Survex Digest, Vol 4, Issue 3

[GRAHAM MULLAN]

Michael Lake said:

| The mag declination correction for a given area might not have a linear
| relationship with the date. Sometimes it is given as so-many degrees per
| year on a map but sometimes it's given as a table of values. I'd rather
| have to add a correction explicitly myself than survex guess it for me
| and not realise it. Also if I get the data wrong for a map by entering
| it incorrectly then the mag dec would be wrong too.
|
| my 2c worth.
|
I agree. Not only that, but many people calibrate their compasses in such a 
way as to include both compass error and magnetic deviation in one figure. 
Letting Survex deal with one part of this (I do not see any way in which it 
can automatically deal with my compass!), will either lead to confusion or 
to some folks not doing it correctly - or at all!

Graham