c field
that I wish to call the reader's attention to, and that is the Electric
Potential of such a field.

Electric potential is to electricity what temperature is to heat, or
pressure is to any medium of different densities. We have already seen,
according to the laws of thermodynamics, that heat will flow from a
higher temperature to a lower one, with the result that work is done. In
the case also of water at two different levels, work can also be done by
the water flowing from a higher to a lower level.

A similar thing happens in electricity; where we have two conductors or
two parts of an electrical fluid at different potentials, electricity
will flow from the place of higher potential, until the potentials are
equalized, in the same way that the temperature of two bodies at
different temperatures would be equalized by the flow of heat.

So that electric potential agrees with our conception of a gravitative
Aether in that, being gravitative, it is denser in those parts nearest
to the attracting body than farther away, and as the elasticity or
pressure is proportionate to the density (Art. 47), therefore we learn
that the electric potential of the Aether, and the thermal condition of
the Aether, if I may use such a term, both agree and coincide with the
density and elasticity of the Aether.

Any equipotential surface which represents a particular aetherial
density, would also correspond with a particular elasticity or pressure
of the Aether, while it would further correspond with a particular
temperature, if such a term is applicable to the Aether.

_Equipotential Surfaces._--The fact that in an electric field there are
different points at different potentials, leads us to the truth that in
an electric field there are also equipotential surfaces; that is to say,
there are surfaces where the electric density or the aetherial density
are equal at all points on such a surface. If, for example, _E_ be an
electrified body (Fig. 9), and _A_ _A'_, _B_ _B'_, represent equipotential
surfaces around the body, then all the points on _A_ _A'_ would be of
equal potential--that is, of equal energy, or pressure.

We have to remember that _A_ _A'_, _B_ _B'_, are sections of a sphere, so
that when the body as _E_ is a sphere, then the equipotential surfaces
are spheres also. This agrees with Art. 77, in which we saw that the
pressure around any body due to aetherial density also possessed
equipotential surfaces.

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