136 Failure of the Fan Yean Reservoir. 



enormous evaporation in this colony, supposing it to be about 

 three feet, only calculated upon a certain supply for 150,000 

 individuals, they, admitting nine feet of evaporation, which 

 is equal to an annual loss of water that would supply 327,000 

 at thirty gallons per head per day, find that there is still 

 sufficient left for a population of 666,000, and very gene- 

 rously leaving one half of this enormous amount for the use 

 of the district, they regard the reservoir scheme as adequate 

 to supply 333,000. Had Mr. Blackburn been spared, how 

 rejoiced he would have been to find his favourite scheme so 

 singularly developed in so short a time. This appears to be 

 another illustration of the wonderful powers of unlimited 

 extension attributed to the Yan Yean scheme. 



The proportion of the Committee's estimate would stand 

 thus : 3,000 gallons per minute for the six summer months, 

 15,000 gallons per minute for three of the winter months, 

 and 48,000 gallons per minute for the other three winter 

 months. 



These large amounts are of course intended to include 

 floods, but as I have elsewhere shown that in some seasons 

 we may have no floods at all, and that the very highest flood, 

 supposing it to last seventy-two hours, would only amount to 

 three feet in the reservoir, or less than one-eighth of the 

 whole, the above figures may be regarded as substantially 

 correct. 



It is a source of great regret to me that my estimate is so 

 much at variance with that of the Committee appointed by 

 the Society, but a thorough conviction that they are in error 

 compels me to call in question the result of their investiga- 

 tions, and to discuss at some length their mode of reasoning 

 on the subject. 



And here it is necessary to state that the Committee^ at 

 present consists of only two members, Mr. Christy, civil 

 eno-ineer, and Mr. Acheson of the Survey Department. 



As orio:inally appointed, the Committee contained the names 

 of Mr. Wekey, the honorary secretary of the Society, and 

 Mr. Hodgkinson, of the Survey Department, who, from his 

 OTckt practical knowledge, and long experience in the colony, 

 and having already devoted much attention to the whole 

 subject of the water supply of the city, was pecuharly fitted 

 to aid their labours. 



The former withdrew on finding, after mature deliberation, 

 that he could not reconcile his own opinions and calculations 



