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Buildings, Telescopes and Telescope Domes Project

John Butler reports that the HLF-supported programme of restoration of three historic telescopes and their domes has continued throughout the year, and that a growing collection of images showing progress with the Telescopes and Telescope Domes restoration project is available on the Armagh Observatory web-site (see http://star.arm.ac.uk/history/Domes/).

The principal items completed under the project during 2004 were the 15-inch Grubb Reflector and its dome, the 10-inch Grubb Refractor and the Robinson Memorial Dome, and finally the new 6-metre diameter Calver Dome.

The 15-inch reflector (1834) by Thomas Grubb, some parts of which were originally made for the Great Markree Refractor, is believed to be the earliest clock-driven reflecting telescope in the world, incorporating a number of pioneering developments in telescope design. It was built for Thomas Romney Robinson, the third director, who used it for early experiments in astronomical spectroscopy, and its design was influential in later, larger telescopes constructed by Thomas Grubb, including the Great Southern Telescope erected in Melbourne, Australia, in 1869. Following its restoration by the Sinden Optical Company in Newcastle upon Tyne, it was returned to Armagh and re-erected on 4 March 2004. The telescope now has a new glass primary mirror to replace the original speculum, broken in the mid-20th century.

The 1827 Dome, at the eastern end of the main Observatory building, was constructed originally for a Herschel Reflector but modified in 1834 to accommodate the 15-inch reflecting telescope by Thomas Grubb. This too has been restored and fitted with a new copper covering. Much of the original fabric has been retained including the wooden dome support structure and parts of the shutter. The dome now turns and opens for the first time in three quarters of a century.

The 10-inch refractor (1885) by Howard Grubb has also been restored by Mr Bertie McClure of Belfast and is now fully operational. A replacement primary lens which was ordered from the Sinden Optical Company has sadly been delayed by difficulties in obtaining flint glass of the requisite quality.

Figure 14: The restored 18-inch Calver reflector in the workshop of the Sinden Optical Company (SOC), Newcastle upon Tyne, summer 2004. Image courtesy of the SOC.

The Robinson Memorial Dome is an early prefabricated building, the design of which is believed to have derived from military buildings used in the Crimean War. This dome has been extensively restored with new wooden cladding and a new floor of recycled pine, and has been sealed to prevent the ingress of moisture and to allow the humidity to be controlled.

The new dome for the 18-inch Calver Telescope is now fully operational and awaits the return of the telescope to Armagh later in 2005. The telescope itself (see Figure 14) has had a chequered history. It came to Ireland first as the property of John Pierce of Wexford, and subsequently came into the possession of William Ellison who presented it to Armagh Observatory as a gift on his appointment as director. George Calver, its maker, was one of the earliest English telescope manufacturers to use glass mirrors instead of `speculum' metal. The telescope was subsequently converted to a Schmidt design by Hargreaves, and is currently undergoing restoration to its original Newtonian form by the Sinden Optical Company.