280 BENJ. PIKE'S, JR. DESCRIPTIVE CATALOGUE. 



Fig. 312. 

 Fig. 311. 



Qe 



midway between c and d by a silken thread, a small ball of 

 cork or elder pith. The ball will immediately be attracted 

 by d, then repelled to c, again attracted, and again repelled, 

 and this will continue for a considerable time : when the 

 motion has ceased, 'apply the discharging rod to the jar, no 

 spark or snap will result proving that the phial has been 

 gradually discharged by the pith or cork ball, the motion of 

 which from d to c likewise proving the opposite electrical 

 states of the outer and inner coatings. Price, $2.50. 



Fig. 313. 



Electrical Flyer. The electrical fly (Fig. 313, as above) 

 represents a light brass fly, consisting of fine wires pro- 

 ceeding from a common centre, and having their pointed 

 ends turned back at right angles, and all in the same direc- 

 tion. If this fly be poised on its centre on a pointed wire 

 inserted in the prime conductor, and the machine be put in 



