magnetic declination
magnetic variation
variation **

The magnetic declination may be read from a compass attached to the base plate.

This is called magnetic declination: the angle formed by the compass needle with the line pointing to true north.

You'll have to take magnetic declination into account if you are trying to navigate with reasonable precision.

These artifacts of occupation can yield the magnetic declination from the last time they were fired or used.

An Isogonal is also the name for a line connecting points at which the magnetic declination is the same.

From 1893 daily observations of the magnetic declination were made at the observatory.

An agonic line is drawn through points of zero magnetic declination.

He showed that in the past half century, magnetic declination in London had shifted by seven degrees.

The reason for the change in magnetic declination and magnetic dip was a mystery.

The local magnetic declination is given on most maps, to allow the map to be oriented with a compass parallel to true north.