HERSCHEL, SIR WILLIAM, an English astronomer; born in Hanover, Prussia, Nov. 15, 1738. The son of a musician, he went to England in 1757, and was employed in the formation of a military band. He had for some time devoted his leisure hours to the study of mathematics and astronomy; and, be ing dissatisfied with the only telescopes within his reach, he set about construct ing instruments for himself. Late in 1779 he began a regular survey of the heavens, star by star, with a 7-foot re flector, and discovered, March 13, 1781, a new primary planet, named by him the GEORGITJM SIDUS. This discovery ex tended his fame throughout the world and brought him a pension of £200. FIe then took up his residence at Datchet, near Windsor, v.-here he made many dis coveries in double and triple stars, on the proper motion of the sun and solar system, the spots at the pole of Mars, and the nebul and cluster of stars ob served by Messier and Mechain. In
1787, he discovered a 2d and 4th satellite of the Georgium Sidus, and in 1790 and 1799, five other satellites, viz., the 1st, 3d, 5th, and 6th. In 1781, George III. defrayed the expense of a 40-foot tele scope. With this magnificent instru ment Herschel discovered the 6th and 7th satellites, and also the spots. belts, and flattening on the four new planets between Mars and Jupiter. We owe to him also the discovery of invisible heat ing rays heyond the red extremity the spectrum. In 1820 he was elected the first President of the Royal Astro nomical Society, and published in the first volume of its " Transactions " a paper on 145 new double stars. He died in Slough, near Windsor, England, Aug. 25, 1822.