ELECTRIC DISTRIBUTION AND CONDENSATION. 63 



ductor can be charged by induction. The charge on 

 the pail, if positive, repels electricity from the ball, 

 through the wire and hand, to the earth ; or, if nega- 

 tive, attracts electricity from the earth; and in either 

 case, a certain degree of equilibrium follows, causing a 

 corresponding convergence of the leaves. 



Entire convergence cannot be produced, since only 

 a small portion of the lines of force from the pail are 

 cut by the ball ; while, in the former experiment, nearly 

 all those from the ball were cut by the pail. For this 

 reason a large ball is best for the second experiment 

 and a small one for the first. 



If the ball, in the second experiment, is lowered by a 

 silk cord instead of a wire, there is no perceptible effect 

 on the leaves, since induction cannot increase nor dimin- 

 ish the electricity of the ball when there is no earth 

 connection. 



COMBINATION OF PAILS. The following experiment 

 was made by Faraday with a combination of hollow 

 conductors : 



Let four pails of different sizes be placed on an insu- 

 lated support, and arranged one within the other as 

 shown in Fig. 12 : and let them be insulated from each 

 other at bottom by cakes of paraffin, or any other good 

 insulator, placed between them. Let silk cords be 

 attached to the three inner ones, and the outer one be 

 connected with an electroscope. 



On lowering the charged ball into the innermost one, 

 the leaves diverge as in the first experiment ; contact 

 between the ball and pail producing no increase of 

 divergence, and the ball is then found to be discharged, 

 as before ; which proves that the interposition of the 

 insulated pails, 2 and 3, has not affected the induction. 



