In Canada's barren backlots is a small area where the compass needle, properly suspended, points directly downward. This phenomenon does not usually terrify observers: they know that they are standing on the north magnetic pole, the umbilicus of the earth's magnetic field. When the magnetic pole changes its location, as it does, the needles of all the world's compasses shift a little too.
Almost the only constant thing about the magnetic pole is the fact that it is forever on the move. Every day it wobbles slightly, and over the years its "mean position" drifts slowly.
The first reliable fix on the pole's...
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