506 Mathematical and Philosophical State of Physical Science. 



to an incorrect conclusion. To claim for all the conclusions 

 which have been published in relation to the molecules the cer- 

 tainty which fairly belongs to some of them would prejudice the 

 whole cause. 



One of the most interesting investigations in molecular me- 

 chanics was published by Helmholtz in 1858. It is a mathe- 

 matical discussion of what he calls ring vortices in a perfect, 

 frictionless fluid. Helmholtz has demonstrated that such vor- 

 tices possess a perpetuity and an inviolability once thought to be 

 realized only by the eternal atoms. The ring-vortices may 

 hustle one another, and pass through endless transformations, 

 but they cannot be broken or stopped. Thomson seized upon 

 them as the impersonation of the indestructible but plastic 

 molecule which he was looking for to satisfy the present con- 

 dition of physical science. The element of the new physics is 

 not an atom or a congeries of atoms, but a whirling vapour. The 

 molecules of the same substance have one invariable and un- 

 changeable mass ; they are all tuned to one standard pitch, and, 

 when incandescent, emit the same kind of light. The music of 

 the spheres has left the heavens and condescended to the rhyth- 

 mic molecules. There is here no birth or death or variation of 

 species. If other masses than the precise ones which represent 

 the elements have been eliminated, whither, asks Maxwell, have 

 they gone ? the spectroscope does not show them in the stars 

 or nebulae ; the hydrogen and sodium of remotest space are in 

 unison with the hydrogen and sodium of earth. 



In the phraseology of our mechanics we define matter and 

 force as if they had an independent existence. But w r e have no 

 conception of inert matter or of disembodied force. All we 

 know of matter is its pressure and its motion. The old atom 

 had only potential energy ; the energy of its substitute, the 

 molecule, is partly potential and partly kinetic. If it could be 

 shown that all the phenomena displayed in the physical world 

 were simply transmutations of the original energy existing in 

 the molecules, physical science would be satisfied. Where 

 physical science ends, natural philosophy, which is not wholly 

 exploded from our vocabulary, begins. Natural philosophy 

 can give no account of energy when disconnected with an ever 

 present Intelligence and Will. In Herschel's beautiful dialogue 

 on atoms, after one of the speakers had explained all the wonder- 

 ful exhibition of nature as the work of natural forces, Hermione 

 replies, " Wonderful, indeed ! Anyhow, they must have not 

 only good memories but astonishing presence of mind, to be 

 always ready to act, and always to act, without mistake, accor- 

 ding to the primary laws of their being, in every complication 

 that occurs." And elsewhere, " Action, without will or effort. 



