60 



IRRIGATION. 



form, and may be of galvanized iron, of zinc, lead, or 

 wrought iron, or of hard brick laid in cement. The dis- 

 charge pipe may be of cast iron. This form of tank 

 has been found to work with the greatest ease ; two quarts 

 of water suddenly discharged into it when full being suf- 

 ficient to set the flush into operation. This apparatus 

 consists of the cylindrical tank, A, with a trapped inlet, 



Fig. 25. SELF-DISCHABGING SLOP-TANK. 



which also forms a movable cover to give access to the 

 inside of the tank. The pipe from the sink discharges 

 over the grating of the inlet, B, as shown in the figure. 

 A socket, c, is prepared for a ventilating pipe. There is 

 also the siphon, D, and what is called the "discharging 

 trough,"/, consisting of a small chamber made to turn 

 round, so that its mouth may be set in the direction that 





