Electricity 



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sitely charged objects on the earth. The loud noise called thunder, 

 which follows lightning, is similar to the crackling noise heard 

 at the time of the discharge of the Leyden jar, except that it is 

 much louder. It continues to rumble because the sound is reflected 

 by the clouds. 



In 1752 Benjamin Franklin proved that lightning is an elec- 

 trical discharge. He built a kite with a pointed wire at the top 

 and flew it during a thunderstorm. At the lower end of the kite 

 string he tied a piece of silk ribbon, a non-conductor, and where 



LIGHTNING 



Electricity out of control. 



U. S. Weather Bureau. 



ribbon and string met he fastened a metal key. The wet kite string 

 was a conductor, and Franklin, putting his knuckle near the key, 

 was enabled to draw electric sparks from the key. There was a 

 difference in potential between the clouds and the ground. This 

 caused electricity to pass from the clouds through the kite, the kite 

 string, the key, and through Franklin to the ground. 



Electron Theory. Scientists have formulated a theory of 

 electricity known as the electron theory, which has been quite 



