Astronomy: a large refracting telescope, in use outdoors. Lithograph by W. Eldridge, 183-.

"On his father's death in 1830 Cooper succeeded to his position as manager of the family estates at Markree, Collooney, co. Sligo, Ireland, and decided to erect an observatory there. He visited Cauchoix in Paris in 1829 and by 1831 was able to purchase from him an object-glass 13⅓ inches across and 25 feet in focal length, the largest then in existence. Used at first on a wooden stand, it was mounted equatorially by Thomas Grubb of Dublin in 1834. Cast iron was employed for the first time as the material of the tube and stand. A dome of the requisite size was considered then not to be feasible, and the instrument was set up in the open air."--Oxford dictionary of national biography