I 



A WEEKLY ILLUSTRATED JOURNAL OF SCIENCE 



" To tJu solid ground 

 Of Nature trusts the mind which builds for ajif."— WORDSWORTH 



THURSDAY, NOVEMBER 7, 187S 



SANITARY ENGINEERING 



Sanitary Engineering. By Baldwin Latham. Second 

 Edition. (E. and F. N. Spon, 1878.) 



IN the introduction to this book great stress is laid on 

 the necessity for sanitary measures being thoroughly 

 carried out in all towns and dwellings ; one might suppose 

 that this was fully admitted on all sides, but we have no 

 doubt that every medical officer of health throughout the 

 country could easily give numberless instances of the 

 greatest possible neglect and callousness on the subject. 

 While all admit the necessity of efficient sanitary works 

 and are generally quite ready to attribute to defective 

 arrangements illness occurring in a neighbour's house or 

 another town, each individual seems to ignore the possi- 

 bility of a terrible punishment falling on him for his ovm. 

 neglect. He should recollect that the punishment which 

 must sooner or later overtake him cannot be moderated 

 by the clemency of a chairman of Quarter Sessions or 

 the gentler feelings of a jur)-, but is ruthlessly adminis- 

 tered by the inexorable laws of nature. 



Mr. Baldwin Latham doubtless finding it almost useless 



to preach to people on the necessity of taking care of 



their own and their neighbours' health very wisely tries 



an appeal to them through their pockets, and shows the 



ount of actual pecuniar>' saving from improvements in 



, sanitary condition of a community. The town of 

 Croydon is taken as an instance ; in this case the average 

 mortality from 1848-55 inclusive •was 24*03 per thousand, 

 while that for the twenty years since 1855, when the 

 sanitary works were nearly completed, has averaged 

 r9'56, showing a saving of 4-47 per thousand. But this 

 is not all that is to be looked for ; there is evidence that 

 at times the mortality of Croydon proper is considerably 

 increased by an impure water supply, and from the lower 

 mortality of Norwood it appears that a still further im- 

 provement could be obtained by the adoption of suitable 

 measures. ^Multiplying the average saving in the rate of 

 mortality by the population and by the assumed value of 

 Vol. XIX. — No. 471 



labour per head taken at 19/. los. per annum after a deduc- 

 tion of nearly one-half for persons of an unsuitable age 

 for work, the author obtains 413,395/. as the value of the 

 saving from the lessened number of deaths in ten years en 

 an average population of 43,912. The saving in cases of 

 sickness not resulting in death is taken at i/. per case on 

 twenty-five times the number of deaths, that being the 

 estimated ratio of cases of illness to deaths ; this gives 

 98,150/. as the result, and to this is added the cost of 

 funerals saved, 3,926 at 5/. each equal to 19,630/., or a 

 total saving of 531,375/ It would appear to us more 

 correct to leave out this last item, as the expense though 

 saved for the present must be regarded as a deferred 

 charge and must be incurred sooner or later. The works 

 having cost in this case 267,665/ there remains as a 

 dividend for the twenty years an amount in the aggregate 

 equal to nearly twice the capital. This in the days of 

 discarded gas and failing banks ought, unaided by the 

 arguments of zymotic disease, to persuade the ratepayer 

 to seek an investment in sanitarj- progress. 



A great number of very useful tables are embodied 

 in the text ; those of the velocity and flow in pipes and 

 sewers from p. 91 to 153 will be found of great service to- 

 the sanitary engineer, being calculated over a much 

 greater range than in other books on the subject, and 

 having been extended in the present edition. We should 

 suggest with reference to tables 29, 30, 31 that a very 

 useful addition to make in a future edition would be a 

 table of areas and hydraulic mean depths with other 

 fractional depths of flow besides one-third and one-half 

 full, and that the use of the velocity and discharge tables 

 would be facilitated by giving the corresponding fall in 

 feet per mile side by side with the given rate of inclina- 

 tion expressed in a numerical ratio. 



A chapter is devoted to the question of the admission 

 of rainfall into sewers ; the reasons for its exclusion as 

 far as practicable are stated to be (i) to increase the 

 manurial value of the sewage ; (2) to obviate the incon- 

 venience attending the purification of a large and uncer- 

 tain volume of sewage in times of rainfall ; and (3) to 

 give to the streams of the country the natural volume 

 of water due to the rainfall withiii their collecting area, 

 and the adoption of this course receives but partial 



