253 Journal Op the Department of AGRlcuL'ftJRE. 



prevent erosion and possible undermining behind them. Ideal waste 

 weirs are very seldom met with, and mostly a waste weir immediately 

 adjoin mg the earth bank must be made. The earth bank is then 

 rfiiried to a point where the ground surface is about 12 inches above 

 the full-supply level of the reservoir, and it then swings round and 

 ran i along the waste weir forming a lining wall. From this point 

 U.^ ground is excavated to a width corresponding with the length of 

 llii waste weir. The depth of the waste channel is level in the line 

 n the centre of the dam and above this line towards the reservoir. 

 i'h i down-stream side of the waste channel is excavated to a slope 

 of 1 in 100, and the bed of the down-stream channel is a little deeper 

 on the side farthest from the dam wall, in order to throw the current 

 away from the dam. The tendency of the flood water to flow down 

 the steep slope and probably damage the toe of the embankment is 

 checked by the above-mentioned lining wall extending for such a 

 'ength that the flood water cannot possibly harm the dam any more 

 see sketch-plan). The height of the lining wall must be such that 

 ne flood water cannot possibly top it. 



The pitching of the dam wall is carried round to the lining wall 

 .^nd all along the inner side of this wall. As a rush of water may 

 be expected round this point of the dam, the pitching is carried well 

 down into the ground resting on very large stones or on a mason wall 

 and is grouted or laid in a wire net with a 6-inch mesh. A better, 

 but more expensive, construction is to let the earth bank abut against 

 a wing wall carried down to good foundation. The lining wall is 

 then an extension of this wing wall on the down-stream side. The 

 roinarks made above with regard to the bed of the waste weir are 

 applicable here. 



It is not uncommon to see the flank waste weir excavated in 

 rock, and, though this is very expensive, it gives a very good waste 

 weir, and generally the rock so excavated can be used for the pitching. 



Export of Grain, etc. 



The following quantities of grain, etc., were exported during 

 January, 1921 (in bags): — Maize, 59,499 ; maize • meal, 33,020; 

 hominy chop, 4400; oats, 10,869; bran, 500; kaffir corn, 302; and 

 millet, 11; total, 108,601. 



The total number of bags exported for the seven months from 

 the 1st July, 1920, to 31st January, 1921, was: — Maize, 356,001; 

 maize meal, 254,054; maize flour, 1199; maize grit (rice), 3111; 

 h' miny chop, 52,716; kaffir corn, 966; oats, 12,006; beans, 1213; 

 jucerne seed, 366; millet, 11; bran, 500; total, 682,143 bags. 



The stocks in hand at all ports at 31st January, 1921, were (in 

 bags): — Maize, 97,322; maize meal, 22,650; oats, 451; rye, 498; 

 hominy chop, 275; kaffir corn, 200; total 121,396. 



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