Febbuart 10, 1911] 



SCIENCE 



223 



periences in this country and abroad as re- 

 gards filtration in intermittent sand filters, 

 contact beds and trickling filters. 



The remaining chapters, pp. 375— i09, con- 

 tain first a full statement of the recent work 

 done in this country in the sterilization or 

 disinfection of sewage, with data as to the 

 efficiency and cost, while the book is concluded 

 with a brief summary of the main features of 

 sewage analysis with particular reference to 

 those tests of most benefit in practical opera- 

 tions. 



The book is very attractively written and is 

 well indexed. There are 113 figures illus- 

 trative of the various distinctive features of 

 the principal processes. The more one studies 

 the book the more apparent it is that there 

 has been a vast amount of study given to the 

 compilation of a wide fund of information so 

 as to embody it compactly for convenient ref- 

 erence. The book is free to an unusual extent 

 of statements to which exceptions will be 

 taken by experienced sanitarians. The prin- 

 cipal points on which there would be differ- 

 ences in opinion are in reference to the re- 

 sidual quantity of dissolved oxygen which 

 would be found in a stream into which sewage 

 has been discharged, and the disparaging 

 reference to automatic controlling devices for 

 the operation of contact beds. 



Taking the book as a whole, it may be 

 safely said that it will be of much assistance 

 in the class-room in teaching this subject to 

 students and especially to the public hygienist 

 desiring to get a general insight into the sub- 

 ject in its broader phases, with ample oppor- 

 tunity to ascertain where the various results 

 with different styles of plants have accom- 

 plished definitely recorded results. 



Geo. W. Fuller 



The Practise and Theory of the Injector. By 

 Strickland L. Kneass. Third edition, re- 

 vised and enlarged. New York and Lon- 

 don, John Wiley and Sons. 175 pages, 53 

 illustrations and diagrams. 

 This book possesses the great merit of hav- 

 ing been written by one who is a master of 

 his subject. It is no ordinary compilation; it 



is the reflection of a life work. Its author for 

 more than a quarter of a century has given 

 serious attention to the problem of perfecting 

 the injector. He has made it a part of his 

 business to study the fundamental principles 

 underlying its action, to conduct experiments 

 which would supply data with which to em- 

 bellish the theory, and to contribute to the 

 working out of actual designs which from time 

 to time have become the standards of a great 

 manufacturing company; yet such is his 

 modesty that nothing which is printed sug- 

 gests his personal activity in the development 

 of the instruments he describes. The book 

 presents in logical order the fascinating story 

 of the development of the steam injector, an 

 instrument which serves to feed water to a 

 steam boiler through the action of a jet of 

 steam drawn from the boiler which is fed. In 

 the language of the book, " ' its mode of ac- 

 tion, extraordinary in appearance, contrary to 

 that which we are in the habit of seeing or 

 supposing, is explained by the simplest laws 

 of mechanics and has been foreseen and cal- 

 culated in advance.' " The book is interesting 

 throughout because its story is well told. It 

 deals with a subject which can not be freed 

 from mathematical theory, in a manner which 

 is sufficiently complete to satisfy the most 

 fastidious lover of equations, and yet the 

 work is so admirably arranged that no one who 

 is interested in the subject is likely to find 

 difficulty in reading it. 



The introductory chapter on the early his- 

 tory of the development of the injector, from 

 which the lines quoted above were taken, is 

 chiefly a story of the achievements of Henri 

 Jacques Giffard, who as early as 1850 had 

 succeeded in developing the principles under- 

 lying the design of the present-day instru- 

 ment. The injector, as a device for feeding 

 boilers, was introduced into England in 1859, 

 and into this country by William Sellers and 

 Company the following year. The story of a 

 demonstration of its action in England by one 

 who had received a sample instrument from 

 France is graphically told as follows : 



I set to work at once, and by good luck coupled 

 up the correct pipes to their proper flanges, but 



