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 ly the 

 Philosophical Society of Victoria, to investigate the alleged 

 insufficiency of supply for the Yan Yean Water Works 

 hy Dr. Willde, 



TO XilE 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. 



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 su-pply 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 

 confficting 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 wc have 



