302 



BENJ. PIKE S, JR., DESCRIPTIVE CATALOGUE. 



and a shock will pass. Now connect the inside of A with 

 the inside of B, and a second shock will be obtained. A 

 series of bottles may thus be arranged, and a series of 

 shocks obtained by one charge only. Price, $3.00. 



Insulated Stand. (Fig. 357.) 

 This is a metallic plate having 

 a brass knob, and insulated by a 

 glass pillar cemented into a ma- 

 hogany base, and useful in many 

 experiments. Place the jar, A, 

 on the insulating stand, B, and 

 attempt to charge it from the 

 prime conductor, you will find 

 it impossible : now apply the 

 knuckle to the outside coating, 

 and continue to turn the ma- 

 chine : for every spark that 

 enters the jar, one will pass be- 

 tween the outside coating and 

 the knuckle, and on applying the 

 discharging rod, the jar will be 

 found to have received a charge. 

 Instead of the knuckle, the knob 

 of a second uninsulated jar, c, may be applied, and both 

 jars will receive a charge. Price, $2.00. 



Fig 358. 



Series of Insulated Jars. (Fig. 358, as above.) This 

 cut represents three or four Leyden jars, each mounted on 

 a base, insulated by a glass pillar, and supported in a hori- 

 zontal manner, by a band encircling the jar, one of them 

 having a hook for the purpose of attaching a chain. 



No charge of any amount can be given to a Leyden jar, 

 if it be insulated ; for, in proportion as the positive electri- 



