On 9/22/01 6:22 PM, John Farber at email@example.com wrote:
>Magnetic declination is not the same thing as magnetic deviation. I think
>you guys are talking about deviation from true North, whereas mag
>declination is the vertical angle the field lines make going into the Earth,
>and that varies by latitude.
Magnetic Deviation is defined as the error in the compass itself, due to
its installation or other surrounding objects with metal fields.
What they really mean is Magnetic Variation, which is the difference
between true north and magnetic north due to the offset in the two poles,
plus any magnetic composition of the earth itself.
Unfortunately, Topographical maps usually refer to Variation as
Declination, hence the confusion.
Bill Coleman, AA4LR, PP-ASEL Mail: firstname.lastname@example.org
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