Telescope speculum grinding tool for Lord Rosse's 72-inch telescope at Birr Castle, Ireland mb-artistname William Theed 'New invented elastic breeches'

'New invented elastic breeches'

pictured at the Royal Ballet rehearsal rooms

pictured in Sheffield

as had Joseph Chamberlain

and others with a kind of stone truncheon'

Telescope speculum grinding tool for Lord Rosse's 72-inch telescope at Birr Castle, Ireland mb-artistname William Theed 'New invented elastic breeches'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