MATTER, SPACE, AND TIME 219 



atomic radiation, it too seemed insufficient. It 

 is worthy of note, however, that Faraday, in his 

 day, and Lord Kelvin, in more recent years, have 

 advocated views differing but Httle from those of 

 Boscovich ; while the school of chemists, who 

 tried to banish from their ken all atomic theories, 

 regarded energy as the only physical reality known 

 to us, and matter as " a complex of energies which 

 we find together in the same place." 



It seemed at first that a real advance had been 

 made when Lord Kelvinapplied the theory of vortex 

 rings, developed by Von Helmholtz and himself, 

 to explain the properties of the atoms of matter. 

 A smoke ring, blown in air, soon dies away, but 

 even this evanescent thing, while it lasts, shows 

 a definite separation fromthe surrounding medium, 

 and maintains an independent existence. Air is 

 an imperfect fluid, and movement in it is resisted 

 by the frictional forces due to its viscosity, but, if 

 we imagine the air to be replaced by a hypothetical 

 perfect fluid, in which there is no viscosity, vortex 

 rings, once formed, will persist for ever. In a fluid 

 not quite perfect, their life will be long, though 

 not eternal. 



Here then was a striking representation of 

 some of the most important properties of the 

 chemical atoms. The structure of interlacing 

 systems of vortex rings gave sufficient complexity 

 to explain radiation, the infinite possibilities of 

 variation in number and arrangement of the rings 

 would account for the relations between different 

 atoms as manifested in the periodic law, while 

 the persistence of matter could be explained if 

 a perfect or nearly perfect fluid were postulated 

 as the basis of the vortex motion. 



