Question

1. Given a magnetic azimuth in 1993 of 169° 18', and a current magnetic bearing of S 8° 26' E. If the current magnetic declination is 4° 15' W, what was the declination in 1993?

Answer 1

True bearing remain constant with time. to obtain declination in 1993 first we need to find out true bearing of that point from given data:

based on current bearings:

True bearing = Magnetic bearing (Current) - Declination (Current)

Note: Here current declination is toward west direction and this declination will be deducted from magnetic bearing.

Magnetic bearing =

In WCB =

Magnetic bearing=  

True Bearing = Magnetic bearing (Current) - Declination (Current)

=

=

In 1993 magnetic bearing was and true bearing is same which is

So magnetic declination = magnetic bearing - true bearing

=

=

Magnetic declination in 1993 was .