46 
Transactions of the Boyal Society of So2ith Africa. 
announce to the Council that this petition had been favourably considered 
by His Majesty in Council, and that a Charter of Incorporation, under the 
Statutes drafted by the Committee, had been duly received. 
Henceforward the Society entered on a new phase of life under its 
new style of The Eoyal Society of South Africa, and now that it is fairly 
launched in its new career we may look forward with confidence to a 
future of increased usefulness. 
I pass now to the main subject of my address to-night, which I propose 
to entitle — 
Some of the Aims of Astkonomy of Peecision. 
The Cape Observatory was established by Order in Council, dated 
October 20, 1820, as the outcome of a resolution by the Board of 
Longitude to the effect — 
..." That it would be highly conducive to the improvement 
of practical astronomy and navigation that a permanent Observatory 
should be established at the Cape of Good Hope, which would afford 
a series of comparative observations made under circumstances the 
most favourable for correcting the unavoidable imperfections de- 
pending on the instruments employed and on the materials sur- 
rounding them by a countervailing tendency to equal and opposite 
errors." . . . 
As is natural under these circumstances that branch of astronomy 
known as astronomy of precision, viz., that which depends on the most 
precise geometrical measurement has always formed the principal item of 
the work of the establishment, and it has been the aim of successive 
astronomers not merely to maintain, but to advance the accuracy of the 
observations for which they have been responsible. 
The science of precise physical measurement is one which does not 
readily appeal to those not immediately concerned, either with the methods 
or results. An authoritative statement that the sun's distance from the 
earth is 92,880,000 miles may excite wonder, but scarcely more than will 
the statement that it is approximately 93,000,000, except in the minds of 
those who are in some measure acquainted with the laborious processes by 
which the two extra figures are derived. In fact, I have not infrequently 
heard the methods of observation used described by some such epithet as 
" hair-splitting." For this reason I think I cannot do better to-night than 
to describe to you, without entering into technical details of the methods 
employed, some of the aims and objects to which modern astronomy of 
precision is devoted, and which render essential none but the highest 
refinements that human ingenuity can devise. 
Perhaps the primary reason why astronomy appeals to the popular 
