498 Prof. J. Loverino- on the Mathematical and 



a 



took form, they also were fitted out with a garment of attractive 

 and repulsive forces acting at a distance ; and the theories of 

 Cavendish, Poisson, iEpinus and Ampere, indorsed as they were 

 by such names as Laplace, Plana, Liouville, and Green, met with 

 general acceptance. 



The seeds, which were destined to take root in a later gene- 

 ration, and disturb, if not dislodge, the prevalent interpretation 

 of the force of gravitation, were sown by a contemporary of 

 Newton. They found no congenial soil in which they could 

 germinate and fructify until the early part of this century. At 

 the present moment we find the luminiferous aether in quiet and 

 undivided possession of the field from which the grosser material 

 of ancient systems had been banished. The plenum reigns 

 everywhere ; the vacuum is nowhere. Even the corpuscular 

 theory of light, as it came from the hands of its founder, required 

 the reinforcement of an gether. Electricity and magnetism, on a 

 smaller scale, applied similar machinery. If there was a funda- 

 mental objection to the conception of forces acting at a distance, 

 certainly the bridge was already built by which the difiiculty 

 could be 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 returns 

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

 magnificent commercial enterprise. 



The discovery of diamagnetism furnished another argument in 

 favour 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 mathematicians 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 mathe- 

 maticians who could translate it into the language of analysis 

 and prove that it had as precise a numerical consistency 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 



