Hygiene, dental and general . Sampling Stations Yearly Averages of Organisms Fig. 35.—Diagram showing the abundance of microorganisms at the various sam-pling stations. by simple and higher plants which grow in such a quantityas to almost clog the stream and furnish protective habita-tions for the millions of tiny animals which nature is usingin the purification process. The accompanying diagram shows the effect upon thestream produced by introducing the sewage effluent, whichcame in between sampling stations No. 1 and No. 2. The othersampling stations indicated in the diagram are approximatel
Hygiene, dental and general . Sampling Stations Yearly Averages of Organisms Fig. 35.—Diagram showing the abundance of microorganisms at the various sam-pling stations. by simple and higher plants which grow in such a quantityas to almost clog the stream and furnish protective habita-tions for the millions of tiny animals which nature is usingin the purification process. The accompanying diagram shows the effect upon thestream produced by introducing the sewage effluent, whichcame in between sampling stations No. 1 and No. 2. The othersampling stations indicated in the diagram are approximately WATER SUPPLY 239. Fig. 36.—This view of the stream taken near Sampling Station No. 4, on July21, 1915, shows how completely the higher acquatic plants fill this part of thestream in summer. These plants strain out the suspended matter and prevent thesmaller plants and animals from being carried down-stream. ;f ; ! _£=j 1 Fig. 37.—A corresponding view January 26, 1916, showing how differently thesame region appears under winter conditions and high-stream flow. The biologicalprocesses of purification are greatly reduced. There is greater dilution but lesspurification. 240 HYGIENE: DENTAL AND GENERAL the following distances below station No. 2: No. (3), 980feet, No. (3a), 2000 feet,. No. (4), 3650 feet, No. (5), 11,580feet, No. (6), 19,700 feet. The storage of water is a simple method of purification andis inexpensive except where there may be a high cost for reser-voir construction. Experiments indicate that all the diseasegerms usually die out in water which has been stored for amonth. In reservoir
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecthygiene, bookyear1920
