Page:A history of the theories of aether and electricity. Whittacker E.T. (1910).pdf/356

 It is possible that hollow vortices are better adapted than ordinary vortex-filaments for the construction of models of the aether. Such, at any rate, was the opinion of Thomson (Kelvin) in his later years. The analytical difficulties of the subject are formidable, and progress is consequently slow; but among the many mechanical schemes which have been devised to represent, electrical and optical phenomena, none possesses greater interest than that which pictures the aether as a vortex-sponge.