272 PURIFICATION OF PUBLIC WATER SUPPLIES. 



date attempted by some means to artificially improve 

 the quality of the water. Of these 94 were but crude 

 attempts to remove the coarser particles in suspension 

 by means of boxes or cribs placed at the intake and 

 filled with stones and gravel, sometimes adding char- 

 coal, and sometimes sjDonge, or even screens of cloth; 

 beds or banks of sand are used in some cases, but with 

 no provision for cleaning, regulation or intelligent con- 

 trol. Thirty-four use a slow, natural filtration by means 

 of wells and infiltration gaileries eicavrjtsd I:, a, porous 

 stratum near a river bank. 



There remained, therefore, in 1890 but slxty-faur mu- 

 nicipal supplies of which it could be said, strictly speak- 

 ing, that intelligent efforts were made for the artificial 

 purification of the water. 



That water may be strongly offensive to the senses 

 and produce no ill effects upon health finds a marked 

 illustration in an investigation conducted by Prof. A. 

 R. Leeds, in relation to the water supplied to the city of 

 Philadelphia, in January, 1883, from the Schuylkill 

 River, which at that time was covered with ice and ex- 

 tremely offensive to smell and taste, the odor being in 

 some instances communicated to the food cooked therein, 

 and gases were evolved sufficient to be ignited. After 

 discussing the causes, etc., Prof. Leeds says: " Letters 

 addressed to eminent physicians in Philadelphia elicited 

 the uniform response that no connection could be es- 

 tablished between the character of Schuylkill water 

 supply in the month of January and any case of disease 

 within their practice." Many forms of algse growths, 

 under certain conditions, impart a very disagreeable 

 odor and taste to water, yet they are usually regarded as 

 having no tendency to produce disease. On the other 

 hand a clear mountain stream has been known to scatter 

 the seeds of suffering and death through an entire com- 

 munity. 



210 



