PROFESSOR LOVERING'S ADDRESS. 313 



surmounted. The turning-point between the old physics and the new 

 physics was reached in 1837, when Faraday published his experiments 

 on the specific inductive capacity of substances. This discovery was 

 revolutionary in its character, but it made no great stir in science at 

 the time. The world did not awake to its full significance until the 

 perplexing problem of ocean-telegraphs converted it from a theoretical 

 proposition into a practical reality, and forced it on the attention of 

 electricians. The eminent scientific advisers of the cable companies 

 were the first to do justice to Faraday. This is one of the many re- 

 turns made to theoretical electricity for the support it gave to the 

 most magnificent commercial enterprise. 



The discovery of diamagnetism fmmished another argument in 

 favor of the new interpretation of physical action. What that new 

 interpretation was, is well described by Maxwell : " Faraday, in his 

 mind's eye, saw lines of force traversing all space, where the mathe- 

 maticians saw centres of force attracting at a distance ; Faraday saw 

 a medium where they saw nothing but distance ; Faraday sought the 

 seat of the phenomena in real actions going on in the medium, they 

 were satisfied that they had found it in a power of action at a distance 

 impressed on the electric fluids." The physical statement waited only 

 for the coming of the mathematicians who could translate it into the 

 language of analysis, and prove that it had as precise a numerical con- 

 sistency as the old view with all the facts of observation. A paper 

 published by Sir William Thomson, when he was an undergraduate 

 at the University of Cambridge, pointed the way. Prof. Maxwell, in 

 his masterly work on electricity and magnetism, which appeared in 

 1S73, has built a monument to Faraday, and unconsciously to himself 

 also, out of the strongest mathematics. For forty years mathemati- 

 cians and physicists had labored to associate the laws of electro-statics 

 and electro-dynamics under some more general expression. An early 

 attempt was made by Gauss in 1835, but his process was published, 

 for the first time, in the recent complete edition of his works. Max- 

 well objects to the formula of Gauss because it violates the law of the 

 conservation of energy. Weber's method was made known in 1846; 

 but it has not escaped the criticism of Helmholtz. It represents faith- 

 fully the laws of Ampere and the facts of induction, and led Weber 

 to an absolute measurement of the electro-static and electro-magnetic 

 units. The ratio of these units, according to the formulas, is a veloci- 

 ty ; and experiment shows that this velocity is equal to the velocity 

 of light. As Weber's theory starts with the conception of action at 

 a distance, without any mediation, the effect would be instantaneous, 

 and we are at a loss to discover the physical meaning which he at- 

 taches to his velocity. Gauss abandoned his researches in electro- 

 magnetism because he could not satisfy his mind in regard to the 

 propagation of its influence in time. Other mathematicians have 

 worked for a solution, but have lost themselves in a cloud of mathe- 



