82 Prof. Faraday on some Points of Magnetic Philosophy. 



fluid or aether is supposed to move in streams through magnets, 

 and also the space and substances around them. Then there is 

 the hypothesis of two magnetic fluids, which being present in 

 all magnetic bodies, and accumulated at the poles of a magnet, 

 exert attractions and repulsions upon portions of both fluids at 

 a distance, and so cause the attractions and repulsions of the 

 distant bodies containing them. Lastly, there is the hypothesis 

 of Ampere, which assumes the existence of electrical currents 

 round the particles of magnets, which currents, acting at a di- 

 stance upon other particles having like currents, arranges them 

 in the masses to which they belong, and so renders such masses 

 subject to the magnetic action. Each of these ideas is varied 

 more or less by different philosophers, but the three distinct 

 expressions of them which I have just given will suffice for my 

 present purpose. My physico-hypothetical notion does not go 

 so far in assumption as the second and third of these ideas, for 

 it does not profess to say how the magnetic force is originated 

 or sustained in a magnet ; it falls in rather with the first view, 

 yet does not assume so much. Accepting the magnet as a 

 centre of power surrounded by lines of force, which, as repre- 

 sentants of the power, are now justified by mathematical ana- 

 lysis (3302.), it views these lines as physical lines of power, 

 essential both to the existence of the force within the magnet, 

 and to its conveyance to, and exertion upon, magnetic bodies at 

 a distance. Those who entertain in any degree the gether notion 

 might consider these lines as currents, or progressive vibrations, 

 or as stationary undulations, or as a state of tension. For many 

 reasons they should be contemplated round a wire carrying an 

 electric current, as well as when issuing from a magnetic pole. 



3302. The attention of two very able men and eminent mathe- 

 maticians has fallen upon my proposition to represent the mag- 

 netic power by lines of magnetic force ; and it is to me a source 

 of great gratification and much encouragement to find that they 

 affirm the truthfulness and generality of the method of repre- 

 sentation. Professor W. Thomson, in referring to a like view 

 of lines of force applied to static electricity (1295. 1304.), and 

 to Fourier's law of motion for heat, says that the lines of force 

 give the same mathematical results as Coulomb's theory, and by 

 more simple processes of analysis (if possible) than the latter* ; 

 and afterwards refers to the "strict foundation for an analogy on 

 which the conducting power of a magnetic medium for lines of force 

 may be spoken off." Van Rees has published a mathematical 

 paper on my lines of force in Dutch J, which has been transferred 



* Phil. Mag. 1854, vol. viii. p. 53. 



t Ibid. p. 56. 



X Trans. Royal' Acad. Sciences of Amsterdam, 1854, p. 17- 



