ELECTRIC EXPERIMENTS. 



231 



with balls, points and pincers. They are supported upon sliding 

 and hinged joints, so that they may be easily placed in any desirable 

 position. If the adjacent ends of the two rods be fitted with ball 

 terminations placed upon the glass table, a small distance apart, a 

 fine wire may be laid from one to the other. One of the rods may- 

 be connected by a wire or chain 

 with the outer coats of a pow- 

 erful battery ; the other rod 

 may be connected by the dis- 

 charger (Fig. 154) with the inner 

 coats of the battery. The cur- 

 rent thus passed along the fine 

 wire may heat it to incandes- p. 



cence, melt or even vaporize it. 



(24.) One of the inevitable experiments with an electric machine 

 consists in "drawing sparks" from the conductor by the hand. 

 When the tension of the separated electricities becomes sufficient 

 to overcome the resistance of the intervening air, they recombine 

 with a sharp explosive sound and brilliant flash of light. If the 



FIG. 172. 



