PRESIDENTIAL ADDRESSES. 547 



During the fifty-six years which have passed 

 since Faraday first offended physical mathematicians 

 with his curved lines of force, many workers and 

 many thinkers have helped to build up the nine- 

 teenth century school of plenum ; one ether for 

 light, heat, electricity, magnetism ; and the German 

 and English volumes containing Hertz's electrical 

 papers, given to the world in the last decade of 

 the century, will be a permanent monument of the 

 splendid consummation now realised. 



But, splendid as this consummation is, we must 

 not fold our hands and think or say there are no 

 more worlds to conquer for electrical science. We 

 do know something now of magnetic waves. We 

 know that they exist in nature and that they 

 are in perfect accord with Maxwell's beau- 

 tiful theory. But this theory teaches us nothing 

 of the actual motions of matter constituting a 

 magnetic wave. Some definite motion of matter 

 perpendicular to the lines of alternating magnetic 

 force in the waves and to the direction of 

 propagation of the action through space, there 

 must be ; and it seems almost satisfactory as a 



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