text: If you have a small compus, as used by the early age sailors, you will see the north is indicated at northen pole, even if you make it rorate, it will come back to its position again and show the north direction. Once you reach the exact north pole, then the compus will not work, it will keep rotating as the magnetic lines will pass through and thus you will know that you are at exact north pole.... and same is true for south pole as well ... hope I have answered your question... :)