Illustration of Magnetic declination

1635 Magnetic declination

The book of science

Tom Sharp

Henry Gellibrand geophysics Illustration of Magnetic declination

Magnetic declination

You see, wherever and whenever you look, a different magnetic declination since the magnetic north pole drifts about the northern regions of the earth and has never in recorded history coincided with the point above which the stars appear to revolve.

True north

In this world, not only in an ideal world, a position that cannot be easily reached may yet be calculated, circumscribed, realized by imperfect beings with crude instruments. Mountains rise, continents move, glaciers carve bays and valleys, but this position never varies, or varies by only a hair.

Polar drift

North and south magnetic poles move in different directions at different rates, suggesting Earth’s magnetic field, the imperfect bundle of many fields, is fragmented, not bent.


Don’t let them fool you, but whom can you believe? It doesn’t dip toward the ground, but turns to the right or to the left. Your brain, it turns out, is easily deceived when given only your point of view. Gullible eyes, gullible ears, and lazy bones often lead a ship astray.

In Valdosta in the state of Georgia during the year in which I was born, the magnetic declination was zero degrees; the geographic north pole and the magnetic north pole were in the same direction (one being farther in that direction than the other).

See also in The book of science:

Readings in wikipedia: