CHAIRMAN’S ADDRESS. VIL 
“The men are to serve the probationary period at Cook’s River 
stockade, where they will be employed at the dam, which is to 
supply Sydney with water.” 
This dam when constructed was not found to exclude the 
salt water, and no further steps were taken in that direc- 
tion. Continuing, Professor Smith states that, “ the great 
drought of 38-39 was succeeded by nine years of abundant 
rain and frequent floods.’’ On reference to the diagram it 
will be seen that for six years the rainfall was all above 
the mean, the average being 61°07 inches, which must have 
raised the level of the ground water, so that although the 
two following years were a little below the mean, the 
streams were probably not much affected, and the next 
year, viz. 1848, the rainfall amounted to over 59 inches, 
which brought the level up again to what it stood at in 
1845, consequently they were not far out in reckoning the 
wet period to be of 9 years’ duration. Thereafter, to 1854, 
a very serious drought must have been experienced, every 
year being below the mean, the average being only 36°78 
inches. ? 
“ During the wet period, the tunnel seems to have kept Sydney 
pretty well supplied,” says Professor Smith, ‘‘at least I find no 
record of scarcity, nor of schemes for increasing the supply ; but 
in the year 1849 there occurred a drought of considerable severity, 
and the water question again started into prominence. In that 
year the rainfall as measured at South Head was only 214 inches, 
(the lowest ever recorded at Sydney), while the population of 
Sydney had increased to about 40,000, or double what it was when 
the Lachlan Swamp was first tapped. I find that in April 1849 
the Water Committee of the City Council directed the City Sur- 
veyor (Mr. F. Clarke) to examine the Swamp and Tunnel, with 
the view of improving the supply. The surveyor sent in his 
report in December, recommending that a dam should be carried 
across the lower part of the swamp, so as to form a lake of 40 or 
50 acres, with an average depth of 4 feet, and to construct a 
