460 



NATURE 



[August 3, 19 16 



expect; he usually has a quick return for his 

 outlay, and he can insure against many of his 

 risks. The farmer, on the other hand, rarely, if 

 ever, works on a contract; he starts expending 

 money in August on a crop that will not be sold 

 for fifteen months ; he does not know definitely 

 what price he will receive, or what yield he will 

 get. The whole thing is a hazard, and he can- 

 not insure against his risks. Consequently he 

 has to allow a large margin for safety, and he 

 balances his risk on the arable land by having a 

 considerable area of grass on which the risk is 

 at a minimum. 



The application of scientific methods has 

 decreased the risk and increased the effectiveness 

 of the capital involved, but, of course, it cannot 

 deal with the great factor of price. This 

 problem is for the statesman, and when he comes 

 to deal with it he will find Mr. Hall's book a 

 useful guide. E. J. R. 



OVR BOOKSHELF. 



The New Public Health. By Prof. H. W. Hill. 



Pp. X + 206. (New York : The Macmillan Co. ; 



London: Macmillan and Co., Ltd., 1916.) 



Price 55. 6d. net. 

 The object of this book is to bring before the 

 general public the newer conceptions of the aims 

 and methods of public health. The older public 

 health mainly dealt with the environment ; the 

 newer is chiefly concerned with the individual. 

 The old teaching stated that infectious diseases were 

 generated in the foul, ill-smelling, unventilated, 

 sunless hovels of the slums ; that a pinhole leak 

 in some plumbing fixture accounted for diphtheria 

 or typhoid fever ; that dampness caused malaria, 

 and impure water yellow fever. The new teaching 

 begins and usually ends with the search for (a) the 

 infected individual, (b) the routes of spread of 

 infection from that individual, (c) the routes of 

 disposal of the excreta of the community, by 

 which, if infection occur, the infecting agent might 

 reach the members of the community. To locate 

 all the infective individuals of the community and 

 to guard all their discharges is the ultimate goal 

 of modern preventive measures. 



The author surveys the sources, routes, and 

 'control of infectious diseases, the old and the new 

 practice in the control of epidemics, and individual 

 and community defence and administration. The 

 book Is written in a vigorous and trenchant style 

 which arrests the attention and carries conviction. 

 The only criticism of it that might be passed is 

 that the casual reader might gather that such 

 factors as garbage heaps and ill ventilation are of 

 little moment to the public health, whereas actually 

 the author indicates that they are not to be neg- 

 lected, though their importance and significance 

 are very different from what used to be considered 

 to be the case. R. T. H. 



The Pathology of Tumours. By Dr. E. H. 



Kettle. Pp. viii+224. (London : H. K. Lewis 



and Co., Ltd., 1916.) Price los. 6d. net. 

 In this book the author gives an excellent account 

 of the characters, occurrence, and general patho- 

 NO. 2A4.0. VOL. Q71 



logy of tumours, innocent and malignant. No 

 doubt students and practitioners will find it of 

 considerable service, though it may be remarked 

 that we fail to find in it any novelty in matter 

 or arrangement, or anything that has not been 

 just as adequately stated in some other books 

 that could be named. The illustrations, how- 

 ever, are both numerous and excellent, and this 

 feature will probably be the one which will recom- 

 mend the book. 



In the opening chapters the general biology 

 of tumours is dealt with, including statistics of 

 occurrence, the experimental study of tumour 

 growth, and the general principles of treatment. 

 Here, however, we fail to find any reference to 

 changes in the body fluids which occur in malig- 

 nant disease, such, for instance, as alterations in 

 the anti-tryptic power and lipoclastic action of 

 the blood-serum. 



In the second part the naked-eye and 

 microscopical characters of the different forms of 

 tumours are described, and finally the occurrence 

 of tumours in the various organs and tissues of 

 the body is detailed. Altogether the book gives 

 a very practical summary of tumour formation 

 and development in general. 



Harper's Hydraulic Tables for the Flow of Water, 

 in Circular Pipes under Pressure, Timber 

 Flumes, Open Channels, and Egg-shaped 

 Conduits, with much Accessory Information. 

 By J. H. Harper. Pp. 192. (London : Con- 

 stable and Co., Ltd., 1916.) Price 8s. 6d. net. 

 With painstaking assiduity, the author has 

 worked out, with the aid of certain well-estab- 

 lished formulae, what he terms a " grill " or net- 

 work of solutions, covering such problems as are 

 likely to arise in actual practice "regarding the 

 flow of water in either closed or open conduits, 

 with any reasonable assumption of rugosity and 

 with any rational arrangement of grade, in quan- 

 tities from a small fraction of a foot to several 

 thousand feet per second." The formulae selected 

 are those of D'Arcy, Bazin, and Kutter — all 

 authoritative in their degree, but labouring under 

 the disadvantage of possessing extremely vari- 

 able coefficients, which render their application 

 a matter of some difficulty, quite apart from the 

 complexity of the expressions themselves. It has 

 recently been shown by Mr. A. A. Barnes that the 

 inherent cause of this diversity lies in the strict 

 adherence to the fundamental equation of Chezy, 

 viz. v — CsJrs, and that if the equation were 

 written in the form v = cr'^s^, coefficients could be 

 determined which are simple In character and 

 constant for the same class of channel. For 

 those who prefer older methods the volume will 

 undoubtedly prove of use in obviating the neces- 

 sity for working out experimental cases in detail. 

 Within the range of the tabulated results, it is 

 easy to interpolate values sufficiently correct for 

 preliminary approximations. The tables are also 

 diagrammatically expressed in charts, and there 

 are some supplementary notes on hydraulic 

 formulae generally, which make the book a 

 succinct little manual on the subject. B. C. 



