1. Geomatic Engineering Lab
Compass Surveying
Geomatic Engineering Lab

3. Prismatic Compass

4. True Meridian and Magnetic Meridian
True meridian : A line or plane passing through the geographical north pole and south pole of any point on the earths surface
Magnetic Meridian : When a needle is suspended freely and balanced properly, unaffected by any magnetic substance, it indicates a direction. This direction is called magnetic meridian.

6. True Meridian and Magnetic Meridian

7. Whole Circle Bearing [WCB] and Quadrantel Bearing [QB]
WCB: the magnetic bearing of a line measured clockwise from the north pole towards a line is known as whole circle bearing of that line
Such a bearing may have any value between 0° to 360°
It can be obtained with the help of a prismatic compass

8. Whole Circle Bearing WCB of AB = θ1 WCB of AC = θ2 WCB of AD = θ3
WCB of AE = θ4

9. Quadrantel Bearing [QB]
The magnetic bearing of a line measured clockwise or counter clockwise from the North Pole or SouthPole which ever is nearer the line towards East or West is known as Quadrantel bearing
This system consists of four quadrants NE SE SW and NW
The value of a quadrantel bearing lies between 0 to 90 degree. But the quadrants should always be mentioned

10. SURVEYOR COMPASS

11. Reduced Bearing [RB]
When the whole circle bearing of a line is converted to quadrantel bearing it is termed as reduced bearing.
Its value lies between 0° and 90° but the quadrants should be mentioned for proper designation.

12. Relation WCB between Corresponding RB Quadrant 0 and 90 RCB = WCB NE
RB = 180- WCB SE
180 and 270
RB = WCB -180 SW
270 and 360
RB = 360 – WCB NW

13. Fore Bearing and Back bearing
The bearing of a line measured in the direction of the progress of survey is called the forebearing [FB] of the line
The bearing of a line measured in the direction opposite to the survey is called back bearing of the line.
In the WCB system
the difference between
the FB and BB should be
exactly 180°

15. Find the interior or included angles

18. Report No.3 [ ]
Q1) Differentiate between true meridian and magnetic meridian with the help of a neat sketch
Q2) What you mean by front bearing and back bearing
Q3) Show a neat sketch of Prismatic compass and mark all the parts of it.

19. Q4) Find the fore bearings only