Failure of the Van Yean Reservoir. 



135 



This estimate is of great importance, as showing the exact 

 amoimt that may be saved by effectually withdrawing the 

 tributaries from the evaporation, and it may be absorption, of 

 the swamps. 



If the two feet five inches, therefore, can be saved, it may 

 be added to the five feet four and a half inches. 



The highest ordinary discharge may be computed thus — 

 the six summer months being taken at 2,537 g-allons per 

 minute, or three feet four inches, as measured by the com- 

 mittee in January. 





ft. 



in. 



Six summer montlis - - - 



1 



8 



Six winter months 



- 5 



^2 



Amount lost in swamps 



2 



5 



Total 



9 



5^ 



Deduct 900 gallons for district - 



- 1 



2 



Highest discharge of river 



8 



3i 



First estimate - - - - 



- 6 



7 



Balance in favour of 2nd estimate 



1 



Si 



Thus my first estimate amounted to six feet seven Inches 

 as the ordinary discharge of the river, so that this second or 

 highest estimate has an advantage of one foot eight and a 

 half inches over the first. It will therefore be seen that, 

 even allowing the river to be level with its banks for six 

 months in the year, for which we have no measurements to 

 guide us, still the result is ve^y little more favourable than 

 the first, and cannot with any certainty be depended on ; and 

 if one-third of the whole, instead of the scanty allowance of 

 900 gallons per minute, Avere left for the use of the district, 

 this highest average discharge would be reduced below my 

 former estimate. 



The Committee, who were appointed by the Society to 

 investigate the subject in a scientific manner, have arrived at 

 results very different from my own. They do not base their 

 conclusions on the measurements at all, which they profess to 

 disregard, but on theoretical principles, and on certain 

 calculations quite original, and apparently adapted to supply 

 any amount of water that may be required In this dry climate; 

 and they have determined that the discharge is three times 

 . greater than my estimate of eight feet. 



Thus, although Mr. Blackburn, who was Ignorant of the 



