Snapshot: The Great Melbourne Telescope
This marvel of 19th-century Irish engineering is being painstakingly restored to full working order by a band of dedicated enthusiasts.
ON 5 November 1868 a long-awaited shipment arrived at the Port of Melbourne – the Great Melbourne Telescope. While construction had begun in Ireland in 1866, a large-scale telescope to observe the Southern Hemisphere’s skies had been in planning since the 1850s.
Sent across the world in parts, it would, after its reassembly at the Melbourne Observatory, become the second largest telescope in existence at the time.
Manufactured by Dublin engineer Thomas Grubb, it was a Cassegrain Reflector telescope with a 48-inch (1.2m) speculum metal mirror. The shipment included, local newspapers announced, “two ponderous and immense wooden cases” containing a 22-foot-long (6.7m) metal lattice tube and huge polished mirrors that weighed several tons, and was being “gradually removed to its destination”.
Enormous bluestone piers to support the instrument were completed on New Year’s Day in 1869 and labourers installed the telescope’s heaviest parts over the following 10 days. By June, the building to house the telescope was completed and, with the instrument tested and calibrated, it opened in August 1869. The telescope became a symbol of colonial scientific endeavour and achievement, its progress reported around the country. Crowds of people would visit when the weather was clear to observe the Moon, sometimes to the detriment of work by the incumbent astronomers.
The telescope was used to examine faint nebulae and galaxies, astronomers recording their observations with technical drawings and sketches. Unfortunately, however, technology had overtaken the telescope’s design during its construction and it was not entirely suited to new advances in astronomical photography and spectroscopy.
Adjustments were made by replacing the smaller mirror at the end of the tube with photographic apparatus to allow for photography of the Moon, and some of these images were declared at the time to be the best astronomical photographs ever taken.
But additional problems in maintaining the speculum’s metal mirrors, combined with the advent of smaller and more agile telescopes, meant the Great Melbourne Telescope only saw occasional use after 1899. The Melbourne Observatory closed in 1944 and the telescope was dismantled and sent to Mount Stromlo Observatory, Canberra, the following year.
After modifications, including shortening of the lattice tube and replacement of the metal mirror with a silvered 50-inch mirror of borosilicate glass, the telescope reopened. In the 1990s, it was converted into Australia’s first fully robotic and computerised digital imaging telescope.
Bushf ires that swept through Canber ra in 2003 destroyed a l l moder n instr uments at the obser vator y but the cast iron spine of the Great Melbourne Telescope survived, relatively unscathed. Five years later the telescope’s remains were recovered by staff and volunteers from Museums Victoria who, in a joint project with the Astronomical Society of Victoria and the Royal Botanic Gardens, Victoria, began refurbishing the telescope.
The project’s volunteers – all engineering and astronomy experts – have met every Wednesday since 2008. Known as “The Barrys” (because four members have Barry as either a first or last name), they have contributed more than 30,000 hours to the project so far. Engineer Barry Adcock described working on the project as a “rare privilege”, saying he was inspired by the telescope’s innovative design.
Assembled in its original form for the first time since it was dismantled 76 years ago, the telescope is now on display in the Pumping Station at Scienceworks in Melbourne, where visitors can watch the restoration being undertaken.
Work continues to restore the full functionality of the telescope and return it to the Melbourne Observatory.