244 DUST AND WATEE. 



selected. The same reasons apply with greater or less 

 force to every other available stream. 



The objection to the Hudson River supply is that 

 there is liability to sewage contamination, but to obviate 

 that the supply is taken at a considerable distance above 

 the city, and before delivery to consumers, the water is 

 subjected to filtration by passing the same through suc- 

 cessive layers of sand, which is subjected to constant 

 cleansing, and frequent renewals. 



It is well known that a chemical analysis of water does 

 not reveal the presence of bacteria, but merely determines 

 the quantity and quality of organic matter. The latter, 

 of course, may suggest sewage pollution, and that we 

 may assume means possibly, dangerous bacteria. So 

 far as we can be certain, the numerous bacteria found in 

 the water of the Hudson River are harmless. The vital 

 question is not how many bacteria, but what Mnd, and 

 if we assume that Hudson river water shows upon bac- 

 teriological examination, that their are neither the bacilli 

 of cholera, or typhoid fever, we may be reasonably sure 

 that the water is not unfit for use. 



Of course in the absence of a cholera epidemic in this 

 Hudson Valley, there is no danger of river contamina- 

 tion from that source. And so far as statistics go, they 

 certainly sustain the results of bacteriological examina- 

 tion, for the relative number of cases of typhoid fever to 

 the population, has declined since the introduction of 

 river water in the city of Poughkeepsie. The danger in 

 country places from contaminated wells is greater than 

 it is in this city. 



Even under the most adverse circumstances there is 

 some consolation in the fact that the bacillus typhosus, 

 while exceedingly tenacious of life in water, under 

 isolated conditions, does not thrive in the presence of 

 other bacteria. Then there is the uncertainty whether 

 in order to communicate typhoid fever, it is not neces- 



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