Surveying- one liners
Few more one liners from Surveying.
1. The tolerance for a 20 m chain is +-5mm.
2. A chain length is measured from outside end of one handle to the outside of other handle while chain is held straight.
3. Normal tension/pull is the amount of tension which neutralizes the pull and sag correction.
4. Surveying map prepared by any country are prepared with reference to the true meridian not magnetic meridian.
5. Prismatic compass has the WCB(Whole Circle bearing system) while Surveying compass has a quadrant bearing system.
6. French cross staff can be used to locate the 45 degrees and 90 degrees offset.
7. Prismatic compass has the circular graduations with zero at South and the needle attached together so, they do not move along with the box, while in surveying compass only needle is constant in North-south direction but the graduation move along with the box.
8. The horizontal angle between magnetic meridian and true meridian at a place is known as the magnetic declination of that place.
9. The difference between the fore bearing and back bearing of a line AB is 180 degrees.
10. The permissible error in the chain survey for rough and hilly areas is 1 in 250.