200 



Our Surroundings 



lines of force coming from these poles are repelled, or driven 

 apart. These results agree with the law of magnetic poles. 



The Earth as a Magnet. The earth is a magnet of great 

 size with a north pole and a south pole. One of its magnetic 

 poles lies near the north pole of the earth and the other near the 

 south pole of the earth. The magnetic poles, however, are not 

 the same as the geographical poles. Dr. William Gilbert, in the 

 year 1600, discovered that the earth is a magnet and that the 

 magnetic poles are not the same as the geographical poles. This 

 discovery led to the explanation of a fact which had troubled 

 mariners in early days, that the compass did not always point 

 exactly north. 



The earth's north magnetic pole, which is of the same nature 

 as the south pole of all other magnets, lies in the region north of 

 Hudson bay and west of Baffin bay. It is not a fixed point, but is 



believed to cover a large area. 

 Within the Antarctic circle, be- 

 tween New Zealand and the 

 south pole, there is a similar 

 region known as the south mag- 

 netic pole. This is of the same 

 nature as the north pole of all 

 other magnets. The cause for 

 the magnetism of the earth is 

 not known. It is believed to be 

 some condition existing deep 

 below the earth's surface. 



The Dipping Needle. The 

 dipping needle is a magnetized 

 needle balanced to rotate ver- 

 tically. It is an interesting fact 

 * ~"~\ that the north end of the dip- 



HO,,O J? 'Z1 * , a, *. P-g needle dips more and more 



earth's magnetic poles. as tne instrument is carried 



north from the equator until a point is reached where it stands 

 vertical. The needle is then over the earth's north magnetic pole. 

 If carried south of the equator, the south end of the needle dips 



