This is well shown by a device of Faraday resembling a small
butterfly net insulated by a glass handle (fig. 5). If the net be
charged it is found that the electrification is only outside, and
if it be suddenly drawn outside in, as shown by the dotted line,
the electrification is still found outside, proving that the
charge has shifted from the inner to the outer surface. In the
same way if a hollow conductor is charged with electricity, none
is discoverable in the interior. Moreover, its distribution on the
exterior is influenced by the shape of the outer surface. On a
sphere or ball it is evenly distributed all round, but it
accumulates on sharp edges or corners, and most of all on points,
from which it is easily discharged.

A neutral body can, as we have seen (fig. 4), be charged by
CONTACT with an electrified body: but it can also be charged by
INDUCTION, or the influence of the electrified body at a distance.

Thus if we electrify a glass rod positively (+) and bring it near
a neutral or unelectrified brass ball, insulated on a glass
support, as in figure 6, we shall find the side of the ball next
the rod no longer neutral but negatively electrified (-), and the
side away from the rod positively electrified (+).

If we take away the rod again the ball will return to its neutral
or non-electric state, showing that the charge was temporarily
induced by the presence of the electrified rod. Again, if, as in
figure 7, we have two insulated balls touching each other, and
bring the rod up, that nearest the rod will become negative and
that farthest from it positive. It appears from these facts that