February 2^, 1922] 



NATURE 



235 



^The book contains i6i pag^es of text. The 

 ithemafics are relegated to a further seventy 

 res of notes, and the arrangement of these is 

 Either tiresome, for the majority of the notes are 

 iply references to original papers, and there is 

 )thing in the text to distinguish between these 

 id the mathematical calculations. 

 [The order of treatment of subjects is mainly 

 itorical, and radiation therefore comes first. 

 lis is probably the best arrangement possible at 

 resent, though when the theory has been reduced 

 a classical form it is to be presumed that such 

 complex question will fall into a much later posi- 

 )n. There follows a short discussion on the 

 jssity of breaking- away from ordinary me- 

 ianics, and then a description of Einstein's hvpo- 

 ;sis of light quanta, and the ingenious deduc- 

 )ns he makes from the fluctuations in radiant 

 irgy. The fourth chapter gives an account of 

 quantum theory in relation to the physics of 

 lids— such questions as specific heats and Born's 

 )rk on the dynamics of crystals. The next 

 ipter deals with gases, where the theory is not 

 "quite so satisfactory. The rest of the book is 

 mainly occupied with the Bohr theory. It includes 

 all the more recent ideas, such as the correspond- 

 ence principle, and also a certain amount about 

 atom models. 



There is little to criticise in such a fair account 

 of the whole theory, but we may venture to say 

 that the author is perhaps inclined to favour 

 Planck's second hypothesis rather more than 

 would the general consensus of present opinion. 

 That hypothesis seems to give rather better agree- 

 ment with experiment in the theory of gases, but 

 neither of Planck's hypotheses has yet been made 

 to cover the facts in a really convincing manner. 

 On the other hand, the second hypothesis is quite 

 foreign to the principles of spectrum theory, which 

 agree exceedingly accurately with experiment. 

 Apart from this, anyone wishing to get a just view 

 of the quantum theory cannot do better than read 

 the book. 



Our Bookshelf. 



Taboo and Gerietics : A Study of the Biological, 

 Sociological, and Psychological Foundation of 

 the Family. By Dr. M. M. Knight, Dr. ha L. 

 Peters, and Dr. Phyllis Blanchard. Pp. xv + 

 255. (London: Kegan Paul and Co., Ltd.; 

 New York: Moffat, Yard, and Co., 1921.) 

 xos. 6d. net. 



This survey of the institutions connected with 

 sexual life and the family falls into three sections. 

 In the biological section Dr. M. M. Knight gives a 

 lucid summary of recent work on sex, drawing the 

 NO. 2730, VOL. 109] 



conclusion that the difference between the sexes is 

 quantitative rather than qualitative. In the second 

 section Dr. Iva Peters surveys the ethnological evi- 

 dence for the taboo of women, and concludes that 

 the modern form of monogamous marriage is essen- 

 tially a survival of a compromise between man's 

 erotic desires and his fears of woman's mana, which 

 has produced an " ideal woman," a type out of 

 harmony with modern developments. This is 

 perhaps the least satisfactory of the three sections. 

 By dwelling too exclusively on taboo and its results 

 it ignores equally important factors in the various 

 social complexes which influence the institution of 

 the family. Dr. Phyllis Blanchard, in dealing with 

 the psychological side of the question, has pro- 

 vided the most stimulating section of the book. By 

 a skilful analysis she places before her readers the 

 chief elements which are responsible for disharmony 

 in modern marriage and the causes which, partly 

 through the increased social activities and individual- 

 ism of women, are bringing about the exclusion of a 

 large body of the female population from participa- 

 tion in carrying on the race. 



Sulfhur and Sulfhur Derivatives. By Dr. H. A. 

 Auden. (Pitman's Common Commodities and 

 Industries.) Pp. xviii-f-ioi. (London: Sir 

 Isaac Pitman and Sons, Ltd., n.d.) 35. net. 

 Dr. Auden gives a very readable and accurate 

 account of the manufacture and uses of sulphur 

 and its derivatives, especially sulphuric acid, and 

 his book should prove useful to students and general 

 readers. Although two illustrations of the Gill 

 furnace are given, its mode of operation (which can- 

 not be seen from the illustrations) is not mentioned. 

 The changes observed on heating sulphur are not 

 quite correctly described (p. 5). Moreover, the 

 statement (p. 29) that " almost the whole supply of 

 ammonium sulphate is at present derived from the 

 distillation of coal " refers only to English practice; 

 in more progressive countries very large quantities 

 are produced from atmospheric nitrogen. Although 

 the earlier history of the contact process is given, the 

 real commercial process (p. 61) is not ascribed to 

 any particular inventor — the work of the Badische 

 Co. would seem worthy of mention, and diagrams 

 of the apparatus would also be useful. 



Examples in Optics. Compiled by Dr. T. J. I 'A. 



Bromwich. Pp. 16. (Cambridge : Bowes and 



Bowes, 192 1.) 2s. net. 

 Dr. Bromwich has collected sixty questions in 

 optics for use in class-room at St. John's College, 

 Cambridge, and has given references to eighty-four 

 Tripos questions set between 1910 and 1921. The 

 examples printed in the pamphlet cover a fairly wide 

 range, and have evidently been selected by an ex- 

 perienced teacher. In many cases the questions have 

 a direct practical application, or point towards a 

 method of making some important optical measure- 

 ment. Special attention may be directed to the 

 examples connected with the cardinal points of a 

 system of lenses or refracting surfaces, which should 

 prove a useful supplement to practical work in the 

 laboratory. 



K 



