of an inch in diameter has too small a weight to be noted in any balance, yet it would be made up of thousands of millions of atoms. Hence if, in the processes to which the substance had been subjected, there had been the total annihilation of thousands of millions of atoms, such phenomenon would not have been discovered by weighing. Neither would it have been discovered if there had been a similar creation or development of new matter. All that can be asserted concerning such events is, that they have not been discovered with our means of observation.
The alchemists sought to transform one element into another, as lead into gold. They did not succeed. It was at length thought to be impossible, and the attempt to do it an absurdity. Lately, however, telescopic observation of what is going on in nebulæ, which has already been referred to, has somewhat modified ideas of what is possible and impossible in that direction. It is certainly possible roughly to conceive how such a structure as a vortex-ring in the ether might be formed. With certain polarizing apparatus it is possible to produce rays of circularly polarized light. These are rays in which the motion is an advancing rotation like the wire in a spiral spring. If such a line of rotations in the ether were flexible, and the two ends should come together, there is reason for
thinking they would weld together, in which case the structure would become a vortex-ring and be as durable as any other. There is reason for believing, also, that somewhat similar movements are always present in a magnetic field, and though we do not know how to make them close up in the proper way, it does not follow that it is impossible for them to do so.
The bearing of all this upon the problem of the transmutation of elements is evident. No one now will venture to deny its possibility as strongly as it was denied a generation ago. It will also lead one to be less confident in the theory that matter is indestructible. Assuming the vortex-ring theory of atoms to be true, if in any way such a ring could be cut or broken, there would not remain two or more fragments of a ring or atom. The whole would at once be dissolved into the ether. The ring and rotary energy that made it an atom would be destroyed, but not the substance it was made of, nor the energy which was embodied therein. For a long time philosophers have argued, and commonsense has agreed with them, that an atom which could not be ideally broken into two parts was impossible, that one could at any rate think of half an atom as a real objective possibility. This vortex-ring theory shows easily how possible it is to-day to think what once was philosophically incredible. It shows that
metaphysical reasoning may be ever so clear and apparently irrefragable, yet for all that it may be very unsound. The trouble does not come so much from the logic as from the assumption upon which the logic is founded. In this particular case the assumption was that the ultimate particles of matter were hard, irrefragable somethings, without necessary relations to anything else, or to energy, and irrefragable only because no means had been found of breaking them.
The destructibility or indestructibility of the ether cannot be considered from the same standpoint as that for matter, either ideally or really. Not ideally, because we are utterly without any mechanical conceptions of the substance upon which one can base either reason or analogy; and not really, because we have no experimental evidence as to its nature or mode of operation. If it be continuous, there are no interspaces, and if it be illimitable there is no unfilled space anywhere. Furthermore, one might infer that if in any way a portion of the ether could be annihilated, what was left would at once fill up the vacated space, so there would be no record left of what had happened. Apparently, its destruction would be the destruction of a substance, which is a very different thing from the destruction of a mode of motion. In the latter, only the form of the motion need be destroyed to
completely obliterate every trace of the atom. In the former, there would need to be the destruction of both substance and energy, for it is certain, for reasons yet to be attended to, that the ether is saturated with energy.
One may, without mechanical difficulties, imagine a vortex-ring destroyed. It is quite different with the ether itself, for if it were destroyed in the same sense as the atom of matter, it would be changed into something else which is not ether, a proposition which assumes the existence of another entity, the existence for which is needed only as a mechanical antecedent for the other. The same assumption would be needed for this entity as for the ether, namely, something out of which it was made, and this process of assuming antecedents would be interminable. The last one considered would have the same difficulties to meet as the ether has now. The assumption that it was in some way and at some time created is more rational, and therefore more probable, than that it either created itself or that it always existed. Considered as the underlying stratum of matter, it is clear that changes of any kind in matter can in no way affect the quantity of ether.