558 



CONDUCTION OF ELECTRICITY. 



metal, i, 2 or 3 cm in diameter, is soldered, and the wire 

 stretched and supported by two stout cords or thin 

 ribbons of silk. The wire should be 1 or 2 m shorter 

 than the length of tho room, and the ends of the silk 



Fro. 303 (an. prof., \ real size.) 



supports tied to nails driven into the wall, or to the 

 hinges of two opposite doors. An electric pendulum is 

 finally suspended at a, in the manner shown in the 

 figure. 



When the rubbed glass rod is moved along the edge 

 of the disc, so that the latter may take up a considerable 

 amount of the electricity of the glass, the pendulum will 

 also become electric, and will be repelled, as in fig. 303 

 B, the electricities being of the same kind, viz., positive. 

 When the disc is now touched by the hand, a small spark 

 passes between disc and hand, the electricity passes away 

 through the body of the experimenter, and the pendulum 

 falls back again into its position of equilibrium. If 



