Failure of the Yan Yean Reservoir. 161 
necessarily restricted to the eastern arm of the Plenty, even 
supposing this source to be one on which we could at all 
times depend. 
In the report of the Select Committee already referred to, 
I find that Mr. Blackburn, after a careful survey of the Yarra, 
ascertained that at a distance of twenty-five miles from Mel- 
bourne there is a sufficient head in the river to supply the 
City on the gravitation principle. Mr. Christy has kindly 
estimated for me the cost of laying a thirty-six inch pipe for 
a distance of twenty-five miles, and it amounts to the enormous 
sum of £369,900. If therefore we are to bring our water into 
the City from this great distance, I think it will not be denied 
that it is far better to leave the eastern arm of the Plenty 
altogether, and go at once to the Yarra, where we shall have 
as much water as a thirty-six inch pipe can deliver, which I have 
no doubt would suffice for a population of at least 500,000. 
And it is also most important to bear in mind that a work 
of such magnitude would never have been thought of for a 
moment if it could have reached no further than the present 
wants of the City. The preference of the gravitation scheme 
was entirely based by the Commissioners on its supposed 
capability of supplying at least four times the present population 
of Melbourne, and on the facility with which it was believed 
that the works could at any time be indefinitely extended; 
and it was only very lately that Mr. Jackson, the engineer 
of the works, is reported to have made similar statements in a 
paper which he read before the Victorian Institute of Science. 
I shall take the liberty of quoting a paragraph from the news- 
paper report :—“ The numerous advantages of the Yan Yean 
Reservoir Scheme were pointed out; several interesting 
particulars were stated in the paper. The Yan Yean scheme 
it appears can be extended indefinitely, without any addition 
to the reservoir, so as to supply Melbourne with water even 
if it attained the population of London. It was suggested 
that the cheapest plan of supplying Geelong might be from 
the same source which is intended to supply Melbourne.” 
It is foreign to my purpose to discuss, in this paper, the 
opinions which Mr. Jackson has published on the subjects of 
which I have treated; but, as it eminently concerns the public 
to know the kind of data upon which the Commissioners base 
their extraordinary expectations of success, I shall add a few il- 
lustrations of the scientific views entertained by their engineer. 
Having disposed of Mr. Hodgkinson’s pumping scheme, and 
all other plans for supplying Melbourne and Williamstown 
s 
