642 



SCIENCE. 



[N. S. Vol. XVIII. No. 464. 



mechanics. There is, I think, a widespread 

 confusion of boundaries which makes this 

 sharp delimitation a thing greatly to be 

 desired, and I have chosen as the title of 

 this preliminary paper 'The Misuse of 

 Physics by Biologists and Engineers' for 

 the reason that, in my opinion, these men, 

 more than any others, violate in their 

 philosophy the essential limitations of sys- 

 tematic physics and confuse the boundaries 

 between systematic physics and statistical 

 physics. 



I do not wish this title to be taken as a 

 challenge to biologists and engineers, but 

 rather as suggesting, in a general way, the 

 error of the indiscriminate application of 

 the philosophy of the exact sciences in the 

 study of natural phenomena. I do not 

 expect, indeed, to make my position en- 

 tirely clear until I have finished with what 

 I have to say about statistical physics, but 

 my position in brief is this, that the idea 

 of quantitative relationships and the idea 

 of one-to-one correspondence in general, as 

 these ideas are known in physics, are in- 

 applicable and necessarily fruitless in such 

 fields as physical psychology and meteor- 

 ology. 



I am led to present this preliminary 

 paper, at this time from having read the 

 recent presidential address of James Swin- 

 burne before the British Institution of 

 Electrical Engineers and a subsequent 

 paper on thermodynamics presented by 

 Mr. Swinburne at the Southport meeting 

 of the British Association in September. 



Mr. Swinburne believes, apparently, that 

 the precise ideas and methods of thermo- 

 dynamics are unconditionally applicable 

 to irreversible processes in general: I do 

 not agree with him in this, and I do not 

 think that the legitimacy and precision of 

 the accepted ideas of thermodynamics es- 

 pecially as represented in the writings of 

 Willard Gibbs can be questioned ; but I do 

 think that the notions of thermodynamics 



are precisely applicable to those types of 

 irreversible processes which constitute per- 

 manently varying states, and approxi- 

 mately applicable to those irreversible 

 processes which involve either appi'oximate 

 states of thermal equilibrium or approxi- 

 mately permanent states of variation. I 

 shall point out the precise application of 

 the ideas of thermodynamics to perma- 

 nently varying states in this preliminary 

 paper, resei'ving the discussion of approxi- 

 mate applications for a subsequent paper. 



The fact is that the precise notions of 

 systematic physics in general are essen- 

 tially inapplicable in the world of actual 

 phenomena, except in so far as these phe- 

 nomena can be approximately correlated 

 to states of equilibrium and to permanently 

 varying states of material systems. I re- 

 member very distinctly the incredulity 

 with which I first encountered, in my early 

 study of physics, the unguardedly sweep- 

 ing generalizations in the treatises which 

 I then read, for example, on the elementary 

 mathematical theory of electricity and 

 magnetism. I could not believe that the 

 phenomena of electricity and magnetism 

 were quantitative in the sense that my 

 then highly abstracted ideas of mechanical 

 phenomena were quantitative. 



In order to give some sort of a prelim- 

 inary notion of what I have in mind in 

 using the terms systematic physics and 

 statistical physics I shall resort to classifi- 

 cation. 



Physics is divided into two branches, 

 namely, systematic phj'sics and statistical 

 physics. 



Systematic physics is again divided into 

 mechanics and thermodynamics. 



Mechanics, in the broad sense here de- 

 fined, treats of those phenomena which can 

 be to- a high degree of approximation cor- 

 related in one-to-one correspondences to 

 states of equilibrium and to simple types 

 of sensible motion such as translatory mo- 



