APPENDIX IX. Magnetic variation
| In the UK, the current magnetic variation can be estimated by assuming (in 2000) a value of 2º 37′ W on the Greenwich Meridian at 50º N, and then allowing an increase of 15′ for each degree of latitude northwards and one of 27′ for each degree of longitude westward. The annual change at present is about 12′ decrease.Historical values of the magnetic variation for London (Greenwich from 1900) are given in the following table: |
|
Year |
Magnetic variation |
|
1580 |
11º 15′ E |
|
1622 |
5º 56′ E |
|
1665 |
1º 22′ W |
|
1730 |
13º 00′ W |
|
1773 |
21º 09′ W |
|
1850 |
22º 24′ W |
|
1900 |
16º 29′ W |
|
1925 |
13º 10′ W |
|
1950 |
9º 07′ W |
|
1975 |
6º 39′ W |
|
1998 |
3º 32′ W |