Lord Rosse's 72 inch (1.8m) reflecting telescope, 1849. William Parsons, 3rd Earl of Rosse (1800-1867) Irish astronomer and engineer, built the then largest telescope on his estate at Parsonstown, Ireland. With it he discovered 15 spiral nebulae, and named the Crab nebula. From his paper 'On the Construction of Specula (Mirrors) of Six-feet Aperture ...' from Philosohical Transactions of the Royal Society, (London, 1849). Engraving.