MODERN VIEWS WITH KESPECT TO ELECTRIC CURRENTS 659 



ratus tuned, as it were, to a higher pitch, in which the same principle's, 

 however, employed, but the ethereal waves are shorter, and thus several 

 stationary waves can be contained in one room. 



The testing coil is then moved to different portions of the room, and 

 the nodes are indicated by the disappearance of the sparks, and the 

 loops by the greater brightness of them. The presence of stationary 

 waves is thus proved, and their half wave-length found from the dis- 

 tance from node to node, for stationary waves can always be considered 

 as produced by the interference of two progressive waves advancing in 

 opposite directions. 



However interesting a further description of Professor Hertz's experi- 

 ments may be, we have gone as far in that direction as our subject car- 

 ries us, for we have demonstrated that the production of a current in a 

 wire is accompanied by a disturbance in the surrounding space; and, 

 although I have not experimentally demonstrated the ethereal waves, yet 

 I have proved the existence of electric oscillations in the coils of wire 

 and the ether surrounding it. 



Our mathematics has demonstrated, and experiments like those of 

 Professor Hertz have confirmed the demonstration, that the wave dis- 

 turbance in the ether is an actual fact. 



The closing of a battery circuit, then, and the establishment of a cur- 

 rent of electricity in a wire is a very different process from the forma- 

 tion of a current of water in a pipe, though, after the first shock, the 

 laws of the flow of the two are very much alike. But even then, the 

 medium around the current of electricity has very strange properties, 

 showing that it is accompanied by a disturbance throughout space. The 

 wire is but the core of the disturbance, which latter extends indefinitely 

 in all directions. 



One of the strangest things about it is that we can calculate with per- 

 fect exactness the velocity of the wave propagation and the amount of 

 the disturbance at every point and at any instant of time; but as yet we 

 cannot conceive of the details of the mechanism which is concerned in 

 the propagation of an electric current. In this respect our subject resem- 

 bles all other branches of physics in the partial knowledge we have of it. 

 We know that light is the undulation of the luminiferous ether, and yet 

 the constitution of the latter is unknown. We know that the atoms of 

 matter can vibrate with purer tones than the most perfect piano, and 

 yet we cannot even conceive of their constitution. We know that the 

 sun attracts the planets with a force whose law is known, and yet we 

 fail to picture to ourselves the process by which it takes our earth within 



