138 CANADIAN DAIRYING. 



SUB-EARTH SYSTEM. 



This plan is recommended by the Ontario Pro- 

 vincial Board of Health, and consists of a reservoir 

 large enough to hold the sewage for a day. This 

 reservoir or tank is divided so that the solids remain 

 in the first compartment and the liquid is siphoned 

 into the second. It is important to have a trap 

 between the tank and the factory in order to prevent 

 odors reaching the building. The liquid is drawn off, 

 as soon as the second compartment is filled, by means 

 of a plug or with an automatic flush valve, into com- 

 mon field tile laid about two feet in the ground, and 

 of sufficient number to hold all the liquid from the 

 tank. If the soil in which the tiles are laid is wet, it 

 will be necessary to drain it before placing the tile for 

 the reception of the sewage. The tile should be 

 placed at such a distance from the factory well that 

 there is no danger of polluting the water. 



FILTER-BED. , 



Where there is sufficient fall from the factory to a 

 point about three hundred feet away, the filter-bed 

 plan is to be recommended. In making such a bed 

 observe the following : 



i. Have tight connections between the gutter in 

 the factory and the drain leading to the bed, with a 

 trap between the two. Lay four or five-inch glazed 

 sewer tile, in as straight a line as possible, from the 

 factory to the filter-bed. These tiles should be 

 cemented at the joints and be laid below frost. At 



