In the following pages of this work the author has endeavoured to perfect a theory, which will bring aetherial physics more into harmony with modern observation and experiments; and by so doing, believes that he has found the key that will unlock the problem not only of the cause of universal gravitation, but also other problems of physical science. The author has taken Newton's Rules of Philosophy as his guide in the making of the new theory, as he believes that if any man knew anything of the rules of Philosophy, that man was Sir Isaac Newton. The first chapter therefore deals with the generally recognized rules which govern philosophical reasoning, the same being three in number; the fundamental rule being, that in making any hypothesis, the results of experience as obtained by observation and experiments must not be violated. In applying the rules to the present theory of the aether, he found that the theory as at present recognized violated two of the most important rules of Philosophy, because, while aether is supposed to be matter, yet it failed to fulfil the primary property of all matter, that is, it is not subject to the Law of Gravitation. If aether is matter, then, to be strictly logical and philosophical, it must possess the properties of matter as revealed by observation and experiment. Those properties are given in Chapter III., where it is shown that they are atomicity, heaviness or weight, elasticity, density, inertia, and compressibility. To be strictly logical and philosophical, the author was compelled to postulate similar properties for the aether, or else his hypotheses would contravert the results of all experience. The application of these properties to the aether will be found in Chapter IV., where the author has postulated atomicity, heaviness or weight, density, elasticity, inertia, and compressibility for the aether, and so brought the theory of the aether into perfect harmony with all observation and experiments relative to ordinary matter. It will be shown that Clerk Maxwell also definitely affirms the atomicity of the aether, while Tyndall and Huyghens also use the term "_particles of aether_" over and over again. Moreover, in view of the most recent researches in electricity made by Sir William Crookes and Professor J. J. Thomson, we are compelled to accept an atomic basis for electricity, and as Dr. Lodge, in his _Modern Views of Electricity_, states that "Aether is made up of positive and negative electricity," then, unless we postulate atomicity for the aether, we have to suppose that it is possible for a non-atomic body (aether) to be made up of atoms or corpuscles, which conclusion is absurd, and therefore must be rejected as illogical and unphilosophical.