482 ELECTRICITY. 



be made of any size or form, or of any substance which 

 is a conductor of electricity. All that is essential is that 

 it should be insulated, that is, supported and surrounded 

 by non-conductors, so that the electricity which it re- 

 ceives may be retained. A conductor of immense size 

 was once constructed of common military drums, coated 

 with tinfoil, and placed one upon another, forming a lofty 

 column, which was supported at the base by a cake of 

 beeswax which cut off all electrical communication with 

 the ground. 



The human body may be used as a prime conductor. 

 In order to insulate it, an instrument is used called an 

 Insulating- Stool. It consists simply, of a stool with 

 glass feet. These feet or legs may be common phials, 

 with the neck cemented into the board, which forms the 

 upper part of the stool. A board supported upon four 

 common tumblers, or a cake of beeswax will answer the 

 purpose equally well. The human body thus insulated 

 may be charged with electricity, and from it the fluid 

 will pass in sparks to the surrounding bodies. Young 

 persons, who amuse themselves with electrical ma- 

 chines, find an inexhaustible source of pleasure from 

 these experiments upon each other. 



Besides the prime conductor, there is another sort of 

 reservoir for the electric fluid when it is developed by 

 the electric machine, which is far more efficient. It is 

 called the Leyden Jar. The reader will recollect that 

 on the subject of the theory of electricity, it was stated 

 that any body, when electrified, and brought near to 

 other bodies, would cause them to assume a contrary 

 electrical state. Consequently, if two prime conductors, 

 one positively electrified, and the other in its natural 

 state, are brought within the influence of each other, 

 the last mentioned will become negatively -electrified, 

 and upon forming a connexion between the two they will 

 both be suddenly discharged. The effect will be in- 

 creased in proportion to the nearness of the two con- 

 ductors. If however there is nothing but air between 

 them, they cannot be brought very near or they will dis- 

 charge themselves through the air. To obviate this dif- 

 ficrity, a thin glass plate may be interposed, and in order 



