MAN'S IMPROVEMENT OF HIS ENVIRONMENT 385 



Filter beds at Albany, N. Y. 



sewage from cities above them on the river has flowed. Filter- 

 ing such water by means of passing the water through settling 

 basins and sand filters removes about 98 per cent of the germs. The 

 result of drinking unfiltered and filtered water in certain large cities 

 is shown graph- 

 ically at right. 

 In cities which 

 drain their sewage 

 into rivers and 

 lakes, the question 

 of sewage disposal 

 is a large one, and 

 many cities now 

 have means of dis- 

 posing of their sew- 

 age in some man- 

 ner as to render it 

 harmless to their 

 neighbors. 



Railroads are often responsible for carrying typhoid and spread- 

 ing it. It is said that a recent outbreak of typhoid in Scranton, 

 Fa., was due to the fact that the excreta from a typhoid patient 

 traveling in a sleeping car was washed by rain into a reservoir near 

 which the train was passing. Railroads are thus seen to be great 

 open sewors. A sanitary car toilet is the only remedy. 



HUNTER, CIV. BI. 25 



Cases of typhoid per 100,000 inhabitants before filtering 

 water supply (solid) and after (shaded) in A, Water- 

 town, N.Y.; Z?, Albany, N . Y. ; C, Lawrence, Mass.: 

 D, Cincinnati, Ohio. What is the effect of filtering 

 the water supply ? 



