THE BACTERIA IN NATURAL WATERS 



11 



Works of Boston contained on the average during the 

 eleven years, 1893-1903, 220 bacteria per c.c, and the 

 effluent 179. In many indi\ddual months, and in some 

 whole years, the effluent contained more than the 

 influent. 



AVERAGE REDUCTION OF BACTERIA BY STORAGE AT 

 LONDON 



(Houston, 1909) 



The seasonal variations in the bacterial content of a 

 large pond or lake follow a somewhat different course 

 from those observed in a stream. Philbrick, in the 

 paper just cited, gives the figures tabulated below for 

 the Chestnut Hill Reservoir of the Metropolitan Water 

 Works (Boston). The averages are based on weekly 

 analyses covering the eleven years, 1893-1903. 



MONTHLY VARIATIONS IN BACTERIAL CONTENT OF 

 CHESTNUT HILL RESERVOIR, 1893-1903 



