2^,2 



NATURE 



[August i8, 1923 



full of interest and demand attention. He is strongly 

 opposed to the use of alcohol and tobacco, and he 

 regards war as an out-of-date and anti-democratic 

 method of settling disputes. At one period he gave 

 much attention to the reform of the American civil 

 service, and in recent years he has devoted a great 

 deal of his time to lectures in America, Europe, and 

 Japan in the cause of international peace, a subject 

 on which he has written several books. When a man's 

 life has been so strenuous and so varied the writing 

 of an autobiography is a task of some magnitude. 

 But it was well worth doing, and it has been well done. 

 We congratulate Dr. Jordan and we thank him. 



C. T. R. 



The Structure of the Atom, 

 (i) The Structure of Atoms. By Prof. Dr. Alfred Stock. 

 Translated from the Second German edition by S. 

 Sugden. Revised and enlarged. Pp. viii + 88. 

 (London : Methuen and Co., Ltd., 1923.) 6^. net. 



(2) La Thiorie des quanta et Vatome de Bohr. Par 

 Leon Brillouin. (Recueil des Conferences-Rapports 

 de Documentation sur la Physique. Vol. 2, i" 

 Serie, Conferences 4, 5, 6. !£dite par la Societe 

 Journal de Physique.) Pp. 181. (Paris : Les 

 Presses universitaires de France, 1922.) 15 francs, 



(3) Institut International de Physique Solvay. Atomes 

 et electrons. Rapports et discussions du Conseil de 

 Physique tenu a Bruxelles du i"' au 6 avril 192 1 

 sous les auspices de I'lnstitut International de 

 Physique Solvay. Pp. vii + 272. (Paris: Gauthier- 

 Villars et Cie, 1923.) 20 francs. 



THE problem of the structure of the atom is one 

 which for many years has exercised a fascina- 

 tion for the scientific mind. Its solution demands the 

 correlation of phenomena from many branches of 

 physics and chemistry, and the repercussion of the 

 current ideas on the subject makes itself felt over a 

 correspondingly wide field. It is a subject on which 

 no worker in physics or chemistry dare allow his 

 knowledge to become out-of-date, and in which other 

 scientific workers take an interest which is by no means 

 entirely extraneous. Owing partly perhaps to the 

 distinction and lucidity of some of its famous exponents, 

 it has also aroused the interest of a wider non-scientific 

 circle and has won for itself a distinctly " good press." 

 In the circumstances it is not surprising that books on the 

 subject, addressed to one or other of these numerous 

 classes of potential readers, should appear at frequent 

 intervals. 



(i) Prof. Stock's little volume is addressed to the 

 chemist, and contains a resume of a series of lectures 

 delivered by him to the works chemists of a well-known 



NO. 2807, VOL. 112] 



German manufactory. He attempts to remove what 

 he describes as the " thorns of theoretical physics and 

 mathematics " which beset the tender feet of the 

 chemist who would wander in the " Wonder-garden " 

 of atomic structure. He has, in fact, pruned so 

 remorselessly that the book resembles rather a sketch 

 plan than a garden, showing little more than the direc- 

 tion of the main paths and the openings into some 

 of the principal alleys. To abandon the metaphor 

 which Prof. Stock himself suggests in his preface, the 

 book contains a fairly complete, but very brief, sum- 

 mary of the various phenomena which have a bearing 

 on the problems of atomic structure ; and a still 

 briefer exposition of some of the current theories. A 

 very interesting volume could be written around the 

 synopsis thus provided. The fact that positive rays 

 and the quantum theory occupy little more than half 

 a page each, while the theory of relativity is consigned 

 to a footnote, indicates the extreme condensation 

 which has necessarily been employed to compress so 

 vast a subject into so narrow a space. The reader will, 

 however, learn from its pages how much there is to be 

 learnt, and a brief bibliography points out the principal 

 sources from which the English reader can obtain 

 further information. 



(2) M. Leon Brillouin's book " La Theorie des 

 quanta et I'atome de Bohr " is addressed to the serious 

 student of the subject. It forms the second volume of 

 the series of reports which the Society Journal de 

 Physique is publishing on various aspects of modem 

 physics, and maintains the high standard which was set 

 by M. de Broglie in his initial volume, " Les Rayons X." 

 Probably no student of physics is entirely ignorant bf 

 Planck's quantum theory, and its apphcation to 

 thermal radiations, or of Bohr's daring and brilliant 

 extension of the quantum principle to the nuclear atom 

 of Sir Ernest Rutherford which resulted in the calcula- 

 tion of the hydrogen spectrum, and the evaluation of 

 Rydberg's constant; certainly one of the greatest 

 achievements of theoretical physics in modem times. 



The later developments of the theory- are far less 

 known, nor has it been, up to the present, at all an easy 

 matter to become acquainted with them. The original 

 memoirs of Bohr and other distinguished workers on 

 the same problem are scattered through the pages of 

 many periodicals in many languages. Moreover, as 

 was inevitable in a problem so complex as that of the 

 motion not of three only but of many attracting and 

 repelling particles, there have been numerous false 

 starts and incorrect conclusions, and it has not infre- 

 quently happened that, after mastering with some 

 difficulty one of these essays, the student has 

 found to his chagrin that it has been superseded by 

 later work. It must be confessed, too, that the pioneers 



