leo" 
VIII. 
ON A HYDRO-DYNAMICAL HYPOTHESIS AS TO ELECTRO- 
MAGNETIC ACTIONS. By PROFESSOR GHORGE 
FRANCIS FITZ GERALD, F.RB.S. 
[Read DecemBEr 21; Received for Publication DecemBer 23, 1898 ; 
Published Marcu 25, 1899. ] 
For many years I have been advocating the hypothesis that the 
ether is of the nature of a fluid full of vortical motion, and that 
electro-magnetic actions are due to particular arrangements of this 
motion, which is, in general, irregular or at least undirected. 
Some years ago, Lord Kelvin, at a meeting of the British 
Association, and subsequently in the Phil. Mag., ser. v., 1887, vol. 
Xxiv., p. 842, published an investigation as to a possible transfer- 
ence of laminar wave disturbance through a turbulent liquid. He 
was not satisfied with the investigation, principally, I believe, 
because it presupposed that there would be inappreciable diffusion 
of motion. I am, however, inclined to think that, if a liquid 
become turbulent by drawing out and twisting together long thin 
vortices, the rate of translation of the vortex cores would ultimately 
become very slow, and that the consequent diffusion of motion 
would become slower and slower as time went on, and the tur- 
bulence become more and more fine-grained. This result follows 
from the continual drawing out of the vortex filaments by their 
tangling with one another. In being thus drawn out, their 
energy of circulation is continually being increased; and as the 
total energy per unit volume of the fluid must remain constant, 
it follows that the energy of translation of vortex core would 
continually diminish. Hence there seems to me every reason to 
believe that wave disturbance can be propagated within such a 
turbulent liquid. 
Subsequently Lord Kelvin showed (Royal Irish Acad. Proe., 
ser. iI. 1889, vol. i., p. 8340) how to calculate a stable, steady 
motion for a hollow vortex surrounded by a tore round which 
the liquid was circulating, and concluded that it would be possible 
