First Try to find this partial diagram on the map (either on the side or in the key) e.g.:

The magnetic declination on a map corresponds to the center of the page on january 1st 1979.

It decreases by 0,07gr (0°4’) each year.

You should now calculate the magnetic declination.

In that case on january 1st 2001 the declination had decreased of :

4’ x 22 years = 88’ = 1°28’

You then need : 5°45’ - 1°28’ = 4°17’

On a compass a precision of 4° will be quite enough. You can now draw the first part of your diagram like this :

Be Careful ! The magnetic declination will change in time but also in space (the above facts are true for France) You should calculate the new declination each time you change of map.

You can now mesaure the difference between the geographical pole NG and the Lamber pole Y with a protractor as shown below

For example if you find 3° you can complete the diagram that way :

Be careful, if the grid is tilted the other way the diagram will look that way :