| Lookup tables magnetic declinations |
| It is generally
accepted by the CLIWOC team that the wind directions, reported by the ships’
officers, were relative to the magnetic North direction. Navigators were
well aware of the difference between the true and magnetic north direction,
but the compasses (we assumed that the bearing-compasses were mostly used
for determining the wind direction) were not always adjusted. Therefore
the wind direction has to be corrected. In the following table the magnetic
declination (or variation, as it is known on board ships) is given for the
whole CLIWOC period (1750-1850) for every 5x5 degree square. To find the
correction, look it up with a rounded (to 5 whole degrees) position and
the year of observation. The found number has to be added to the wind direction. |
Table name: MagneticDeclination |
|
|
Field name |
Description |
|
Lat |
Latitude in decimal degrees; North is positive, South is
negative |
|
Lon |
Longitude in decimal degrees; East is positive, West is
negative |
|
Year |
Year |
|
Declination |
Declination in degrees |