A MODEL OF NATURE. 179 



constitution throughout, but that adjacent minute parts are distin- 

 guishable from each other by being cither of different natures or in 

 different 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 

 matter must be divided. 



The particles, for instance, need not be different 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, differing 

 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. Tin 1 view that the constitution of matter is atomic may and 

 does receive support from theories in which 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 any means 

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

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

 are parts of that medium existing in a special state, have both played 

 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 primary medium which 

 constitutes a physical connection between them, and through which 

 their mutual actions arise and are transmitted. 



PROPERTIES OF THE BASIS OF MATTER. 



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

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

 separate particles or of differentiated portions of the medium, which 

 has properties different from those of matter in bulk. 



For if the basis of matter had the same constitution as matter, the 

 irregular heat movements could hardly be maintained either against 

 the viscosity of the medium or the frittering awa} T of energy 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 by a process of self-cooling. No such phenomenon is known, 

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

 are fixed by the uncertainty of experiment, we are compelled to 

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



