H 



NATURE 



[February 4, 1892 



Many of the old topics enlarged upon by Carpenter are 

 treated with increased amplitude in the present edition. 

 Excellent plates (some of them coloured) illustrate the 

 Desmids, the Diatoms (the old crux of the sculpturing of 

 the valves is more than ever to the fore), the Monads, the 

 Rotifers, and the Foraminifera. Three coloured plates 

 of the structure of Acari are introduced ; they are very 

 interesting, but surely out of proportion in a work on the 

 microscope where no adequate illustrations of the Ciliate 

 Infusoria are given, and where the account of the pheno- 

 mena of conjugation in that class is far from being up j 

 to date both as to statement and illustration. 



I do not wish to speak unkindly of an old friend, even j 

 when rigged out in such a strangely variegated new set of 

 clothes as are those furnished to " The Microscope " in 

 its seventh edition. There is a great deal of very in- j 

 teresting matter ; there are numbers of excellent woodcuts 

 and plates in the book, some old and a great many new — 

 one thousand in all. The defect of all the earlier 

 editions remains in the present— namely, that whilst you 

 may find several pages, plates, and figures about one 

 subject connected with microscopy, you will find only 

 three lines or nothing at all about another. So long as 

 Dr. Carpenter wrote successive additions to the book, 

 one understood why some subjects should be treated 

 fully and others passed over, and at any rate one knew 

 who was responsible for any statement or omission. 

 Now the book has (so far as its second half is concerned) 

 lost its authoritative character, and is more than ever a 

 patchwork of paragraphs on arbitrarily selected subjects, 

 the responsibility for which is divided in some mysterious 

 way between the editor (who, of course, does not claim 

 to be another Carpenter), and certain Fellows of the 

 Royal Microscopical Society. 



I should wish, on the other hand, to express the 

 opinion that the first half of the book (which alone really 

 deals with the microscope and the art of microscopy, 

 and is not by Dr. Carpenter, but entirely new — by Dr. 

 Dallinger) is a work of high scientific value — by far the 

 best on the subject — and one which every worker with 

 the microscope should thoroughly study and take to 

 heart. E. Ray Lankester. 



ELEMENTARY THERMODYNAMICS. 



Elementary Thennodynamics. By J. Parker, M.A. 

 (Cambridge : University Press, 1891.) 



IN a six-lined note, which does duty as preface, the 

 author of " Elementary Thermodynamics " tells the 

 beginner what to omit. From a beginner's stand-point 

 the book must therefore be judged. A first glance will 

 probably startle the reader into exclaiming, What can 

 Kepler's laws have to do with Carnot's principle ? For- 

 tunately, however, the sections containing Kepler's laws, 

 and much other apparently irrelevant matter, are those 

 the beginner is advised not to read. With the mere 

 remark that all this is preliminary to an elementary 

 exposition of Darwin's calculations in tidal friction, it 

 will best serve all purposes to confine the attention 

 strictly to things thermodynamic. The most important 

 chapters, alike from the teacher's and pupil's points of 

 NO. I 162, VOL. 45] 



view, are the first and third, dealing with the foundations 

 of the science. 



The first chapter is headed "The Conservation of 

 Energy." It develops in mathematical form the general 

 differential equation of energy, but is lamentably feeble 

 in the physical or experimental side. True, there is a 

 brief discussion of some of Joule's experiments ; but we 

 venture to think it would require a greater than Joule to 

 find that a calorie was equivalent to 4i,539,7S9'8 ergs ! 

 A little further on, the latent heat of ice under a pres- 

 sure of one atmosphere is given as 79 "25 calories, or 

 3,292,025,964 ergs ! ! Surely it " was the most unkindest 

 cut of all" thus to spurn the 0-15. The truth taught 

 here is, that ten-place logarithms do bare justice to 

 " Parkerian " reductions. 



A novelty of treatment is the division of forces into 

 contact-forces and ether-forces. To Prof. Lodge is as- 

 cribed the doubtful honour of having suggested this 

 treatment. Contact-forces, we are told, exist between 

 particles in contact ; while " the principal ether-forces 

 in Nature which do work, in addition to gravitation and 

 radiation forces, are those which give rise to chemical, 

 physical, electric, and magnetic actions." It is not easy 

 to see the exact meaning of the word " physical " in this 

 definition. If it includes elasticity, cohesion, adhesion, 

 and capillarity, why should pressure, impact, and fric- 

 tional effects be excluded 1 Is there, indeed, any evidence 

 of the existence of contact-forces (in Mr. Parker's sense) 

 hQtwi&&n particles f To our gross senses, visible masses 

 seem to get into contact with each other ; but, when once 

 we introduce an ether as the vera causa of all actions 

 between bodies not in apparent contact, we are compelled 

 to regard this ether as an ocean in which matter is an 

 archipelago of particles or a swarm of maelstroms. How, 

 then, can "contact-forces" exist at all, since ether must 

 intervene between particle and particle ? In any case an 

 elementary text-book is hardly the place to introduce 

 crude ethereal speculations. 



Chapter iii. is devoted to " Carnot's Principle," and 

 these two most significant words form head-lines to 136 

 pages of a book that just tops the 400. This is good. 

 Nevertheless, the " principle " itself, so far as we can 

 discover, is never once explicitly stated. The chapter 

 opens with a brief historic sketch, in which we are told 

 that Clapeyron brought Carnot's work " prominently " 

 forward in 1834. Yet it was not till fourteen or fifteen 

 years later that Thomson discovered to the scientific 

 world the greatness of Carnot, and clearly pointed out 

 the necessity for modifying Carnot's reasoning so as to 

 bring it into accord with the true theory of heat. From 

 Thomson's second paper (1849) Clausius dates his in- 

 spiration. Of all this Mr. Parker says nothing, nor does 

 he seem to be aware that Thomson, two years before 

 Clausius and Rankine published anything, pointed out 

 how Carnot's principle led to the conception of an abso- 

 lute scale of temperature. Moreover, there can be no 

 question that Thomson first gave an unexceptionable 

 enunciatioft of the "axiom" underlying Carnot's prin- 

 ciple. Such particulars are probably of no interest to an 

 author who defines " the very important axiom . . . 

 substantially due to Carnot " in language which may be 

 thus paraphrased : No mechanical work can be gained 

 from a cycle of operations imposed upon a system in 



