PHYSICAL SCIENCE 49 



inquiry. If light be an electro-magnetic wave, it 

 must originate in the vibrations of electric charges, 

 and from this idea a theory of matter was built up 

 by Lorentz and Larmor. The ultimate particle be- 

 came electrical in nature, and matter was resolved 

 into a collection of disembodied electric unit charges 

 or electrons. When Thomson's corpuscles became 

 known, they were identified with the electrons of 

 Lorentz and Larmor. 



A moving electric charge is accompanied by electro- 

 magnetic energy and momentum in the surrounding 

 medium, and thus work must be done to set the 

 charge in movement or to stop it when travelling. 

 Here we have an explanation of the familiar pheno- 

 menon of mass or inertia we explain, in fact, Galileo's 

 law of continued motion in terms of an electrical 

 theory of matter. 



In this way the conception of matter has been 

 resolved into that of electricity, and a striking unity 

 reached between the two branches of science, dynamic 

 and electrical. 



But, as we have no special electrical sense, mechani- 

 cal force is a more familiar conception to our minds 

 than electrical force. Hence, perhaps, arise the 

 efforts which have been made to express an electric 

 charge in its turn in mechanical conceptions, such 

 as a strain knot in the luminiferous aether. 



Whatever be the fate of these attempts, there 

 seems no philosophical reason, save the structure of 



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