The most plausible is that of a medium neither solid, liquid, nor gaseous in the ordinary sense, but in the ideal state of a 'perfect fluid.' Out of such an ether Lord Kelvin, with exquisite ingenuity, constructed his 'vortex-atoms,' which 'had their day and ceased to be.' Other ideas now prevail. 'The present tendency of physical science,' the late Mr. Preston wrote in 1890,[74] 'is to regard all the phenomena of Nature, and even matter itself, as manifestations of energy stored in the ether.' The more closely we look into the things around us, the more strongly the persuasion is forced upon us that what we call ether, electricity, and matter are really varied forms of one primal substance. Two comprehensive schemes of molecular physics, resting upon the basis of this unifying thought, have lately been elaborated--one by Dr. Larmor, the other by Professor Osborne Reynolds. They have nothing in common beyond the largeness of their synthesis. In every respect they are radically unlike, save in regarding the intangible ether as the one material reality. Dr. Larmor, however, is not quite confidently explanatory. He presents no cut-and-dried theory of the universe; its haunting mysteries are not ignored in his efforts to rationalize them. He is vividly aware of the difficulties besetting the endowment of the ether with the type of elasticity which it is recognised to possess. He can only surmise that it results from particular modes of motion--from 'kinetic stability' ensuing upon a special dynamical state. The medium may thus be thought of as pervaded by 'a structure of tangled or interlaced vortex filaments, which might resist deformation by forming a stable configuration.'[75] But the details of any such scheme of action are evidently far too intricate to be easily unravelled; what concerns us here is to point out that no simple structureless fluid can avail to maintain cosmical communications.