ESTABLISHING A SOLAR OBSERVATORY IN AUSTRALIA. 67 
representatives from the observatories and scientific bodies of Austria, 
Belgium, France, Germany, Great Britain, Holland, Hungary, India, 
Italy, Russia, Servia, Spain, Switzerland, and the United States. 
_ Australia is not represented upon the International Committee, 
though her co-operation is earnestly desired for the following 
reasons :— 
The Establishment of a Solar Observatory in Australia is essential for 
the completion of the International Scheme. 
(a) Because it would fill a gap at present existing in the chain of 
Observatories round the Earth.—The existence of the International 
Union for Solar Research is due to the fact that several problems 
connected with the sun depend for their solution upon a continuous 
series of observations made through the twenty-four hours, during 
which period the earth rotates once about her axis, and presents 
different parts of her surface in succession to the sun. It has thus passed 
out of the scope of two or even three stations to deal with such ques- 
tions; what are required are Observatories B 
spaced regularly round the earth so 
that the sun may be observed at one of 
them when observations are unfavourable or 
impossible at the others. At present the 
stations are concentrated in three well- 
defined areas, which are marked A, B, C a A 
in the sketch, and which are separated by 
approximately 90° of longitude. The 
great gap between. India and America, 
at D, could be filled by an Australian 4 
Observatory, whose erection would enable he circle represents the 
the changes in the form of sun-spots, Equator. 
their numbers and areas, and the variations A—India. 
in the prominences and in the distribution Ge NN a Ger- 
of metallic vapours over the solar disc to Gish den (Mt, "Wilson, 
‘be kept under continual observation Washington, &c.) 
D—Australia. 
throughout the whole twenty-four hours. 
(b) Because a Solar Observatory is required South of the Equator.— 
If we neglect Mauritius, where solar work is confined to direct photo- 
graphs of the sun’s disc, no station south of the Equator contributes 
towards the International Scheme, though work with the spectro- 
heliograph is required in south latitudes, and that most important 
branch of study—solar radiation—must eventually be undertaken in 
the same part of the world. For this work a fully-equipped observatory 
exists at Washington, and though the Smithsonian Institution has 
repeatedly urged the necessity of an additional station in south latitudes, 
and has pointed out the benefits that may reasonably be expected from 
a full study of this subject, the problem is not attacked elsewhere. 
(c) Because Australia’s Climatic Conditions are uniquely Favour- 
able.—With her almost perpetual sunshine Australia is particularly 
suitable for this work, and besides the promise that her clear skies give 
of excellent photographic results, the feature that makes Australian 
co-operation especially desirable is that observations would be possible 
F2 
