for the folks down under (anzacs)

[goo]

been reading some stuff on antartic polar expidetions in the early 20th century (scott, shackelton, mawson, hurley, etc.)
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some of them traveled to the magnetic south pole (the point at which a magnetic compass will point straight down).
so i was wondering... if i brought a magnetic compass fron new york to oz or New Zealand would it point north or south?
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hey, the only dumb question is thd one you don't ask.
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iceman goo.
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http://farm4.static.flickr.com/3466/...g?v=1233612889

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[mozark]

Well, if you're in Oz or NZ the red end of the needle is still going to point north, well actually towards Ellesmere Island, which at least a couple of years ago was magnetic north. Magnetic north is picking up speed, it's moving around at, something like 40 kilometers a year now.

MM

[goo]

so the red end points to the north magnetic pole which may or may not be 180 degrees from the south mag pole, right?
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http://www.aad.gov.au/asset/images/4...from_space.gif
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Geomagnetism - North Magnetic Pole

.. this does relate to enfields because some milsurp ammo attracts a magnet and depending on the magnetic orientation of the shooting range, a windage correction may be required.

[Alan de Enfield]

so the red end points to the north magnetic pole which may or may not be 180 degrees from the south mag pole, right?
...
http://www.aad.gov.au/asset/images/4...from_space.gif
...
Geomagnetism - North Magnetic Pole

.. this does relate to enfields because some milsurp ammo attracts a magnet and depending on the magnetic orientation of the shooting range, a windage correction may be required.

Goo - surely thats not right :
If you make a wind-age correction for wind then you must make a magnetic-age for magnetic fields.
That leads to another question - if the wind-age allowance (say) left to right, is the same as the magentic-age correction needed right to left would they cancel each other out, and would you need to check each bullet before firing to see if it was magnetic and hence needed the magnetic-age deviation allowance ?
There are many other permutations possible - maybe you have opened up a totally new aspect to long distance target shooting, Wind-age, Magnetic-age in additon to correolis effect, bullet drop etc. What about ridge lift, wave and thermal activity ?

[goo]

its a proven fact that the japaneese suffered the greatest amount of head shots in the pacific during ww11 despite having smaller heads than the good guys. it was subsequently determined that their helmets had never been magnafluxed and were therefore magnetic. the logical assumption was that the jap's helmets actually attracted errant bullets to their intended targets even if they were fired inacurately.

[Paul S.]

Just to throw a small spanner in the works; a compass bought in New York - say a Silva for instance, might not work in Oz.

Apparently the needle/compass disk is weighted to balance and work in a particular meridian band. I think Silva uses 4 different bands. The Silva I brought from Oz wouldn't work in North America. I ended up giving up on Silvas and going back to the old Prismatic. It works anywhere.

[mozark]

That's interesting. I wonder if it's because the shape of the magnetic field is a huge torus.

My Silva broke years ago anyway. Good surplus prismatic compasses are cheap, and as you say, work anywhere. The Silva's are good for learning orienteering, though.

MM