can be done simultaneously from one position of the observer. Tripod stand may be or may not be provided . The instrument may be used even by holding by hand.