Adelaide Observatory's George Dodwell uses Cordillo Downs station for 1922 eclipse test of Einstein's relativity
Cordillo Downs, once Australia's latest sheep station in South Australia's far north east, was the site of an expedition, organised by Adelaide Observatory, to observe an eclipse of the Sun and test Albert Einstein's theory of relativity.
Adelaide Observatory, under South Australian government astronomer George Dodwell (1909-52), played its role in a concerted effort to test Albert Einstein’s theory of relativity in 1922. Einstein’s prediction that starlight was deflected by the Sun could be tested by taking photos during a total eclipse.
The eclipse passing over Australia in 1922 was ideal for the test and Cordillo Downs station, in the far north-east of South Australia was (with Wallal in Western Australia and Goondiwindi in Queensland) to be sites for expeditions by international observer scientists. Cordillo Downs had been part of Australia’s largest sheep station with a flock of about 85,000 by 1905.
The 1922 expedition, organised by the Adelaide Observatory on West Terrace, brought the latest equipment to the station. The Allegheny Observatory in Pennsylvania, US, had loaned a quadruplet camera for photographing the eclipse field at Lick Observatory in Western Australia and a 40-feet lens of six-inch aperture for photographing the Sun’s corona.
Under a clear Cordillo Downs sky, with 3 minutes 52 seconds of total eclipse, four plates were obtained with the Allengeny camera and 14 with the coronograph. Comparison plates of the eclipse field were taken at the site in August 1922 and March 1923. Measurements and calculations for Cordillo Downs plates were made by C.R. Davidson of the Greenwich Observatory, London.
Astronomer royal Frank Dyson wrote to Dodwell about the Cordillo Downs result that “under difficult conditions, you have every reason to be satisfied and I offer heartiest congratulations”.
Dodwell, who had been helped by Adelaide University physics professor Kerr Grant in the expedition, was proud of the result. When South Australian optometrists Carl Laubmann and Harold Pank made a world research trip, Dodwell arranged for them to personally deliver a report on the South Australian observations to Albert Einstein.
