Telescope speculum grinding tool for Lord Rosse's 72-inch telescope at Birr Castle, Ireland mb-code 1645554 1820 (1821)

1820 (1821)

'The murder'd cherub

Dish thought to have been used by Princess Elizabeth in 1554

Cassius Clay combing his hair

Telescope speculum grinding tool for Lord Rosse's 72-inch telescope at Birr Castle, Ireland mb-code 1645554 1820 (1821)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