June 12, 1914] 



SCIENCE 



873 



volume is not intended to be exhaustive. It 

 is such a statement of the essential principles 

 of American water purification practise as 

 Mr. Hazen's large experience as a consulting 

 engineer in this field has led him to believe 

 "would be useful to beginners. There is no 

 better text-book for persons desiring a knowl- 

 edge of water purification in the United 

 States. 



There are eighteen chapters in Mr. Hazen's 

 book, including such topics as water supplies 

 from rivers, lakes and wells; the history of 

 water purification in the United States; stor- 

 age of filtered water; use and measurement 

 of water; suitable pressure to be supplied in 

 water works systems; effect of iron pipes on 

 water, and the layout of works. The subjects 

 dealt with include sand filters, mechanical 

 filters, coagulation basins and aeration. 



The book is well-illustrated with half-tones 

 and is produced with the usual excellence of 

 the Wiley press. The first edition, published 

 seven years ago, has been revised and ex- 

 panded. 



Houston, the bacteriologist and director of 

 water examination of the Metropolitan 

 Water Board of London, has produced a book 

 in which he has explained his views as to the 

 extent of the danger to be apprehended from 

 polluted river water and how that danger is 

 avoided without filtration by London, the 

 largest and one of the healthiest cities in the 

 world. 



The American arguments which have been 

 built up without opposition in the last twenty 

 years and which seek to account for much of 

 the excessive prevalence of typhoid in Ameri- 

 can cities as caused by polluted surface water 

 are declared to be inconclusive and not in con- 

 sonance with ascertainable facts. 



Dr. Houston maintains that a watershed 

 may be exposed to manifold pollution and the 

 river draining from it impure, as judged by 

 ordinary chemical and bacterial tests, but the 

 water may nevertheless be shown to contain 

 none, or scarcely any, of the microbes of 

 water-borne diseases when tested by methods 

 of proved value. 



The American theory to the effect thait the 



incidence of tuberculosis, pneumonia and 

 other diseases not otherwise suspected of be- 

 ing water-borne can be greatly reduced by im- 

 proving a public water supply is incredible to 

 Dr. Houston. 



The book is actually, but not formally, di- 

 vided into two parts : The first tends to free 

 the River Thames and the River Lee, which 

 supply London with 80 per cent, of its drink- 

 ing water, from the full gravity of the charge 

 of being sewage-polluted rivers, and the sec- 

 ond presents evidence that the self -purification 

 process employed by London to prepare the 

 water for consumption is uniformly efficient. 

 There are eleven short chapters. The topics 

 include water and disease; the financial value 

 of pure water; sterilization processes; storage 

 in relation to purification; the question of 

 abstraction; sources of water; bacterial meth- 

 ods and much information about the remark- 

 able water supplies for London over whose 

 quality the author has had ofiScial supervision 

 for many years. 



George A. Soper 



New York City 



Studies in Seeds and Fruits. An Investiga- 

 tion with the Balance. H. B. Guppy. Lon- 

 don : Williams and Norgate. 1912. Pp. 

 xii + 528. 



A careful reading of the research work, de- 

 tailed in this volume, has abundantly repaid 

 the reviewer. Guppy commenced the inves- 

 tigation, as a study of the rest-period of seeds, 

 using in his research merely a sharp knife, 

 pocket lens, balance and oven. The first chap- 

 ter details the history of the investigation. 

 The second chapter describes the three condi- 

 tions of the seed, viz., the soft pre-resting 

 seed, the contrasted, hard-resting seed and the 

 soft, swollen seed on the eve of germination. 

 Observations by means of the balance are 

 made on seeds in all three of these stages. The 

 third chapter is concerned with the imperme- 

 ability of seeds and its significance, the fifth 

 is a classification of seeds according to their 

 permeability, or impermeability, while the 

 sixth chapter gives additional evidence. The 

 whole book is full of tables and is loaded with 



