MAXWELL'S "ELECTRICITY AND MAGNETISM" 259 



also, are usually, men of " paper " science, kid-gloved and black-coated with no 

 speck but of ink. 



Finally, the man of real power, though (to all seeming) perfectly unconscious 

 of it who goes straight to his mark with irresistible force, but neither fuss nor 

 hurry reminding one of some gigantic but noiseless " crocodile," or punching engine, 

 rather than of a mere human being. 



The treatise we have undertaken to review shows us, from the very first pages, 

 that it is the work of a typical specimen of the third of these classes. Nothing is 

 asserted without the reasons for its reception as truth being fully supplied there 

 is no parade of the immense value of even the really great steps the author has 

 made no attempt at sensational writing when a difficulty has to be met ; when 

 necessary, there is a plain confession of ignorance without the too common ac- 

 companiment of a sickening mock-modesty.... 



The main object of the work, besides teaching the experimental facts of electricity 

 and magnetism, is everywhere clearly indicated it is simply to upset completely the 

 notion of action at a distance. Everyone knows, or at least ought to know, that 

 Newton considered that no one who was capable of reasoning at all on physical 

 subjects could admit such an absurdity: and that he very vigorously expressed this 

 opinion. The same negation appears prominently as the guiding consideration in the 

 whole of Faraday's splendid electrical researches, to which Maxwell throughout his 

 work expresses his great obligations. The ordinary form of statement of Newton's 

 law of gravitation seems directly to imply this action at a distance ; and thus it was 

 natural that Coulomb, in stating his experimental results as to the laws of electric 

 and magnetic action which he discovered, as well as Ampere in describing those of 

 his electrodynamic action, should state them in a form as nearly as possible analogous 

 to that commonly employed for gravitation. 



The researches of Poisson, Gauss, etc., contributed to strengthen the tendency to 

 such modes of representing the phenomena ; and this tendency may be said to have 

 culminated with the exceedingly remarkable theory of electric action proposed by 

 Weber. 



All these very splendid investigations were, however, rapidly leading philosophers 

 away towards what we cannot possibly admit to be even a bare representation of the 

 truth. It is mainly to Faraday and W. Thomson that we owe our recall to more 

 physically sound, and mathematically more complex, at least, if not more beautiful, 

 representations. The analogy pointed out by Thomson between a stationary distri- 

 bution of temperature in a conducting solid, and a statical distribution of electric 

 potential in a non-conductor, showed at once how results absolutely identical in law 

 and in numerical relations, could be deduced alike from the assumed distance-action 

 of electric particles, and from the contact-passage of heat from element to element 

 of the same conductor. 



After quoting Maxwell's own frank and ample acknowledgement of his 

 debt to these two men, Tait continued : 



It certainly appears, at least at first sight, and in comparison with the excessively 



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