526 Reading-Course for Farmers. 



In all these cases in which the preliminary tank is used it must be 

 observed that while not necessary, it secures much better results to in- 

 troduce directly below the tank a receiving tank which operates at certain 

 intervals so that the sewage may be discharged onto the be, Is or ground 

 intermittently instead of in a more or less continuous small stream. The 

 reason for this is that if the sewage trickles out on a bed it is absorbed 

 immediately by that part of the bed nearest the inlet and the other parts 

 of the bed do not work. On the other hand, if the flow comes out on the 

 bed once a day, with a rush, the whole bed is covered, every part does its 

 share and no part is overburdened. This reasoning holds true equally 

 with furrows or with grass or with subsoil pipes. If the first tank holds 

 about one day's supply, 300 gallons, it should be about five feet long, three 

 feet wide and five feet deep, the extra depth being given to allow deposits 

 to take place. The intermediate tank might be circular, four feet in 

 diameter and four feet deep. This tank can be provided with an auto- 

 matic discharging siphon southat the tank will discliarge itself whenever 

 it gets full, or it may have a simple flat valve which can be lifted by hand 

 every morning as a regular duty of the farm. The area needed for the 

 artificial beds has been already mentioned. The area for natural beds 

 depends entirely on the quality of the soil. The hardest clays with only 

 three to four inches of top soil ought to have an area 100 feet/SC[uare for 

 every ten persons in the house. If the soil is porous and the discharge 

 takes place once a day, twenty-five feet square for each ten persons would 

 be enough. It is not possible to get too much land ready, and, on the 

 other hand, it is not difficult to add to the area prepared if the sewage 

 remains on the land in pools. The fundamental principle is to bring the 

 sewage in small infrequent quantities in contact with the surface part of 

 the soil, letting the bacteria act and so destroying the organic matter. 

 It should not be difficult with this in mind to arrange tanks and land 

 areas to bring about the desired result, viz., the disposal of the fouled 

 water in an efficient and wholesome fashion. 



