MEETINGS OF SOCIETIES. ' Gor 
of the lake has fallen 7 inches by evaporation; in this interval, accord- 
ing to the records of rain gauges at each end of the lake, 3-55 inches of 
rain has fallen, so that ignoring the water which may have 1un from the 
hills during these rains, the lake has lost all the rain falling into it and 
7 inches more, that is 10} inches. During the past 14 years the lake 
has lost by evaporation i2 feet; and in May, 1878, the railway survey 
carried down the western /side showed that the lake was then 6 feet 
below its 1871 level, or 2225 feet above the sea. It appears, therefore, 
that in seven years, 1871 to '78, the lake lost 6 feet, and again, from 
May, 1878, to February, 1885, say seven years, the lake again lost 6 
feet by evaporation, and this of course in addition to all the rain which 
fell during that period. Taking the records at Goulburn and Gungah- 
leen, near the lake, the average rainfall for the first seven years was 
27°95 inches, and during the next seven years 23°68 inches. One 
would expect to find more evaporation during the drier years, but this 
is not borne out by observations. From the rainfall and recorded 
evaporation the lake, therefore, lost by evaporation at least 3 feet per 
annum. I say at least because some rain water must have run into the 
lake in addition to that which fell into it directly, but its amount 
cannot be determined. In future the recording gauge will determine 
this, and perhaps then we may apply the experience gained to esti- 
mating how much ran in during the past 14 years. That the gauge 
will serve this purpose is proved by what it has already done. On 
March the 11th a strong northerly wind came on, and in three days the 
lake lost by evaporation 1$ inch. On April 14 and 15 1:10 inches rain 
fell, with a strong wind, and by the 17th the lake had lost all the rain 
by evaporation, and was atthe same level as on the 13th. On the 
other hand, in calm or almost calm weather, three, and even four, days 
pass without any loss by evaporation. It should be stated with regard 
to the rain on 14th and 15th April, that although 1:70 inches fell at 
Douglas, only 0°77 inches fell at the north end of the lake, and the rise 
in the water due to it was 14 inch, so that it would appear but little of 
that rain water came down the hills into the lake. The evaporation on 
the lake on a windy day shows to what extent the wind affects it. No 
doubt its effect on a large body of water is much greater than ona 
small one, because on the lake in calm weather the lower air must get 
to a certain extent saturated with moisture, and there being no wind to 
carry it away, evaporation practically ceases; but where small quan- 
tities of water are placed to test evaporation, there is abundant means 
for the evaporated water to get away in the surrounding air which is 
not saturated. Evidence is accumulating that the evaporation from 
large tanks is not so great as has been supposed. The heat is, no doubt, 
very great, but the total absence of wind in the interior for considerable 
periods, is obviously, from what has been shown to-night, an important 
condition for the saving of water. At Bourke, recently, I was very 
much struck with the absence of wind, especially on the surface of the 
ground, and the self-registering anemometer which I erected there in 
March last bears important and measurable testimony on this point. 
The recording parts are so easily moved that they work satisfactorily 
with a velocity of one mile per hour. Taking the total number of miles 
of wind recorded at Bourke by an anemometer placed 25 feet above the 
ground during 30 days, I find it is 2350 miles, or about 78 miles a day 
only. The strongest wind in that period shows 50 miles of wind in 5} 
