December 22, 1923] 



NA TURE 



89: 



Mr. Freshfield to take a midsummer holiday in Corsica. 

 Still, here is a fine feast for all who like to commune 

 in spirit with a fellow-lover of the hills. The papers 

 entitled " Behind the Bemina " (Val Malinco, Val 

 Masino, and Val Codera) and " The Bergamasque 

 Alps " are a sequel to " The Italian Alps/' and in 

 revisiting these enchanted glens the author recaptures 

 and reproduces the charm of " that large utterance of 

 the earlier gods." The Maritimes and the Gran Sasso 

 are exactly the setting for him, and wherever Mr, 

 Freshfield goes he takes with him the classic writers 

 who have fed his imagination and formed his style. 

 It gives a certain pleasure to catch him out in a mis- 

 quotation, and that from Milton, a common mis- 

 quotation from whom dogs Mr. Freshfield's name. 

 It will be found on page 46. 



Expositions of Atomic Physics. 



(i) Recent Developtnents in Atomic Theory. By Prof. 

 Leo Graetz. Translated by Dr. Guy Barr. Pp. 

 xi + 174. (London: Methuen and Co., Ltd., 1923.) 

 95. net. 



(2) The New Physics : Lectures for Laymen and Others. 

 By Prof. Arthur Haas. Authorised Translation by 

 Dr. Robert W. Lawson. Pp. xi+165. (London: 

 Methuen and Co., Ltd., 1923.) 65. net. 



(3) The A B C of Atoms. By Bertrand Russell. Pp. 

 175. (London : Kegan Paul and Co., Ltd. ; New 

 York : E. P. Dutton and Co., 1923.) 45. Gd. net. 



(4) Modern Electrical Theory. By Dr. Norman Robert 

 Campbell. Supplementary Chapters. Chapter 17 : 

 The Structure of the Atom. (Cambridge Physical 

 Series.) Pp. x+i6i. (Cambridge: At the Uni- 

 versity Press, 1923.) 10s. net. 



THE theory of atomic structure has, during the 

 past few years, reached a stage of sufficient 

 success and stability for it to be possible to describe 

 many of its features in a simple manner. There is a 

 general agreement as to the validity of certain funda- 

 mental conceptions, such as the nuclear structure, the 

 interpretation of isotopes, and the general functions of 

 the outer electrons, while, to turn to more delicate 

 points, the quantum theory and the wave theory of 

 radiation, like an ill-assorted couple of individually 

 worthy people, have learnt to live together in peace by 

 a tacit agreement not to insist too much on each other's 

 faults, so that it is possible for their friends to ignore 

 their essential incompatibility. In short, the times 

 seem propitious for popular summaries of recent 

 advances in molecular physics, and a large number of 

 such books, appealing to various circles of readers, have 

 recently appeared, some of wliich are now before us. 



(i)^England is traditionally successful in the writing 

 of simple scientific expositions for general reading, so 



NO. 2825, VOL. 112] 



that it is the more astonishing that two of these books 

 should be translations from the German, and that these 

 two should be but representatives of a large number 

 of such translations not of works, like Sommerf eld's 

 celebrated treatise, distinguished by great learning and 

 great industry, but of ordinary lectures and essays 

 peculiar for neither novelty of matter nor elegance of 

 exposition. It is difficult, for example, to find any 

 compelling reason for the appearance of Prof. Graetz's 

 book in English dress. This summary of recent atomic 

 theory was written while the War was still in progress 

 (in fact, part of it is based on lectures delivered in 

 territory occupied by the Germans), and, while it has 

 been revised by the insertion of new matter, im- 

 perfectly incorporated with the old, the last revision 

 was nearly two years ago. In consequence, the book 

 is seriously behind the times. To take one example 

 only : it is stated, in what purports to be an exposition 

 of Bohr's views, that the electrons are arranged in 

 concentric rings, each ring containing a number of 

 electrons, the model for neutral helium, in particular, 

 being figured with two electrons at opposite ends of the 

 diameter. 



Apart from being out-of-date, the book is vitiated 

 by a deplorable looseness of expression which is very 

 liable to mislead the general reader for whom it is in- 

 tended. We are told that radium emanation loses its 

 activity, " unlike radium, thorium, etc., which keep 

 their activity for ever " ; that for reflection to take place, 

 X-rays must fall on the crystal at practically grazing 

 incidence ; that the nuclear charge determines the 

 ordinal number in the periodic system, " and therefore 

 determines also its atomic weight." The account of 

 positive rays is bad. In short, the author does not seem 

 to be sufficiently familiar with his material. Altogether, 

 the book is superfluous, and it is a pity that such praise- 

 worthy production in the matter of paper and print as 

 it enjoys should not be devoted to a better object. 



(2) The book of Prof. Haas's is a better perform- 

 ance, but is scarcely what it is implied to be, a book 

 for laymen. In a hundred and fifty small pages, the 

 author runs quickly through the electromagnetic theory, 

 the kinetic theory of gases, the electron theory, the 

 quantum theory, recent work on the structure of the 

 atom, and the theory of relativity. It is scarcely 

 necessary, in the face of this programme, to labour the 

 fact that the treatment is far too laconic to be of use to 

 any one with but little foreknowledge of the subjects 

 handled. The language is simple enough, but such 

 features of modem physics as the conception of a black 

 body, the gyromagnetic effect, the quantum of action, 

 and so on, cannot be clearly explained in single para- 

 graphs by the mere device of omitting mathematical 

 symbols. 



