Some basic questions.....?

Question

1) Why compass needle shows only North-South direction,though our Earth has a filed 0.3 Oerstead at Equator & 0.6 Oerstead at Poles.
2) On what basis North,South,East & West directions had been classified.
3) Why there the magnetic axis of Earth tilted around 11.7deg, with respect to our geographic axis.

Answer 1

Nobody knows for sure why the earth's magnetic field behaves as it does; trying to get good data from a thousand miles underground is not a trivial task. When considering the earth's field, it is important to consider both the vertical and horizontal components; the total field is of course the vector sum of these. If all you are doing is using a compass, the vertical portion of the field doesn't much matter -- except in aircraft compasses, which have a small weight to counteract the vertical component. This weight gives the compass some interesting (and annoying) properties when the aircraft is turning.

Answer 2

Well, I'm not an expert, but I''m goingt say:
1. Because the compass was inveted long before anyone knew what the heck you are talking about!
2. N&S are the directions the compass points, E&W, the location the sun rises and sets. (we're talking about sailors, not scientists)
3. The Magnetic axis was determined first using the compass, The geographic axis was determined after scientists learned better methods of determining such things.