24 "Nature's flbfraclcs. 



to the front. The truth is that they depend 

 upon each other. Electricity would be robbed 

 of a large part of its importance as a factor 

 in modern life if it were not for its relation to 

 magnetism. Even electric lighting would be 

 impossible, commercially, if it were not for the 

 part magnetism plays in the production of 

 electricity for this purpose. It could not be 

 successfully carried on with any battery but 

 the storage-battery, and the storage-battery is 

 dependent upon the dynamo, and the dynamo 

 is a magneto-electric machine. When we 

 come to analyze the relation between magnet- 

 ism and electricity we cannot separate them 

 without robbing each of a large part of its 

 usefulness. They are interdependent forces. 

 As in the case of electricity there have been 

 many theories regarding magnetism. One 

 philosopher in the old days accounts for the 

 variation of the compass-needle on the theory 

 that there are two globes, one revolving with- 

 in the other, and that any derangement of their 

 normal movements in relation to each other 

 affects the needle. Evidently there were 

 cranks in those days as well as now. Another 

 theory -of magnetism was that there were two 

 fluids a boreal and an austral one devel- 

 oping north polarity and the other south 

 polarity. In the next chapter the nature of 

 magnetism in the light of modern investiga- 

 tion will be discussed. 



