|Title||Photograph, telescope speculum for Lord Rosse's telescope at Birr Castle, Ireland by unknown artist|
|Description||A view of the speculum on supporting levers supported on a cast iron rail carriage. The carriage is shown on a turntable situated to the north side of the Parsonstown 72-inch reflecting telescope. The background is screened off by a dark cloth over which some details of trees and part of the supporting structure for the telescope are visible. The image was intended to show the weights and levers for counterpoising the secondary triangles. The instrument, the largest reflecting telescope in the world when built, was at Birr Castle, Parsonstown, Ireland. The image is inscribed in ink, verso 'Original from which copy was made on reduced scale'. An engraved version of this photograph was published in William Parsons' paper as figure 2 from plate 24.|
Subject: Scientific Instruments / Astronomy
Published in Philosophical Transactions as 'On the construction of specula of six-feet aperture; and a selection from the observations of nebulæ made with them'.
Received by the Royal Society on 5 June 1861. Read 20 June 1861.
|Physical description||Albumen print, mounted on card|
|Related material||DOI: 10.1098/rstl.1861.0029|
|Related records in the catalogue||PT/62/8|
|URL description||Digital version available on The Royal Society Picture Library|
Fellows associated with this archive
|NA8084||Parsons; William (1800 - 1867); 3rd Earl of Rosse||1800 - 1867|