A MODEL OF NATURE. 179 



constitution throughout, but that adjiiccnt minute parts are distin- 

 guishable from each other by l^eing- either of dilierent natures or in 

 ditt'erent states. 



And here it is necessary to insist that all these fundamental proofs 

 are independent of the nature of the particles or granules into which 

 \natter nuist be divided. 



The particles, for instance, need not be diti'erent in kind from the 

 medium which surrounds and separates them. It would suffice if they 

 were what may be called singular parts of the medium itself, diffei'ing 

 from the rest only in some peculiar state of internal motion or of dis- 

 tortion, or by being in some other way earmarked as distinct individ- 

 uals. The view that the constitution of matter is atomic may and 

 does receive support from theories in Avhich definite assumptions are 

 made as to the constitution of the atoms, but when, as is often the 

 case, these assumptions introduce new and more recondite difficulties, 

 it must be remembered that the fundamental hypothesis — that matter 

 consists of discrete parts, capable of independent motions — is forced 

 upon us by facts and arguments which are altogether independent of 

 what the nature and properties of these separate parts may be. 



As a matter of history the two theories, which are not by an}^ means 

 mutually exclusive, that atoms are particles which can be treated as 

 distinct in kind from the medium which surrounds them, and that they 

 are parts of that medium existing in a special state, have both plaj^ed 

 a large part in the theoretical development of the atomic hypothesis. 

 The atoms of Waterston, Clausius, and Maxwell were particles. The 

 vortex-atoms of Lord Kelvin, and the strain-atoms (if I may call them 

 so) suggested by Mr. Larmor, are states of a ]n'imary medium which 

 constitutes a physical connection between them, and through which 

 their mutual actions arise and are transmitted. 



propp:kties of the basis of matter. 



It is easy to show that, whichever alternative be adopted, we are 

 dealing with something, whether Ave consider it under the guise of 

 separate particles or of ditferentiated portions of the medium, which 

 has properties different from those of inatter in bulk. 



For if the l)asis of matter had the same constitution as matter, the 

 irn^gular heat movements could hardly be maintained (iither against 

 the viscosity of the medium or the frittering away of energ3' of 

 motion which would occur during the collisions between the particles. 

 Thus, even in the case in which a hot body is prevented from losing 

 heat to surrounding objects, its sensible heat should spontaneously 

 decay ])v a process of self-cooling. No such phenomenon is known, 

 and though on this, as on all other points, the limits of our knowledge 

 are tixed by the uncertainty of expei'imeni. we ai'<' compelled to 

 admit that, to all appearance, the fundamental medium, if it exists, is 



