Manchester Memoirs, Vul. in. (1908), No. 10. 25 



than understood, the suggestion of an electric theory of 

 matter on the analogy of the vortex illustration lay open 

 to dynamical development. Such a picture must, on 

 principles clear ever since the time of Ampere, give 

 positive and negative electrons, which differ essentially 

 only as a system differs from its mirror-image, or as a 

 right hand differs from a left hand : and the suggestion was 

 obvious, to pass from the Daltonian principle of the 

 identity of all atoms of the same substance, to the 

 hypothesis of the equality of all electrons, except as 

 regards this distinction into positive and negative. We 

 are thus invited to discuss how far progress is possible 

 towards a mode of representation of physical nature on 

 this foundation alone. It will help towards wider synthesis ; 

 but we know in advance that it will hardly avail us further 

 than the interactions between molecules across intervening 

 aether. 



The early extension of Dalton's principles which arose 

 from Gay Lussac's laws of multiple combining volumes 

 in gases, had already proceeded in this direction. To 

 Avogadro the Daltonian atom itself appeared as a more 

 ultimate constituent in the molecule, which is the actually 

 subsisting discrete element of matter,* 



Limitations 



The fundamental limitation of any conceivable atomic 



* The working of the presumption in favour of the simplicity of nature is 

 illustrated by the relations of Avogadro to Dalton. For want of the sim- 

 plifying idea of the molecule Dalton was logically compelled to reject the 

 view, afterwards associated with Avogadro, that all gases contain the same 

 number of particles : but he fell back on the next simplest hypothesis, by 

 asserting that che particles of all gases are accompanied by the same amount 

 of caloric in their 'heat atmospheres.' On the other hand, Avogadro 

 demurred to this hypothesis, as really irrelevant to the particular question at 

 issue. Yet Dalton's instinct for simplicity proved to be right, though the 

 repelling heat atmospheres of the period were wrong. 



