SIERRA NEVADA, 1, a mountain range in South Spain, 60 m. in length; lies for the most part in Granada, crossing the province E. and W. in bold, rugged lines, and clad on its higher parts with perpetual snow, whence the name; Mulhacen (11,660 ft.) is the highest peak. 2, A mountain system in California, stretching NW. and SE. 450 m., and forming the eastern buttress of the Great Central Valley; highest peak Mount Whitney (14,886 ft.). 3, A lofty mountain group in Colombia, South America, stretching NE. almost to the borders of Venezuela.

SIEYES, ABBE, a conspicuous figure all through the French Revolution, the Consulate, and the Empire, who thought in his simplicity that the salvation of France and the world at large depended on sound political institutions, in the drafting of which he spent his life; was born in Frejus, of the bourgeois class; represented Paris in the States General; sat in the Centre in the Legislative Assembly; renounced the Christian religion in favour of the Goddess of Reason; projected a constitution which was rejected; supported Napoleon; fled to Belgium on the return of the Bourbons, and returned to France in 1830, by which time he was politically defunct (1748-1836).

SIGISMUND, emperor of Germany, son of the Emperor Charles IV., was markgrave of Brandenburg, king of Hungary, and palatine of the Rhine; struggled hard to suppress the Hussites; held the Council of Constance, and gave HUSS (q. v.) a safe-conduct to his doom; he is the “Super Grammaticam” of Carlyle’s “Frederick” (1362-1437).

SIGISMUND is the name of three kings of Poland, the last of whom died in 1632.

SIGNORELLI, LUCA, the precursor of Michael Angelo in Italian art, born at Cortona; studied at Arezzo under Piero della Francesca, and became distinguished for the accurate anatomy of his figures and for the grandeur and originality of design exhibited in his admirable frescoes of religious subjects at Loretto, Orvieto, and elsewhere (1441-1525).

SIGOURNEY, MRS., American authoress, was a prolific writer; wrote tales, poems, essays, chiefly on moral and religious subjects; was called the American Hemans (1791-1863).

SIGURD.  See SIEGFRIED.

SIKHS (lit. disciples), a native religious and military community, scattered, to the number of nearly two millions, over the Punjab, and forming some fifteen States dependent on the Punjab government; founded (1469) by Baber Nanak as a religious monotheistic sect purified from the grosser native superstitions and practices; was organised on a military footing in the 17th century, and in the 18th century acquired a territorial status, ultimately being consolidated in to a powerful military confederacy by Ranjit Singh, who, at the beginning of the 19th century, extended his power over a wider territory.  In 1845-46 they crossed their E. boundary, the Sutlej, and invaded English possessions, but were defeated by Gough and Hardinge, and had to cede a considerable portion of their territory; a second war in 1848-49 ended in the annexation of the entire Punjab, since when the Sikhs have been the faithful allies of the English, notably in the Indian Mutiny.