In message <[EMAIL PROTECTED]>, Silas Higgon
<[EMAIL PROTECTED]> writes
>Hello dialists,
>
>I am a newcomer to the internet and have been following your discussions
>with interest. I am a dial maker and am sometimes asked to make a
>wall-dial for another country. If I am sent a compass bearing for the wall
>I am left with the problem of magnetic variation and have to ask the
>customer to take sun readings so that I can calculate the wall direction.
> It would be much simpler if I could find the magnetic variation of a place
>by some means. Can anyone please help?
>
>Silas
Dear Silas,
As an aviator, I can tell you that aviation charts show
'isogonals', usually in 0.5 degree intervals. They give the date of
validity and a note saying how much the change is per annum.
The bad news is the cost of these charts. For Southern England
it is about 12 pounds, and there are three covering the UK. I can
possibly find you an old map if that helps?
Regards,
Mike Cowham.
