We might conceive of four or any number of these rings uniting together to form a separate element, and then each element would simply be a multiple of the unit vortex ring, and so possess regular multiples of the atoms of electricity, each multiple representing a distinct element. We will now let Professor Thomson speak for himself on the matter, and will describe the theory in his own words, always keeping in mind the hypothesis that the unit vortex ring is itself composed of a definite number of atoms of electricity or electrons, as proved by Faraday. See _Appendix C_. In the work already referred to, Professor Thomson states: "We may suppose that the union or pairing in this way of two vortex rings of different kinds is what takes place, when two elements of which these vortex rings are atoms combine chemically; while, if the vortex rings are of the same kind, this process is what occurs when atoms combine to form molecules. Now let us suppose that the atoms of different chemical elements are made up of vortex rings, all of the same strength, but that some of these elements consist of only one ring, others of two rings linked together, others of three loops, and so on. Then if any of these rings combine to form a permanent combination, the strength of all the primaries in the system so formed by the combination must be equal." "Thus an atom of one element may combine with another atom of the same kind, to form a molecule of that substance consisting of two atoms. Again, three of these atoms may combine, and form a system consisting of three primary elements, but the chance of their doing so is small compared with the chance of two pairing; so that the number of systems of this kind will be small compared with the number of the systems consisting only of two atoms. We might have systems of four atoms, but the number would be small compared with the number of systems that consist of three atoms."