Rosse
WILLIAM PARSONS, THIRD EARL OF, an English astronomer; born in York, England, June 17, 1800. Though a representative Irish peer, Lord Rosse's chief attention was devoted to the study of practical astronomy. In 1827 he constructed a telescope, the speculum of which had a diameter of three feet, and the success and scientific value of this instrument induced him to attempt to cast a speculum twice as large. After many failures, Lord Rosse succeeded in 1845 in perfecting machinery which turned out the huge speculum, weighing three tons, without warp or flaw. It was then mounted in his park at Parsonstown, at a cost of $150,000 on a telescope 54 feet in length with a tube 7 feet in diameter.
A series of cranks, swivels, and pulleys enables this huge instrument to be handled almost with as much ease as telescopes of ordinary size. The sphere of observation was immensely widened by Lord Rosse's instrument, which has been chiefly used in observations of nebulæ.
He died Oct. 31, 1867.