ELECTRIC DISTRIBUTION AND CONDENSATION. 65 



when but one pail was used: which proves that the 

 interposition of interior surfaces has no effect on induc- 

 tion ; nor can it prevent the entire charge from going 

 to the outside surface when the four pails are in electric 

 connection; for if the three inner pails be now removed, 

 they will be found to have lost their charge; but there 

 will be no change in the divergence of the leaves. 



This experiment is an actual demonstration of what 

 has already been stated, that the interior of a solid con- 

 ductor, or the shell of a hollow conductor, may be 

 regarded as composed of an infinite number of equipo- 

 tential shells or surfaces, from which a charge of elec- 

 tricity must always pass to the outside surface. 



FARADAY'S HOLLOW CUBE. A most remarkable ex- 

 periment in this connection was made by Faraday with 

 a hollow cube of wood, measuring twelve feet each way, 

 covered with tin-foil, insulated and charged by a power- 

 ful electric machine. 



He says : " I went into this cube and lived in it, 

 using lighted candles, electrometers, and all other tests 

 of electrical states. I could not find the least influence 

 upon them, or indication of anything particular given 

 by them, though all the time the outside of the cube 

 was powerfully charged, and large sparks and brushes 

 were darting off from every part of its outer surface." 



This experiment verifies the statement made on page 

 12 in regard to zero potential ; showing that however 

 strong the electrification, no indications of electric action 

 are perceptible within a space where there is perfect 

 equilibrium. So that even if the whole earth were as 

 powerfully charged, in proportion to its size, as Fara- 

 day's cube, we, who live on it, could perceive no electric 

 action, if the charge were as uniform as on the cube. 



