276 FAEM BUILDINGS IN SOUTH AFRICA 



down-stream of the intercepting trap a foul air outlet pipe should take 

 off. This pipe may be attached to the end wall of the cow-byre, and 

 should be carried well above the eaves of the roof. Its upper end should 

 be protected by a wire balloon. In Fig. 208 a standard intercepting trap 

 is shown, fitted with a cleaning arm with air-tight plug, and a vent for the 

 foul air pipe. 



The sumps are shown with a concrete bottom, and 9-inch hard brick 

 walls rendered on the inside with cement mortar. They are provided 

 with a concrete top recessed to receive a stone or concrete slab cover, 

 though a cast-iron cover, as shown in Fig. 210, may be fitted if desired. 

 Each sump should have its bottom at least 18 inches below the centre- 

 line of the drain pipe leaving it, so as to trap solid manure and prevent 

 it from getting into the drain pipe. 



If the other end of the drain discharges freely in air into the liquid 

 manure tank, no special fresh air inlet will be required there. 



The drainage from other buildings should discharge into similar 

 sumps, connecting with the main drain. In Fig. 156a the sumps which 

 receive the piggery drainage are shown covered by iron gratings. 



The liquid manure tank, adjacent to the dung-stead, may be con- 

 structed entirely of concrete, or the walls may be built of hard-burned 

 bricks, rendered with cement plaster. From the tank the liquid manure 

 may be pumped, and distributed over the dung in the dung-stead so as 

 to improve the manurial value of the latter. Or, alternatively, the 

 liquid manure may be led over the land. The urine, as a rule, will 

 be sufficiently diluted for use for irrigating purposes, by the water used 

 in washing out the stock houses which finds its way into the drains. 



The only really satisfactory type of liquid manure pump is one 

 the working part of which consists of a number of cast-iron discs 

 attached at intervals to an endless chain (see Fig. 213). When the 

 pump is operated these discs pass upwards through the delivery pipe, 

 carrying between them the liquid to be elevated. This type of pump 

 has no valves to cause trouble by becoming choked. 



The dung may be confined to the dung-stead by dwarf walls. In 

 order to prevent the impoverishment of the manure by the action of 

 the weather, the ideal dung-stead should be roofed. It should also have 

 an impervious floor sloping towards, and draining into, the liquid 

 manure tank. Flies lay their eggs in the dung if they can gain access 

 to it, in fact heaps of stable manure are their favourite breeding places. 



