On June 3, 1769, James Cook, Joseph Banks and their team recorded the Transit of Venus at Tahiti on behalf of the Royal Society of London.
Then, following “secret orders”, Cook and his men sailed to the Western Pacific Ocean and became the first Europeans to sight the east coast of Terra Australis Incognita, the legendary southern land. As a result, colonies were established and prospered.
By 1874, 125 years after Cook’s observations at Tahiti, the next Transit of Venus was due. Australia, by then, had become a thriving scientific community.
During transit, Venus appears as a small black disc travelling across the Sun. This unusual astronomical phenomenon occurs in a predictable pattern and was used, then, to determine the size of the solar system.
Henry Russell, an ambitious astronomer, ran Sydney Observatory. He believed that the 1874 Transit of Venus would bring international recognition to the Sydney Observatory.
With Royal Society of New South Wales support, Russell received a Government donation of £1000.
He required three suitable sites for observing stations to supplement Sydney Observatory.
These three sites needed desirable geographical positions, reliable weather and, Russell said, “telegraphic convenience for determining longitude”.
Alfred Fairfax, successful Sydney merchant and enthusiastic amateur astronomer, owned a four-inch refracting telescope, one of the best in Australia. Fairfax offered the telescope and his home beside the newly-opened Western rail and electric telegraph lines. Russell accepted because the “clear and steady atmosphere” at Fairfax’s home, Woodford, made it a “most promising station”. Eden and Goulburn were also selected.
Additional instruments were acquired including a telescopic photoheliograph to capture the transit.
On Monday November 23, P.F. Adams, NSW Surveyor General, marked out the site for the observatory, “about 200 yards westerly from Mr Fairfax's house, and the same distance northerly from the Western Railway and Telegraph Lines”.
By December 5, timber-framed canvas-cladded buildings were erected and instruments installed. On December 6, the observatory, connected to the electric telegraph system, received time-signals from Sydney Observatory.
On December 9 there was a clear sky but a hot dry westerly wind soon became gale-force. By 10.30am the temperature in the clock room reached about 34° C.
The adverse effects of the rising temperature on the observers and the accuracy of the clock concerned Adams.
“My greatest anxiety,” he reported, “was for the maintenance of an even temperature for the clock as possible”. Inside they used a fan and applied wet blankets to exterior walls.
The heat affected the telescopic equipment but, finally, quality images of the transit were obtained.
Russell noted approvingly that the results from Woodford were excellent.
The successful Transit of Venus project saw Sydney Observatory recognised in international astronomy.
Robyne Ridge is publicity officer for Blue Mountains Historical Society.
