On the 21 September 1922 an eclipse of the sun passed across the centre of Australia providing optimum conditions for observations.

The scientific community used this opportunity to confirm Einstein's prediction that light passing the sun would be bent by gravity, by 1.76 seconds of arc. As a result a number of eclipse expeditions made their way across Australia in August 1922.

The expedition to Goondiwindi, in Queensland, consisted of two teams; one under the direction of Dr. J. Baldwin of Melbourne Observatory, the other from Sydney Observatory was under W. E. Cooke. In addition there were representatives from Sydney University, The British Astronomical Association, New South Wales, Branch, and a photographer Russell Grimwade who was a sponsor of the Melbourne group.

These groups set up their instruments on the racecourse near the township. Sydney Observatory moved the astrograph, used for the ''Mapping the Stars'' project, from the Red Hill Observatory in Sydney to a specially built enclosure on the racecourse.

In the end the Sydney Observatory obtained 74 photographs during the eclipse, using both the astrograph and an old photo-heliograph originally used for the Transit of Venus in 1882. The photographic results were not known immediately but the Goondiwindi plates were disappointing as only two of the eight taken with the astrograph appeared to be free of distortion.

Fortunately the Wollal photographs produced much better results. And in May 1923 by Frank Dyson, Astronomer Royal at Greenwich Observatory published the following comments in the journal Science, … happily, the enthusiasm, time, labour and money devoted to this expedition have been rewarded … the amount of displacement of a ray of light which would graze the sun values from 1.86 seconds of arc to 1.59 with a mean value of 1.74 seconds agreeing exactly with Einstein's prediction.

Geoff Barker, Curatorial, October, 2008

References
Campbell, W. W., 'The Total Eclipse of the Sun, September 21, 1922', Astronomical Society of the Pacific, provided by the NASA Astrophysics Data System, May 2008
Catalogue record, University of Malbourne Archives, http://app1.lib.unimelb.edu.au/cgi-bin/mua-search?tdetails=3214;imgdetails=3214, accessed April, 2008
Cooke W. E., The Total Solar Eclipse of the Sun, 1922, September 21, Sydney Observatory Monograph, Alfred James Kent, Government Printer, 1923
Dyson, Frank, Turner, H. H., 'The Confirmation of the Einstein Prediction', Science, New Series, volume 57, number 1481, 18 May, 1923, American Association for the Advancement of Science, stable URL, http://www.jstor.org/stable/1646760

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