NOVEMBEB 15, 1907] 



SCIENCE 



663 



moval of bacteria rests on the town drawing 

 water from streams rather than on the com- 

 munity which discharges a reasonable puri- 

 fied sewage into them. In chapter five he 

 points out the difficulty of securing good 

 ground water supplies in America and con- 

 trasts this condition with that which obtains 

 in northern Europe, particularly in Germany. 

 It is evident that the water supplies of the 

 United States must be drawn mainly from 

 rivers and in this connection the author might 

 well have emphasized somewhat more dis- 

 tinctly than he has done the modern dictum 

 of sanitary science that no surface supply can 

 be considered entirely safe for drinking with- 

 out preliminary treatment. Filtered river and 

 lake supplies must in the end offer the well- 

 nigh universal solution of the water problem. 



The question of tastes and odors in water is 

 particularly well treated. Their origin is dis- 

 cussed in chapter one, a clear distinction be- 

 ing made between the odors of putrefaction 

 produced at the bottom of reservoirs and the 

 odors caused by the growths of organisms at 

 their surface. The merits of stripping and of 

 the copper sulphate treatment are conserva- 

 tively handled and in chapter nine tlie re- 

 moval of tastes and odors by filtration and 

 aeration is discussed. 



The subject of water filtration in general 

 suffers a little, as pointed out above, by the 

 lack of preliminary general statements, but 

 the account of recent progress is excellent and 

 the discussion of the possibility of securing a 

 higher percentage purification than is ob- 

 tained by sand filters to-day is eminently sug- 

 gestive. Here, as elsewhere, the engineer can 

 furnish any results for which it is worth while 

 to pay. 



The last six chapters of the book must be 

 particularly commended; here, Mr. Hazen suc- 

 ceeds admirably in making complicated prob- 

 lems stand out clearly in their main outlines. 

 In chapter eleven the fundamental engineer- 

 ing principles underlying construction, with 

 its necessary allowance for excessive demands, 

 and in chapter twelve the problem of securing 

 adequate pressure, are excellently treated. 



Chapter thirteen contains a good statement 

 of the importance of metering water with a 



table which shows in a striking way the exces- 

 sive consumption, in the neighborhood of 200 

 gallons per capita per day, in the large cities 

 which have no meters, a wanton waste of 

 water which is cut down more than three 

 quarters by the installation of a considerable 

 proportion of metered services. 



Chapters fourteen and fifteen deal with the 

 financial aspects of the water-works problem. 

 Mr. Hazen estimates that the amount of 

 money spent on construction and maintenance 

 of water-works is no less than thirty millions 

 per year and that, of this, something like one 

 quarter is wasted by careless and inexpert 

 methods. The problem of securing pure and 

 wholesome water supply is a difficult one and 

 requires technical expert service of a high 

 grade. 



It might be shown how in some lines of work 

 the development is so rapid that even the most 

 recent text-books are hopelessly out of date; how 

 the subjects are becoming so complex that only 

 the principles and not the important details can 

 be treated in them; how the most efficient works 

 are designed by groups of men, each attending to 

 the parts which he best understands, and all under 

 the general direction of a chief who has a clear 

 idea of the end to be reached and the way of 

 reaching it, though he may know less of many of 

 the details than his subordinates; how the only 

 way to learn a business is to be brought up in it; 

 and how it can not be learned by a casual in- 

 spection from the outside. 



Mr. Hazen rightly pays a tribute to the 

 faithful, devoted and inadequately remuner- 

 ated work of water boards and water superin- 

 tendents at the present day, but his presenta- 

 tion makes it increasingly clear that the 

 water supply problem is one of the many 

 municipal questions which must be treated as 

 technical engineering problems demanding ex- 

 pert service, properly rewarded, and unfettered 

 by any demands other than those of economy 

 and efficiency. The attainment of these ends 

 will be furthered appreciably by a book so 

 excellent, in the main, as Mr. Hazen's. 



C.-E. A. WiNSLOw 



Die Ausgleichungsrechnung nach der Methods 

 der Kleinsien Quadrate. By F. E. Hel- 

 MERT, Director of the Eoyal Prussian Geo- 



