1886.] Va?i Wyk's Vlei Reservoir. 223 



placing of a layer on the face of the inner slope, immediately below 

 the pitching. This method can certainly not do much harm, but it is 

 doubtful if it does much good, at all events for banks of any great 

 height, for in this hot climate, when the water in the reservoir is low 

 the paddle is liable to crack and this materially affects its usefulness. 



Another plan is to construct a puddle wall in the centre of the bank, 

 continuing it down till the rock or an impermeable strata is reached. 

 This was the method adopted here. The use of this puddle wall is to 

 prevent as far as possible a leakage of water through the bank, which 

 might prove dangerous to its safety, and which is generally caused by 

 bad workmanship, use of permeable material or the burrowing of crabs 

 , and mice. 



Most people know what the meaning of puddle is, but for the 

 benefit of those who do not, the following description may be useful. 

 The material used is clay, freed from roots, stones and dirt. When 

 made by hand, it is mixed with water, cut up and worked with spades, 

 well tramped and kneaded until it is of the consistency of putty. 

 It was made in this manner for Van Wyk's Vley reservoir. If the 

 clay is pure, as much sand may be mixed with it as is consistent with 

 its holding water, for if there be too little sand it is liable to crack in 

 dry weather. This would more particularly apply to puddle laid on 

 the slope than to that in the centre of a bank. If too much sand is 

 used the puddle will become porous and therefore useless for the 

 purpose for which it is required. 



After the puddle was made, it was brought on to the bank in carts 

 drawn by mules, which were found to be much better than bullocks or 

 donkeys for this part of the work, and then spread in horizontal 

 layers about 9 inches thick, well beaten down to the preceding layer, 

 which was first thoroughly wetted, so that the layers would 

 amalgamate together. 



Each layer as far as possible was carried the entire length of the 

 bank at once, but where this could not be done steps, of a thickness of 

 one layer, were left so that a proper junction could easily be made. 



The forming of the bank and the puddle core were carried on 

 simultaneously in the following manner. When a layer of puddle 

 was finished, it was allowed to dry till it was sufficiently stiff to bear 

 the pressure of the earth placed alongside it. This was brought on in 

 mule carts, while the bullock and donkey carts were worked towards 

 the outside of the bank. This way of working was necessary because 

 bullocks and donkeys cannot be guided so well as mules or horses, and 



