Autograph Letter Signed ‘Rosse’, to “Dear Sir Frederick”, regretting he is unable to accept his invitation. A good one page example, 7 x 4 inches. 13 Connaught Place, 10 June 1852. William Parsons, third earl of Rosse (1800–1867), astronomer, President of the Royal Society. In the 1840s he built the Leviathan of Parsonstown, a 72 inch telescope at Birr Castle, Parsonstown, County Offaly. Rosse also led the society’s committee, set up in 1852, to oversee the construction of a large reflector in the southern hemisphere.