Mr. S. T. Preston on Action at a Distance. 39 



the contraction of the bar (within certain limits) under an 

 applied pressure — the bar being elastic partly through the 

 elasticity of the open structure of its molecules*. 



Fourthly, it appears to be assumed by Mr. Browne that 

 the postulate of " action at a distance " affords an alternative 

 explanation of facts, as on page 444 it is remarked as fol- 

 lows, viz.: — . ... "it must be held to be demonstrated that 

 the phenomena of cohesion cannot be explained] except on 

 the hypothesis of action at a distance." 



It may, surely, well be asked here how that which is in itself 

 inexplicable can explain any thing, or how the assumption of 

 an occult quality can throw light upon any problem whatever. 



In conclusion, it cannot fail, I think, to be apparent (as an 

 important fact) to an impartial observer, that a movement in 

 accordance with the kinetic theory is the only possible (or con- 

 ceivable) motion that can naturally maintain itself among par- 

 ticles of matter left to themselves in free space (if we refrain 

 from attributing to matter occult and mystical qualities, which 

 only involve every thing in obscurity). 



The application of the kinetic theory to the phenomena of 

 sound, light|, gravity, and (possibly) to the motions of the 

 larger-scale stellar masses of the universe § immersed in the 

 kinetic aether (as developed by me in former essays in this 

 Journal and elsewhere) would seem to afford some hope of 

 ultimately correlating a wide range of phenomena under one 

 fundamental cause of extreme simplicity. 



* To afford some rough idea of the mode in which molecules of open 

 structure may be conceived to be held together (in cohesion) by the pres- 

 sure of streams of particles, I would refer to my paper entitled "A Sug- 

 gestion in regard to Crystallization/' Phil. Mag. April 1880. 



t The italics are mine. 



\ ' Nature,' Jan. 15, 1880, u On a Mode of Explaining the Transverse 

 Vibrations of Lio-ht." 



§ Philosophical Magazine, August 1879 and November 1880. 



The difficulty of the explanation of magnetism (alluded to by Mr. Browne 

 on page 444) may be freely admitted. But magnetism is a somewhat 

 special phenomenon, dependent possibly on special (or secondary) condi- 

 tions. It would surely be scarcely reasonable to expect that the theory 

 should be capable of giving full satisfaction in all cases. It would be even 

 strange if some difficulties did not present themselves at the outset. We 

 can only say that by explaining some important or fundamental facts (such 

 as gravitation, some effects of cohesion, &c), the tope may be reasonably 

 entertained that an addition to knowledge will throw light upon others — 

 so long as we hold to strict mechanical conceptions, and do not close the 

 door to discovery by postulating the mystery of " action at a distance." 

 (See also paper " On Method in Causal Research," Phil. Mag. May 1880, 

 in connexion with this.) 



Among all the arguments expended on a action at a distance," it cer- 

 tainly appears strange that the one firm and indisputable fact is not more 



