Irrigation on the Orange River. 77 



crosses its course nearly at right angles, and it is here, in a rocky- 

 pool some 200 yards from the main stream, that the intake of the 

 water is made. 



Above this pool a small hill rises and protects a shelf of ground a 

 couple of acres in extent, and 6 feet below the general level of the 

 irrigable. Here two shafts have been sunk 60 feet deep and 8 feet 

 in diameter, lined with hammer-dressed stone, and above each shaft 

 is a wooden frame carrying a double " Noria " pump. 



Now any attempt to supply these shafts from the river by means 

 of a level tunnel, whether open or by pipes laid there below the 

 minimum river, would soon be frustrated by being silted up, so to 

 obviate this an incline tunnel was driven from a point in one shaft 

 15 feet above minimum, and issuing from the bank of the river 

 into a rocky pool 2 feet above low water. I should mention that 

 this pool is supplied from up-stream, where the river runs sharply 

 across a basaltic dyke ; no matter how low the river may be, the 

 minimum level of this pool is constant. 



In the inclined tunnel a syphon is laid, as shown, and by exhaust- 

 ing this syphon the water enters the pumping shafts and rises to the 

 level of the pool. 



The two shafts are in communication at the bottom by means of 

 31, connecting drift 2 feet 6 inches wide and 4 feet high, so that it 

 and the shafts can be easily cleaned from any silt that may 

 accumulate. During the past season, however, while the pumps 

 were running the rush of water from the syphon and the churning 

 action of the " Noria " buckets showed that very little cleaning up 

 of the shafts would ever be necessary. By opening the exhaust of 

 the syphon a thorough flushing is given to the pipe, which prevents 

 the slightest chance of its clogging up, even at the muddiest state of 

 the river. In practice we flush the syphon once a day, when the 

 river is very dirty, and find this quite sufficient. 



It would appear that this simple system is well worth the notice 

 of riparian owners, as I am convinced it embodies a means which 

 many might avail themselves of to great advantage. 



The two double "Noria" pumps and syphon exhaust pump are 

 driven from a counter-shaft actuated by an 18-b.h.p. oil engine. 

 There are a pair of these engines, so that in droughty times there is 

 no delay in pumping while an engine is being cleaned up. The 

 plant is so arranged that other shafts may be sunk and other pumps 

 and power added in proportion as the land is brought under cultiva- 

 tion, and the whole system supplied by the one syphon common to 

 all the shafts. 



The pumps discharge the water into a stout galvanised trough 



