ANNIVERSARY ADDRESS. 25. 
to test evaporation, there is abundant means for th 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 in the inland plains, 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-register- 
ing anemometer which I erected there in March last bears impor- 
tant and measurable testimony on this point. The recording 
parts are so easily moved that they work satisfactorily with a 
velocity of 1 mile per hour. Taking the total number of miles of 
wind recorded at Bourke by an anemometer placed 25 feet above 
the ground during thirty days, I find it is 2,350 miles, or about 
78 miles a day only. The strongest wind in that period shows 50 
miles of wind in five and a half hours, and the smallest record for 
a day is 25 miles—little more than a mile per hour. In Sydney 
during the same period 7,050 of wind miles were recorded, and it 
is not uncommon to record in Sydney in three days as much wind 
as was recorded at Bourke in thirty days. 
Lake George is called a fresh-water lake, and sume have even 
gone so far as to propose to use it as a reservoir for the supply of 
towns. When there I ascertained that no one could use the water 
on account of its purgative properties, one glassful being quite 
enough to satisfy those who made use of it; and it is there said 
that the water running into the lake from the Currawang copper 
mine had poisoned all the fish. This is not literally true, for 
there are still fish in the lake ; but very many were killed some 
years since, presumably by the cause mentioned. I obtained some 
of the water, and am indebted to Mr. Dixon, of the Technical 
College Laboratory, for the following interesting information as 
to what the water contains :—It is quite evident that with 187°5 
grains of mineral matter per gallon the water cannot be used for 
domestic purposes ; and from the fact that this matter is constan 
