December 8, 1904] 



NA TURE 



125 



LETTERS TO THE EDITOR. 

 [The Editor does not hold himself responsible for opinions 

 expressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part of Nature. 

 No notice is taken of anonymous communications.] 



The Definition of Entropy. 



There is, I fear, a difficulty in drafting Prof. Bryan's 

 definition so as to be clear as well as accurate. This arises 

 when the definition is first given with reference to the 

 entropy of the working substance, because the non-available 

 energy is not necessarily a portion of the energy of the 

 substance. The terms available energy, free energy, bound 

 energy, and non-available energy are continually used 

 loosely in thermodynamics as if they referred to portions of 

 the energy of the working substance. I know from experi- 

 ence the difficulty of defining the entropy of the working 

 substance in terms of dissipation or degradation, without 

 reference to the state of things outside the substance, and 

 in a paper on the factors of heat I adopted the notion of 

 reduction of " transfer credit," so that increase of entropy 

 went with lessening of capacity for transforming heat into 

 work with change of volume. In my book on " Entropy " 

 the whole treatment is essentially from the dissipation or 

 degradation point of view, but entropy is first defined in 

 connection with the irreversible increase of entropy in an 

 isolated system. It is thus defined : " Increase of entropy 

 is a quantity which, when multiplied by the lowest available 

 temperature, gives the incurred waste." 



May I say that I am e.xceedingly glad to find Prof. Bryan 

 treating the subject from the same point of view, as it is 

 strong evidence that my treatment is essentially right. 



41 Palace Court, W. J. Swinburne. 



Mr. Swinburne has directed attention to an obscure point 

 in my letter of November lo which is calculated to produce 

 quite the contrary impression to what I intended. In 

 defining available energy relative to a given temperature, it 

 was not my intention to exclude work that the system was 

 capable of producing by expansion or otherwise without 

 using the reversible engines, and instead of '* maximum 

 amount of energy " I meant maximum amount of work. 

 By work I refer to ordinary mechanical energy as opposed 

 to what Mr. Swinburne calls " wasle energy." The point 

 to which I wished to direct attention was the desirability 

 of basing a definition of entropy on non-available energy, 

 and the use of the term " relative " in this connection, or 

 at least some equivalent language (as implied in my words, 

 " The definition may be stated somcv'hat as follows "). 



So far as I am able to judge, both from Mr. Swinburne's 

 book and from some correspondence with the author, it 

 would appear that the conclusions to which I am being led 

 bv independent working in regard to entropy agree closely 

 in many substantial points with those at which he has 

 arrived. Since the controversy referred to there have been 

 one or two papers published on the subject by other writers 

 with which I altogether disagree. G. H. Bryan. 



Craniology of Man and the Anthropoid Apes. 



In reading Mr. Macnamara's Hunterian oration of 

 February, 1901, I find these words : — 



" Prof. Deniker in his work on the embryology and de- 

 velopment of the anthropoid apes has shown that in con- 

 sequence of the early closure of the anterior sutures of the 

 skull of these animals the fore part of their brain does not 

 increase beyond the size it had attained at the end of the 

 first year of life ; but in man these sutures do not consoli- 

 date until a much later period, so that the anterior lobes 

 of his brain are enabled to expand, and actually become far 

 more perfectly developed than the corresponding lobes 

 among anthropoid apes." 



This being so, I ask : — 



(i) Has the experiment ever been tried of keeping the 

 sutures of an infant ape open by artificial means? And if 

 it has, 



(2) Has the brain been found to expand and become more 

 perfectly developed ? 



For if so we should expect the ape to manifest an intelli- 

 gence not far short of that of a man. A. T. Mundy. 



NO. 1832, VOL. 71] 



In answer to Mr. A. T. Mundy's questions, it seems 

 to me that it would be impossible in a young 

 living ape, by artificial means, to prevent his frontal 

 suture from closing, and if we could succeed in keep- 

 ing it open I question if any marked increase in the 

 size of the animal's frontal lobes would augment his in- 

 tellectual capacity. It is not only the great size of man's 

 cerebrum as compared with that possessed by anthropoid 

 apes which gives him greater intellectual power, but, as I 

 have stated in the passage quoted by Mr. Mundy from my 

 Hunterian oration, the frontal and parietal lobes of the 

 human brain are " far more perfectly developed than the 

 corresponding lobes among anthropoid apes." This is 

 especially the case with respect to those motor and psychical 

 areas of man's cerebral convolutions which control his 

 power of intelligent speech ; these areas of the brain are 

 deficient in the anthropoid apes. It is probable that man's 

 ability to make use of articulate language, and through 

 this means to think, has led to the great development of 

 the psychical elements of his brain. A comparison of the 

 size and conformation of the cranium of Tertiary man with 

 that of existing Englishmen is an indication of the length 

 of time it has taken for the human cerebrum, and therefore 

 intellect, to reach its present stage of evolution. Man and 

 anthropoid apes we hold to be derived from a common 

 ancestral stock ; the former, under the action of natural 

 selection and other causes, including, I think, not only 

 an inherent capacity of cerebral but also of cranial growth, 

 have gradually developed, whereas anthropoid apes, from 

 arrest of cranial and cerebral growth, have not reached the 

 standard attained by human beings ; the difference between 

 these two orders of beings, however, is one of degree, and 

 not of kind. N. C. Macnamara. 



November 26. 



Pinnipedia a Suborder of Cetacea ! 



One is so much accustomed to encounter strange asser- 

 tions in regard to zoology in the non-scientific Press that 

 one takes little notice of them ; but when one reads under 

 the head of "Science," as may be read in this day"s 

 Athenaeum (p. 767), a reviewer of Mr. Millais's " Mammals 

 of Great Britain and Ireland " complaining of that work 

 that " Nowhere is it stated, as it should be, that the Sub- 

 order Pinnipedia belongs to the order Cetacea," one is 

 tempted to ask to what end have writers on classification 

 laboured, if such an assertion as this is to pass un- 

 challenged? If, by a slip of the pen, "Cetacea" was 

 written for " Carnivora," one can sympathise with the re- 

 viewer, for all are liable to such unhappy accidents ; but the 

 general drift of his remarks seems to forbid that charitable 

 construction, for in the preceding paragraph it is expressly 

 stated that the Carnivora, except the Mustelidas, are dealt 

 with in the volume. F. Z. S. 



December 3. 



The Late Mr. Assheton Smith. 



The man of ample means, and who is a lover of living 

 creatures, has a great opportunity. Mr. Assheton Smith 

 had this opportunity, and he used it not only to gratify his 

 own pleasure, but to share it with others. There was 

 nothing that he liked better than to go the round of his 

 park with a guest, and to point out and discuss the characters 

 and habits of the animals which he had gathered together 

 from various quarters of the globe. With the late squire 

 such a ramble was no ordinary treat. One felt, too, that 

 in this man the beasts had a true friend, that he had studied 

 them and knew their ways, and that he would do his utmost 

 to make their lot as happy as possible. To such a man science 

 owes a great debt. Not only does he afford the student an 

 opportunity of studying animals in favourable circum- 

 stances, but he is able to place material at the disposal of 

 the laboratory and museum when these animals have paid 

 nature's last demand. For a number of years I have had 

 the good fortune to act, as it were, as prosector to his 

 menagerie, and both my students and I have been able to 

 carry out not a few studies in comparative anatomy. Some- 

 times, playfully, he would accuse me of possessing the 

 " evil eye," as he said that an animal was not likely to 

 survive long should I express a desire to have it eventually 



