GO ELEMENTS OF STATIC ELECTRICITY. 



the same results will follow. And this cylinder may 

 be composed either of sheet metal or wire gauze without 

 affecting the results. 



Cylinders of the latter kind are often used to protect 

 electroscopes from the induction of electrified bodies 

 in their vicinity. 



Repeat these experiments, communicating the charge 

 to the inside surfaces of the globe and cylinder, and the 

 results will be the same ; showing that no charge can 

 remain on the inside. 



Fig. 10 Faraday's Bag. 



BAG EXPERIMENT. To test this more thoroughly, 

 Faraday constructed a cone-shaped linen bag, shown in 

 Fig. 10 ; attached to its mouth a ring insulated on a 

 stand, and to its apex two silk cords, by which either 

 surface could be turned outward. 



An electric charge was communicated to it, and, on 

 testing with the proof plane and electroscope, was found 

 to be entirely on the outer surface. The surfaces were 

 now reversed, and the charge was found to have been 

 reversed also, going to the outside, as before. 



PAIL EXPERIMENT. The following experiment by 

 Faraday shows the effect of induction on a hollow con- 

 ductor : 



Let a tin pail J., Fig. 11, or any similar hollow con- 



