TAIT'8 " THERMODYNAMICS." 



*f nrmadynamit. If the total actual heat of a homogeneous and uniformly 

 1x4 mUUBM Iw aoactit^J *o b divided into any number of equal parts, the effects of those 

 iwru in caving work to be performed are equal." 



We find it difficult enough, even in 1878, to attach any distinct meaning 

 to the total actual heat of a body, and still more to conceive this heat 

 divided into equal parts, and to study the action of each of these parts ; but 

 a if our powers of deglutition were not yet sufficiently strained, Hankino follows 

 this up with another statement of the same law, in which we have to assert 

 >ur intuitive belief that 



If the absolute temperature of any uniformly hot substance be divided into any number of 

 +^1 part*, the effect* of those parts in causing work to be performed are equal." 



The student who thinks that he can form any idea of the meaning of this 

 sentence is quite capable of explaining on thermodynamical principles what 

 Mr Tennyson says of the great Duke : 



"Whose eighty winters freeze with one rebuke 

 All great self-seekers trampling on the right" 



Prof. Clausius does not ask us to believe quite so much about the heat 

 in hot bodies. In his first memoir, indeed, he boldly dismisses one supposed 

 variety of heat from the science. Latent heat, he tells us, "is not only, as 

 its name imports, hidden from our perceptions, but has actually no existence;" 

 " it has been converted into work." 



But though Clausius thus gets rid of all the heat which, after entering 

 a body, is expended in doing work, either exterior or interior, he allows a 

 certain quantity to remain in the body as heat, and this remnant of what 

 should have been utterly destroyed lives on in a sort of smouldering existence, 

 breaking out now and then with just enough vigour to mar the scientific coherence 

 of what might have been a well compacted system of thermodynamics. 



Prof. Tait tells us : 



"The source of all this sort of speculation, which is as old as the time of Crawford and 

 Irvine and which was countenanced to a certain extent even by Rankine is the assumption that 

 bodies must contain a certain quantity of actual, or thermometric, heat. We are quite ignorant 

 of the condition of energy in bodies generally. We know how much goes in, and how much 

 comes out, and we know whether at entrance or exit it is in the form of heat or of work. But 

 that u all." 



If we define thermodynamics, as I think we may now do, as the investi- 

 gation of the dynamical and thermal properties of bodies, deduced entirely 



