Telescope, zenith-sector telescope in wooden case, brass / glass / wood, maker unknown, 1827-1830, used at Parramatta and Sydney Observatory, New South Wales, Australia
In 1846 the Lords of the Treasury requested Sir George Gipps, the then Governor, provide further information on the state of Parramatta Observatory and a commission, under Captain P.P. King, was set up to report on the Observatory. The resulting report found that from around 1837 the health problems of the Government Astronomer, James Dunlop, had led to a decline in activity. In 1847 the observatory was closed and the instruments put into storage.
Before storage however P.P. King listed the instruments then at Parramatta Observatory and this zenith-sector was included in the inventory. According to King the instrument was still in its box, and apparently unused. The zenith-sector was a highly specialised instrument and presumably was not one of those which came over with Thomas Brisbane in 1821. It is more likely that it was purchased after 1827 when Carl Rumker was appointed Government Astronomer and before 1830 when he was dismissed.
In 1829 Rumker left for England to purchase new instruments and to bring books containing the Parramatta observations to London for reduction and possible publication. The zenith-sector may have been one of the instruments Rumker purchased before his dismissal and this could account for Dunlop's lack of interest in using the instrument.
The zenith-sector was a special kind of telescope which were used to measure stars near their zenith. Their long focal lengths made them better suited for measuring small deviations in the stars zenith distance when it culminated. As their name implies they were set up almost vertically and the tube was only allowed a small amount of movement in the meridian plane. Their movements while tracking a star were read using a micrometer and gave very precise measurements.
This zenith-sector is one of the largest, and most specialised, of the early Parramatta Observatory instruments and is a rare example of early nineteenth century instrument making. This instrument remains of national significance due to its pioneering role in Australian science and its association with Australia's earliest astronomers. It is also of international significant for its association with early nineteenth century astronomical instruments.
King, H., C., The History of the Telescope, Dover Publications, New York, 1955
Hawkins, J., Observatories in Australia 1788-1830, The Australian Antique Collector, p.103. Date not acknowledged, Powerhouse Blue Object File
Bergman, G.F., 'Rumker, Christian Carl Ludwig, cited in, (ed) Pike, D., Australian Dictionary of Biography, Volume 1, Melbourne University Press, London and New York : Cambridge University Press, 1966
Richardson, W., Catalogue of 7385 Stars, Cheifly in the Southern Hemisphere, prepared from observations made in 1822, 1823, 1824, 1825 and 1826, at the Observatory at Paramatta, New South Wales, Printed by William Clowes and Sons, For His Majesty's Stationary Office, 1835, p.iv
Geoff Barker, August, 2007