This telescope was installed in the South Dome at Sydney Observatory in 1874 and is now the oldest working telescope in Australia. It was used by Henry Chamberlain Russell, Government Astronomer at Sydney Observatory from 1870-1905, to view the transit of Venus that occurred on 9 December 1874. The telescope is therefore important because of its use in the observation of a rare astronomical event, as well as for its age and its connections to the history of the Sydney Observatory site and the early astronomical community in Sydney.
The telescope was purchased by Russell in preparation for the upcoming transit of Venus. The transit of Venus is a rare event in which Venus passes in front of the Sun (something that occurs because Venus orbits closer to the Sun than the Earth does), that occurs less than twice per century. The telescope is an 11.4 inch refractor telescope, meaning that it uses curved lenses to collect and focus the light, allowing the user to better see distant objects. The telescope lenses and brass eyepiece end were made in Hamburg, Germany, by Hugo Schroeder, a highly-regarded optician, and it is now one of very few Schroeder telescopes still in existence.
The telescope was adapted for taking photographs of the 1874 transit. It was fitted with a camera and enlarging lens that magnified the sun's image to four inches, and wet collodion photographic plates were placed at the end of the camera to capture the image. The camera end passed into a dark room tent raised inside the dome and connected to the telescope by a flexible sleeve. A shutter was used to take the picture which was developed on the spot and another inserted immediately. Three persons working in this fashion managed to take one photo per minute.
Over the next thirty years various other changes were made to the telescope including the addition of a new drive mechanism (H10268) around 1914, made by German Gustav Heyde, which would improve the ability to track objects as they moved across the sky. In 1982 the Observatory closed as a working facility and was converted into a Museum. The telescope remains in regular use as part of the public tours run at the Observatory, and provides a spectacular view of the Moon, Solar System planets and many other objects.
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Sarah Reeves, February 2017.