Summary

Great Melbourne Telescope at the Melbourne Observatory, circa 1875.

The 48 inch equatorial reflecting telescope was constructed by Thomas Grubb, Dublin and installed at the observatory in 1868-1869. The telescope was used at Melbourne Observatory from July 1869 to 1892 to observe changes in the nebulae of the southern hemisphere. Thereafter it was used only intermittently.

The person depicted is believed to be Joseph Turner, who was employed at the Melbourne Observatory as Assistant Astronomer, from 1873 to 1883, and during this period was the main observer to work with the Great Melbourne Telescope. The photograph was taken between these two dates, and most likely during the earlier part of the period around 1875.

The image is part of a photograph album used at Melbourne Observatory in the late 19th century. Photographs in the album include the main Melbourne Observatory building, Great Melbourne Telescope, 8 inch transit telescope, recording equipment, observatories in other cities and countries, astronomers, astronomical photographs of sun and stars.

Description of Content

Overall view of the Great Melbourne Telescope in its purpose-built GMT House at the Melbourne Observatory, circa 1875. The photograph is taken from a vantage point on the elevated timber walkway around the external wall of the building near the north-west corner, with the moveable gable roof rolled back to reveal the telescope, A smartly dressed gentleman in a coat and bowler hat is standing in front of the south pier supporting the telescope, and is resting his right hand on the counterweights used to relieve the load in the south bearing of the polar axis. The person depicted is believed to be Joseph Turner, Assistant Astronomer, who was employed at the Melbourne Observatory as the observer with responsibility for the Great Melbourne Telescope from 1873 to 1883. Beside him in an alcove within the pier is the clockwork mechanism that provided power to the right-ascension drive allowing the telescope to automatically track objects in the sky for up to two hours.

Significance

Statement of Significance:

The Great Melbourne Telescope was built by Thomas Grubb of Dublin in 1868 and erected at Melbourne Observatory in 1869. It was a reflector telescope with a speculum (metal) mirror of 48 inches diameter; at the time it was the second largest telescope in the world and the largest in the southern hemisphere.

The design and construction was overseen by a committee of eminent British astronomers, who developed the telescope to study the nebulae of the southern hemisphere skies. It was the first major telescope built by Thomas Grubb, and revolutionary in many aspects of its design. The firm went on to make many of the major telescopes around the world in the second half of the 19th century.

The telescope never lived up to expectations, due to difficulties with constant tarnishing of its mirrors, flexure in the mirrors, and its relative unsuitability for the new astronomical techniques of photography and spectroscopy.

The telescope was operated at Melbourne Observatory by a dedicated Great Melbourne Telescope Observer: Albert Le Seuer (1869-70), E F MacGeorge (1870-72), Joseph Turner (1873-83), Pietro Baracchi (1883-92); thereafter it was used only intermittently.

When Melbourne Observatory closed in 1944, the telescope was sold to the Commonwealth Observatory at Mount Stromlo, Canberra.

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