Failure of the Yan Yean Reservoir. 157 
It also appears that the immense extent of the reservoir, 
which has always been regarded as its greatest advantage, is 
in reality so serious an evil as to involve the failure of the 
whole scheme. 
It is quite clear that the difference between the amount of 
rain and evaporation will represent the amount of loss depend- 
ing upon the wide extent of the surface exposed. This 
difference is six feet, and is equal to nearly twice the whole 
discharge of the river, as measured by your Committee, above 
Yan Yean, and is nearly equal to Mr. Blackburn’s estimate 
of all the tributaries above the swamps. The whole amount 
thus lost by evaporation in the reservoir, or nine feet, being 
sufficient to supply a population of 245,500, at the rate of 
forty gallons per head per day, or 491,000 at twenty gallons, 
which is equal to a loss of 9,820,000 gallons of water per day. 
With an unlimited supply of water this immense loss would 
have signified little, but when the sources of supply are so 
remarkably inadequate, the case presents a very different 
aspect. 
The foregoing considerations afford no prospect whatever 
of success to the Yan Yean scheme with the existing sources 
of supply, but it has always been regarded as capable of inde- 
finite extension from other sources. It becomes necessary, 
therefore, to consider this part of the subject, in order to ascer- 
tain how far it may be possible, or practicable, to supplement 
the reservoir, and thus render it equal to supply, not only 
the present wants of the City, but a large prospective increase 
of population. 
For this purpose it has been proposed to bring the Merri 
Creek, the Diamond Creek, the King Parrot Creek, and even 
the Goulburn River itself, into the reservoir. 
With regard to the Goulburn River, if it were practicable 
to bring it ints the reservoir, by means of an aqueduct, and 
if the expense of such an undertaking would not be beyond 
the means of the colony, there cannot be a doubt that this 
would render the Yan Yean scheme eminently successful, and 
Melbourne might then boast of being better supplied on the 
gravitation principle than any other city in the world. 
I feel incompetent to give an opinion in a case involving so 
many difficult questions, and that could only be determined 
by experienced engineers, after complete surveys of the 
intermediate country; but it appears to me, independently of 
the expense, which would be enormous, to be altogether 
chimerical. The great dividing granite ranges, which must 
