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ELECTRICITY. 



ball a is fastened at one extremity of a 

 1 light and slender rod c a, moving on the 

 centre c. The part b is inserted into 

 the prime conductor. When the con- 

 ductor is charged, the stem c b and the 

 ball a become similarly electrified and of 

 course repel each other. The ball ac- 

 cordingly rises up the quadrant c a to a 

 height which depends upon the intensi- 

 ty of the charge. This is called the 

 Quadrant Electrometer. 



There is a Silver Leaf Electrometer, extremely deli- 

 cate in its structure and operations. Two slender strips 

 of silver or gold leaf are suspended from the same point. 

 The electricity causes them to diverge. Various other 

 instruments for the purpose of indicating the presence of 

 electricity, have been contrived, but they are all on the 

 principle of the divergence of light bodies freely sus- 

 pended, and similarly electrified. 



3. The divergent hair. If an individual whose hair is 

 loose and flexible, stands upon the insulating stool and is 

 electrified, the hairs of the head, each being repelled by 

 the others, stand out in all directions, and present a very 

 grotesque appearance. Sometimes a little image is made 

 with hair of a peculiarly dry and flexible character, to 

 be attached to the prime conductor. 



4. The electrical snow storm. A hollow metallic cup 

 is placed upon the prime conductor and filled with light 

 shavings of pith, or small pieces of paper, or any other 

 similar substance. When the conductor is electrified 

 these become mutually repulsive, and fly off in every di- 

 rection, producing what the electricians call an electrical 

 snow storm. 



5. The electrical jet . A little vessel with a hole in its 

 side, so small that the water oozes through in drops, is 

 hung upon the prime conductor. When the apparatus 

 is charged, the mutual repulsion of the particles causes 

 the water to fly out in a stream. 



6. The. thread of sealing wax. Attach a small piece 

 of soaliug-wax to the extremity of a wire, and warm it 

 so as to render it ready to drop ; and at the same time 



