Wednesday, March 11, 2020

FUNDAMENTALS OF SURVEYING : Magnetic Declination


> It is the horizontal angle between true meridian and magnetic meridian at a place shown by the needle at the time of observation.
> Eastern or positive declination: when magnetic meridian is to the right or eastern of true meridian.
Declination east (+ve)                                    Declination west (-ve)
> Western or negative decli8nation: when declination is to the left or western side oftrue meridian.
> Mariners call declination as variation. Must be having adjustable coils to avoid dip.
> “Isogonics lines” are the lines drawn through the points of same declination.
> “Agonic lines” are the line made up ofjoining points having zero declination.

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