waves of light are
electro-magnetic waves; a firm foundation for this hypothesis is
furnished by showing the actual existence in free space of
electro-magnetic transverse waves which are propagated with a velocity
akin to light."

Again, in his paper on "Electric Radiation," he not only showed how the
radiation was propagated in straight lines, like light, but also proved
that while it was reflected by metals, the electric beam was able to
pass through doors and stone walls, and adds, "that it was with
astonishment that one saw the electric beam appear inside a closed room
after its passage through the door."

Thus Hertz has shown that both electric and magnetic effects are
propagated through the Aether with finite velocity, and that that
velocity is exactly the same as the velocity of light. He further proved
that this propagation takes place in straight lines, in the same way
that radiant heat and light are propagated. This being so, it is
necessary for us to apply these truths to the solar system, with a view
to find out what such a result teaches us.

We have seen in a preceding article, that the sun is an electrified
body; therefore it, too, must generate these electro-magnetic waves, and
radiate them into space on every side with the velocity of light. Let us
try to picture the scene. Let _S_ represent the sun, and the circle
round it represent the equipotential spheres which exist round the sun.
(See Figs. 10 and 11.) As the intensity of the electric force is greater
nearer the sun than further away, these equipotential surfaces will be
closer nearer the sun than further away.

Then let the straight lines which radiate out from the sun represent the
path of an electric ray. It can be easily seen that these electric rays
cut the equipotential surfaces at right angles, as they pass from the
centre of the sun outwards into space. Now these lines not only
represent the path which the electric ray takes in its journey through
space, but exactly coincide with the electric lines of force as
conceived by Faraday. This great thinker and experimentalist not only
conceived lines of magnetic forces existing in the dielectric or medium
between two electrified bodies, which in this case is the Aether, but
also conceived lines of electric force which started at a conductor, or
an electrified body, and radiated out into space.

Thus a line of electric force has a definite direction, and always
starts from an electrified b