Credit: © The Royal Society
    Image number: RS.9080
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    Telescope speculum grinding tool for Lord Rosse's 72-inch telescope at Birr Castle, Ireland

    Date
    1861
    Object type
    Archive reference number
    Material
    Technique
    Dimensions
    height (print): 104mm
    width (print): 98mm
    Subject
    Content object
    Description
    Plate 24 figure 4 from the paper "On the construction of specula of six-feet aperture; and a selection from the observations of nebulae made with them", by William Parsons, 3rd Earl of Rosse, Philosophical Transactions of the Royal Society, volume 151 (1861) pp.681-746. A front view of the cast iron grinding tool used to produce the speculum of the reflecting telescope at Birr Castle, Parsonstown. The face has straight cast grooves forming squares and circular, lathe-cut groves The tool is shown suspended on gimbals from a pulley. The image is inscribed in pencil, verso "Original Lord Rosse's paper".
    Object history
    This photograph was supplied for reproduction in the journal Philosophical Transactions of the Royal Society.
    Associated place
    <The World>
       > Europe
          > Ireland
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