Northern and Southern hemisphere compasses

[samvara]

Interesting trivia

This has to do with the fact that the magnetic field lines, to which a compass needle aligns, point into the earth at the north and south magnetic poles. In the northern hemisphere the north end of the needle is pulled downwards, and the south end is counterweighted to balance the needle. When you use a northern hemisphere compass in, say, Australia, the south end of the magnet is pulled downwards by the magnetic field, and is also heavier than the north end - resulting in a needle that catches and drags on the bottom of the compass housing when the compass is held horizontal.

Am waiting with interest to see if a dive compass purchased in Australia works in the states.

Comments

[juffles.livejournal.com]

Also causes havoc for a lot of elite orienteers who travel to world champs etc - last time we had a national-level comp in WA there was a call for people with spare southern hemisphere compasses they could lend to a bunch of swedes who'd come down. :)

[black-samvara.livejournal.com]

Had no idea it made a difference, seems obvious now. I was inspired to investigate after meeting divers with gear from Northern hemisphere who said they were having trouble.