602 REPORT— 1895. 



electrostatic actions, toth quantitatively and qualitatively, and a more speculative 

 one as to currents and magnetism. I could only succeed in proving at that time 

 that if the filaments were distributed according lo the same laws as electric lines 

 of force, the distribution would be one of equilibrium. Larmor ^ has recently 

 proved that this is also the necessary distribution for any type of a rotationally 

 elastic ether, and consequently also for this particular case. Currents along a 

 wire were supposed to consist of the ends of filaments running along it, with dis- 

 appearance of the hollow companions, the filaments producing at the same time a 

 circulation round the wire. A magnetic field was thus to be regarded as a flow 

 of the ether, but probably with the necessary accompaniment of rotational elements 

 in it. 



This latter, however, was clearly wrong, because each kind of filament would 

 produce a circulation in opposite directions. The correct deduction would have 

 been to lay stress on the fact that the field is due to the motion through the 

 stationary ether of the vortex filaments, the field being perpendicular to the fila- 

 ment and to its direction of motion. This motion would doubtless produce 

 stresses in the cell-ether due to deformations of the cells, and be the proximate 

 cause of the mechanical forces in the field. In any case, it is not difficult to 

 show that a magnetic field cantiot be due to an irrotational flow of the ether alone.'^ 

 Such electrostatic and magnetic fields produce states of motion in the medium, but 

 no bodily flow in it ; consequently we ought not to expect an effect to be produced 

 on the velocity of transmission of light through it. 



The fundamental postulate underlying this explanation of electric action is 

 that when two diflerent kinds of m.atter are brought into contact a distribution of 

 vortex Hlaments in the neighbourhood takes place, so that a larger number stretch 

 from_ one to the other than in the opposite direction — the distinction between 

 positive and negative ends being that already indicated. To see how such a 

 distribution may be caused, let us consider each vorte.x atom to be composed of a 

 vortical mass of our secondary medium or cell-structure ether. The atom is much 

 larger than a cell, and contains practically an infinite number of them. It is a 

 dynamical system of these cells with equilibrium of energy throughout its volume. 

 The second atom is a dynamical system with a diflerent equilibrium of energy. 

 AVhere they come into contact there will be a certain surface rearrangement, 

 which will show itself as a surface distribution of energy in a similar manner to 

 that which exists between a molar collection of one kind of molecules in contact 

 with one of another, and which shows itself in the phenomenon which we call 

 surface tension. In the present case the eflect may take place at the interface 

 of two atomic systems in actual contact, or be a difl-'erence eflect between the two 

 interfaces of the ether and each atom when the latter are sufficiently close. The 

 surface effect we are now considering shows itself as contact electricity. 



Such a distribution of small vortex filaments, stretching from one atom to 

 another, will tend to hold them together. We therefore get an additional cause 

 for aggregation of atoms. This does not exclude the others already referred to. 

 They may all act concurrently, some producing one effect, some another — one 

 combining, perhaps, unlmown primitive atoms into elements, one elements into 

 chemical compounds, and another producing the cohesion of matter into masses. 



On this theory the difference between a conductor and a dielectric is that in 

 a dielectric the ends of the filaments cannot pass from atom to atom, possibly 



' ' A Dynamical Theory o£ the Electric and Luminiferous Medium,' PMl. Trans., 

 1894, p. 748. 



- To prove this, consider a straight conductor moving par.allel to itself and per- 

 pendicular to a uniform magnetic field. There exists a permanent potential difference 

 between its ends. If, however, the field cons'sts of a flow of ether, the effect is the 

 same as if the conductor is at rest, and the direction of the magnetic field shifted 

 through an angle. But this is the case of a conductor at rest in a field, and there 

 is therefore no potential difference between the ends. Hence a magnetic field must 

 consist of some structure across which the conductor cuts. A field may possiblj' 

 demand a flow of the ether, but, if so, it must carry in it some structure definitely 

 oriented at each point to the direction of flow. 



