229 



33. If electricitj^, and therefore magnetism^ consist also of 

 vibratory motion (an assumption wliich the obvious interchange 

 of the former with other forms of energy necessitates), then the 

 probable form of electric and magnetic wave-motion becomes 

 an interesting subject of inquiry. It must be observed that 

 both electricity and m.agnetism possess a dual character not 

 common to other forms of energy ; there is positive and negative 

 electricity, austral and boreal magnetism, but there is no 

 analogous a and b condition in light or heat. Now, is there 

 any conceivable kind of wave- motion that would present this 

 duality of character? Undoubtedly there is — namely, a helical 

 wave, in which the motion of each disturbed particle is in a 

 circle, the plane of which is perpendicular to the direction of 

 the wave. If a helix be called positive when it turns from 

 left to right, and negative when it turns the contrary way, from 

 right to left, then a progressive motion in the same helix will 

 appear positive or negative, according to the end at which it is 

 viewed ; also, opposite motions in the same helix may be con- 

 ceived to interfere, and to give rise to repulsion, while opposite 

 motions in opposite helices would progress without interference 

 — like two series of waves on the surface of the water crossing 

 each other — and this may, perhaps, be the source of electrical 

 attraction. 



34. It has recently been stated that no physicist of note has 

 suggested the nature of the motion which constitutes electricity 

 and magnetism. That may be so, but it is a fact that some 

 years have elapsed since the above suggestion w-as first made by 

 the writer : it has also been made by some others. 



35. The intimate relation — it mav be said the identitv — of 

 electricity and magnetism mav be shown by means of De la 

 Rive's floating battery, consisting of a small voltaic element, 

 floating in a vessel of water, the electrodes of which are 

 connected with the ends of a small cylindrical cod of insulated 

 copper wire resting horizontally on the element. This coil 

 manifests all the properties of a floating magnetic needle, 

 taking its position in the magnetic meridian, and one end being 

 attracted, and the other repelled, by either of the poles of a 

 bar-magnet. Since magnetic eff'ects are ordinarily exhibited 

 by steel or iron, it might be supposed by some that this metal 

 is essential to the development of magnetic energy ; it is, 

 however, merely the ordinary and most susceptible vehicle of 

 magnetism. Since magnetic energy is manifested in a direction 

 at right angles to the electric current that produces it, the 

 dynamic difficulty of resolving one helical wave into another 

 at right angles to the former must not be lost sight of, but it is 

 probably not insuperable. There is, however, some valid 



