4 o6 THE POPULAR SCIENCE MONTHLY. 



metallic wires. The grand consequence of this last discovery was 

 the cognizance of a new fact : that what had hitherto been con- 

 sidered 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 demon- 

 stration 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 kilo- 

 metres. 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 polariza- 

 tion. This result renders all theorizing on the matter superflu- 

 ous : 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 elec- 

 tricity in the universe light would disappear. Suppress the lu- 

 miniferous 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 pos- 

 sesses all Nature and even man. The eye itself is, in fact, an elec- 

 trical organ. 



The influence of this new system of physics upon the develop- 

 ment of natural science and the manifold applications in practical 

 life of which it is capable can not easily be overrated. Only re- 

 cently 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 elec- 

 tricity 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 form- 

 ula 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, Princi- 

 ples of Mechanics in a New Connection, found among his unpub- 

 lished papers at the death of Prof. Hertz. Its appearance is 

 eagerly watched for by the scientific world. 



