Zoom-in
Image by mathematical CGI artist Paul Nylander
But Helge Kragh 's book Quantum Generations: A History of Physics in the Twentieth Century tells us the real story; and the fact that this theory wasn't considered as fictional at the end of the 19ths century :
The most important of the nonelectromagnetic theories was the vortex atomic theory, originally suggested in 1867 by William Thomson (later, Lord Kelvin) and subsequently developed by a whole school of British mathematical physicists. According to this theory, the atoms were vortical modes of motion of a primitive, perfect fluid, usually identified with the ether. In his Adams Prize essay of 1882, young J. J. Thomson gave an elaborate account of the vortex theory and extended it to cover chemical problems, including affinity and dissociation. The theory was also applied to electromagnetism, gravitation, and optics and was an ambitious attempt to establish a unitary and continuous "theory of everything" based solely on the dynamics of the ether. As late as 1895, William Hicks gave an optimistic report on the state of art of the vortex atom at the annual meeting of the British Association for the Advancement of Science (BAAS). Hicks's view of the goal of theoretical physics is worth quoting at some length:
While, on the one hand, the end of scientific investigation is the discovery of laws, on the other, science will have reached its highest goal when it shall have reduced ultimate laws to one or two, the necessity of which lies outside the sphere of our recognition. These ultimate laws—in the domain of physical science at least—will be the dynamical laws of the relations of matter to number, space, and time. The ultimate data will be number, matter, space, and time themselves. When these relations shall be known, all physical phenomena will be a branch of pure mathematics. (BAAS Report 1895, 595)
So Einstein must have been well aware of these theories, and that's probably why he alluded to "The juggler on the boat" (see topic: The Genius of Einstein).
Antje Pfannkuchen tells the whole story of the "Vortex-motion" concept in her paper The Unseen Universe of art: Vortex motion in the Ether (link to pdf)
Let me sketch out briefly the physics in question so I can then introduce their translation. The main point of interest is vortex motion. It started in hydrodynamics with a paper by the German scientist Hermann von Helmholtz who wrote on “Vortex motion in ideal fluids” in 1858. This text which brought the image of the vortex into the scope of 19th century physics was translated into English by Peter Guthrie Tait, a physicist and close collaborator of William Thomson’s or, as he is better known today: Lord Kelvin …
… Kelvin who had written in his paper on Vortex atoms: “To generate or to destroy ‘Wirbelbewegung’ (vortex motion) in a perfect fluid can only be an act of creative power.”We know now that atoms aren't build up out of this structure but electrons, protons and photons might be as long as we don't have any photographic proof. As a matter of fact it turned out that the core of organic cells has an almost unbelievable helix-structure (DNA).