The monster telescopes, erected by the Earl of Rosse, Parsonstown, with an account of the manufacture of the specula, and full descriptions of all the machinery. Connected with these instruments (1844)
Parsonstown : Shields · leaf 21
q always the same. After many endeavours to remedy this defect, it was found that a certain result was obtained by spreading over the metal a layer of powdered charcoal two case constant, and amounted to ,4th of the zinc employed. The bed was cast in eight pieces, each being of the shape of figure… … was five inches and a-half, and it weighed four hundred and fifty pounds. ‘The eight portions were soldered together along the sides, and iron bolts used to secure the joinings more perfectly. However, it was found when the Speculum was fastened on that the joints had given in different places,
Rosse, William Parsons, Earl of, 1800-1867 · Telescopes
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