KINETIC OR MECHANICAL VIEW uF NATURE. 85 



,02. 

 Elastic di«- 



to see the physical signiticance of this correspondence.* 

 " I have deduced the relation between the statical ami 

 dynamical measures of electricity, and have shown by a 

 comparison of the electro-magnetic experiments of .MM. 

 Kohlrausch and Weber willi the velocity of light as 

 found by M. Fizeau, that the elasticity of the magnetic 

 medium in air is the same as that of the luminiferous 

 medium, if these two coexistent, coextensive, and equally 

 elastic media are not rather one medium." - 



After having pointed out this remarkable correspond- 

 ence and other analogies between electrical and optical 

 properties which could be verified by experiment, Max- 

 well seems to have felt satisfied tliat a dynamical or turtai.cea 



" of tnt; same 



kinetic explanation of electric and magnetic phenomena 'nedium. 

 based upon rotary and translational motions and elastic 

 strains in the magnetic field was quite possiljle. The 

 detailed descriptions given in his earlier papers he looked 

 upon merely as crude mechanical devices by which some 

 of the known effects of magnets and currents could be 

 described. The valuable result was, that the electro- 

 magnetic field could 1)6 looked upon as a mechanical 

 system ; that the observed actions at a distance could 

 be conceived as communicated through this mechanical 

 system in definite measurable time ; and that certain 

 analogies had been pointed out as existing between 



^ ' Philos. Mag.,' January and Feb- 

 ruary, 1862 ; ' Coll. Papers' vol. i. 

 p. 492. 



- Cf. ' Coll. Papers,' vol. i. p. r.OO : 

 " The velocity of transvense undula- 

 tion.s in our hypothetical medium, 

 calculated from the electro-magnetic 

 experiments of MM. Kohlrausch and 



Weber, agree.s so exactly with the 

 velocity of light calculated from the 

 optical experiment,s of M. Fizeau, 

 that we can scarcely avoid the in- 

 ference that light consists in the 

 transverse undulation.s of the .sjime 

 medium which is the cause of electric 

 and magnetic phenomena." 



