gas, vapour, medium, or whatever we choose to call the substance
occupying the space around it_, just as the motion of a rifle-bullet is
impeded by the resistance of the air."

What is the testimony of our own personal observation and experiments to
such an impossible entity as a frictionless medium? Can any of the
readers tell me of any medium, be it solid, liquid, or gaseous, that
they have ever heard of, or read of, or experimented with, that
possesses the quality of being frictionless? The answer is unanimously
in the negative. But a frictionless medium was absolutely imperative to
the success of the Newtonian aspect of the Law of Gravitation. If the
Aether had not been frictionless, then the First Law of Motion would
have been violated, and a body, as for example a planet set in motion,
would not then have moved with uniform motion, but would have been
brought to a standstill by the resistance of the Aether. Accepting
therefore experience as a guide, as we are bound to do if we wish to be
strictly philosophical, as Newton pointed out, then we are compelled to
come to the conclusion that there is no such thing in the entire
universe as a frictionless medium. Such a hypothesis is contrary to all
laws and rules of Philosophy, and to continue to advocate its claims is
to remain where we are in relation to the cause of Gravitation, and in
complete ignorance of the beauty and harmony of the wonderful physical
mechanism that underlies the whole of the universe. Of course, if
experience and observation are no guide to Philosophy, then we will let
imagination run riot, and postulate the most extravagant explanations
for the varied phenomena of the heavens. With experience of no account,
we will affirm that the moon is made of green cheese, that the earth is
flat, that the sun revolves round the moon, and a host of other absurd
hypotheses that require no correction by experience and observation. But
there, a truce to such absurd imaginations. Experience is a guide to
Philosophy, its claims are recognized by the greatest Philosopher the
world has ever known, and therefore as either experience or a
frictionless medium has to go, we will part with the frictionless
medium, and endeavour to make a hypothesis of the Aether that is in
greater harmony with our Rules of Philosophy.

ART. 15. _Second Law of Motion._--The application of Newton's Rules of
Philosophy to the Second Law of Motion is attended with greater success
than