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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

Pages: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Introduction    Dial types    Hours (types of)    Time (types of)    Illustration
Symbols    Equations    Biographies    Chronology    Sources    Appendices