182 



SCIENTIFIC THOUGHT. 



the general scientific intelligence, revealed itself as the 

 measure of the disorder which prevails in the motion of 

 the ultimate material elements of a system. 1 Faraday's 

 lines of force and the whole elaborate imagery invented 

 and afterwards discarded by Maxwell to describe the 

 interaction of magnets, electric currents, and charged 

 bodies, have proved to be most valuable instruments of 

 thought a useful scientific shorthand in the hands of 

 the teacher, as in those of the practical electrician. And 

 although the illustrious propounder of the vortex-atom 

 theory of matter seems latterly to have discouraged the 

 use of this kinetic contrivance as not likely to lead 

 to any great revelations regarding the ultimate constitu- 

 tion of matter or the nature of the imponderable, 2 the 



1 Helmholtz, in his first memoir 

 on the thermodynamics of chemi- 

 cal processes ('Sitzungsberichte der 

 Akademie zu Berlin,' 2nd February 

 1882), after having established the 

 formulae for the free energy in iso- 

 thermal processes without reference 

 to kinetic hypothesis, concludes his 

 exposition with the following re- 

 marks : " We require, finally, an 

 expression in order to be able to 

 distinguish clearly what in theoreti- 

 cal mechanics is termed vis viva or 

 actual energy from the work equiva- 

 lents of heat, which are indeed 

 mostly to be regarded likewise as 

 vis viva of invisible molecular mo- 

 tion. I would suggest that the 

 former should be called the vis 

 viva of orderly motion. I call 

 orderly all motion in which the 

 compounds of velocity of the 

 moving masses are differentiable 

 functions of the space co-ordinates. 

 Disorderly motion would then mean 

 all motion in which the motion of 

 each particle has no similarity to 

 that of its neighbours. We have 



every reason to believe that heat- 

 motion is of the latter kind, and one 

 might in this sense regard entropy 

 as the measure of disorder. For 

 our means, which compared with 

 molecular structure are coarse, only 

 orderly motion can be freely con- 

 verted again into other forms of 

 mechanical work" (' Wissenschaftl. 

 Abhandl.,' vol. ii. p. 972). 



2 "I am afraid it is not possible 

 to explain all the properties of 

 matter by the vortex-atom theory 

 alone that is to say, merely by 

 motion of an incompressible fluid ; 

 and I have not found it helpful in 

 respect to crystalline configurations, 

 or electrical, chemical, or gravita- 

 tional forces. . . . We may expect 

 that the time will come when we 

 shall understand the nature of an 

 atom. With great regret I abandon 

 the idea that a mere configuration 

 of motion suffices" (Lord Kelvin, 

 quoted by Prof. S. W. Holman in 

 ' Matter, Energy, Force, and Work,' 

 New York, 1898, p. 226). 



