. 260 Remarks on the principal Rocks 
reservoir, it is only necessary to assume sixteen inches for 
each of the three summer months, therefore, Dr. Davey has 
allowed a large deduction from the true evaporation, to 
compensate for the extent of the reservoir, or any other 
accidental canse that might operate to retard the evaporation 
from the surface. : 
What possible reason, or excuse, then, can be given for re- 
jecting Dr. Davey’s estimate of nine feet? According to my 
judgment the conclusion is irresistible that his estimate 1s 
confidently to be depended on, and I feel warranted in de- 
ducting the three feet four inches from Mr. Hodgkinson’s 
estimate, which is equivalent to supply 90,909. 
Having thus stated the points of difference between myself 
and Mr. Hodgkinson, and which constitute the data on which 
we depend for our water supply, and having shown that they _ 
are not based on correct or scientific principles, and are, 
therefore, unworthy of your confidence, and that, on a 
thorough investigation of the subject, there are no data to 
show that there will be any water for the city derivable from 
Yan Yean, I have little to add. 
T shall submit, therefore, that the Philosophical Society has 
now 2 very important duty to perform; aduty to themselves, 
as the interpreters of science in this colony; a duty to the 
Government and the Legislative Council, who look to them 
for a scientific opinion to aid them in the decision of the 
question, if it be proper to allow the Yan Yean works to be 
proceeded with; and a duty to the public, whose health, and 
comfort, and pecuniary interests are so seriously involved in 
the success or failure of the Yan Yean Reservoir scheme: 
and I trust that the Philosophical Society will no longer 
hesitate to pronounce an opinion on the subject. 
Art. XXI.—Remarks on the favourable Geological and 
Chemical Nature of the principal Rocks and Soils of Victoria, 
in reference to the production of ordinary Cereals and Wine. 
By Cuement Hopexinson, Esq, C. E., Survey De- 
partment. 
Havine visited the four principal Australian Colonies and 
been connected with agricultural pursuits in New South 
Wales, I have long held the opinion that Victoria will 
eventually produce more wheat and wine than any other Aus- 
' tralian Colony; partly, because this territory contains the 
