The hypothesis of electricity being the fundamental basis of all matter made in the last chapter on the "Unity of the Universe," receives confirmation from Sir Oliver Lodge in his _Modern Views of Matter_, where he writes, page 13: "The fundamental ingredient of which, in this view, the whole of matter is made up, is nothing more or less than electricity, in the form of an aggregate of an equal number of positive and negative electric charges. This, when established, will be a unification of matter such as has through all the ages been sought; it goes further than had been hoped, for the substratum is not an unknown and hypothetical protile, but the familiar electric charge." APPENDIX C The hypothesis that all elements have definite quantities of electricity in them, or a definite number of electrons, as suggested on page 335, receives added weight by the testimony of Sir Oliver Lodge in the work already referred to. Writing on the subject, he says: "It is a fascinating guess that the electrons constitute the fundamental substratum of which all matter is composed. That a grouping of say 700 electrons, 350 positive and 350 negative, interleaved or interlocked in a state of violent motion so as to produce a stable configuration under the influence of their centrifugal inertia and their electric forces, constitutes an atom of hydrogen. That sixteen times as many, in another stable grouping, constitute an atom of oxygen. That some 16,000 of them go to form an atom of sodium; about 100,000 an atom of barium; and 160,000 an atom of radium." From these extracts, taken from _Modern Views of Matter_, the author claims that the theory of the Aether presented to the reader in _Aether and Gravitation_ receives added confirmation and support. * * * * * ERRATA The author regrets that Professor J. J. Thomson's name has been incorrectly spelled in several places. INDEX Aberration of light, 69, 149, 218 Absorption, 104-6 Acceleration, 239 Actinic rays, 141 Action at a distance, 96, 174, 176 and re-action, 20, 251 Adams' discovery of Neptune, 25 Aether is matter, 54-8 is atomic, 59-67 is gravitative, 64-9 density of, 69, 71, 136, 243 elasticity of, 74-7 inertia of, 76, 330 its motions, 80 compressibility of, 291, 315 waves, 79-80 Aetherial basis of matter, 326 Affinity, chemical, 43 Aldebaran, 312 Aluminium, 79 Ampère, 192 Ampère's theory of magnetism, 193 Andromeda, 314 Annual magnetic variation, 208 Annular nebulae, 320 Aphelion of earth, 36 Arago, M., 321 Arcturus, 312 Areas, Kepler's law of, 36 Asten, Von, 234, 296 Asteroids, 31 Atmosphere, 68, 73, 102, 225 Atom, vortex, 45, 46, 61 what it is, 43 electron, 63 Boscovitch, 61 hard, 61 size of, 43 Attraction, electrical, 2, 286 of gravitation, 13, 24, 31 magnetic, 195 Balance, Torsion, 187