The Mechanical Handling and Storing of Material

THE WAREHOUSING OF GRAIN 669 to the use of such material are—its weight, the consequent necessity for stronger foundations, and the need for making the divisions thicker than when using wood. Iron has the distinct advantage that the silo walls can be thinner than in the case of any other material, but its non-absorbent nature, and the fact that it is a good con- ductor of heat, curtail its use for this purpose, as it transmits to the grain every change in temperature, and therefore causes condensation against the silo walls, with the consequent formation of rust and mould. Fig. 942. Collapse of Encl Wall of Silos at Isleworth. Ferro-concrete is the material most largely used at the present day. If well constructed, no detriment will be caused to the structure through uneven expansion of the material. The first type was probably the Monier, followed by the Hennebique, and constructed of an iron or steel framework filled in with concrete, whilst the most modern construction consists of steel rods embedded in cement. In the case of silo walls constructed of brickwork, these should be built in cement and not used until they are thoroughly set, or better still, hoop iron should be built in, at least at the end walls. Fig. 942 shows the results of non-observance of this rule.