162 



ALEX. L. DU TOIT. 



The map has been plotted to show grains per gallon, and 

 in compiling it the high values from certain shallow bores, 

 as well as from some deeper ones, have been rejected, the 

 inclusion of which would prejudice the meteoric aspect 

 somewhat. The lines of equal salinity should be considered 

 in relation to the movement of the water as inferred from 

 the courses of the isopotentials (see Diagram IV). It might 

 be observed also that, when the amounts of sodic carbonate 

 were plotted in a similar manner, there was generally more 

 uniformity exhibited in regard to the quantities dissolved 

 and their distribution. 



The conclusions from the variation in the chlorine con- 

 tent are as follows: — The water entering at the high 



Diagram IV. — Isopotentials for 1912; the figures represent hundreds of 

 feet above sea-level. 



