236 Transactions of the Boyal Society of South Africa. 
I think I am sufficiently voicing the view of those who took part in 
the original discussions at Paris when I state that they, as a body, 
attached greater importance to the complete and thorough systematic 
record of the phenomena prevailing during their own generation than 
to the immediate interpretation of these phenomena. It was felt to 
be a scientific duty, incumbent on them, to provide so far as lay 
within their means and capacity data which should be beyond reproach. 
By this means they were preparing the ground and planting the 
seed which they hoped would yield a rich crop of scientific results, 
even though it should remain for their children's children to reap the 
harvest. 
Much has already been attained. The ghosts which beset the use 
of photography in relation to the science of exact measurement have 
in a large measure been laid, and photographic methods have now 
been successfully used for some of the most delicate measurements 
ever attempted even by direct visual operation. 
I have in mind such questions as the determination of the distances 
or annual parallaxes of the fixed stars and of the parallax of the sun, 
in connection with which, under the auspices of the Paris Conference, 
an extensive photographic campaign combined with visual methods 
was undertaken on the occasion of the near approach of the planet 
Eros in the years 1900-01. 
The discovery of the latter planet was itself a product of photography, 
while by similar means the number of known minor planets has within 
the last few years increased by leaps and bounds, until at the present 
day they are nearly seven hundred in number. 
Photography has also been prolific in the discovery of variable 
stars and new stars, and the tracing of their light changes. All these 
purposes will be greatly facilitated by the existence of a reliable chart 
or catalogue containing more especially the fainter stars about w^hich 
our exact knowledge hitherto has been almost non-existent. 
Time must elapse before we can expect to be able to evaluate 
with certainty the slow changes of position due to proper motion 
at least in relation to the previously uncatalogued faint stars, but 
this is to-day one of the greatest desiderata for the advancement of 
our knowledge of the universe, and is one of the purposes for which 
the photographic catalogue was primarily intended. 
By photographic methods and by co-operative effort throughout 
the world alone has it been possible to collect evidence on a sufficiently 
wholesale scale, so that already we are beginning to feel the solution 
of some of the most profound problems relating to the universe almost 
within our grasp. 
