Yan Yean Reservoir. 187 
the engineering plans and operations adopted for the storage 
and conduction of the Plenty water, as the high professional 
standing of the engineer to the commission, and the adminis- 
trative ability of the president, should be a sufficient guarantee 
that the details of the scheme will be efficiently carried out. 
I cannot but regret that I have been compelled to express 
my dissent from the views entertained by several gentlemen 
whose judgment and ability I deeply respect, and to whom I 
beg to apologise for the introduction of their names into this 
paper. 
ArT. XV.—Report of the Commissioners appointed by the 
Philosophical Society of Victoria, to investigate the alleged 
insufficiency of supply for the Yan Yean Water Works 
by Dr. Wilkie. 
TO THE PRESIDENT AND MEMBERS OF THE PHILOSOPHICAL 
SOCIETY OF VICTORIA. 
Mr. PRESIDENT AND GENTLEMEN,—In compliance with 
your resolution of the 9th on January last, requesting us to 
report on the alleged insufficiency of supply available for the 
Yan Yean Water Works, as conveyed in a paper read before 
your Society by Dr. Wilkie on the same day, we have the 
“honour of laying before you the following report. 1 
Our first step in the prosecution of this inquiry, was, to 
proceed to the Yan Yean reservoir, and to examine its modes 
of supply, as also the drainage-basin of that part of the River 
Plenty that is intended to feed it, where we made measure- 
ments of discharge, in order to guide our conclusions. 
Our subsequent investigations were directed to ascertaining 
the different sources of supply and loss, and therefrom ob- 
taining the available amount. 
Foremost among the causes of loss stand evaporation, in 
soils and still water, the former of which, from the various 
conflicting conditions under which it occurs in this instance, 
cannot be easily ascertained from scientific deductions, but is 
rather a practical question, to be dealt with by the results it 
exhibits; the latter we obtained from the careful experiments 
and deductions of Dr. Davy, to whom we are much indebted 
for communicating the results of his valuable experiments. 
Our aim in arriving at and adopting our conclusions, have 
been rather to exaggerate our amounts of loss, while we have 
