TRANSACTIONS OF SECTION A. 627 



ita more superficial movements, but not much of them ; that thus, hy patient obser- 

 vation and use of analogy, we can compile, in merely tabular form, information as 

 to the manner iu which it works and is likely to go on working, at any rate for 

 some time to come ; but that any attempt to probe the underlying connection is 

 illusory or illegitimate. As a theoretical pi-ecept this is admirable. It minimises 

 the danger of our ignoring or forgetting the limitations of human faculty, which 

 can only utilise the imperfect representations that the external world impresses on 

 our senses. On the other hand such a reminder has rarely been required by the 

 master minds of modern science, from Descartes and Newton onwards, whatever 

 their theories may have been. Its danger as a dogma lies in its application. 

 Who is to decide, without risk of error, what is essential fact and what is intellec 

 tual scaffolding ? To which class does the atomic theory of matter belong ? That 

 is, indeed, one of the intangible things which it is suggested may be thrown over- 

 board in sorting out and classifying our scientific possessions. Is the mental idea 

 or image, which suggests, and alone can suggest, the experiment that adds to our 

 concrete knowledge, less real thin the bare phenomenal uniformity which it has 

 revealed ? Is it not, perhaps, more real in that the uniformities might not have 

 been there in the absence of the mind to perceive them ? 



No time is now left for review of the methods of molecular dynamics. 

 Here our knowledge is entirely confined to steady states of the molecular system : 

 it is purely statical. In ordinary statics and the dynamics of undisturbed 

 steady notions, the form of the energy function is the sufficient basis of the 

 whole subject. This method is extended to thermo-dynamics by making use of 

 the mechanically available eni^rgy of Rankine and Kelvin, which is a function of 

 the bodily configuration and chemical constitution and temperature of the system, 

 whose value cannot under any circumstances spontaneously increase, while it 

 will diminish in any operation which is not reversible. In the statics of systems 

 in equilibrium or in steady motion, this method of energy is a particular case of 

 the method of Action ; but in its extension to thermal statics it is made to include 

 chemical as well as contigurational changes, and a new point appears to arise. 

 Whether we do or do not take it to be possible to trace the application of the 

 principle of Action throughout the process of chemical combination of two mole- 

 cules, we Cfrtainiy here postulate that the static case of that principle, which 

 applies to stei^dy systems, can be extended across chemical combinations. The 

 question is suggested whether extension would also be valid to transformations 

 which involve vital processes. This seems to be still considered an open question 

 by the best authorities. If it be decided in the negative a distinction is involved 

 between vital and merely chemical processes. 



It is now taken as established that vital activity cannot create energy, at any 

 rate in the long run which is all that can from the nature of the case "be tested. 

 It seems not unreasor£.ble to follow the analogy of chemical actions, and assert 

 that it cannot in the long run increase the mechanical availability of energy — that 

 is, considering the organism as an apparatus for transforming energy without 

 being itself in the long run changed. 13ut we cannot establish a Carnot cycle for 

 a portion of an organism, nor can we do so for a limited period of time ; there 

 might be creation of availability ace mpanied by changes in the organism itself, 

 but compensated by destruction and the inverse changes a long time afterwards. 

 This auiounts to asserting that where, as in a vital system or even in a simple 

 molecular combination, we are unable to trace or even assert complete dynamical 

 sequence, exact thermodynamic statements should be mainly confined to the 

 activity of the existing organism as a whole: it may transform inorganic material 

 without change of energy and without gain of availability, although any such 

 statements would be inappropriate and unmeaning as regards the details of the 

 processes that take place inside the organism itself. 



In any case it would appear that there is small chance of reducing these ques- 

 tions to direct dynamics ; we should rather regard Carnot's principle, which in- 

 cludes the law of uniformity of temperature and is the basis of the whole theorv, 

 as a property of statistical type confined to stable or permanent aggregations of 

 ajatter. Thus no dynamical prcrof ixom molecular coasidcratious coiiid be regarded 



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