x Proceedings. 
February 20th, 1855. 
Montuty MeEeEtina. 
The President of the Society having been detained, Mr. Justice 
Barry was invited to take the chair. 
The reading of the minutes of the last meeting was postponed 
to the next meeting. 
The following Gentlemen were announced to have been admitted 
members of the Society, since the last meeting :— 
The Honourable the Attorney-General, W. F. Stawell, Hsq.; 
Captain Pasley, R. E., Colonial Engineer; Wm. M’Crea, Esq., 
Colonial Surgeon; W. H. Archer, Esq., A. Registrar-General. 
The Honorary Secretary, informed the meeting that, in 
compliance with the resolution of the last meeting, the com- 
mission appointed to investigate the statements set forth in a 
paper read by Dr. Wilkie, on the Yan Yean Reservoir, went up to 
that district and examined the reservoir, as well as the Plenty 
River and its sources. They made measurements of the Plenty at 
various parts, with the view of ascertaining the average quantity 
of water the river is capable of discharging. ‘They likewise made 
measurements of the main tributaries, viz., the western and eastern 
arms, and traced the source of the latter to the top of Mount 
Disappointment. The report of the commission, however, as it 
involved a vast amount of calculation, as well as actual experiments 
upon the evaporation, could not be laid before this meeting with all 
the necessary details. He stated further that the commissioners 
had furnished Dr. Wilkie with the result of their. measurements 
founded on which data his present paper was enlarged and amended_ 
Dr. Wilkie then read a paper on the Yan Yean Reservoir, founded 
on the data above referred to. He endeavoured to show that there 
would not be sufficient water in the reservoir, after deducting the 
evaporation, to supply more than 75,000 individuals at forty gallons 
per head per diem; and he argued that on the constant-service 
principle, the supply might be found altogether insufficient even 
for that number; he stated that it had been found by the ex- 
perience of other cities that forty gallons could not be depended on 
as a sufficient supply. He showed that from fifty to 100 gallons 
per head per day were frequently used, and that several cities in 
England have been obliged to abandon the constant-service principle 
altogether from an insufficient supply of water. Dr. Wilkie also 
strongly objected to the principle of storing water in a swamp, 
and thought that it would become very much deteriorated and 
incurably infected with animalcule and vegetable productions 
which no filtration could remove. He entered at ereat length into 
