theory of light, as the
conclusion that he arrived at in that theory was, that the light waves
were identical in nature and character with electro-magnetic waves
produced by an electro-magnetic source.

Up to the present we have only dealt with the electric character of
those waves, and have therefore now to deal with the magnetic character
of the same. So that throughout the whole realm of space, and indeed
wherever there is Aether, there we have the conditions which give rise
to magnetic phenomena, such as those already indicated.

It matters not whether it be in the atomic systems whose combinations
comprise all material forms of life with which we are familiar, or
whether it is in the systems of planets that revolve around their
central sun, or whether it be in the constellations that fill the
universe, wherever we find the Aether, there we find the conditions in
that Aether which will produce all the results ordinarily produced by
magnetism, or with which magnetism is associated, and it is to the
application of these phenomena to our solar system that we will now turn
our attention.

ART. 87. _The Earth a Magnet._--If there is any fact in relation to a
planet that holds good, it is that the earth, with which planet we are
more intimately associated than any other, is a magnet.

This truth was clearly explained by Dr. Gilbert about the year 1600 in
his work on "De Magnete." Not only has the earth geographical North and
South poles, but it has also magnetic North and South poles, and indeed
has all the phenomena incidental to a magnet, such as magnetic dip and
magnetic lines of force, as we shall see later on.

We know, however, that the earth is simply one of a system of planets,
which revolves with all the others of that system round its central body
the sun; and the question arises, whether the earth is the only one out
of all the planets that is actually a magnet. Suppose it is affirmed
that the earth is the only planet which is a magnet. On what basis would
such a statement be made? The only ground for making such a statement
that I can see is, that we have never lived on Mars or Jupiter or
Saturn, or any of the other planets, and therefore been unable to
experiment on them, which reason is totally insufficient and inadequate
for such a conclusion.

If philosophy simply dealt with the results attained by such limited
reasoning, then the progress of science would be retarded, and would be
limited and con