MISCELLANEOUS. 



453 



structed for from $15 to $20. The great danger 

 from the cess-pool lies in the contamination of the 

 water supply if secured from wells in the vicinity. 

 Grease is also apt to collect upon the wall and pre- 

 vent the liquids from seeping through. Often lye is 

 used for dissolving this grease and overcomes the dif- 

 ficulty. The solids settle in the cess-pool, and must 

 be removed at stated intervals, perhaps once in two 

 years. 



The Septic Tank. If the sewage is carried into a 

 large reservoir where it may be allowed to remain for 



SECTION THROUGH SEPTIC TANK 



IV I TH FILTER .BED, 



some time, it is purified by bacterial action. There 

 is one kind of bacteria which attacks the solids of the 

 sewage and causes them to decay if the sewage is al- 

 lowed to remain in a quiet dark reservoir for a short 

 time. This action causes the sewage to clarify and 

 the insoluble parts to settle to the bottom of the tank. 

 The purified sewage may be led anywhere to water a 

 garden or a field without any danger of contamina- 

 tion. The flow of the sewage into the septic tank, 

 the name given to the reservoir, should be as quiet 

 as possible so as not to disturb the bacterial action. 

 For this reason, low partitions are placed across 

 the tank, over which the sewage must pass in a thin 

 stream. 



The Filter Bed System. The bacterial action may 

 be accomplished in another way by allowing the sew- 

 age after settling in a tank to be discharged at inter- 



