302 FARM BUILDINGS IN SOUTH AFRICA 



The temperature of the room is lowered, and kept low, by continuous 

 evaporation of some of the moisture in the walls and roof. 



The principle of evaporation for cooling purposes is not new, canvas 

 water-bags being familiar to all. This principle has also been applied 

 to household cupboards, built with canvas or Hessian walls, and supplied 

 with water from a paraffin tin standing on top. 



Around one such room, built in Australia, a frame-work carrying wire 

 netting, over which creeping plants can be trained, was erected a foot 

 or two away from the canvas walls and ceiling. The water is supplied 

 from a tank filled by a wind-mill, the surplus water which drains away 

 from the canvas roof and walls being used for irrigation purposes in 

 an adjoining garden. 



Protection of Buildings from Lightning 



The absolute protection from lightning of a corrugated iron building 

 is simple and inexpensive. All that is necessary is to insure good 

 metallic connection between the roofing iron and the iron of the walls, 

 and either to carry the iron sheets of the walls into the ground for 

 2 or 3 inches, or to provide a number of iron strips having their upper 

 ends metallically connected to the corrugated iron of the walls, and their 

 lower ends buried in the ground to a depth of at least one foot. Such 

 iron strips might be situated at each corner of the building and also, if 

 the size of the building calls for it, in intermediate positions such that 

 adjacent strips are not more than 30 feet apart. 



In the case of a stone, brick, or wooden building with an iron roof ; 

 if rain-water guttering and down-pipes are provided, the former should 

 be joined by metal to the corrugated iron of the roof at frequent intervals, 

 and the latter should have their lower ends electrically connected to the 

 earth by strips of iron metallically connected to the down-pipes and 

 having their lower ends extending at least one foot into the ground. If 

 no rain-water guttering and down-pipes are provided, the iron of the 

 roof should be connected with the ground by strips of iron, which should 

 be as straight as possible. For dwelling-houses of ordinary size, one iron 

 strip at each corner of the building will be sufficient. 



Buildings with thatched roofs can be protected by numerous barbed 

 wires metallically connected to the galvanised iron ridge capping of the 

 roof, carried down the sides and ends of the building (simply lying on 



