HERSCHEL

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HERSCHEL, sir William; a distinguished astronomer; son of a musician of Hanover; born November 15, 1738. Being destined by his father for his own profession, he was placed, at the age of 14, in the band of the Hanoverian footguards. He went to England in 1757, and was employed in the formation of a military band, and in conducting several concerts, oratorios, &c. Although enthusiastically fond of music, he had for some time devoted his leisure hours to the study of mathematics and astronomy; and, being dissatisfied with the only telescopes within his reach, he set about constructing one for himself, in which arduous undertaking he succeeded, having, in 1774, finished an excellent reflecting instrument of five feet with his own hands. Encouraged by his success, he proceeded to complete larger telescopes, and soon constructed a seven, a ten and a twentyfeet reflector, having, in the latter case, finished nearly two hundred objectmirrors before he could satisfy himself. From this period he gradually withdrew from his professional engagements. Late in 1779, he began a regular survey of the heavens, star by star, with a sevenfeet reflector, and, after 18 months' labor, discovered, March 13,1781, a new oprimary planet, which he named the Georgiwn Sidus, George III, by the ssttlement of a salary upon him, enabled him to devote the rest of his life to astronomy. At Slough, he commenced the erection of a telescope of the enormous dimensions of 40 feet, and completed it in 1787. Its diameter was 4^ feet, and it weighed 2118 pounds. With this powerful instrument, he continued to prosecute his discoveries, regularly communicating the results to the royal society, till the year 1818.In 1783, he had discovered a volcanic mountain in the moon, and, from farther observations made With his large instru ment, in 1787, two others were distinguished, emitting fire. He also ascertained that the Georgium Sidus was surrounded With rings, and had six satellites, and acquired far more knowledge of the appearance, satellites, &c, of Saturn, than had before existed. The four new plan ets discovered by Piazzi, Olbers and HardingCeres, Pallas, Juno and Vestahe observed with his usual accuracy. Ho fixed their diameter, which Schroter had determined to be from one to four seconds, at less than one second, and made an ingenious hypothesis, in respect to theii nature and formation. (See Planets.) He ascertained also the important fact, that Saturn's ring revolves in 10 hours 32 minutes. He was constantly engaged in determining the orbits and physical constitution of individual stars ; in fixing their relative positions to one another, and to the Milky Way; in ascertaining the greatest possible distance of distinct vision with the aid of the best instruments. An account of most of his labors is found in the Philosophical Transactions and other English periodicals; but some of them are still imprinted. Herschel received much assistance in making and recording observations from his sister Caroline ; and this lady herself discovered several comets. In 1802, he laid before the royal society a catalogue of 5000 new nebula?, nebulous stars, planetary nebulae, and clusters of stars which he had discovered, and, in consequence of the important additions made by him to the stock of astronomical knowledge, received from the university of Oxford the honorary degree of doctor of laws an honor which was followed up, in 1816, by the Guelphic order of knighthood from the king. He continued his astronomical observations till within a few years of his death, which took place at Slough; and he was buried at Upton, Berks, in August, 1822. His son, John F. W. Herschel, has distinguished himself by his skill in mathematics and natural philosophy. Herschel's gigantic telescope, of 40 feet focus, is capable of being moved in any direction, by machinery, which turns on a vertical axis. He found with it the time of Saturn's rotation ; and his observations agree with the results at which Laplace arrived by a mathematical analysis deduced from the laws of gravitation. He discovered, likewise, that this singular planet revolves upon an axis per pendicular to the plane of its orbit. From observations made with his large telescope, he concluded that light does not come directly from the body of the sun, but from very bright, phosphorescent clouds, formed in the sun's atmosphere. The discovery of Arago, that the sun's rays are not polarized, confirmed the opinion of Herschel. Moreover, he found that the red rays in a beam of light give out more heat than the other six rays together.