RT Journal Article T1 A model instrument: the making and the unmaking of a model of the Airy Transit Circle A1 Daniel Belteki YR 2020 VO IS Spring 2020 K1 Airy Transit Circle K1 Exposition Universelle 1855 K1 Greenwich K1 History of models K1 Royal Observatory K1 Sir George Biddell Airy K1 South Kensington Museum AB The Airy Transit Circle defined the position of the Greenwich Prime Meridian for decades. A set of models depicting the celebrated instrument and its parts was exhibited at the Exposition Universelle held in Paris in 1855. After the exhibition, the models were transferred for display at the South Kensington Museum, where it remained until it was deaccessioned in 1928. The article investigates why the set of models were seen as ‘mysterious’ in both Paris and London, despite being the instrument that marked Longitude Zero for the British Empire, and why such a prestigious instrument failed to capture the public imagination. This is shown by highlighting the contradictory interpretations of the models by the various networks of individuals and institutions within which they were discussed and transmitted. NO The Royal Observatory at Greenwich will be referred to in the rest of the article as the ROG and as ‘the Observatory’. NO The Transit Circle is still on display today at the ROG, and it occupies the same position where it was erected by George Airy in 1850 (Object ID: AST0991). The Great Equatorial was repurposed in 1895 as the guiding telescope for the Thompson 26-inch Photographic Refractor, which was moved to the new site of the Observatory at Herstmonceux in the 1950s. NO For a detailed analysis of the history of the longitude problem see Dunn, R and Higgitt, R, 2014, Ships, Clocks, and Stars: The Quest for Longitude (Glasgow: Collins). NO Augustus De Morgan, in one of his letters to William Rowan Hamilton, jokingly described his theory about Airy that the Astronomer Royal preserved even his blotting papers. See Graves, R G, 1889, Life of Sir William Rowan Hamilton, vol. III (Dublin: Hidges, Figgis, & Co.), p 381; the ‘Airy Papers’ (RGO 6) today form part of the RGO Archives at the Cambridge University Library and take up around 12 cubic metres of storage space. NO For an overview of the approach see Law, J and Callon, M, 1988, ‘Engineering and Sociology in a Military Aircraft Project: A Network Analysis of Technological Change’, Social Problems, 35/3, pp 284–297, and Latour B, 2005, Reassembling the Social: An Introduction to Actor-Network-Theory (New York: Oxford University Press). NO For an overview of the approach see Law, J and Callon, M, 1988, ‘Engineering and Sociology in a Military Aircraft Project: A Network Analysis of Technological Change’, Social Problems, 35/3, pp 284–297, and Latour B, 2005, Reassembling the Social: An Introduction to Actor-Network-Theory (New York: Oxford University Press). NO Lyon Playfair to Airy, 3 February 1855, RGO 6/442 46–47 NO Two out of the four new instruments are now in the collection of the Science Museum: the Altazimuth and the Reflex Zenith Tube. NO The whereabouts of the Jones Mural Circle is unknown. The Troughton Transit Instrument (Object ID: AST0982) and Mural Circle (Object ID: AST0973) are currently exhibited at the Meridian Building of the ROG. NO In addition, observations with it provided fundamental positional data on celestial bodies. For the contribution of Greenwich to time distribution see Morus, I, 2000, ‘The nervous system of Britain: space, time and the electric telegraph in the Victorian age’, The British Journal for the History of Science, 33/4, pp 455–475, and Howse, D, 1997, Greenwich Time and the Longitude (London: Philip Wilson Publishers Limited). NO ‘New Greenwich Observatory’, Daily Mail, 16 April 1899, p 12 NO See Charles May’s detailed abstract titled ‘On the Application of Chilled Cast Iron to the Pivots of Astronomical instruments’, published in 'Notices and Abstracts of Miscellaneous Communications to the Sections', in Report of the Twenty-First Meeting of the British Association for the Advancement of Science (London: John Murray, 1852), pp 114–115. NO Airy to Henry Cole, 11 June 1857, RGO 6/4 511 NO H C Owen to Lord Wrottesley, 14 December 1854, RGO 6/442 17–18 NO From the same letter we learn that Airy’s proposal to exhibit models of the instruments (except for the American Barrel) at the Great Exhibition of 1851 was rejected. See Airy to H C Owen, 23 December 1854, RGO 6/442 21–22. NO See the correspondence between Airy and various members of the Board of Trade (H C Owen, Lyon Playfair, Cpt. Francis Fowke), January 1855, RGO 6/422 25–40. NO Airy to Playfair, 29 January 1855, RGO 6/422 40 NO Playfair to Airy, 30 January 1855, RGO 6/422 41–4; Airy to Playfair, 3 February 1855, RGO 6/422 48 NO Admiral William Henry Smyth to Airy, 30 January 1855, RGO 6/422 447-448; Airy to Smyth, 30 January 1855, RGO 6/422 449 NO Fowke to Airy, 6 February 1855, RGO 6/422 51 NO Airy to Fowke, 7 February 1855, RGO 6/422 52–53 NO Airy to William Simms, [undated], RGO 6/422 418; Airy to Fowke, 7 February 1855, RGO 6/422 54–55 NO Ground Plan of the Models of the Greenwich Transit Circle in the Paris Universal Exhibition of 1855, RGO 6/422 201 NO Airy’s Astronomer Royal journal (RGO 6/25) includes several entries related to the construction of a model for this purpose. See entries 9 February and 17 February 1848 about its construction. See entries 19 April, 27 April, 2 May, 4 May, 6 May, 10 May 1848 for private viewings of the model by Lord Wrottesley, Captain Smyth, Samuel Hunter Christie, Admiral Beaufort, Richard Sheepshanks, and Colonel Sabine. The entry for 3 June 1848 further denotes the display of this model at the annual visitation of the Observatory. NO Airy’s direct involvement was reflected in his internal notes sent to the carpenter of the ROG, John Green. See ROG 6/422 218–228. For Airy assigned the responsibility to Dunkin see Airy to Dunkin, 26 March 1855, RGO 6/422 177–178. NO Dunkin to Airy, 12 April 1855, RGO 6/422 181–182 NO Dunkin to Airy, 15 April 1855, RGO 6/422 184–185 NO Dunkin to Airy, 19 April 1855, RGO 6/422 186–187 NO Dunkin to Airy, 19 April 1855, RGO 6/422 186–187 NO Airy to Playfair, 24 April 1855, RGO 6/422 88–89 NO Dunkin to Airy, 3 May 1855, RGO 6/422 196 NO Dunkin to Fowke, 3 May 1855, RGO 6/422 91–92; Airy to Fowke, 5 May 1855, RGO 6/422 93–94 NO Airy to Playfair, 10 May 1855, RGO 6/422 97–98 NO Dunkin to Airy, 30 April 1855, RGO 6/442 195; Dunkin to Airy, 4 May 1855, RGO 6/442 197–198 NO ‘The Opening of the Paris Exhibition’, Illustrated London News, 9 June 1855, p 583 NO Ibid NO Playfair to Airy, 8 May 1855, RGO 6/422 95–96 NO ‘Palais de l’Industrie’, Norfolk Chronicle, 19 May 1855, p 4 NO ‘Palais de l’Industrie’, Norfolk Chronicle, 19 May 1855, p 4 NO Smyth to Airy, [undated], RGO 6/442 451 NO Airy to Le Verrier, 9 May 1855, RGO 6/442 260–261 NO Airy to Dunkin, 30 April 1855, RGO 6/442 193–194 NO Airy to Le Verrier, 29 May 1855, RGO 6/442 263–264 NO Lajugie to Airy, 1 November 1855, RGO 6/442 248–249 NO Airy to Fowke, 15 November 1855, RGO 6/442 130–131 NO Henry Cole to Airy, 27 November 1855, RGO 6/442 134–135 NO Airy to Cole, 29 November 1855, RGO 6/442 136–137 NO Dunkin to Lightly & Simon, 4 December 1855, RGO 6/442 28. It is unknown what happened to the model that was in the possession of the Royal Astronomical Society. NO E T Loseby to Airy, 22 October 1855, RGO 6/442 296 NO Airy to Loseby, 23 October 1855, RGO 6/442 297 NO Cole to Airy, 20 March 1857, RGO 6/4 497–498 NO While his contribution was unaccredited at the time, Main confirmed in another book that he wrote the account. For Main’s account see John Weale, London Exhibited in 1851 (London: John Weale, 1851), pp 652–656. For Main referring to himself as the author of the description see Robert Main, Rudimentary Astronomy (London: John Weale, 1852), p 29. NO Airy, [Description attached to the model of the Transit Circle exhibited at the South Kensington Museum], RGO 6/4 511 NO Airy to Green, 26 March 1857, RGO 6/732 310 NO The northern and southern ends can be determined based on the positioning of the counterpoises (running around an arch) that are always attached to the eastern pier of the Transit Circle. NO ’The South Kensington Museum’, Illustrated London News, 4 July 1857, p 5 NO Catalogue of the Educational Division of the South Kensington Museum (London: George E. Eyre and William Spottiswoode, 1867), p 337 NO Entry from the 1895 catalogue in the technical file of the model, Science Museum. PB The Science Museum Group SN 2054-5770 LA eng DO 10.15180/201305 UL https://journal.sciencemuseum.ac.uk/article/a-model-instrument/ WT Science Museum Group Journal OL 30