112 Failure of the Yan Yean Reservoir. 
bourne with water, or the great importance of the interests 
involved in the probable success or failure of this under- 
taking, the subject, I think, is one which merits the atten- 
tion of the members of the Philosophical Society. 
The gravitation system has, of late years, been very much 
adopted wherever it has been found practicable; because, 
although the first cost may be great, it possesses the advan- 
tage of a constant supply of water, at a high pressure, and at 
a comparatively small annual expenditure. 
It becomes a matter of important calculation, therefore, in 
every case, to determine whether it is better, in a pecuniary 
point of view, to obtain river water in the immediate neigh- 
bourhood of a town by steam power, or to bring it from a 
distant and higher level by gravitation. 
Accordingly, about six years ago, the late Mr. Blackburn, 
at that time City Surveyor, directed his attention to the 
problem of procuring water for the city by gravitation, and. 
it is to that gentleman that we are indebted for pointing 
out the natural adaptation of Yan Yean for a large re- 
servolr. | 
In recommending his favourite scheme to the public, 
there is no doubt that Mr. Blackburn had satisfied himself 
that there would be an ample supply of water for the re- 
servoir. In his calculations, however, he placed great de- 
pendence on the natural advantages of the Yan Yean basin, 
in supplying a large supplemental amount of water from 
surface drainage, and in storing the flood water of the 
Plenty, independently of its ordinary discharge. 
He also calculated that his gravitation scheme in 1851 
would cost, including distribution pipes for the city, only 
84,7002. to supply a population of 70,000, at 40 gallons 
per head per day; while the lowest cost for supplying the 
same population at the same rate by steam power, from the 
Yarra, he estimated at 76,7002. The annual current ex- 
penses attending the gravitation scheme, he estimated at 858/., 
against 3,8942, as the expenses attending the pumping 
scheme. i 
It must be regarded as a singular fact in the history of 
Melbourne, that with the river Yarra so easy of access, 
and so peculiarly adapted by nature to furnish an un- 
limited supply of the purest water, no steps were taken to 
supply this large city until February, 1853. 
At that date, four Commissioners of Sewerage and Water 
Supply, were appointed under an Act of Council, and their 
