metallic wires. The grand consequence of this last discovery was the cognizance of a new fact: that what had hitherto been considered as a current of electricity in a wire is really a movement along the surface of the wire. Maxwell's magnetic theory of light found further corroboration by the experimental demonstration of electric power as propagating from its center in waves similar to sound. The electric undulations are subject to the same process of reflection, refraction, absorption, etc., as the rays and waves of light, from which they are in the end distinguished only by their considerably greater length, measured sometimes by kilometres. The crowning experiments of this course finally changed what had hitherto been looked upon as a coincidence between two orders of distinct phenomena into a demonstration of identity. By gathering the electric spark in the focus of a large concave mirror, whence it came forth in the form of a rectilinear beam, the properties of the electric ray were shown to be identical with those of a luminous ray, the former producing phenomena which have heretofore been observed only in light—those of polarization. This result renders all theorizing on the matter superfluous: the identity of the two powers springs from the experiment itself; ocular proof is produced for the proposition that light is in its very essence an electrical phenomenon, whether it be the light of the sun, of a candle, or of a glowworm. Suppress electricity in the universe—light would disappear. Suppress the luminiferous ether—electric and magnetic forces would cease to act through space. Even a body not casting light can be a center of electrical action if it radiates heat. Electricity therefore possesses all Nature and even man. The eye itself is, in fact, an electrical organ.
The influence of this new system of physics upon the development of natural science and the manifold applications in practical life of which it is capable can not easily be overrated. Only recently a new application of Hertz's discovery was made by an American, who is trying to develop photographs by the agency of the Hertzian waves, as science has named them—that is, by electricity instead of light. Hertzian waves, Hertzian investigations, apparatus, and methods form henceforth an essential part of all hand and text books of electricity. The facts established by Hertz's experiments have been molded into a mathematical formula by their author, who in this purely theoretical work also has shown himself to be a master of high genius in the realm of abstract science. There is at present in press and will soon be issued by T. A. Barth, at Leipsic, a comprehensive work, Principles of Mechanics in a New Connection, found among his unpublished papers at the death of Prof. Hertz. Its appearance is eagerly watched for by the scientific world.
