240 FARM BUILDINGS IN SOUTH AFRICA 



all round the tank, the legs of the V-shaped bars being kept in place by 

 the heavy hoop iron clips through which they pass. 



The concrete is deposited in layers 9 inches thick, that being the vertical 

 distance between adjacent horizontal f-inch rods, and on top of each 

 layer a f-inch horizontal rod is laid in the position shown in the 

 drawings, and tied with wire to the £-inch rods where it crosses them, 

 before proceeding with the next layer. These horizontal rods pass 

 right round the tank, crossing the outslope and the vertical wall at 

 the in-end of the tank at vertical intervals of 9 inches. The join 

 between any two separate days' work should always be grouted with 

 1 to 1 grout as already explained for the bottom, and great care should 

 be taken that all surfaces on which fresh concrete is to be laid are clean 

 and free from earth, which is apt to fall on them from the earthen sides 

 of the excavation. 



It will be noted that only alternate V-shaped rods run right to the 

 top of the walls, the others being shorter and bent over at the top to 

 anchor them securely. 



Any joints which are made should be as in Fig. 186, and the two 

 systems of £-inch and f-inch rods should be tied together with wire at 

 all points where they cross each other. 



It will generally be found that the moulds can be safely moved up 

 after allowing 24 hours for the concrete last laid to set. 



The concrete is put in rather wet and should be thoroughly 

 jogged into place with crow-bars to ensure that no blank spaces are 

 left in the mass. 



Plastering. — For plastering purposes the sand should be screened 

 through a No. 12 sieve, that which passes through the sieve being used. 

 The plaster consists of 1 part cement to 2 parts sand, and is applied 

 to an average thickness of £ inch, making up the thickness of the walls 

 to 6 inches. It may be finished off as smoothly as possible, except in 

 places on which the animals have to tread, which should be rough 

 finished by brushing over with a stiff brush while the surface is still 

 soft. Surfaces should be thoroughly wetted before plastering them. 



Capacity Scale. — The capacity of the tank at different depths has 

 been calculated, and the results are shown in Fig. 188 in the form of 

 a scale, which may be scribed on the side of the tank while the plaster 

 is still soft. The dimensions 3 feet 3f inches up to 6 feet f inch, supposed 

 to be measured vertically, give the positions of the respective horizontal 



