ORATORIO, a musical composition on a sacred theme, dramatic in form and associated with orchestral accompaniments, but without scenic accessories; it derives its name from the oratory of St. Philip Neri at Rome, in which a composition of the kind was first performed, and was a musical development of the MIRACLE PLAYS (q. v.).

ORATORY, CONGREGATION OF THE, community of secular priests formed by St. Philip of Neri (q. v.), and bound by no religious vow, each one of which is independent of the others; it consists of novices, triennial fathers, decennial fathers, and a superior, their functions being to preach and hear confession.

ORCAGNA, a Florentine painter, sculptor, and architect, did several frescoes; was architect of the cathedral of Orvieto; his masterpiece an absolutely unique marble tabernacle in the church of Or San Michele, Florence (1329-1389).

ORCHARDSON, WILLIAM QUILLER, English genre-painter, born in Edinburgh; his pictures are numerous, and among the best and most popular, “The Challenge,” “The Queen of the Woods,” “On Board the Bellerophon,” “The Mariage de Convenance”; b. 1835.

ORCUS (i. e. place of confinement), another name for Hades, or the “World of the Dead”; also of the god of the nether world.

ORDEAL, a test by fire, water, poison, wager of battle, or the like, of the innocence or guilt of persons in appeal thereby to the judgment of God in default of other evidence, on the superstitious belief that by means of it God would interfere to acquit the innocent and condemn the guilty, a test very often had recourse to among savage or half-civilised nations.

ORDERICUS VITALIS, a mediaeval chronicler, born near Shrewsbury; was a monk of the Abbey of St. Evreul, in Normandy; wrote an ecclesiastical history of Normandy and England—­a veracious document, though an incondite; d. 1143.

ORDERS IN COUNCIL are issued by the British Sovereign, with the advice of the Privy Council, and within limits defined by Parliament.  In cases of emergency these limits have been disregarded, and Parliament subsequently asked to homologate the action by granting an indemnity to those concerned.

OREADES in the Greek mythology nymphs of the mountains, with special names appropriate to the district they severally inhabit.

OREGON (314), one of the United States, on the Pacific seaboard, with Washington, Idaho, Nevada, and California on its inland borders, nearly twice the size of England, has the Coast Mountains along the W., the Cascade range parallel 60 m.  E., and 70 farther E. the Blue Mountains.  The centre and E. is hilly, and affords excellent grazing and dairy-farming ground; the western or Willamette Valley is arable, producing cereals, potatoes, tobacco, hops, and fruit.  Between the Coast Mountains and the sea excessive rains fall.  The State is rich in timber, coal, iron, gold, and silver; and the rivers (of which the Columbia on the