Telescope speculum grinding tool for Lord Rosse's 72-inch telescope at Birr Castle, Ireland mb-artistname William Theed and Wilhelm I of Prussia

and Wilhelm I of Prussia to his right

The Looking Glass

as had Joseph Chamberlain

pictured in Sheffield

with the woman on the right carrying a shawl over her arm

Telescope speculum grinding tool for Lord Rosse's 72-inch telescope at Birr Castle, Ireland mb-artistname William Theed and Wilhelm I of PrussiaPlate 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