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Description: | 18th century instrument for positional measurement of stars with telescope mounted on an equatorial mount having finely graduated scales. Brass with 18" circles. Originally made by Sisson. Afterwards divided anew, with an achromatic telescope and 'refraction apparatus' (to correct for atmospheric refraction) added by Ramsden.
"Equatorial Telescope by Sisson and Ramsden This weighty 19th century telescope was a gift to the Castlehill Observatory founded by Professor Patrick Copland on behalf of Marischal College. It was donated in 1781 by the third Earl of Bute, Chancellor of Marischal College and former Prime Minister of Great Britain, who was a keen amateur scientist and astronomer with an impressive private collection of apparatus. The telescope with its large and finely divided scales was intended for accurate positional astronomy. It had been made some years earlier by Jeremiah Sisson, one of the foremost precision instrument makers in London but, incredibly enough, was re-divided by Jesse Ramsden in 1782 on the instructions of Lord Bute. Ramsden was the doyen of accurate scale division, being the first to automate the process successfully. It was reported of Professor Copland, who went to London to supervise the building of Castlehill Observatory instruments, that 'the Professor has acquired so great influence over him [Ramsden] that he has prevailed with him to lay aside instruments for his Favourite the Duke of MarleboroughÂ…and set a dozen of his best Men at work on his Equatorial and Transit Instruments'. The transit was a second gift from Lord Bute. The Castlehill Observatory was receiving privileged treatment."
Author: Reid,John.S Date: 1989 Purpose: University.Newsletter
Acquisition source: Presented to Marischal College by Lord Bute | License: | http://www.abdn.ac.uk/historic/Copyright_terms_conditions.shtml | Publisher: | ABDNP University of Aberdeen, Natural Philosophy Collection of Historical Scientific Instruments | Rights holder: | 47718 | Temporal: | 1760-1777 | Source: | University of Aberdeen | Creator: | J. Sisson | Identifier: | http://calms.abdn.ac.uk/Geology/dserve.e... | Go to resource |
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