46 THE POPULAR SCIENCE MONTHLY. 



elusions. Dr. Folsom, in the " Report of the State Board of Health of 

 Massachusetts for 1876," also attacks this branch of the question, re- 

 marking that " excessive dilution simply dhninishes the chances of 

 danger from any particular tumblerful." He here states a case of 

 transmission of disease in dilute sewage, to which special attention is 

 invited, as showing quite conclusively the fatal result ensuing from 

 reposing too great faith in the extermination of disease-germs by oxi- 

 dation, and of reducing the chances of transmitted disease by diffusion 

 of disease-germs through a large body of running water. Dr. Folsom 

 says : " The most striking case illustrating this law is one reported by 

 Dr. E. D. Mapother, of Dublin. Forty cases of typhoid fever occurred 

 in a liospital which received its supply from a river. The cause was 

 traced to some barracks tioenty-five miles higher up, from which ty- 

 phoidal dejections had been emptied through drains into the river." 



It would be easy to multiply authorities on this point. Suffice it to 

 say that this pernicious theory is happily exploded, and that the Second 

 English Rivers Pollution Commission publish conclusions, based on the 

 examination of some two thousand samples of water claimed to be 

 drinkable, condemning river-water because it is liable to contamination 

 from drainage of eidtivated land, towns, and manufactories. They 

 state that " the admixture of even a small quantity of these infected 

 discharges (of persons suffering from cholera or typhoid fever) with a 

 large volume of drinking-water, is sufficient for the propagation of 

 those diseases among persons using such water." The case related by 

 Dr. Folsom, previously quoted, as well as numberless others of a similar 

 sort, proves the accuracy of this conclusion. 



The English commissioners then classify potable waters as follows, 

 and, when we consider the high authority for this scale of "wholesome- 

 ness, it would seem that it should carry great weight with it. Though 

 often published before, it cannot be too frequently repeated : 



[1. Spring- water. 

 Wholesome. \ 2. Deep-well water. 



I 3. Upland surface-watar. 

 (Very palatable.) 

 c ( 4. Stored rain-water. 



IS C SP I CI O T ' S - 



( 5. Surface-water from cultivated land. 



(Moderately palatable.) 



T^ (6. River-water to which sewaG;e gets access. 



Dangerous. -^ ^ ^, „ „ ° ^ 



i 7. Shallow-well water. 



While wholesale river-pollution from any source is utterly inad- 

 missible on any sanitary grounds, so infinitesimal pollution by dilute 

 sewage, indirectly discharged into the water-course, is equally danger- 

 ous, and attended with sure though more remote fatal results, " espe- 

 daily if human excreta he present in any form ichatever.'''' The whole 

 subject is intimately connected, but it is to this latter point more 

 particularly that this paper leads, as touching the pollution of entire 



