4'80 Dr. R. Hare's Objections to the Theories severally of 



64'. The charge which may exist in a coated pane affords 

 another exemplification of statical or electro-eethereal polarity.* 

 In this case, according to Faraday, the particles of glass are 

 thrown into a state of electro-polarity, and are, in fact, par- 

 tially affected as if they belonged to a conductor ; so that in- 

 sulators and conductors differ only in the possession in a high 

 degree by the one, of a susceptibility of which the other is 

 possessed to an extent barely perceptible. The facts seem to 

 me only to show, that either an insulator or conductor n)ay 

 be both affected by the. same polarizing force, the transmission 

 of which the one facilitates, the other prevents. 1 am under 

 the impression that it is only by the disruptive process that 

 electricity passes through glass ; of course involving a fracture. 

 It gets through a pane or jar, not by aid of the vitreous par- 

 ticles, but in despite of their opposing coherence. The glass 

 in such cases is not liable to be fused, deflagrated, or dissi- 

 pated, as conductors are. It is forced out of the way of the 

 electrical waves, being incapable of becoming a party to them. 

 Discharges will take place through a vacuity, rather than 

 through the thinnest leaf of mica. But if, as Faraday has 

 alleged, from within a glass flask hermetically sealed, an 

 electrical charge has been found to escape after a long time, 

 it proves only that glass is not a perfect insulator, not that 

 perfect instdation and 'perfect conduction are different extremes 

 of the same properly. On the contrary, the one is founded 

 upon a constitution competent to the propagation within it of 

 the electro-polarizing waves, with miraculous facility, while 

 the other is founded either on an absolute incapacity, or com- 

 paratively an infinitely small ability to be the medium of their 

 conveyance. The one extremely retards, the other excessively 

 expedites its passage through a space otherwise void*. 



Competency of a Wire to convey a Galvanic Discharge is as its 

 sectional area, while statical discharges of frictional electri- 

 city preferring the surface are promoted by its extension. Yet 

 in proportion as such discharges are heavy, the ability of a 

 "mre to convey them atid its mag7ietic energy become more 

 dependent on its sectional area and less upon extent of sur- 

 face. 



65. Reference has been made to two modes of electrical 

 conduction, in one of which the efficacy is as the surface ; in 

 the other, as the area of a section of the conductor. Although 

 glass be substantially a non-conductor, the power of tlie sur- 

 face of glass when moistened, or gilt, to discharge statical 



* By a void, I mean a Torricillian vacuum. The omnipresence of tlie 

 electro-aether must render the existence of a perfect void impossible. 



