172 



HOW WE PRODUCE ELECTRICITY 



Now they use a gyro-compass which is not magnetic and 

 which is superior to the old type. When Lindbergh made 

 his astonishing solo flight, he was able to put his ship 

 down on the field near Paris because he had worked out 

 his course exactly and had used the magnetic compass in 

 doing this. 



Can you tell why a dipping compass needle would turn completely over if carried 

 around the earth through the poles ? 



SELF-TESTING EXERCISE 



Select from the following list of words those which best fill the spaces 

 in the sentences below and arrange the words in proper numerical order. 

 A word may be used more than once. 



brass magnetic 



iron magnetized 



steel wood 



silver non-magnetic 



hard lines 



soft surfaces 



center (middle) opposite 



