232 



FARM BUILDINGS IN SOUTH AFKICA 



be rigid and, in order to prevent adherence to the concrete, their faces 

 should be given a coat of whitewash each time they are moved upwards, 

 preparatory to being refilled. The top of the form illustrated by Fig. 181 

 should be truly level when the form is set in position, so that we get 

 a fair start with the form shown in Fig. 182. The latter form is provided 



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Fig. 183. — Section between piers. 



with bolts. The upper row of bolts will leave holes in the concrete, 

 which serve to receive the lower row of bolts when the form is moved 

 up for the next fill. The bolts should be greased, so that they can be 

 easily withdrawn from the concrete ; the holes left by the bolts in the 

 walls of the tank should be filled in, as soon as possible, with 1 : 2 



