Sir W. Snow Harris’s Researches in Statical Electricity. 89 
result of the operation is to cause an electrical accumulation on 
the interior surface of the glass. The great difference in the 
two cases simply consists in the more or less perfect application 
of the coatings to the dialectric medium upon which the charge 
depends. If we could suppose our hollow metal globe sur- 
rounded by a second external globe of metal, the two globes 
being near cach other, but not anywhere touching, then we 
should have the two cases identical, as seen in the very ingenious 
apparatus employed by Faraday (Experimental Researches, 1195). 
If, further, we imagine that, subsequently to the charging of 
this system, both the globes were removed, as in the case of the 
mercury coatings, Exp. 5, and the intermediate air to remain, as 
it were, fixed and immoveable, then would be developed upon 
the boundaries of this stratum all the phenomena of the hollow 
glass globe above described; the charge would remain with the 
air. If, in the case of the charged glass globe, we allowed the 
interior metallic coating to remain under the form of thin me- 
tallic leaf attached to the glass, then the final experimental con- 
ditions would be identical. As it is, we operate upon the charge 
in the case of the hollow metal sphere, through the medium of 
the coating; in the case of the glass globe, we come into contact 
more immediately with the charge itself. 
11. The theoretical view, therefore, of the celebrated experi- 
ment of what has been termed a charged hollow sphere, and 
which appears the best adapted to explain the pheenomena, is that 
of charged electrics generally. The free electricity first commu- 
nicated to the imner coating, viz. the metallic sphere, operates by 
induction upon the nearest matter susceptible of electrical change 
(3), and thereby developes or calls into operation the opposite 
electricity. The opposite forces thus brought into life tend to 
combine and exhibit attractive force, and consequently come as 
near together as want of conducting power in the intervening 
restraining dialectric will permit: the imparted electricity must 
therefore necessarily find its way upon the exterior surface of 
the hollow metal globe without the aid of any kind of repulsive 
force to which the phenomenon has been hypothetically attri- 
buted. It is in virtue of this kind of action that we are said to 
charge simple insulated conductors generally. The amount of 
charge, however, or quantity of electricity which can be sustained 
by them under a given electrometer indication, can never be so 
great as in the case of systematically coated electrics of compa- 
ratively small thickness. The case of simple conductors is much 
the same thing as the case of extremely thick glass, or the limit- 
ing of the free action of one of the coatings of an electrical jar ; 
in either case the quantity of electricity which can be accumu- 
lated under a given degree of the electrometer is greatly dimi- 
