"I need hardly say that I do not intend it to be supposed that the ether is actually made up of wheels and india rubber bands, nor even of paddle-wheels, with connecting canals. I think, however, that we may learn several things as to the conditions that the elements of ether should fulfill if they are to represent Maxwell's equations by motions in ways analogous to those of my model." Fitzgerald
"All theories of the ether that suppose it to be simply a jelly with matter spread through it, likes grapes in a jelly, hardly seem to attribute sufficient importance to the difficulty of explaining upon any such simple hypothesis such phenomena as Electricity and magnetism; and although the equations of motion of the jelly may fairly well represent the equations of motion of the ether, as regards its propagation of light, yet the properties of a jelly prevent our supposing continuous rotation of its elements, which seems almost necessary in order that the same quantities which represent small motions in the light-propagation may represent known phenomena in Electricity and magnetism.
Although Professor Stokes seems to think that there is no contradiction in supposing the ether to be a jelly, and at the same time sufficiently little rigid to permit the free motion of matter through it, nevertheless, there is no doubt that this is a serious stumbling-block in the way of a general acceptance of the hypothesis that the ether is, in all respects, like a thin jelly, and I hardly think the difficulty diminished when its strains, as a rigid body, are required to be capable of producing permanent electrical forces." Fitzgerald
"In discussing the result of Michelson and Morley's experiments, from which they concluded that the ether is carried along by the Earth in its motion, Mr. Larmor shows that such a hypothesis is quite inconsistent with the fact of aberration and with the tenability of Sir George Stoke's suggestion that ether is like a very soft jelly. How such a soft material could be the means by which tramcars are driven by shearing stresses seems an additional difficulty in the way of this suggestion." Fitzgerald
"There are, of course, many ways in which matter may move through the ether besides by displacing it; as, for instance, in the way in which a volume of liquid water might pass through ice, namely by dissolving in front, and by freezing as fast behind, and such hypotheses do not require any limit to be assigned to the rigidity of the ether. In all these cases it is, of course, evident, that when once it is shown that the energy of the medium depends on quantities which obey the laws of Maxwell's electric and magnetic induction and displacements, it follows that the forces on the places that represent the electrified and magnetized bodies must be the known electric and magnetic attractions and repulsions; and one great difficulty in framing hypotheses as to the connexion of the ether and matter is explaining how the matter moves through the ether." Fitzgerald
"I cannot conclude without protesting strongly against Sir William Thomson's speaking of the ether as like a jelly. It is in some respects analogous to one, but we certainly know a great deal too little to say that it is like one. May be Maxwell's conceptions as to its structure are not very definite, but neither are anybody's as to the actual structure of a jelly, and there is no real difficulty in supposing a medium whose condition is represented by symbols that obey the laws that James Clerk Maxwell has shown should be the laws of symbols representing the condition of a medium that would explain electric and magnetic phenomena ... It seems ... likely that what he Maxwel called 'electric displacements' are changes in structure of the elements of the ether, and not actual displacements of the elements ... so that I think the word 'displacement' was unfortunately choosen. I also think that Sir William Thomson, notwithstanding his guarded statements on the subject, is lending his overwhelming authority to a view of the ether which is not justified by our present knowledge, and which may lead to the same unfortunate results in delaying the progress of science as arose from Sir Isaac Newton's equally guarded advocay of the corpuscular theory of optics." Fitzgerald
"There seems no doubt that the simplest theory as to the constitution of the ether is that it is a perfect liquid; it seems almost impossible to explain electric and magnetic phenomena without some further hypothesis ... Now, it seems certain that the only way in which a perfect liquid can become everywhere endowed with properties analogous to rigidity is by being everywhere in motion. The most general supposition of this kind would be, that it was what Sir William Thomson has called a vortex-sponge, i.e., everywhere endowed with vortex motion, but with this motion so mixed up as to have within any sensible volume an equal amount of vortex motion in all directions. There are many ways in which this supposition seems to be in accordance with what we know of the properties of the ether." Fitzgerald