S ANNIVERSARY ADDRESS. 
1877 «i it eid ... 2 feet 6-7 inches 
1878. ve Daye BR 
1879. ‘ ee ee re 
1880. bo 52 capt oy 
1881. sence Dicgy OD aigy 
1882 E ayy Oy 
1883. See te gee ae 
elas | in 
2: 45 BAB 
In examining this question, I looked for some mark of old sur- 
veys which might show what the evidence of a longer period would 
be, but I have failed to find any mark put in with such care as the 
investigation demands. There is, however, one mark on the 
north-east face of the round tower on Fort Denison, which was 
put in by H.M.S. “Herald,” during her survey of Sydney harbour. 
It is cut in the stone, 3 feet above mean sea-level, and is marked 
with the broad-arrow under it. I have been at some trouble to 
find out on what observations this mark was based ; but although 
Ihave learned that the survey was made in 1857, and that the 
“Herald” was in port from February 26 to December 21, 1857, 
TI cannot learn how long the tide observations were continued, but 
I hope still to do so. The time and method of taking mean sea- 
level might account for a difference from the true mean of 4 or 5 
inches, as is shown by the different monthly means from the 
recording tide-gauge, and until I can learn on what observation 
the “ Herald’s” mark depends, it cannot be used as evidence of 
change of level of the land. I have, however, connected it care- 
fully with the zero of the tide-gauge, and if it exactly represents 
mean sea-level in 1857, it proves that the land has risen 5 inches 
in twenty-seven years; but since the tide-gauge shows no change 
whatever during twelve of these years, there can I think be no 
doubt that the mark was put in upon insufficient data ; persis 
only day-tides were observed. 
In the course of conversation. with ae late Rev... W. B. 
Clarke on the question of the elevation of. the coast, he 
