xisting dynamical science."

I hope, therefore, to be able in this work to do something towards
clearing the completed Law from some of the outside props, which have
long hidden the simplicity, beauty and harmony of the physical working
of Gravitation from the eyes of those who feign would see its wonderful
mechanism.

In the elaboration and development, therefore, of the physical cause of
Gravitation, it will be necessary to conceive a medium, whose properties
and motions shall be able to account for all the movements of the
planets, comets, suns and stars that the Laws of Motion now account for.
Instead, however, of there being several Laws purely and simply
mathematical in their application, there will be one physical medium,
which will by its properties and motions account for--and that in a
satisfactory manner--all the motions of the heavenly bodies. That such a
medium is required in the scientific world is proved by the statement
made by Professor Glazebrook, in his work on J. C. Maxwell, page 221,
where he says: "We are still waiting for some one to give us a theory of
the Aether, which shall include the facts of electricity and magnetism,
luminous radiation, and it may be Gravitation."

ART. 17. _Summary of the Chapter._--In summing up the contents of this
chapter, we find therefrom, that there is a Universal Law in existence
that is known as the Law of Gravitation. The physical cause of this Law,
however, is unknown; Newton suggesting that it was due to the properties
of an aetherial medium that pervaded the universe.

To form a right conception of this medium, and to develop the hypotheses
of the same on strictly philosophical lines, it is essential for us to
know the rules which govern the making of any hypothesis.

Those rules, according to Newton, and other philosophers, are chiefly
three in number, and form the very essence of any philosophical
reasoning. Any departure from those rules will entail partial or entire
failure in the success of the undertaking.

The application of Newton's rules to parts of the great Law of
Gravitation show that some of those parts are not fully in harmony with
the rules which Newton laid down in his _Principia_.

Any physical theory that may be hereafter suggested as the physical
basis for the Law of Gravitation, must itself not only account for the
various forces already referred to, but must itself fulfil the Rules of
Philosophy laid down by Newton. That is to say,