lviii Zhe Transactions of the. South African. Philosophical Society 
That these views have been very largely shared by astronomers 
appears to be evidenced by the fact that, in the scheme which I pro- 
posed for execution in 1889, no fewer than twenty-seven observatories 
co-operated in observing the comparison stars on the meridian, and all 
the observatories in the Northern Hemisphere which are provided with 
modern heliometers took part in the work in co-operation with the 
Cape Observatory. Professor Auwers, the official head of German 
astronomy, came to the Cape to share my labours. 
Dr. Gill then proceeded to give a detailed account, with the aid of 
diagrams, of the observations carried out in 1889 on the minor planets 
Victoria and Sappho. He showed that the observations of Victoria had 
been designed to furnish, concurrently with a determination of the solar 
parallax, a determination of the mass of the moon. He exhibited a 
diagram which showed that the apparent tabular errors of Victoria were 
represented by a curve of twenty-seven days’ period, which curve was 
exactly accounted for by an error of ,4, part in the hitherto accepted 
constant of the lunar perturbation. The direct determination of this 
constant has hitherto rested on meridian observations at Greenwich, 
Konigsberg, Paris, and Washington. The results from these different 
authorities differed more inter se than did any of the fifteen independent 
sets of results derived from the observations of Victoria from their 
mean ; and it seems certain that through these few months of refined 
observation in 1889 we have arrived at a more accurate knowledge of 
the mass of the moon than that obtained by meridian observations 
during three-quarters of a century at the principal observatories. The 
results of the solar parallax derived in separate groups—of which there 
were fifteen for Victoria and six for Sappho—were then shown, and 
proved to be much better in accord not only than the results derived 
by combining the observations of different transit of Venus stations, 
but were also actually more concordant than were the results derived 
by different astronomers from the discussion of the self-same observa- 
tions of a transit of Venus. 
Dr. Gill concluded that the sun’s mean distance was, in the nearest 
round numbers, 92,700,000 miles, and that these figures could not be 
100,000 miles in error, and that the mass of the moon was slightly 
greater than <4, part that of the earth. 
Dr. Gill then proceeded as follows : 
I have addressed the Society at such length on a special subject that 
but little time is left to review the work of the Society, and of scientific 
workers in South Africa generally, during the past two years. 
THE GEODETIC SuRVEY.—The completion of this work has been 
already mentioned in connection with its scientific importance as a con- 
