ELECTRIC EXPERIMENTS. 



227 



FIG. 163. 



are to be put into communication with the 

 prime conductor ; the larger central bell is 

 in communication with the earth. The clap- 

 pers are suspended by silk threads. When 

 the machine is slowly worked, the bells begin 

 to ring. Explain. 



(8.) In the "Leyden jar and bells," shown 

 in Fig. 163, the left-hand bell is in communi- 

 cation with the outer coat of the jar ; the clap- 

 per is suspended by a silk thread. When the 

 jar is charged and placed in position as repre- 

 sented, the bells begin to ring and continue to 

 do so for a considerable time. Explain. 



(4.) The " metallic plates and dancing images" are 

 represented in Fig. 164. The images are made of pith. 

 The upper plate is in communication with the prime 

 conductor ; the lower one with the earth. When the 

 machine is worked, the images dance in a very ludi- 

 crous manner. Explain. Pith balls may be substi- 

 tuted for the images, the resulting phenomena being 

 known as " Volta's hail." The experiment may be 

 simplified by electrifying the inner surface of a glass 

 tumbler by rubbing it upon the knob of the prime 

 conductor, and placing the tumbler over some pith 

 balls on the table. 



FIG. 164. 



FIG. 165. 



(5.) In the " electric swing," shown in Fig. 165, 

 the boy is suspended by silk cords. One of the 

 insulated knobs is in communication with the 

 earth ; the other with the prime conductor. 

 When the machine is worked, the boy swings to 

 and fro. Explain. 



(6.) Electrify a glass rod. Toss a small sheet 

 of gold leaf into the air. Bring the rod near the 

 leaf. The leaf is drawn toward the rod and then 

 thrown off. Chase the leaf with the rod without letting it touch 

 the ground. Explain. 



(7.) Fasten one end of a long, small copper wire to the prime 

 conductor. Near the other end of the wire, tie a silk cord and hang 

 it from the ceiling or other support so that the end of the vertical 

 part of the wire shall be at a convenient height. To this end of the 

 wire attach a tassel about four or five inches long made of many 

 strips of light tissue paper. Work the machine and the leaves will 



