September 9, 1920] 



NATURE 



41 



la ted list of symbols and their meanings — more 

 especially now, when an excellent scheme for 

 standardising these has been evolved by the 

 Royal Aeronautical Society. The designer who 

 will use the book as a work of reference doubt- 

 less has a better initial acquaintance with its 

 notation, but since he will require to read the 

 book piecemeal we suspect that his difficulties will 

 be very much the same. For him it is most im- 

 portant that each several argument shall be as 

 far as possible self-contained, with assumptions 

 clearly stated at the outset. Now in some sec- 

 tions of the chapters on stability we can almost 

 feel Mr. Thomson developing his thought as he 

 proceeds : the discussion of a problem is begun 

 with insuificient data ; the scarcity becomes ap- 

 parent as the analysis proceeds ; assumptions 

 have to be made, and are made, sometimes with 

 little justification other than that of necessity. 

 The sequence is typical of engineering as distinct 

 from purely scientific investigations, since 

 "engineering " (we believe the modification of 

 Samuel Butler's epigram is due to Prof. Unwin) 

 "is the art of drawing sufficient conclusions from 

 insufficient premises " : but it is not a suitable 

 arrangement when the results of these investiga- 

 tions come to be "written up" for the practical 

 man, who is apt to become bewildered by the 

 steady accretion of assumptions, and even to be 

 doubtful, at the finish, whether any new result has 

 been obtained at all. 



One feature of this book will, we believe, be 

 of the very greatest service to its readers: there 

 are practically complete references to original 

 sources of information, even in instances where 

 the reports quoted had not passed from the type- 

 written to the final form at the time of writing. 

 (Incidentally, their authors' names are somewhat 

 frequently misspelt.) The advantages of this in- 

 formation will be apparent to every serious 

 reader, and of immense service to the designer. 

 The book's own index is not equally successful; 

 Mt all events, we have not found it of much assist- 

 ince in compensating for the faults of arrange- 

 ment which we have noticed above, and of which 

 ithcr instances might be given — such as the in- 

 ' lusion of actual experimental data, and of a care- 

 fully reasoned plea for further experiments on 

 l)ody-resistance, in a chapter ostensibly dealing 

 with experimental methods, of a paragraph and 

 three diagrams bearing on the distribution of 

 forces between the upper and lower planes of 

 a biplane under the chapter heading of "centres 

 'if pressure and wing-moments," and of Fig. 94, 

 in illustration of experimental apparatus, in a 

 I'hapter which otherwise is devoted to the dis- 

 cussion and application of experimental data. 

 NO. 2654, VOL. 106] 



We have failed in our intention if the foregoing 

 criticisms suggest that we consider this an un- 

 sound or a carelessly written book ; on the con- 

 trary, we are convinced that readers who have 

 had some first-hand acquaintance with the work 

 3f which it treats will read it with real pleasure 

 — and, after all, no better proof of its excellence 

 oould be adduced. Our only reason for thus 

 emphasising the importance of arrangement and 

 presentation is that we hope soon to see a second 

 and revised edition in which these aspects have 

 received greater attention : very little labour, we 

 believe, would be required to make this work as 

 satisfactory, regarded as a text-book of design, 

 as it already is in essentials, whereas the im- 

 pression which it will make upon the ordinary 

 reader as it stands is not likely to do justice to 

 its verv real merits. 



Food Poisoning. 

 Food Poisoning and Food Infections. By Dr. 

 William G. Savage. (Cambridge Public 

 Health Series.) Pp. ix + 247. (Cambridge: At 

 the University Press, 1920.) Price 155. net. 



THE subject of this work is one not only of 

 great importance in medicine, but also of 

 much scientific interest. It necessarily covers a 

 very wide field, for the production of disease by 

 food may depend upon any one of a large number 

 of different conditions. A food may be inherently 

 poisonous, or its ill-effects may depend upon some 

 abnormal sensitiveness on the part of the con- 

 sumer ; it may acquire poisonous properties as the 

 result of putrefactive or other chemical changes 

 on keeping; it may become the vehicle of metallic 

 poisoning from contact with containing- vessels, 

 or of bacterial infection resulting from animal 

 disease, or from subsequent contamination with 

 pathogenic organisms. Dr. Savage has rendered 

 a great service, alike to medicine, to public 

 health, and to pure science, in gathering together 

 in a small volume the most recent and authorita- 

 tive information upon the various ways in which 

 health may be prejudicially affected by food. 

 There is no one who could more fittinglv have 

 undertaken the task, for the subject is one of 

 which he has a wide practical experience, and 

 which he has made peculiarly his own. So well 

 has he done the work that scarcely any unfavour- 

 able comment suggests itself, and a review must 

 take thrf form, most pleasant to the reviewer, of 

 a short account of the way in which Dr. Savage 

 has treated his subject. 



The first chapter is occupied by a short his- 

 torical review, and the author then passes on to 

 animal infections transmissible to man, a subject 



