equal to that of light. If the body be a sphere, then the waves will be
spherical in shape, and will proceed from the generating source in the
shape of concentric spheres as indicated in the figure. Before
proceeding any further, it is necessary that we should look at the
electric field from the physical aspect, with a view to discover
something of what takes place therein. As has already been indicated,
all electric phenomena are due to motions of the universal Aether.

It was left for Faraday to give us a true conception of an electric
field, and for Maxwell to perfect that conception and give us a physical
aspect of the same. Faraday conceived that stretching out from a magnet
or electrified body through space, that is, through the Aether, were
what he called "Lines of Force," and that these lines of force indicated
not only the direction of the magnetic and electric forces, but also
their intensity or power.

Where the lines of force were closest together, there the electric or
magnetic energy was the greatest and most intense; and where they were
the farthest apart, there the field was weakest in energy. An
illustration of the magnetic lines of force may be obtained by placing a
piece of paper over a magnet, and then strewing iron filings over the
same, when it will be seen that the iron filings will arrange themselves
in certain curved lines, which Faraday called Magnetic Lines of Force.
In this way Faraday mapped out the lines of force, relative not only to
single magnets, but also to magnets with poles placed in various
positions relatively to poles of other magnets.

Now as there are lines of force which reveal the intensity and direction
of the magnetic energy, so there are lines of force radiating out from
electrified bodies which reveal the intensity and power of the electric
field. The electric lines of force are radial, and are shown in the
figure (Fig. 9) by the straight lines _D_ _F_, _D_ _H_, _D_ _K_.

If an electrified pith ball, for example, be hung up in a room, then the
lines of force, which extend from the ball, indicate the stress in the
Aether surrounding the pith ball, so that if a hair be placed across
these lines of force, any movement of the pith ball will be indicated by
the motion of the hair.

It was Clerk Maxwell, however, who gave to the world a true physical
conception of Faraday's Lines of Force, in his paper on "Physical Lines
of Force."[25]

In the opening words of that paper