e in the sun's electric field.

Such a question can best be answered from the consideration of
experiments and theories advanced first by Faraday, who gave to the
world his theory of Induction, which we shall now consider.

Let _A_ be an electrified body (Fig. 13), and _C_ be a body not
electrified, but situated within the electric field of _A_. Then it can
be experimentally proved, that _C_ will also become an electrified body
by induction. As is well known, there are two kinds of electricity,
Positive and Negative. We will suppose _A_ to be charged with positive
electricity. Then it can be proved that _C_ will also be charged with
negative electricity on the half nearest to _A_, while the other half
will be charged with positive electricity.

[Illustration: Fig: 13.]

Now how has this result been brought about? According to Faraday's
theory the particles of air, the dielectric, between _A_ and _C_ play a
most important part in the process. As a matter of fact, each atom or
particle of air is polarized, as the process of separating the two kinds
of electricity is termed, so that every atom has one half of it covered
with positive electricity, and the other half with negative electricity.

For example, let _A_ and _C_ be the same brass balls with the particles
of air between them, _A_ being the positively charged ball and _C_ the
unelectrified ball, the shaded parts representing positive electricity
and the unshaded parts negative electricity.

Then _A_ will act inductively on the unelectrified ball _C_ through the
medium of the particles of air _d_, _e_, _f_, _g_, _h_. The electrified
ball _A_ will act first on the layer of particles next to it, attracting
their negative electricity and repelling the positive according to the
well-known law that "Unlike electricities attract, like electricities
repel each other."

The positive electricity in the first layer then acts in the particles
of the next layer in the same way, and thus the inductive action is
transmitted through the particles, from layer to layer, until we come to
the last layer of particles next to the ball _C_.

As the half of each atom or particle nearest to _C_ is positively
electrified, then the half of the ball _C_ nearest to the layer becomes
negatively electrified, while the half further away is positively
electrified. Thus we say that _C_ has become electrified by induction
through the polarization of the particles of air which lie between the