ELECTRICITY. 



385 



What experi- 

 ments illustrate 

 the attractive 

 and repulsive 

 forces of elec- 

 tricity f 



FlO. 324. 



cai Battery. This may be effected by forming a connec- 

 tion between all the wires proceeding from the interiors 

 of the jars, and also connecting all their exterior coatin"-s. 



Such aa arrangement is represented by Fig. 323. The discharge of elecJ- 

 tricity from such a combination is accompanied by a loud report : and when 

 tlie number of the jars is considerable, animals may be killed, metal wires 

 be melted, and other effects produced analogous to those of Hghtning. 



755. By means of an electrical machine and the Leydcn 

 Jar, many interesting and amusing electrical experiments 

 may be performed. 



The phenomenon of the repulsion of substances similarly 

 electrified, may be illustrated by means of a doll's head cov- 

 ered with long hair. When this is at- 

 tached to the prime conductor of an elec- 

 trical machine, the hairs stand erect, and 

 give to the head a most exaggerated ap- 

 pearance of fright. See Fig. 324. 



The same thing may be shown by plac- 

 ing a person on a stool with glass legs, 

 BO that he be perfectly insulated, and 

 making him hold in his hand a brass rod, 

 the other end of which touches the prime 

 conductor ; then on turning the machine, 

 the hairs of tho head will diverge m all 

 directions. 



If a small number of figures are cut 

 out in paper, or carved out of pith, and 

 an excited glass tube be held a few 

 inches above them on a table, the figures 

 will immediately commence dancing up and down, assuming a variety of droll 

 positions. The experiment can bo shown better by means ^^^ ^95 



of an electrical machine than with the excited tube, by 

 suspending horizontally from the prime conductor a metal 

 disc a few inches above a flat metal surface connected with 

 the earth, on which the figures are placed. On working 

 the machine, the figures will dance in a most amusing 

 manner, being alternately attracted and repelled by each 

 plate. See Fig. 325. 



„^ . ,,. The electrical bells, Fig. 326, which are 



What iB the , . . • \ 1 • 



experiment of rung by electric attraction and repulsion, 



the electrical are good illustrations of these forces. Where 

 bells? ° 



three bells are employed, the two outer 



bells A and B, are suspended by chain.s, but the central 



one and the two clappers hang from silken strings. The 



middle bell is connected with the earth by a chain or wire. 



17 



