Guiding telescope with Merz lens, metal / glass, used at Sydney Observatory, maker unknown, Sydney, Australia, 1888-1890
There are two main types of telescopes. One uses a curved reflecting mirror to capture an image of the astral bodies the other uses a refracting lens to magnify the image.
This guiding telescope was used in conjunction with Sydney astrograph (H10255) employed in the mapping the stars project. In 1887 astronomers from around the world embarked a massive new enterprise; known as the Carte du Ciel (Mapping the Stars) project it involved photographing and measuring the stars in both hemispheres. Australia was actively involved in project with observatories in Sydney, Melbourne, and Perth keen to participate in this international project. Each observatory was allocated a zone of the sky and was expected to record it using instruments of a standard pattern.
British institutions preferred to patronize a British maker Howard Grubb of Dublin who took on the work of constructing seven of the astrographs needed.
Melbourne and Perth requested Grubb telescopes but Sydney only wanted the lens. This was because Russell believed there was now enough expertise in the colony to finish the rest of the instrument and perhaps also because he was aware of the pressure Grubb would be under to complete his orders on time. As it was the Melbourne and Sydney's equipment ordered in 1888 arrived in 1890. The Perth telescope arrived in 1897.
The casing and mounts for the 13-inch refracting telescope which housed the Grubb lens were made in New South Wales. This illustrates how the skills of local manufactures had developed since Australia's formative yeas when all instruments were ordered from Europe or America. The making of the casing and mounts for the telescope was divided between two local Sydney firms, Mort's Dock and Engineering Co. and the Atlas Engineering Co. The clockwork microscopes, all the smaller parts and the putting together of the instrument were all done by Mr. W. I. Masters, the instrument maker at The Sydney Observatory.
This guiding telescope was probably put together at the same time as the Sydney astrograph, perhaps by I. W. Masters who worked at Sydney Observatory. The telescope has an aperture of 18 centimetres and the lens was taken from a telescope brought from Merz and Sons in 1861. The guiding telescope was rigidly fixed to the astrograph and guiding wires were fitted in the eyepiece to allow movement in two directions.
Its use as guiding telescope for one of the earliest astrographs in Australia means it is nationally significance while the role it played in 'Mapping the Stars' project also gives it international significance.
Russell, H. C., Description of the Star Camera at The Sydney Observatory, Alfred James Kent, Government Printer, 1923, p.4
King, H., C., The History of the Telescope, Dover Publications, New York, 1955, p.300
Glass, I. S., Victorian Telescope Makers; the Lives and Letters of Thomas and Howard Grubb, Institute of Physics Publishing, Bristol and Philadelphia, 1997
Wood, Harley, Astrographic Catalogue 1900.0, Sydney Section, Dec. -51° to -65°, V.C.N. Blight, Government Printer, New South Wales, 1971.
Geoff Barker, August, 2007