Lord Rosse's great reflecting telescope

Lord Rosse's great 72-inch (1.828m) diameter reflecting telescope of 1845, called the Leviathan of Parsonstown. Mounted between two brick walls, it could move only in a north-south direction. The instrument viewed from the south, showing the position of the when a man entered the tube to fix the small speculum and to remove the cover of the large one for the night's work. The Earth's rotation provided movement in an east-west direction. From his paper 'On the Construction of Specula of Six-feet Aperture' in "Philosophical Transactions of the Royal Society" (London, 1849). William Parsons, 3rd Earl of Rosse (1800-1867).