776 MAIZE 



CHAP, hitherto been very largely used in the construction of silos, on 

 XVI - account of the abundance of timber in that country and the 

 comparative ease and cheapness of erection, and wood is con- 

 sidered one of the best materials for the preservation of silage. 

 It is not likely, however, to be much used in South Africa, 

 on account of its scarcity and want of durability. 



For durability, either reinforced concrete, stone, or brick, 

 or a combination of these materials, is to be recommended. 

 Reinforced concrete is probably the best material, especially 

 for circular silos, but requires more skilled labour in the con- 

 struction, and is consequently more costly. Stone or brick 

 structures require less skill in building, and as either one or 

 other of these materials can usually be readily obtained 

 throughout South Africa, they are likely to enter more largely 

 into the construction of silos. 



Whatever material is used — whether concrete, stone, brick 

 or wood — the foundation should always be of some material 

 that is not subject to early decay, more particularly if it 

 extends for some depth below the surface of the ground. In 

 a dry soil a good quality of brick or stone built with lime 

 mortar is sufficient, but if there is a tendency to dampness, 

 either cement concrete or stone, built with cement mortar and 

 plastered on the outside with any damp-proof composition, 

 forms the best foundation. It is important that the founda- 

 tion should go down to a solid bottom, and it should extend 

 a few inches above the highest point of the ground, and be 

 covered on top with a damp-proof course to prevent moisture 

 from rising to the structure above. 



749. Reinforced Concrete. — The methods of building with 

 either brick or stone are too well known to everybody to require 

 any explanation, but concrete construction being less familiar, 

 a short description of the materials used and methods adopted 

 in the erection of reinforced concrete silos may be useful. The 

 walls, only, need to be described, as the foundations, floor, roof, 

 doors and other parts can be practically the same as for brick 

 or stone silos. The concrete should be composed of one part 

 best Portland cement, two parts clean sharp sand and four 

 parts stone broken to such a size as will pass through a ring of 

 1 inch diameter, all thoroughly mixed together to the proper 

 consistency with clean water. The reinforcement should con- 



