ANNIVERSARY ADDRESS. 49 
Evaporation.—In its bearing upon a question of evaporation, 
which is of vital importance in Australia, I may mention that 
M. Hohnel, the well known botanist, has recently stated that 
in Europe, full grown “ Poplars, Oaks, Ashes,” and other large 
trees, transpire daily from eleven to twenty-two gallons of water, 
and he computes that a properly filled wood of mature beeches, 
two acres in extent transpires during six months of the year, 
June Ist to December Ist, from 500,000 to 700,000 gallons of 
water. If wetake the mean of these two quantities as an average 
effect, or that an ordinary beech wood of two acres in extent tran- 
Spires in the six months 600,000 gallons, it strikes one as an 
enormous quantity, it is in fact equal to thirteen inches of rain, 
and a fir wood which transpires very slowly, gives off water in six 
months equal to nine inches of rain. 
Meteorology.—During the past summer our weather has been 
the cause of more than the ordinary amount of popular discussion, 
and it has likewise been to us who are watching it day by day of 
more than ordinary interest. The question most prominent is— 
why all this dryness inland and all the rain on the coast? With the 
help of Mr. Hunt, who prepares the daily weather chart, I have 
been watching the changes very closely, with the result that all the 
main features which give rise to the above mentioned weather 
conditions are clearly made out. For the five months of the past 
summer, December to March, we have had a constant succession 
of anti-cyclones of a peculiar type; for while the ordinary summer 
weather here is made up of passing anti-cyclones with well-marked 
low pressures between—which low pressures are distinguishing 
features, for they deposit rain in the Western Districts and facili- 
tate the southerly progress of tropical rains—the recent anti- 
cyclones have had no effective low pressures between, and, con- 
sequently little or no rain in the Western Districts. Further, 
the latitude of the centres of the anti-cyclones has been greater 
than usual; so that when they move forward slowly or, as they 
sometimes do, stop south of Adelaide for several days, there is 
time for their distinctive wind circulation to make itself felt, and 
D—May 4, 1892, 
