SKETCH OF HEINRICH HERTZ. 723 



ing the Englisli-speakiTig world to appreciate tlie importance of Lis dis- 

 coveries. A natural bent of iiiiud toward the qiiestious at issue had 

 awakened the young professor's creative powers; his complete concen- 

 tration upon the vital point and his intuitive perceptions led him to 

 definite results and complete success where so many able minds had 

 searched in vain. In the April number of this magazine Herbert 

 Spencer, speaking of the late Professor Tyndall, gives a number of 

 traits that apply with singular force and exactness to Professor Hertz, 

 Of these the first is "the scientific use of the imagination." It may 

 well be said that with this constructive imagination, as Mr. Spencer 

 terms it, originated Professor Hertz's rare success as a discoverer and 

 as an instructor. 



To find out the most effective arrangement of electrical conductors 

 and to secure t\\e conditions which would produce the strongest vibra- 

 tions at regular intervals and iu quickest succession, we might say the 

 adjustment of his instruments was the first part of his work. Having 

 brought about electric undulations up to several hundred millions iu 

 one second, Hertz proved through experiment that the waves of elec- 

 tricity are transversal like those of light, and that the transmission 

 requires a certain lapse of time. He ascertained exactly the velocity 

 of electricity; it is found by multiplying the length of wave, which he 

 measured, by the duration of the vibration, which can be calculated, 

 and he found this velocity to be, as Maxwell had supj)Osed, equal to 

 that of light, and, moreover, equal to the velocity of electric waves in 

 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 cor- 

 roboration 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 retiection, 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 kilometers. The crowning experiments of this 

 course finally changed what had hitherto been looked upon as a coin- 

 cidence between two orders of distinct phenomena into a demonstration 

 of identity. By gathering the electric sjiark iu 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 here- 

 tofore been observed only in lights — 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 projyosition that light is in its very essence an electrical phe- 

 nomenon, whether it be the light of the sun, of a candle, or of a glow- 

 worm. Supi^ress electricity in the universe, light would disax^pear. 



