Failure of the Yan Yean Reservoir. 155 
land. This is well exemplified in Melbourne, where we have 
many showers of rain which do not extend ten miles out of town. 
I have allowed four inches for dew over the whole basin of 
the Plenty, an amount of water which would give eight feet 
eight inches in the reservoir; although it is very probable, in 
this dry climate; that there may not be two inches; and I 
have allowed two inches for the reservoir, without any scien- 
tific data to show that dew would be deposited at all; and, 
from an estimate which I have made of the whole watershed 
of the Plenty, based on scientific data, it appears that I have 
given the reservoir the advantage of nearly the whole amount. 
And, what is of greater importance than all else, I have 
deducted nothing from the supply of ordinary seasons on ac- 
count of droughts, of which we have had ample and painful 
experience in other parts of Australia; and a gentleman, who 
has recently returned from Adelaide, has told me that they 
have scarcely had any rain there for the last eighteen months. 
I must not omit to mention here, that it is intended to have 
two intermediate reservoirs betwixt Melbourne and Yan 
Yean,—the one at Pentridge, the other near the Plough Inn. 
Your Committee requested information respecting their extent 
of surface, with a view to determine the amount of loss from 
evaporation, but they were refused all information on the 
subject. I have, therefore, been unable in my estimate to 
make the necessary deduction for their evaporation. 
T shall only further add, in support of my statement that 
ample justice has been done to all the sources of supply, tha 
while I place implicit confidence in Mr. Hodgkinson’s opinion 
respecting the retentive nature of the bottom of the reservoir, 
there are not wanting others, who have had great experience in 
this colony, who think that the chances are very great indeed 
that in some parts of the vast extent of the reservoir, the 
water will find its way through the fissures of the clay slate 
to a lower level. I need not say there is no remedy in such 
acase. £2,000,000 would not suffice to puddle a surface of 
7,000,000 square yards. 
When this scheme was first proposed, I felt astonished to 
think that the Plenty could supply so much water as was 
alleged. I imagined, however, that the deficiency might 
robably be made up by the winter rains over an extensive 
district. And although I considered this a very objectionable 
source, I entertained the hope, that with a depth of 25 feet, 
and a current established through the reservoir by means of 
the river, and with a perfect system of filtration, the water 
