224 



SCIENCE. 



[N. S. Vol. XVI. No. 397. 



hours, and 27.5 meters away in 7 hours ;* 

 showing what we started out to say, that the 

 soil cannot be depended upon to hold back all 

 the organisms from wells, and certainly not 

 when in dangerous proximity to barnyards 

 and privies; moreover, the above typhoid fe- 

 ver statistics appear to fully warrant this con- 

 clusion. As regards the belief in dangers 

 from damp cellars, the writer is of the opin- 

 ion that this fear on the part of the more in- 

 telligent of the human race is well founded. 

 Damp cellars usually mean damp walls and 

 dampness of the air of the house ; this not only 

 leads to undue abstraction of animal heat and 

 lowers the vitality of the inmates, but also 

 influences the cutaneous functions and favors 

 the development of catarrhal and rheumatic 

 affections, and a bronchial catarrh thus pro- 

 duced renders the mucosa vulnerable to the 

 invasion of tubercle bacillus. This would ap- 

 pear to explain the undue prevalence of con- 

 sumption in some of the damp prisons, the 

 relation between dampness of soils and con- 

 sumption, as first pointed out by Bowditch 

 and Buchanan, and the good effects of drain- 

 age in the reduction of consumption. In spite 

 of these differences of opinion, we predict that 

 Professor Sedgwick's hope that his book may 

 find a useful place in sanitary edvication, both 

 professional and popular, will be fully realized. 

 Professor Mason's book on 'Water Supply' 

 has reached the third edition since 1896, and 

 is well and favorably known. The book is 

 divided into eleven chapters, dealing with the 

 history of water supplies, drinking water and 

 disease, artificial purification of water, nat- 

 ural purification of water, rain, ice and snow, 

 river and stream water, stored water, ground 

 water, deep-seated water, quantity of per cap- 

 ita daily supply, action of water upon metals. 

 The appendix deals with analysis of city water 

 supplies, tjTphoid fever death rates for Amer- 

 ican and European cities, effects of contami- 

 nated water upon fish, use of sea water for 

 street washing, sewer flushing, etc. It is an 

 excellent work from a sanitary standpoint, 

 and will continue to enjoy its present pop- 



* Zeitschrift f. Byg., Vol. XX., p. 66 ; see also 

 Professor Pfuhl's experiments in the same jour- 

 nal for 1897, p. 549. 



ularity. The chapters on the ' chemical and 

 bacteriological examination of water' have 

 been omitted from the present edition, as they 

 have been published in a separate book for the 

 more convenient use of students. 



Professor Horrock's book, an introduction 

 to the bacteriological examination of water, 

 will be a welcome addition to the working li- 

 brary of the sanitarian. While assuming a 

 knowledge of elementary bacteriology, the au- 

 thor in Chapter I. gives directions for the col- 

 lection of samples, followed in Chapter II. 

 by the method pursued in qualitative bacte- 

 riological analyses and the preparation of 

 water plates. The next chapter deals with 

 multiplication of the water microorganisms, 

 the inflvience of light, rest and movement, sed- 

 imentation, chemical conditions upon the du- 

 ration of bacterial life, and the action of 

 electricity on bacteria. Chapter IV. considers 

 the bacterial contents of snow, ice, hail and 

 rain, and of waters from rivers, lakes, wells 

 and springs. We quite agree with him and 

 Mace that the number of microorganisms 

 present does not give any accurate informa- 

 tion as to the value of a water, for it is after 

 all the character of the germs which concerns 

 us most, at the same time Mace suggests the 

 following classification, based upon a long se- 

 ries of examinations : 



Microorganisms per (-.c^ 

 Very good water contains from 0- .50 



Good 

 Mediocre 

 Bad 

 Very bad 



50- 500 



500- 3,000 



3,000- 10,000 



10,000-100,000 



Chapter V. contains a very satisfactory 

 presentation of the action of sand filters in 

 the elimination of bacteria, which he consid- 

 ers, like most authors, as partly mechanical 

 and partly vital. 



Chapters VI. to XV. are devoted to the 

 qualitative bacteriological analyses of water 

 and constitute the most valuable part of the 

 book to the student. Chapter XV. describes, 

 the mode of action and utility of the Pasteur, 

 Chamberland and Berkefeld filters and the 

 methods of testing water filters, and the final 

 chapter gives a summary of the procedure rec- 

 ommended for the bacteriological examination 

 of water and preparation of nutrient media. 



