FUTILITY OF A SANITARY WATER ANALYSIS 51 



natural drainage from occupied land is not always innocuous; but 

 when this is combined with those direct and generally surreptitious 

 pollutions, the effect is sometimes more acute than that produced by 

 the everyday discharges from a city sewer. It will be necessary merely 

 to recall the history of some of our classic typhoid epidemics to dem- 

 onstrate this. The Plymouth, Pa., epidemic was caused by a single 

 focus of infection upon a sparsely settled drainage area. The New 

 Haven epidemic arose from a similar cause, and upon a drainage 

 area not only sparsely settled, but supposedly well protected. It 

 is especially significant, too, that the Lowell and Lawrence epidemics 

 did not have as their immediate cause the infected sewage from cities 

 above on the Merrimack, but, as shown by Professor Sedgwick, 

 from one or two incidental pollutions of Stony Brook. The same 

 principles apply forcibly to the more recent epidemics at Butler, 

 Pa., and Ithaca, N. Y. These remarkable instances illustrate the 

 dangers of surface-water drainage from sparsely settled countries; 

 it is obviously unnecessary to discuss similar dangers from water 

 into which city sewage is poured. The question whether a river 

 water will purify itself from such discharges in a given distance 

 below a sewer outlet does not enter even remotely into this considera- 

 tion, for, assuming that the sewage discharges would be purified, 

 the incidental pollutions above a water intake would still constitute 

 a grave danger. In the case of the Lowell and Lawrence epidemics, 

 for example, perfect sewage purification at Manchester, Concord, 

 and other cities on the Merrimack above the Lowell intake would 

 not have prevented the scourge of typhoid. Therefore it is contended 

 that, if we accept the principle that no surface-water draining from 

 an inhabited area is safe in its raw state for domestic consumption, 

 we shall err, if we err at all, upon the safe side, and there is no 

 question that we shall save lives. What, then, is the necessity for 

 analyzing river water for pollution, if we are all agreed that it must 

 inevitably be polluted ? 



Upland conserved supplies present a different phase of the ques- 

 tion. If a drainage area contributing to a reservoir is in primeval 

 condition with respect to population, it is generally admitted that the 

 water must be wholesome. Why, then, make sanitary analyses 

 to determine the presence of sewage? If it be contended that this 



