manner, and on the same principle (1375.), from the
molecular theory.

1377. Here I think my view of induction has a decided advantage over
others, especially over that which refers the retention of electricity on
the surface of conductors in air to the _pressure of the atmosphere_
(1305.). The latter is the view which, being adopted by Poisson and
Biot[A], is also, I believe, that generally received; and it associates two
such dissimilar things, as the ponderous air and the subtile and even
hypothetical fluid or fluids of electricity, by gross mechanical relations;
by the bonds of mere static pressure. My theory, on the contrary, sets out
at once by connecting the electric forces with the particles of matter; it
derives all its proofs, and even its origin in the first instance, from
experiment; and then, without any further assumption, seems to offer at
once a full explanation of these and many other singular, peculiar, and, I
think, heretofore unconnected effects.

[A] Encyclopaedia Britannica, Supplement, vol. iv. Article Electricity,
pp. 76, 81. &c.

1378. An important assisting experimental argument may here be adduced,
derived from the difference of specific inductive capacity of different
dielectrics (1269. 1274. 1278.). Consider an insulated sphere electrified
positively and placed in the centre of another and larger sphere
uninsulated, a uniform dielectric, as air, intervening. The case is really
that of my apparatus (1187.), and also, in effect, that of any ball
electrified in a room and removed to some distance from irregularly-formed
conductors. Whilst things remain in this state the electricity is
distributed (so to speak) uniformly over the surface of the electrified
sphere. But introduce such a dielectric as sulphur or lac, into the space
between the two conductors on one side only, or opposite one part of the
inner sphere, and immediately the electricity on the latter is diffused
unequally (1229. 1270. 1309.), although the form of the conducting
surfaces, their distances, and the _pressure_ of the atmosphere remain
perfectly unchanged.

1379. Fusinieri took a different view from that of Poisson, Biot, and
others, of the reason why rarefaction of air caused easy diffusion of
electricity. He considered the effect as due to the removal of the
_obstacle_ which the air presented to the expansion of the substances from
which the electricity passed[A]. But platina balls show the phenomena _in
vacuo_ as