228 FARM BUILDINGS IN SOUTH AFRICA 



is left open round the eaves, and is provided with a ventilator, at 

 the peak, made of plain galvanised iron sheeting as shown. It may be 

 advisable to net in the eaves with ordinary wire-netting, to prevent 

 birds from nesting there. 



Filling Door. — The arrangement of the filling door is much the same 

 as that of the door already described for a stone silo, and no further 

 description of how to erect it, and the roof which covers it, is necessary, 

 especially if the drawings be closely studied. 



Emptying Chute. — The emptying chute is the same as that already 

 described for a stone silo, which description may be referred to. 



Materials Required. — The amounts of cement, sand, and broken stone 

 required for this silo have been worked out in Chapter XXVI; they 

 are : 47 casks (or 94 bags) cement, 13£ cubic yards sand, 26^ cubic yards 

 broken stone. 1:2:4 concrete is used. 



Only the best of materials should be used. The sand should be quite 

 clean, and should contain a large proportion of coarse grains. The 

 broken stone should be small enough to pass a f-inch mesh, and should 

 be retained on a £-inch mesh. 



The amounts of other materials required can be readily estimated from 

 the drawings. 



