5>4 



NATURE 



[September 30, 1897 



widest sense. Unfortunately he totally misunderstands, 

 if we are not mistaken, Newton's position. 



It will be noticed that Newton puts his hypothesis 

 among his famous Queries; he never abandoned the 

 reserve expressed in his " Regulae Philosophandi." ^ 



And secondly, when M. Mabilleau says that the theory 

 of gravitation " means nothing if it does not mean that 

 each atom of one body gravitates independently towards 

 each atom of . . . (any other) body," because Newton said 

 that the gravitation of a celestial body is the sum of the 

 gravitations of all the masses of which it is composed, 

 he appears to have been misled by the ordinary language 

 of infinitesimal analysis. The atomic hypothesis essen- 

 tially involves the discontinuity of all bodies. The theory 

 , of gravitation is equally true on the supposition that they 

 are continuous, and, as a matter of fact, discontinuity of 

 internal constitution is not taken into account in the 

 mathematical analysis of gravitational phenomena. The 

 point is of importance in judging M. Mabilleau's per- 

 sonal views, because, regarding Newton's law as " dans 

 I'ordre des expressions phenomenales, la plus parfaite des 

 formules, etant la generalisation et la plus haute et la plus 

 exacte tout ensemble," he fallaciously adduces it as one 

 of his most powerful arguments in favour of atomism. 



M. Mabilleau discusses in some detail the views of 

 Newton's contemporaries, Locke and Leibniz, those of 

 Maupertuis, and later the dynamic theory of Boscovich. 

 But from the time of Newton onwards he seems not 

 only to have little acquaintance at first hand with his 

 facts, but to be deserted by the powers of analysis and 

 critical judgment shown earlier in the book. In his rapid 

 rush through modern text-books and the popular articles 

 of the Revue Scientifiqiie^^ he passes over the supremely 

 important period of Black, Cavendish, Priestley and 

 Lavoisier, in which the experimental method for com- 

 paring quantities of matter, failing which all theories of 

 conservation of matter had been sterile, was arrived at ; 

 but quotes approvingly a view of " the great chemist 

 Fechner" (who wrote two unimportant papers on 

 chemistry) with regard to the connection between 

 Newton and Dalton. He then analyses Dalton's work 

 with some accuracy, and passes on to a resume of the 

 development of the atomic theory in chemistry since 

 Dalton's time, mainly derived from Sir Henry Roscoe's 

 address to the British Association in 1887, and Sir W. 

 Crookes' lecture on the evolution of the elements. He 

 notices the importance of modern theories of organic 

 chemistry, but he fails altogether -to recognise that 

 (together with certain recent developments of chemical 

 physics) they form absolutely the mainstay of the atomic 

 theory in science. It is often hardly realised how un- 

 productive of practical results the atomic theory has been 



i '_' In the particles [of bodies] that remain undivided, our minds are able 

 to distinguish yet lesser parts, as is mathematically demonstrated. But 

 whether the parts so distinguished and not yet divided, may, by the powers 

 of nature, be actually divided and separated from one another, we cannot 

 certainly determine " {Principia, trans, by Motte, edit. 1803, ii. 161). 



'■^ In which he misspells the names of most of the people he quotes, whether 

 they are French or not. Thus we find, almost throughout, Schutzemberger 

 for Schutzenberger, Malard for Mallard, Wurtz for Wurtz, Hoffmann for 

 Hofmann, Thornsen for Thomsen, lungfleisch for Jungfleisch, Kirchoff for 

 Kirchhoff, Lockyers for Lockyer, Krug (p. 521) for Kruss, Carnelly for 

 Carnelley, K6kul6 for Kekule, &c. In one or two places Boyle is written 

 Bayle, which might lead to confusion. But the climax is attained when, 

 after some hesitation between the spellings Prout and Proust, with reference 

 to the work done by these two chemists, the one English, the other French, 

 M. Mabilleau identifies them boldly by writing (p. 516) " Prout (ou Proust)." 

 Earlier in the volume we find Munck everywhere for Munk, &c. 



NO. 1457, VOL. 56] 



elsewhere. Incidentally M. Mabilleau makes many 

 mistakes, which imply a curious failure in the power to 

 grasp a new subject, indispensable to the historian. 

 Victor Meyer is supposed to have decomposed the atoms 

 of simple substances ; Joule to have proved that any 

 change in molecular constitution is accompanied by an 

 absorption of heat, and thereby to have inaugurated 

 thermo-chemistry in 1872 (!) ; &c. The function of the 

 atomic theory in physics is discussed in the brief space 

 of five pages, devoted chiefly to the transformation, of 

 crystal forms with increase of temperature, and after a 

 scarcely sufficient account of modern criticisms of the 

 idea of continuity in pure mathematics, M. Mabilleau's 

 book concludes. 



He sums up in favour of the existence of atoms con- 

 trolled by a transcendental law given at the creation of 

 the world, the last sentence of the book being " Voltaire 

 nous avait bien dit que la philosophie corpusculaire est 

 le plus court chemin pour trouver I'Ame et Dieu." 



This sentence explains the whole book, which is rather 

 like the special pleading of an extremely supple-minded 

 barrister than the work of an impartial historian. M. 

 Mabilleau's book was written as a prize essay, and it 

 obtained a prize from the French Academie des Sciences 

 morales et politiques. But it was evidently written in 

 a limited time, and, in consequence, M. Mabilleau's 

 references are (and he does not conceal the fact) 

 mainly second-hand. With references of this kind only 

 an expert can deal with any degree of safeness, and in 

 scientific matters, as we have seen, M. Mabilleau is far 

 from being such. 



For the historian of philosophy, M. Mabilleau's cornl- 

 pilation will be useful. To the logical analysis of modern 

 molecular and atomic theories, to which Stallo, Lasswitz, 

 Mach, Pearson, Ostwald, and others have made valuable 

 contributions, and which is still far from being exhausted, 

 he adds nothing. 



In conclusion, we may note that the book, though 

 admirably printed and well arranged, has a most meagre 

 table of contents and no index. P. J. Hartog. 



MAXWELL'S EQUATLONS OF THE ELECTRO^ 



MAGNETIC FIELD. 

 Theory of Electricity and Magnetism. By Charles 



Emerson Curry, Ph.D. With a preface by Prof. 



Boltzmann. Pp. xv -f- 442. (London : Macmillan and 



Co., Ltd., 1897.) 



A WORK on electricity and magnetism which, start- 

 ing from the differential equations of the electro- 

 magnetic field, works backwards to the experimental 

 phenomena, cannot well be used as a text-book by the 

 beginner, but may be of great value to one who has 

 already studied the facts and theories of the subject in 

 their historical order. Of such a nature is Dr. Curry's 

 treatise, the avowed object of which is, after forming 

 certain conceptions and making various assumptions con- 

 cerning the ether which practically constitute a formu- 

 lation of Maxwell's theory, to derive therefrom, and 

 explain thereby, all electric and magnetic phenomena. It 

 is, in fact, a study in the interpretation of differential 

 equations in terms of mechanical analogies or concrete. 



