continued until 1890, when Wilhelmina, daughter of William III, became queen. In 1908 she decreed that her descendants should be styled princes and princesses of Orange-Nassau.
Orange Free State Former province, central South Africa. Before the arrival of the Europeans, the area was the home of Bantu- speaking peoples. Afrikaners came in large part during the Great Trek of the 1830s. Britain administered the territory from 1848 to 1854; then the indepen¬ dent Orange Free State was established. British rule was reimposed fol¬ lowing the South African War in 1902, though self-government was later restored. In 1910 it became the Orange Free State province of the Union of South Africa (from 1961 the Republic of South Africa). After the South African elections of 1994, it became the province of Free State. Blacks make up about 80% of the population; most of the whites speak Afrikaans. The province’s capital is Bloemfontein.
Orange River River, southern Africa. It rises in the Lesotho Highlands as the Sinqu River and flows west as the Orange across South Africa. It passes the southern edge of the Kalahari Desert and winds through the Namib Desert before draining into the Atlantic Ocean in South Africa. It forms the border between South Africa and Namibia. It is about 1,300 mi (2,100 km) long. There are some irrigated sections along the river and many dams but no large towns.
orangutan \d-'raq-9- l tar)\ or orang Species (Pongo pygmaeus , fam¬ ily Hominidae) of arboreal great ape, found only in the lowland swamp forests of Borneo and Sumatra but originally in the tropical forests of South Asia as well. The orangutan (Malaysian for “person of the for¬ est”) has a short thick body, long arms, short legs, and shaggy reddish hair. Males are about 4.5 ft (137 cm) tall and weigh about 185 lb (85 kg); females are smaller. Orangutans are placid, deliberate, ingenious, and persistent. Males have flat, fatty cheekpads and a baglike, pendulous swelling at the throat. Orangutans use all four limbs to walk and climb.
They eat mostly figs and other fruits and some leaves, bark, and insects.
They sleep in trees on a platform built of interwoven branches. Adults are solitary and live far apart, com¬ ing together only for a brief court¬ ship. The mother carries and nurses the single young for almost three years. Though generally silent, the adult male has a loud, roaring “long call.” The orangutan is an endangered species.
Oranjestad Vo-'ran-yo-.statV Seaport and chief administrative town (pop., 2000: 26,355), Aruba, Netherlands Antilles. It is located on the western coast of this Caribbean island. It is a free port and a petroleum¬ processing and shipping centre.
oratorio Large-scale musical composition on a sacred subject for solo voices, chorus, and orchestra. The term derives from the oratories, com¬ munity prayer halls set up by St. Philip Neri in the mid 16th century in a Counter-Reformation attempt to provide locales for religious edification outside the church itself, and the oratorio remained a nonliturgical (and non-Latin) form for moral musical entertainment. The first oratorio, really a religious opera, was written in 1600 by Emilio del Cavaliere, and the ora¬ torio’s development closely followed that of opera. Giacomo Carissimi pro¬ duced an important body of Italian oratorios, and Marc-Antoine Charpentier transferred the oratorio to France in the later 17th century. In Germany the works of Heinrich Schutz anticipate the oratorio-like Passions of Johann Sebastian Bach. The most celebrated oratorio composer was George Frideric Handel; his great English works include the incomparable Messiah (1742). Handel inspired Franz Joseph Haydn’s great Creation (1798) and exerted great influence on the 19th-century oratorio, whose composers include Hector Berlioz, Felix Mendelssohn, and Franz Liszt. Though the oratorio thereafter declined, 20th-century oratorio composers included Edward Elgar, Igor Stravinsky, Arthur Honegger, and Krzysztof Penderecki.
Orbison, Roy (b. April 23, 1936, Vernon, Texas, U.S.—d. Dec. 6, 1988, Hendersonville, Tenn.) U.S. singer and songwriter. He formed his first
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1414 I orbital ► order
musical group at age 13. His first single, “Ooby Dooby” (1956), was fol¬ lowed in the early 1960s by a string of hits, carefully crafted ballads of loneliness and heartache that included “Only the Lonely,” “I Can’t Stop Loving You,” “Crying,” “In Dreams,” and “Oh, Pretty Woman.” He was known for his soaring voice, one of the most operatic in all rock music. His career waned after the death of his wife in a motorcycle accident (1966) and the death of two sons in a fire (1968). He made a comeback in the 1980s; with Bob Dylan, George Harrison (1943-2001), and Tom Petty (b. 1953) he formed the band the Traveling Wilburys.
orbital Mathematical expression, called a wave function, that describes properties characteristic of no more than two electrons near an atomic nucleus or molecule. An orbital can be considered a three-dimensional region in which there is a 95% probability of finding an electron. Atomic orbitals are designated by a combination of numerals and letters (e.g.. Is, 2 p, 3d, 4 f). The numerals are the principal quantum number and are related to the atomic energy level and distance from the nucleus; the letters indi¬ cate the orbital’s angular momentum and hence its shape. An s orbital with zero net orbital angular momentum is spherical. A p orbital with one fundamental unit of angular momentum, fi, is shaped somewhat like a dumbbell ( fi is Planck’s constant, h, divided by 2k). The shapes of the other orbitals are more complicated. Molecular orbitals have geometries determined by the overlap of two or more atomic orbitals and are desig¬ nated by Greek symbols, e.g., a and n.
orca See killer whale
Orcagna \or-'kan-ya\, Andrea orig. Andrea di Cione (b. c. 1308, Florence?, Republic of Florence—d. c. 1368, Florence) Florentine painter, sculptor, and architect. A goldsmith’s son, he was the leading member of a family of painters and the most prominent Florentine artist of the mid 14th century. His altarpiece for the Strozzi Chapel in Florence’s Santa Maria Novella (1354-57) shows his ability to unify the multiple panels of a polyptych. As a sculptor he is known for a single work: the taber¬ nacle in the guild oratory of Or San Michele (1352-60), a decorative structure of great complexity that is among the finest examples of the expressive art that sprang up in Tuscany after the Black Death. He was employed as architect on Florence’s Duomo (cathedral) in 1357 and
1364-67.
orchestra Instrumental ensemble of varying size and composition. Today the term orchestra usually refers to the traditional large Western ensemble of bowed stringed instruments with brass, woodwind, and percus¬ sion instruments, with several players to each string part. The develop¬ ment of the orchestra coincides with the early history of opera. A major antecedent of the modern orchestra was that of the mid-17th-century French court, especially as employed by Jean-Baptiste Lully; it was domi¬ nated by 24 bowed strings but also often included woodwind instruments. Trumpets, horns, and timpani were often added in the early 18th century p_ and were standard by the time of Franz Joseph Haydn. During the 19th
century there was a considerable expansion, particularly in the number wm and variety of wind and percussion instruments; some works called for
ifl well over 100 musicians. The symphony orchestra changed little in the
20th century. See also orchestration.
brasses
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orchestration Art of choosing which instruments to use for a given piece of music. The sections of the orchestra historically were separate
ensembles: the stringed instruments for indoors, the woodwind instru¬ ments for outdoors, the horns for hunting, and trumpets and drums for battle or royal ceremony. Once entirely dependent on what was available or customary, composers began to explore the musical potential of instru¬ mental combinations with the advent of the modern orchestra in the mid- to late 18th century. The first great orchestration text was written by Hec¬ tor Berlioz in 1844.