Observations

Talk by Dr Richard Gillespie on the Great Melbourne Telescope – a brief report

GMT mirror at the Museum of Victoria's store

One of the two original 1.2 metre metal mirrors for the Great Melbourne Telescope at a Museum of Victoria store. Picture and copyright Nick Lomb ©, all rights reserved

On 23 September 2010 your blogger attended the joint annual lecture of The Royal Society of Victoria and The Royal Historical Society of Victoria. The talk was given by Dr Richard Gillespie, Head, History & Technology Department of the Museum of Victoria and was titled “The Great Melbourne Telescope: restoring our astronomical heritage.”

The GMT has been discussed previously on this blog – here and here. However, outside of Sydney Observatory, the restoration of the GMT is the country’s most exciting project in astronomy education and heritage and so deserves continuing coverage. Here is a brief report on Richard’s talk, with any errors of course my own:

The story of the GMT begins in November 1856 with another talk. It was given to the Philosophical Institute, a predecessor organisation of the Royal Society of Victoria, by William Wilson, foundation professor of mathematics at the new University of Melbourne. Professor Wilson, an energetic young man in his late 20s, advocated a large southern telescope. An initial problem with the idea was where to site it for at that at the time there were two observatories in Melbourne, one at Williamstown under the direction of Robert LJ Ellery and the other on Flagstaff Hill run by George Neumayer. This problem was solved when the two combined to form Melbourne Observatory in 1863.

GMT eyepieces at the Museum of Victoria's store

The eyepieces that were used with the GMT are impressively large. They are at a Museum of Victoria store. Picture and copyright Nick Lomb ©, all rights reserved.

Professor Wilson received endorsement for the telescope from the Royal Society in London as long as the cost was borne by Melbourne. Surprisingly, obtaining funding from the Victorian Government was not as difficult as it would seem. The gold rush had quickly increased the wealth of the Colony so that money was available. There was also the support of the Government Treasurer George Verdon. Verdon was a Williamstown merchant who had worked as a voluntary assistant to Ellery at the Williamstown Observatory before becoming an MP in 1859. Funding of £6000 was granted initially and later topped up with another £5000. In an echo of modern times a subsequent government tried to rescind the contract for the telescope, but it had already been signed and so the telescope proceeded.

The telescope, built over two years by the telescope maker Howard Grubb of Dublin, arrived in Melbourne in 1869. It was the first time that such a large telescope had been built with an equatorial mounting. It was huge – the main mirror was 1.2 metres wide and weighed a ton. The whole telescope weighed nine tons and had a tube that was 14 metres long. It was placed in a building with a roll-off roof and located some distance away from the other buildings of Melbourne Observatory so that the mass of metal should not disturb readings by magnetic instruments.

Nick Lomb and Barry Clark at the GMT house

Nick Lomb and Barry Clark standing on what had been the foundations of the Great Melbourne Telescope. Picture and copyright Jenny Andropoulos ©, all rights reserved

The telescope achieved success with two short exposure photographs, one of the Moon and one in 1883 of the Great Nebula in Orion, which was the first photograph of a nebula in the southern sky. Still, according to Dr Gillespie, the main observing aims of the telescope were flawed. These were to reobserve and sketch the nebulae that had been observed by Sir John Herschel from South Africa in the 1830s. However, sketches made by different observers with different telescopes cannot be directly compared and it would not have been possible to ascertain if the nebulae had shown changes in the intervening few decades.

The GMT was mothballed in the 1880s and in the 1940s sold for scrap to Mount Stromlo Observatory. There parts of it were used for a 50-inch telescope, which itself went through a number of rebuilds over time. This telescope was destroyed in the Stromlo fire of 18 January 2003. An interesting sidelight is that on 2 May 1958 part of one of the GMT piers became the foundation stone for the dome of the Australian Academy of Science in a ceremony in Canberra conducted in the presence of the then prime minister, Robert Menzies, who said:

This is like me, it comes from Melbourne and has been planted now here and it is one of the old piers of the Melbourne Observatory, dating back to 1870. I was very kindly forwarded with the history of it, which I read with immense pleasure, particularly when I discovered that at the time when they were discussing establishing an Observatory in Melbourne and this stone became one of the piers supporting it, the Committee in Melbourne, it’s to be admitted, recommended that the Observatory ought to be established in that City, not only because of its geographical position, but because of the clearness of the air; a quality about Melbourne that I have always asserted but which I find constantly denied by those people unfortunate enough to be born in other places.

Today, as described in a previous blog post, the GMT is rising phoenix-like from the ashes and it is hoped that eventually it will be reinstalled as a working and useable telescope.

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