THE EARTH AS A MAGNET 81 



size and bulk from bowlders to clay. The interior of the earth 

 is probably solid rock, although hot enough to be liquid, if it 

 were not for the pressure upon it. 



References : 



1. 1002:114-119. Shape of the Earth. 



2. 1002 : 129-130. Density of the Earth. 



3. 1103 : 21-23. Relation of the Earth to the Sun. 



4. 1304 : 13-28. General Features of the Earth, 

 a. 1001 : 45. General Features of the Earth. 

 6. 1004 : 78-88. General Features of the Earth. 



c. 1302 : 26-29. Structure of the Earth. 



d. 1302 : 29-33. The Earth's Crust Mantle Rock. 



e. 1303 : 15-17. Structure and Temperature of Earth. 

 /. 1305 : 41-42. Internal Condition of the Earth. 



g. 1309 : 18-22. Shape, Size, and Density of the Earth. 



h. 1310 : 307-308. Form of the Earth. 



i. 1311 : 1-12. Changes on the Earth. 



j. 1312 : 16-19. Shape, Size, and Structure of the Earth. 



61. THE EARTH AS A MAGNET 



The ordinary magnet is a piece of hardened steel, which, 

 having been rubbed by another magnet, or influenced by an 

 electric current, is capable of attracting pieces of iron or steel. 

 If we suspend such a magnet by a fine thread, or on a delicate 

 pivot, we will find that it takes a definite direction, the ends 

 pointing north and south. This is due to the magnetism of 

 the earth. 



The points toward which the needle directs itself are called 

 the magnetic north and south poles, but they do not lie at the 

 geographical north and south poles. Thus, if we go east or 

 west, there will be a decrease or increase in the variation be- 

 tween the true north and the north which is indicated by the 



G 



