The Rosse six-foot telescope ( also known as Leviathan of Parsonstown). A reflecting telescope of 72 in (1.8 m) aperture; which wa largest telescope in the world from 1845 until the construction of the 100-inch (2.5 m) Hooker Telescope in 1917. The Rosse six-foot telescope was built by William Parsons; 3rd Earl of Rosse on his estate; Birr Castle; at Parsonstown; Ireland 1911 Astronomy for All by Burgel; Cassell