Mar 14 2017

A Primer on North Declination & Variation by Tamia Nelson

A magnetic compass is a simple instrument. Or so it appears. A needle or card, a graduated housing, maybe a lanyard ring… And that’s that. It doesn’t beep or chirp, it boasts no colorful map display, and it won’t tell you how far it is to your lunch stop. But twist and turn the compass as much as you like, and the needle (or card) continues to point toward the north. Magic? No. Magnetism. And before some physics Ph.D. takes me to task for playing fast and loose with the truth, I should add that the compass needle doesn’t really “point” north. Its orientation is determined by the north-south lines of force established by the earth’s local magnetic field. Still, the result is the same. The needle…er…points north.

What’s that? You’re not impressed? You say your GPS can do this, too, plus show you exactly where you are on the map? Right—though unless your GPS also incorporates a fluxgate (electronic) compass, it will lose track of north just as soon as you stop moving. Nonetheless, by comparison with the all-seeing, all-knowing GPS, the magnetic compass is a one-trick pony.

But what a trick! This simple, trembling needle—a Chinese invention, by the way—gave medieval Europe the key that eventually unlocked all the rooms in Gaia’s great house. That’s no small achievement. And the compass still has a place in paddlers’ packs—or better yet, on their decks and in their hands. A compass is self-powered and self-contained. It doesn’t depend on satellite coverage or batteries, and it’s not subject to sudden, inexplicable crashes. Every electronic device I’ve owned has failed me sooner or later, almost always without warning. No compass has ever let me down.

As simple and straightforward as a compass appears, however, it holds a dark secret. Its north is not the cartographer’s “true” north. Its needle doesn’t point the way to the soon-to-be open waters lapping around the North Pole. And therein lies a story: the story of the other north pole… Read more…

Two Norths

Originally published at Paddling.com on March 14, 2017