PRESIDENTIAL ADDRESS. 31 
The large work by Mr. G. H. Knibbs, C.M.G., the Com- 
monwealth Statistician, based on the Census of Australia, 
has attracted considerable attention. 
The staff of the Sydney Observatory, under Professor 
W. E. Cooke, has devoted much of its time to the prepara- 
tion for publication of measures of the plates taken at 
Pennant Hills in connection with the photographic survey 
of the heavens, and in other circumstances this work would 
by now have been published. 
Physics—E. M. Wellisch, Lecturer in Applied Mathe- 
matics in the University of Sydney, has contributed im- 
portant papers with regard to the motion of ions and elec- 
trons through gases. 
The Reverend Father Pigot has carried out valuable 
work in his seismological laboratory. Early in the year 
our members were invited to contribute toward a fund to 
defray the expenses of a research into the nature of earth 
tides at present being carried out by him at Cobar. Father 
Pigot was invited, before the outbreak of war, by the Inter- 
national Gecdetic Society to install a pendulum of extra- 
ordinary precision, in a situation and at a point removed 
from the influence of ocean tides and solar thermic action. 
He selected a deep level in one of the mines at Cobar, and 
received generous facilities at the hands of the Great Cobar 
Company. This work has not been conducted previously, 
under such favourable conditions, in many respects in any 
part of the world. Moreover, no earth-tide records have 
hitherto been obtained outside of Germany and Russia, save 
in the neighbourhood of Chicago, where the conditions 
are far from ideal. After exercising much patience and 
ingenuity in the accurate installation of the pendulum, 
Father Pigot has succeeded in overcoming many of the 
preliminary difficulties, and has now his first tracings of 
the earth tide—an achievement which will undoubtedly 
