1893.] the Electric and Luminiferous Medium. 44 9 1 



or we may take the case of several linear circuits in the field, and 

 obtain the formula 



T = \ 2i 2 Jf r -1 cos e ds ds + St^ f j r~ l cos e dsi ds 2 , 



which is sufficiently general to cover the whole ground of electro- 

 dynamics. 



Our result is in fact that a linear current is a vortex ring in the 

 fluid aether, that electric current is represented by vorticity in the 

 medium, and magnetic force by the velocity of the medium. The 

 current being carried by a perfect conductor, the corresponding 

 vortex is (as yet) without a core, i.e., it circulates round a vacuous 

 space. [The strength of a vortex ring is, however, permanently con- 

 stant ; therefore, owing to the mechanical connexions and continuity 

 of the medium, a current flowing round a complete perfectly conduct- 

 ing circuit would be unaffected in value by electric forces induced in 

 the circuit, and would remain constant throughout all time. Ordinary 

 electric currents must therefore be held to flow in incomplete conduct- 

 ing circuits, and to be completed either by convection across an 

 electrolyte or by electric displacement or discharge across the inter- 

 vals between the molecules, after the manner of the illustration given 

 above. December 7, 1893.] 



ISTow we are here driven upon Ampere's theory of magnetism. 

 Each vortex-atom in the medium is a permanent non-dissipative 

 electric current of this kind, and we are in a position to appreciate 

 the importance which Faraday attached to his discovery that all 

 matter is magnetic. Indeed, on consideration, no other view than 

 this seems tenable ; for we can hardly suppose that so prominent a 

 quality of iron as its magnetism completely disappears above the 

 temperature of recalescence, to reappear again immediately the iron 

 conies below that temperature ; much the more reasonable view is 

 that the molecular rearrangement that takes place at that temperature 

 simply masks the permanent magnetic quality. In all substances 

 other than the magnetic metals, the vortex atoms pair into molecules 

 and molecular aggregates in such way as to a large extent cancel each 

 other's magnetic fields ; why in iron at ordinary temperatures the 

 molecular aggregates form so striking an exception to the general rule 

 is for some reason peculiar to the substance, which, considering the 

 complex character of molecular aggregation in solids, need not excite 

 surprise. 



We have now to consider the cause of the pairing together of atoms- 

 into molecules. It cannot be on account of the magnetic, i.e., hydro- 

 dynamical, forces they exert on one another, for two electric currents 

 would then come together so as always to reinforce each other's mag- 

 netic action, and all substances would be strongly magnetic. The 

 ionic electric charge, which the phenomena of electrolysis show to 



2 i 2 



