Yan VYean Reservoir. 185 
I have arrived, therefore, at the conclusion, that in ordinary 
years no fear need be entertained, but that a very abundant 
supply of water will be derivable from Yan Yean, for a 
population three times greater than the present population 
of Melbourne. But that, whenever this colony is again 
afflicted with such another drought as that of 1838 and 1839, 
a failure in the supply would occur. 
The great area of the reservoir will cause the water to be 
occasionally so violently agitated by wind as to obviate some 
of the evils that arise from the storage of water. I do not, 
therefore, anticipate that the Plenty water will undergo 
much deterioration in the reservoir, unless during the preva- 
lence of an extraordinary drought. 
It has been suggested, that if an additional supply of 
water be required, it could be conveyed into the reservoir 
either from the King Parrot Creek, on the other side of the 
- main dividing range, or from the Diamond Creek. 
I believe the able engineer of the Water Commission 
could not have examined these streams closely. For I have 
inspected the source of the King Parrot Creek, and being 
also acquainted with the country within the watershed of 
the Diamond Creek, I am induced, from my local knowledge, 
to form a very unfavourable opinion of this mode of increas- 
ing the supply. 
In the case of the King Parrot Creek, a drift-way of 
considerable length would have to be made, at a great depth 
below the surface, through hard, igneous or plutonic rock, 
and the difficulties attending the execution of such an exces- 
sively costly work, would probably be augmented by the 
influx of water during its progress. With regard to the 
Diamond Creek, several of its tributaries, and steep interven- 
ing schistoze ranges, would have to be crossed, before the 
waters of the main creek could be conveyed to the Yan Yean 
Reservoir. In point of fact, the western tributary of the 
tine bands of mist defining the courses of rivers or large sheets of water; and 
in Australia I have occasionally, on clear nights, seen similar mists suspended 
over lagoons, and which mists saturated my hair with moisture on traversing 
them. Mists of this very circumscribed nature are much less frequent in Aus- 
tralia than in Europe; yet, if they resulted, as some have supposed, from the 
temperature of the air being below that of the surface of the water, such mists 
ought to be of more frequent occurrence here, where the temperature of the 
atmosphere during night is so remarkably less than during day, and conse- 
quently the temperature of water surfaces during night generally greater than 
that of the air. I venture to hope that the phenomena connected with vapour 
in the atmosphere here will be elucidated by Mr. R. Brough Smyth, whose 
accurate and judiciously conducted observations will ultimately render his name 
our chief authority on the Meteorology of this Colony. 
x 
