242 NOTES UPON FLOODS IN LAKE GEORGE. 
made at Goulburn on the Hawkesbury side of the lake, and at 
Gungahleen on the other side, that the bes rainfall on the two 
catchments there is about the same. So that ver y heavy floods in 
the river coincide in time with very heavy peel in the lake. I 
mention this because from it we may reasonably infer the state 
of Lake George from the state of the Hawkesbury during the years 
1816, 1817, and 1818, In the autumn of 1816 there were vai 
great floods in the Hawkesbury, while the three preceding 
had been very dry, and there seems to be no doubt that in 1816 the 
lake suddenly rose, as shown in the diagram, for when found in 
1818 it was ‘‘ full of water.” 
have been working now for many years trying to elucidate 
the sort of mystery that seemed to hang about Lake George, and 
lake and other matters, on February 18th, 1885, I erected the lake 
register described in my anniversary address to the Royal Society, 
May, 1885, and took the 0 line of its printed sheet as datum line, 
there being at the time no other available ; the recording pencil was 
made to mark at the zero, so that the water level on February, 1885, 
is the zero of the lake register. But it was known that careful 
levels had been taken of the base line at the other side of the lake, 
and that Mr. Chisholm, Mr. Kenny, and others had frequently noted 
the condition of the lake and measured the depth of the water ; 
and it was obviously very desirable to connect all these measures, 
and also the still sie ones on the original surveys of the land 
round the lake. These go back to 1828 and are invaluable as 
Peak data jfconees much that is unreliable. I began by 
ing in twelve ¢ places, some distance apart, the difference in 
Seccl ginal “the 1874 flood line and the then height of the 
ei all together it would be necessary to do four things. First, to 
take a line of levels from the top of the terminal stone of the base 
line to the water, which would connect the base line datum with 
the lake register datum. Next to take sounding of the lake over 
the same ground that Mr. Chisholm had gone before, and to 
the deepest place. This would connect Mr. Chi sholm’s sounding 
with the lake register datum, and i all notes in which the 
depth of the lake was given ; and thirdly, to find the fall per mile 
at each end of the mee so that the surveys and references 
to the size of the lake might be — into statements 
of the height or rather depth of the water, and thus connect 
them with all the others ; and lastly, to find the present length of 
