Britannica Concise 2005

aplastic \a-'plas-tik\ anemia or anemia of bone-marrow failure Inadequate blood-cell for¬ mation by bone marrow. Pancytope¬ nia is the lack of all blood-cell types (ERYTHROCYTES, LEUKOCYTES, and PLATE¬ LETS), but any combination may be missing. Drug, chemical, or radiation exposure most often causes the dis¬ ease, but about half of all cases have no known cause. It may occur at any age. Acute disease may be quickly severe, even fatal; chronic disease has symptoms including weakness, shortness of breath, headache, fever, and pounding heart. There is usually a waxy pallor. Hemorrhages occur in mucous membranes, skin, and other organs. Lack of white blood cells lowers resistance to infection and becomes the major cause of death. Very low platelet count may lead to severe bleeding. The treatment of choice is bone-marrow transplantation. Otherwise treatment involves avoiding any known toxic agent and giving fluids, glucose, and proteins (often intravenously) as well as blood components and antibiotics.

aplite or haplite Any igneous rock of simple composition, such as granite composed only of alkali feldspar, muscovite mica, and quartz; in

a more restricted sense, uniformly fine-grained (less than 0.08 in., or 2 mm), light-coloured igneous rocks that have a characteristic granular tex¬ ture. Unlike pegmatite, which is similar but much coarser-grained, aplite occurs in small bodies that rarely contain zones of different minerals. The two rocks may occur together and are assumed to have formed at the same time from similar magmas.

Apo \'a-po\, Mt. Active volcano, Mindanao, Philippines. Located west of Davao City, it is the highest point in the Philippines, at 9,690 ft (2,954 m). In 1939 its slopes and immediate vicinity were incorporated into Mount Apo National Park, which includes numerous peaks and valleys as well as Malasita Falls and Sibulao Lake.

apocalypse Vs-'pa-ko-.lipsV In many Western religious traditions, the period of catastrophic upheaval expected to occur just before the end of the world, when God will come to sit in judgment on humankind. The belief that the world will come to a violent and cataclysmic end exists in Judaism and Christianity as well as in Zoroastrianism. Several of the pro¬ phetic works of the Hebrew Scriptures, notably the book of Daniel, include visions of the apocalypse. The book of Revelation (or Apocalypse) gives a dark and dramatic picture of the end of time, when the wicked will be punished and the good will triumph through God’s intervention. The approach of the Last Days is expected to be marked by famines, wars, earthquakes, plagues, and other natural disasters, along with signs in the heavens. Today apocalyptic themes are emphasized by various religious groups (e.g., fundamentalist Christians) and have also been taken up by science-fiction writers. See also eschatology; millennialism.

Apocrypha \3-'pa-kr3-fo\ In biblical literature, works outside an accepted canon of scripture. In modern usage the Apocrypha refers to ancient Jewish books that are not part of the Hebrew Bible but are con¬ sidered canonical in Roman Catholicism and Eastern Orthodoxy. Among the various books included are Tobit, Judith, Baruch, and the Maccabees as well as Ecclesiasticus and the Wisdom of Solomon. Protestant churches follow Jewish tradition in judging these works apocryphal or noncanon- ical. The term deuterocanonical is used to refer to works accepted in one canon but not all. Pseudepigrapha are spurious works for which biblical authorship is claimed.

Apollinaire \a-p6-le-'ner\, Guillaume orig. Guillelmus (or Wil¬ helm) Apollinaris de Kos- trowitzky (b. Aug. 26, 1880,

Rome?, Italy—d. Nov. 9, 1918,

Paris, Fr.) French poet of Polish- Italian birth. Arriving in Paris at age 20, Apollinaire always kept his early years obscure. In his short life he took part in all the avant-garde movements that flourished at the beginning of the 20th century. His poetry was characterized by daring, even outrageous, technical experi¬ ments. Because of his efforts to cre¬ ate an effect of surprise by means of unusual verbal associations and word patterns, he is often considered the herald of Surrealism. His poetic masterpiece was Alcools (1913). His death resulted from a head wound received in World War I.

Apollo Most widely revered of the Greek gods. He communicated the will of his father Zeus, made humans aware of their guilt and purified them of it, presided over religious and civil law, and foretold the future. His bow symbolized distance, death, terror, and awe; his lyre symbolized music, poetry, and dance. As a patron of the arts, he was often associated with the Muses. He was also a god of crops and herds. He became associated with the sun, and was even identified with Helios, the sun god. Also associated with healing, he was the father of Asclepius. By tradition, Apollo and his twin, Artemis, were born at Delos to Leto. Apollo’s oracle was established at Delphi; the Pythian Games commemorated his killing (while still an infant) of the serpent Python to take the shrine. His many lovers fared poorly: the fleeing Daphne became a laurel tree; the unfaithful Coronis was shot by Artemis, and Cassandra, who rejected him, was doomed to utter true prophecies no one would believe. See photograph opposite page.

Apis, bull deity, painted on the bottom of a wooden coffin, c. 700 bc; in the Roemer und Pelizaeus Museum, Hildesheim, Ger.

BAVARIA VERLAG

Apollinaire, drawing by Pablo Picasso from the frontispiece to Calligrammes,

1918

H. ROGER-VIOLLET

© 2006 Encyclopaedia Britannica, Inc.

Apollo ► Appalachian Geosyncline I 89

Apollo NASA manned Moon-landing project of the 1960s and ’70s. The Apollo spacecraft, supplied with their own low-powered rockets, could brake on approach to the Moon and go into lunar orbit. They also could release part of the spacecraft, the lunar module, with its own rocket power, to land astronauts on the Moon and bring them back to the lunar orbiter. In July 1969 Apollo 11 made the first lunar landing (see Edwin Aldrin; Neil Armstrong). In 1970 Apollo 13 was damaged by an explosion in an oxygen tank but returned safely to Earth. Later Apollo missions explored the lunar surface extensively, collecting samples of Moon rocks and installing instruments for research. Apollo 17, the program’s final lunar flight, took place in 1972. In total, 12 American astronauts walked on the Moon during six successful lunar-landing missions.

Apollo asteroid See Earth-crossing asteroid

Apollo Theatre During and after the Harlem Renaissance, a centre of African-American popular music on 125th Street in New York City’s Harlem district. Built in 1914, it hosted musical performers such as Bill Robinson, Billie Holiday, Bessie Smith, Ethel Waters, Duke Ellington, and oth¬ ers in the 1930s and ’40s; stars such as Ella Fitzgerald, Sarah Vaughan, and James Brown were discovered on Wednesday amateur nights. In the 1960s the Apollo featured soul artists such as the Supremes, Stevie Won¬ der, and Marvin Gaye. Converted into a movie theatre in 1975, it was reopened as a performance venue in 1983.

Apollonius Dyscolos V.ap-o-'lo-ne-os-'dis-ko-losV (fl. 2nd century ad) Greek grammarian. Apollonius is considered the founder of the system¬ atic study of grammar. Priscian based his work on the writings of Apol¬ lonius. Four of Apollonius’s works survive: On Syntax and the shorter treatises On Pronouns , On Conjunctions, and On Adverbs.

Apollonius of Perga (b. c. 240 bc, Perga, Anatolia—d. c. 190 bc, Alexandria, Egypt) Mathematician known as “The Great Geometer.” His Conics was one of the greatest scientific treatises of the ancient world. In it he introduced the terms parabola, ellipse, and hyperbola. Because Con¬ ics was fundamental to later advances in optics and astronomy in the Islamic world, a 9th-century Arabic translation survived to fill in for some of the missing Greek original. Generally, his other writings survive only as titles.

Apollonius of Rhodes (b. c. 295 bc) Greek poet and grammarian. He served as librarian of the famous Library of Alexandria. His Argonautica, a romantic epic in four books about the Argonauts, is derived from Homer and is noted for its suggestive similes, vivid descriptions of nature, and fresh handling of old episodes.

apologetics Branch of Christian theology devoted to the intellectual defense of faith. In Protestantism, apologetics is distinguished from polem¬ ics, the defense of a particular sect. In Roman Catholicism, apologetics

refers to the defense of the whole of Catholic teaching. Apologetics has traditionally argued positively to quell believers’ doubts and nega¬ tively against opposing beliefs to remove obstacles to conversion. It attempts to take objections to Chris¬ tianity seriously without giving ground to skepticism. Biblical apol¬ ogetics defended Christianity as the culmination of Judaism, with Jesus as the Messiah. In the 2nd and 3rd cen¬ turies a number of Christian writers defended the faith against the criti¬ cisms of Greco-Roman culture, and in the 5th century St. Augustine wrote his monumental City of God as a response to further criticisms of Christianity following the sack of Rome in 410. John Calvin’s “natural theology” attempted to establish reli¬ gious truths by rational argument. The late 18th-century argument that a universe exhibiting design must have a designer continues to be used; apologists have also dealt with the challenges of Darwinism, Marxism, and psychoanalysis. See also Apologist.

Apologist Any of the Christian writers, primarily in the 2nd century, who attempted to provide a defense of Christianity against Greco-Roman culture. Many of their writings were addressed to Roman emperors and were submitted to government secretaries in order to defend Christian beliefs and practices. The Apologists tried to prove the antiquity of Chris¬ tianity as the fulfillment of Old Testament prophecy, and they argued that the worshipers of the mythological gods were truly godless. They also insisted on the philosophical nature of their faith and its high ethical stan¬ dards. Greek Apologists include Justin Martyr and Clement of Alexandria. Latin Apologists of the 2nd century include Tertullian. See also apologetics.

apology In literature, an autobiographical form in which a defense is the framework for discussion of the author’s personal beliefs. Examples include Plato’s Apology (4th century bc), in which Socrates answers his accusers by giving a history of his life and moral commitment, and John Henry Newman’s Apologia pro Vita Sua (1864), an examination of the principles that inspired his conversion to Roman Catholicism.

apomixis X.a-po-'mik-sosV Reproduction by special tissues without fer¬ tilization. Examples include parthenogenesis in animals (in which a new individual develops from an unfertilized egg) and apogamy in plants (in which the generating tissue may be either the gametophyte or the sporo- phyte). Apomixis provides for the preservation of traits favourable to indi¬ vidual survival, but it eliminates the longer-term evolutionary advantage of genetic contribution from two parents.

apoptosis X.a-pop-'to-sosV or programmed cell death Mechanism that allows cells to self-destruct when stimulated by the appropriate trig¬ ger. It may be initiated when a cell is no longer needed, when a cell becomes a threat to the organism’s health, or for other reasons. The aber¬ rant inhibition or initiation of apoptosis contributes to many disease pro¬ cesses, including cancer. Though embryologists had long been familiar with the process of programmed cell death, not until 1972 was the mecha¬ nism’s broader significance recognized. Apoptosis is distinguished from necrosis, a form of cell death that results from injury.

Apostle Any of the 12 disciples chosen by Jesus. They were Peter, James and John (sons of Zebedee), Andrew, Philip, Bartholomew, Matthew, Tho¬ mas, James (son of Alphaeus), Thaddaeus or Judas (son of James), Simon the Cananaean or Zealot, and Judas Iscariot. The 12 were privileged to attend Jesus continually and receive his teaching. Peter, James, and John formed an inner circle and were allowed to witness such events as the Transfiguration and the agony of Jesus at Gethsemane. After the defec¬ tion and death of Judas Iscariot, Matthias was elected an Apostle. Paul also claimed the title on the ground that he had seen the Lord and been commissioned by him.

Apostolic succession V.a-po-'sta-likN In Christianity, the doctrine that bishops represent an uninterrupted line of descent from the Apostles of Jesus. This succession gives bishops special powers, including the right to confirm church members, ordain priests, consecrate bishops, and rule over the clergy and church members of a diocese. Clement, bishop of Rome, stated the doctrine as early as ad 95, and it is accepted by Roman Catholic, Eastern Orthodox, Old Catholic, and several other churches. Some Protestant churches maintain that succession is spiritual and doc¬ trinal rather than ritual and historical.

apotheosis Vo-.pa-the-'o-sosX Elevation to the status of a god. The term recognizes that some individuals cross the dividing line between human and divine. Ancient Greek religion was disposed to belief in heroes and demigods, and historical figures were sometimes worshiped as gods. Until the end of the republic the Romans accepted only one apotheosis, iden¬ tifying the god Quirinus with Romulus. The emperor Augustus ordered Julius Caesar recognized as a god and thus began a tradition of deifying emperors.

apotropaic eye V.a-po-tro-'pa-ikN Painting of a large eye or eyes used to ward off evil. The symbol appears most commonly on Greek drinking vessels from the 6th century bc and was perhaps thought to keep danger¬ ous spirits from entering the mouth with the wine. It is also used in Turk¬ ish and Egyptian art.

Appalachian Geosyncline Great downbuckle in the Earth’s crust in the region of the present Appalachian Mountains. It was in the Appa¬ lachians that James Hall first worked out the geosynclinal theory of moun¬ tain building (see geosyncune).

Apollo Belvedere, restored Roman copy of the Greek original attributed to Leochares, 4th century bc; in the Vati¬ can Museum, Rome

AUNARI—ART RESOURCE/EB INC.

© 2006 Encyclopaedia Britannica, Inc.

90 I Appalachian Mountains ► Appleseed

Appalachian Mountains Mountain system, eastern North America. The Appalachians, among the oldest mountains on Earth, extend almost 2,000 mi (3,200 km) from the Canadian province of Newfoundland and Labrador in the northeast southwestward to Alabama in the U.S. They include the White Mountains in New Hampshire, the Green Mountains in Vermont, the Catskill Mountains in New York, the Allegheny Mountains primarily in Pennsylvania, the Blue Ridge Mountains in Virginia and North Carolina, the Great Smoky Mountains in North Carolina and Tennessee, and the Cumberland Plateau extending from West Virginia to Alabama. Their highest peak is Mount Mitchell in North Carolina. See also Appa¬ lachian Geosyncune; Appalachian National Scenic Trail.

Appalachian National Scenic Trail Footpath, Appalachian Moun¬ tains, U.S. Extending over 2,000 mi (3,200 km) from Mount Katahdin, Maine, to Springer Mountain, Georgia, along the crest of the mountains, the trail passes through 14 states, 8 national forests, and 2 national parks. Hikers and volunteers maintain the shelters and campsites. The trail’s highest point is Clingmans Dome (6,643 ft [2,025 m]) in the Great Smoky Mountains. With its first section opened in 1923, the trail was completed in 1937 and became part of the National Trail System established by the U.S. Congress in 1968.

Appalachian orogenic \,6r-3-'je-nik\ belt Mountain range that extends more than 1,860 mi (3,000 km) along the eastern margin of North America, from Alabama to Newfoundland. It was formed by the progres¬ sive eastward addition of material to the continental margin of North America. The earliest Appalachian sediments were deposited near the start of the Cambrian Period.

Appalachian Revolution See Alleghenian orogeny

Appaloosa Colour breed of horse popular in the U.S. It is said to have descended in the Nez Perce Indian territory of North America from wild mustangs, which in turn descended from the horses of Spanish explorers.

Appaloosas have several distinctive colour patterns and all the regular coat colours of horses. They stand 14-16 hands (about 56-64 in. [142- 163 cm]) tall and weigh 1,000-1,100 lbs (450-500 kg). Though light, they are also sturdy.

appanage Va-po-nij\ In France, primarily from the 13th to the 16th century, the giving of lands or pen¬ sions to children of the royal family.

Established to provide for the younger brothers and sisters of the king, appanages also helped develop royal administration within the lands con¬ cerned. The Ordinance of Moulins (1566) made royal lands inalienable, so all appanages would eventually revert to the crown. They were abol¬ ished during the French Revolution but were briefly reestablished between 1810 and 1832.

appeal Resort to a higher court to review the decision of a lower court, or to any court to review the order of an administrative agency. Its scope is usually limited. In the U.S., the higher court reviews only matters in the record of the original trial; no new evidence can be presented. The Supreme Court of the United States hears appellate cases that it regards as having important implications; otherwise, appeals generally stop with the United States Courts of Appeals. See also certiorari.

appeasement Foreign policy of pacifying an aggrieved nation through negotiation in order to prevent war. The prime example is Britain’s policy toward Fascist Italy and Nazi Germany in the 1930s. Neville Chamberlain sought to accommodate Italy’s invasion of Ethiopia in 1935 and took no action when Germany absorbed Austria in 1938. When Adolf Hitler pre¬ pared to annex ethnically German portions of Czechoslovakia, Chamber- lain negotiated the notorious Munich Agreement.

Appel \'a-pel\, Karel (b. April 25, 1921, Amsterdam, Neth.) Dutch painter, sculptor, and graphic artist. He attended Amsterdam’s Royal Academy of Fine Arts (1940-43) and was cofounder of the COBRA group of northern European Expressionists. In 1950 he moved to Paris; by the 1960s he had settled in New York City. An exponent of expressive abstrac¬ tion, he developed a painting style characterized by thick layering of pig¬ ment, violent colour and brushwork, and crude, reductive figures. His

figurative sculptures are executed in metal and wood. He painted portraits of jazz musicians and a number of public works, including a mural in the Paris UNESCO building.

appendix in full vermiform appendix Vestigial hollow tube attached to the cecum of the large intestine. The human appendix, usually 3-4 in. (8-10 cm) long and less than 0.5 in. (1.3 cm) wide, has no diges¬ tive function. Its muscular walls expel their own mucous secretions or any intestinal contents that enter it. Blockage of the opening may prevent expulsion and cause appendicitis: fluids collect, bacteria propagate, and the appendix becomes distended and inflamed; tissue in the appendix begins to die, and the organ may burst, causing peritonitis. Its symptoms may begin with moderate pain in the upper abdomen, about the navel, or all over the abdomen. Nausea and vomiting may then develop. The pain may shift to the right lower abdomen. Fever is usually present but is sel¬ dom high in the early phases. Differentiating acute appendicitis from other causes of abdominal pain requires careful examination. Treatment is removal of the appendix (appendectomy).

Appian Way Va-pe-3n\ Latin Via Appia. First and most famous of the ancient Roman roads, running from Rome to Campania and southern Italy. Begun in 312 bc by the censor Appius Claudius Caecus, the road originally ran 132 mi (212 km) to ancient Capua; by 244 bc it extended 230 mi (370 km) to the port of Brundisium (Brindisi) in Italy’s heel. Built of smoothly fitted blocks of lava on a heavy stone foundation, the road provided a long-lasting surface for transporting merchandise to these sea¬ ports (and thence by ship to Greece and the eastern Mediterranean). Remains can be seen today outside Rome.

apple Fruit of the genus Malus, in the rose family, the most widely cul¬ tivated tree fruit. Malus species are native to the temperate zones of both hemispheres. They require a considerable period of dormancy, well- drained soil, careful pruning in early years of growth, and a rigorous pest- management program for mature trees. The apple is one of the pome (fleshy) fruits. Apples at harvest vary widely in size, shape, colour, and acidity, but most are fairly round and some shade of red or yellow. The thousands of varieties fall into three broad classes: cider, cooking, and dessert varieties. Varieties that ripen in late summer generally do not store well, but those that ripen in late autumn may be stored for as long as a year. The largest producers of apples are the U.S., China, France, Italy, and Turkey. Eaten fresh or cooked in various ways, apples provide vita¬ mins A and C, carbohydrates, and fibre.

Apple Computer, Inc. Microcomputer design and manufacturing company, the first successful personal-computer company. It was founded in 1976 by Steven P. Jobs and Stephen G. Wozniak, whose first computer was manufactured in the Jobs family’s garage. The Apple II (1977), with its plastic case and colour graphics, launched the company to success, earning Apple over $100 million by 1980, the year the company first offered stock to the public. The 1981 introduction of IBM’s PC, running a Microsoft Corp. operating system, marked the beginning of long-term competition for Apple in the personal-computer market. The Macintosh, introduced in 1984, was the first personal computer to use a graphical user interface and a mouse. The “Mac” initially sold poorly, and Jobs left the company in 1985, but eventually it found its niche in the desktop pub¬ lishing market. Meanwhile, Microsoft’s Windows operating system eroded Apple’s market share. Apple recalled Jobs in 1997. He returned the company to profitability by introducing more innovative products, such as the iMac. Apple introduced iTunes, software for playing music that has been converted to the MP3 format, and the iPod portable MP3 music player in 2001; in 2003 the company began selling downloadable copies of major record company songs in MP3 format over the Internet.

apple scab Disease of apple trees caused by the fungus Venturia inaequalis , producing dark blotches or lesions on the leaves, fruit, and sometimes young twigs. Affected plants may drop their fruit prematurely, resulting in potentially high crop losses. Apple scab is found wherever apples are grown but is most severe where spring and summer are cool and moist. All apple species are affected. Regular spraying with fungicides is the most effective method of controlling the disease.

Appleseed, Johnny orig. John Chapman (b. Sept. 26, 1774, Leominster, Mass.—d. March 18?, 1845, near Ft. Wayne, Ind., U.S.) U.S. pioneer and folk hero. He was trained as a nurseryman and began c. 1800 collecting apple seeds from cider presses in Pennsylvania. He then trav¬ eled west to the Ohio River valley, planting apple seeds along the way. He tended 1,200 acres of his own orchards and was responsible for hun-

m > i

Appaloosa

SALLY ANNE THOMPSON

© 2006 Encyclopaedia Britannica, Inc.

applied psychology ► aquaculture I 91

dreds of square miles of others, having sold or given away thousands of apple seedlings to pioneers. His kind and generous nature, devout spiri¬ tuality, affinity for the Indians and the wilderness, and eccentric appear¬ ance (including bare feet, a coffee-sack shirt, and a mush pan for a hat) helped make him a figure of legend.

applied psychology Branch of psychology concerned with solving practical problems of human behaviour by using the findings and meth¬ ods of psychological science. Intelligence testing, legal problems, indus¬ trial efficiency, motivation, and delinquency were among the first areas of application in the early 20th century. World Wars I and II fostered work on vocational testing, teaching methods, evaluation of attitudes and morale, performance under stress, propaganda and psychological warfare, and rehabilitation. The aviation and aerospace industries were important for the development of engineering psychology, the study of human- machine relationships. Other areas include consumer psychology, school psychology, and community psychology. See also industrial-organizational psychology; psychometrics.

applique See quilting

Appomattox \,a-p3-'ma-t3ks\ Court House Former town, southern central Virginia, U.S., site of the surrender of Robert E. Lee to Ulysses S. Grant on April 9, 1865, effectively ending the American Civil War. It was virtually deserted after the removal of the county seat to the new town of Appomattox in 1892. It became a national historical monument in 1940 and a national historical park in 1954.

apprenticeship Training in an art, trade, or craft under a legal agree¬ ment defining the relationship between master and learner and the dura¬ tion and conditions of their relationship. Known from antiquity, apprenticeship became prominent in medieval Europe with the emergence of the craft guilds. The standard apprenticeship lasted seven years. Dur¬ ing the Industrial Revolution a new kind of apprenticeship developed in which the employer was the factory owner and the apprentice, after a period of training, became a factory worker. The increasing need for semiskilled workers led to the development of vocational and technical schools in Europe and the U.S., especially after World War II. Some industries in the U.S., such as construction, continue to employ workers in an apprenticeship arrangement.

approximation, linear See linear approximation

APRA Va-pra\ in full Alianza Popular Revolucionaria Ameri¬ cana Party founded by Victor Raul Haya de ia Torre (1924), which domi¬ nated Peruvian politics for decades. Largely synonymous with the so-called Aprista movement, it was dedicated to Latin American unity, the nationalization of foreign-owned enterprises, and an end to the exploi¬ tation of Indians. Supported by workers and middle-class liberals, the party wielded significant power, but conservative forces took extraordi¬ nary measures to prevent Haya de la Torre from ever gaining the presi¬ dency. An APRA candidate, Alan Garcia, finally became president in 1985. See also indigenismo.

apraxia \a-'prak-se-o\ Disturbance in carrying out skilled acts, caused by a lesion in the cerebral cortex; motor power and mental capacity remain intact. Motor apraxia is the inability to perform fine motor acts. Ideational apraxia is loss of the ability to plan even a simple action. In ideokinetic apraxia, there is no coordination between formation of ideas and motor activity; affected persons can do certain things automatically but not delib¬ erately. Constructional apraxia is the inability to put together elements to form a meaningful whole.

apricot Fruit of the tree Prunus armeniaca, in the rose family, culti¬ vated generally throughout the temperate regions of the world and used fresh, cooked in pastries, or preserved by canning or drying. Apricot trees are large and spreading, with heart-shaped, dark green leaves. Flowers are white. The fruit is nearly smooth and generally similar to the peach in shape but with little to no hairiness when ripe. Apricots are a good source of vitamin A and are high in natural sugars. Dried apricots are an excel¬ lent source of iron.

April Fools' Day or All Fools' Day First day of April, named for the custom of playing practical jokes on that date. Though it has been observed for centuries in several countries, including France and Britain, its origin is unknown. It resembles the Hilaria festival of ancient Rome (March 25) and the Hou festival of India (ending March 31). The custom of playing April Fools’ jokes was brought to America by the British.

April Theses Program developed by Vladimir Ilich Lenin during the Rus¬ sian Revolution of 1917, calling for Soviet control of state power. In the theses, published in April 1917, Lenin advocated seizing power from the Provisional Government, withdrawing from World War I, and distribut¬ ing land among the peasantry. The theses contributed to the July Days uprising and the Bolshevik coup d’etat in October.

apse Semicircular or polygonal termination to the choir, chancel (see cathedral), or aisle of a public build¬ ing, first used in pre-Christian Roman architecture. Originally a large niche to hold the statue of a deity in a temple, the apse also appeared in ancient baths and basili¬ cas. The domed apse became a stan¬ dard part of the Christian church plan.

Apuleius \,a-p3-la-3s\, Lucius (b.

c. ad 124, Madauros, Numidia—d. after 170?) Roman Platonic philoso¬ pher, rhetorician, and author. His The Golden Ass, a prose narrative of the ribald adventures of a young man who is changed into an ass, was long influential. This novel, considered a revelation of ancient manners, is valuable for its description of the ancient religious mysteries.

Apuleius’s philosophical treatises include three books on Piato, two of which survive.

Apulia See Puglia

Apure \a-'pii-ra\ River River, western Venezuela. The major navi¬ gable tributary of the Orinoco River, the Apure rises in the Cordillera de Merida and flows about 510 mi (820 km) northeast and east through the heart of Venezuela’s Llanos (plains), the country’s principal cattle-raising area.

Apurimac \,a-pur- , e-,mak\ River River, southern Peru. Arising in the Andes Mountains in Peru, it is the most distant source of the Amazon River. It flows northwest to join the Urubamba River and form the Ucayali River. For most of its 430-mi (700-km) length, it flows through narrow canyons, and its course is interrupted by falls and rapids. Short stretches of its lower course are also called the Ene River and the Tambo River.

Aqa Khan See Aga Khan

Aqaba Va-ko-boV Gulf of Northeastern arm of the Red Sea, between Saudi Arabia and the Sinai Peninsula. It varies in width from 12 to 17 miles (19 to 27 km) and is 100 miles (160 km) long. Its head touches Egypt, Israel, Jordan, and Saudi Arabia. Its only sheltered harbour is Dhahab (Dahab), Egypt; Jordan and Israel created the ports of Al-'Aqabah and Elat, respectively, as outlets to the Red Sea and the Indian Ocean.

Aqhat Epic Va-kat\ Ancient West Semitic legend explaining the earth’s barrenness during the dry summer months, known only in fragmentary form from three tablets excavated in northern Syria and dating to about the 14th century bc. It records the birth of a prince, Aqhat, in response to prayers. As a youth, Aqhat comes into possession of a bow intended for the goddess Anath and is killed by her when he refuses to part with it. His death brings famine, and his father and sister set out to avenge him, but there the text ends.

Aqmola See Astana

aquaculture or fish farming or mariculture Vmar-s-.kol-choA Rearing of fish, shellfish, and some aquatic plants to supplement the natu¬ ral supply. Fish are reared in controlled conditions worldwide. Though most aquaculture supplies the commercial food market, many govern¬ mental agencies engage in it to stock lakes and rivers for sport fishing. It also supplies goldfish and other decorative fish for home aquariums and bait fish for sport and commercial fishing. Carp, trout, catfish, tilapia, scal¬ lops, mussels, lobsters, and oysters are well-known species raised through aquaculture.

Apse, basilica of S. Vitale, Ravenna,

526-547

AUNARI—ART RESOURCE

© 2006 Encyclopaedia Britannica, Inc.

92 I aquamarine ► Arab-lsraeli wars

aquamarine Pale greenish blue or bluish green variety of beryl that is valued as a gemstone. The most common variety of gem beryl, it occurs in pegmatites, in which it forms much larger and clearer crystals than emer¬ ald, the dark green variety of beryl. Aquamarine occurs in Brazil, which is the chief source, and in such other sites as the Ural Mountains, Mada¬ gascar, Sri Lanka, India, and Maine, New Hampshire, Connecticut, North Carolina, and Colorado in the U.S. Heat treatment is commonly used to improve the colour of gem beryls.

aquarium Receptacle for maintaining aquatic organisms, either fresh¬ water or marine, or a facility in which a collection of aquatic organisms is displayed or studied. The first display aquarium opened in Regent’s Park, England, in 1853. Many of the world’s principal cities now have public aquariums as well as commercial ones; other aquarium facilities serve chiefly as research institutions. Regardless of size—whether a small one-gallon jar or a huge million-gallon tank—aquariums must be con¬ structed with care; many substances, especially plastics and adhesives, that are nontoxic to humans are toxic to water-breathing animals. The pri¬ mary requirement for maintaining aquatic organisms is water quality.

Aquarius (Latin: “Water carrier”) In astronomy, the constellation lying between Capricorn and Pisces; in astrology, the 11th sign of the zodiac, governing approximately the period January 20-February 18. It is usually represented as a man pouring a stream of water out of a jug, probably because in ancient times the rising of Aquarius coincided in the Middle East with the annual arrival of floods or rainfall. In the astrological con¬ cept called the Great Year—the 25,000-year period it takes the earth to pass through the influence of the entire zodiac—the early 19th century was the beginning of the Age of Aquarius.

aquatint Method of etching that produces finely granulated tonal areas rather than lines, so that finished prints often resemble watercolour or wash drawings. A copper plate is exposed to acid through a layer of granulated resin or sugar, which yields a finely speckled gray tone when the plate is inked and printed. The texture and depth of tone are controlled by the strength of the acid baths and the length of time the plate is exposed to them. Aquatint became the most popular method of producing toned prints in the late 18th century; its most notable practitioner was Francisco Goya. In the 19th century Edgar Degas and Camille Pissarro experimented with it, and in the 20th century the sugar aquatint was employed by Pablo Picasso, Georges Rouault, and Andre Masson.

aquavit \'a-kw9-,vet\ (from Latin aqua vitae , “water of life”) Scandi¬ navian clear distilled liquor flavoured with caraway seeds. Distilled from a fermented potato or grain mash, filtered with charcoal, and usually bottled without aging, aquavit has an alcohol content of 42^45% by vol¬ ume. Most aquavits are sweet and spicy. It is usually served chilled and unmixed, in small glasses.

aqueduct Conduit built to carry water from its source to a main distri¬ bution point. Ancient Rome’s aqueduct system, an extraordinary feat of engineering, brought water to the city from as far as 57 mi (92 km) away. Only a portion of the Roman aqueducts utilized the familiar stone arch; most were underground conduits made of stone or terra-cotta pipe. Modern aqueduct systems employ cast iron or steel. See also water-supply system.

aquifer \'a-kwa-far\ In hydrology, a rock layer or sequence that con¬ tains water and releases it in appreciable amounts. The rocks contain water-filled pores that, when connected, allow water to flow through their matrix. A confined aquifer is overlain by a rock layer that does not trans¬ mit water in any appreciable amount or that is impermeable. There prob¬ ably are few truly confined aquifers. In an unconfined aquifer the upper surface (water table) is open to the atmosphere through permeable over- lying material. An aquifer also may be called a water-bearing stratum, lens, or zone.

Aquinas Vs-'kwI-nosV Saint Thomas (b. 1224/25, Roccasecca, near Aquino, Terra di Lavoro, Kingdom of Sicily—d. March 7, 1274, Fos- sanova, near Terracina, Latium, Papal States; canonized July 18, 1323; feast day January 28, formerly March 7) Foremost philosopher and theo¬ logian of the Roman Catholic church. Born of noble parents, he studied at the University of Naples, joined the Dominicans, and taught at a Domini¬ can school at the University of Paris. His time in Paris coincided with the arrival of Aristotelian science, newly discovered in Arabic translation; his great achievement was to integrate into Christian thought the rigours of Aristotle’s philosophy, just as the early Church Fathers had integrated Pla¬ to’s thought in the early Christian era. He held that reason is capable of

operating within faith; while the philosopher relies solely on reason, the theologian accepts faith as his starting point and then proceeds to conclu¬ sion through the use of reason. This point of view was controversial, as was his belief in the religious value of nature, for which he argued that to detract from the perfection of creation was to detract from the creator. He was opposed by St. Bonaventure. In 1277, after his death, the masters of Paris condemned 219 propositions, 12 of them Thomas’s. He was never¬ theless named a Doctor of the Church in 1567 and declared the champion of orthodoxy during the modernist crisis at the end of the 19th century. A prolific writer, he produced more than 80 works, including Summa contra Gentiles (1261—64) and Summa theologica (1265-73). See also Thomism.

Aquino \9-'ke-no\, (Maria) Corazon orig. Maria Corazon Cojuangco (b. Jan. 25, 1933, Manila, Phil.) President of the Philippines (1986-92). Born into a politically prominent family, she married Benigno Simeon Aquino, Jr. (1932-83), who became the most prominent oppo¬ nent of Pres. Ferdinand Marcos. Benigno was assassinated in 1983 on his return from exile, and Corazon became the opposition candidate for presi¬ dent in 1986. Though Marcos was officially reported the winner, there were widespread allegations of voting fraud; high officials in the military supported Aquino, and Marcos fled. As president, Aquino introduced a hugely popular constitution. Over time her popularity declined amid charges of corruption and economic injustice.

Aquitaine Historical region, southwestern France. It was roughly equivalent to Aquitania, the Roman division of southwestern Gaul, which consisted of the area between the Pyrenees Mountains and the Garonne River. Conquered by Clovis in ad 507, it was later made a subkingdom by Charlemagne in the 8th century. After the Carolingian decline, it became a powerful duchy, which by the 10th century controlled much of France south of the Loire. It passed to the Capetian line when Eleanor of Aquita¬ ine married Louis VII (1137); on her second marriage, to Henry II of England (1152), it passed to the English Plantagenets. The name Guyenne, a cor¬ ruption of Aquitaine, came into use in the 10th century, and the subse¬ quent history of Aquitaine is merged with that of Gascony and Guyenne.

AR-15 See Ml 6 rifle

Ara Pads Va-ra-'pa-sis\ (Augustae) Latin "Augustan Altar of Peace" State monument built by Caesar Augustus in Rome’s Campus Martius (13-9 bc) to commemorate his victorious return from Spain and Gaul. It consists of an altar on a podium enclosed by walls. Its lavish sculptural decoration is among the finest examples of Roman art; reliefs representing the ceremonial procession at the altar’s dedication are the first in Western art that can strictly be called documentary, showing iden¬ tifiable individuals in a contemporary event.

Arab Any member of the ARABic-speaking peoples native to the Middle East and North Africa. Before the spread of Islam in the 630s, the term referred to the largely nomadic Semitic peoples of the Arabian Peninsula; it came to apply to Arabic-speaking peoples from Africa’s Mauritanian and Moroccan coasts east to Iraq and the Arabian Peninsula and south to The Sudan after their acceptance of Islam. Traditionally, some Arabs are desert-dwelling pastoral nomads (see Bedouin), whereas others live by oases and in small, isolated farming villages. While most Arabs are Mus¬ lims, some are Christian. The term has also been used in a political sense by Arab nationalists to describe a greater sociolinguistic or ethnic ideal (“the Arab nation”). See also Pan-Arabism.

Arab-lsraeli wars Series of military conflicts fought between various Arab countries and Israel (1948—49, 1956, 1967, 1969-70, 1973, and 1982). The first war (1948-49) began when Israel declared itself an inde¬ pendent state following the United Nations’ partition of Palestine. Protest¬ ing this move, five Arab countries—Egypt, Iraq, Jordan, Lebanon, and Syria—attacked Israel. The conflict ended with Israel gaining consider¬ able territory. The 1956 Suez Crisis began after Egypt nationalized the Suez Canal. A French, British, and Israeli coalition attacked Egypt and occu¬ pied the canal zone but soon withdrew under international pressure. In the Six-Day War of 1967, Israel attacked Egypt, Jordan, and Syria. The war ended with the Israel occupying substantial amounts of Arab territory. An undeclared war of attrition (1969-70) was fought between Egypt and Israel along the Suez Canal and ended with the help of international diplomacy. Egypt and Syria attacked Israel in 1973 (the Yom Kippur War), but, despite early Arab success, the conflict ended inconclusively. In 1979 Egypt made peace with Israel. In 1982 Israel invaded Lebanon in order to expel Palestinian guerrillas based there. Israel withdrew from most of Lebanon by 1985 but maintained a narrow buffer zone inside that coun-

© 2006 Encyclopaedia Britannica, Inc.

Arab League ► Arabic philosophy I 93

try until 2000. See also Yasir ‘Arafat; Hafiz al-Assad; Menachem Begin; David Ben-Gurion; Camp David Accords; Moshe Dayan; Hezbollah; Gamal Abdel Nasser; Yitzhak Rabin; Sabra and Shatila massacres; Anwar el-Sadat.

Arab League or League of Arab States Regional organization formed in 1945 and based in Cairo. It initially comprised Egypt, Syria, Lebanon, Iraq, Transjordan (now Jordan), Saudi Arabia, and Yemen; join¬ ing later were Libya, Sudan, Tunisia, Morocco, Kuwait, Algeria, Bahrain, Oman, Qatar, the United Arab Emirates, Mauritania, Somalia, the Pales¬ tine Liberation Organization, Djibouti, and Comoros. The league’s original aims were to strengthen and coordinate political, cultural, economic, and social programs and to mediate disputes; a later aim was to coordinate military defense. Members have often split on political issues; Egypt was suspended for 10 years (1979-89) following its peace with Israel, and the Persian Gulf War (1990-91) also caused deep rifts. See also Pan-Arabism.

arabesque Style of decoration characterized by interlacing plant forms and abstract curvilinear motifs. It is typical of Islamic ornamentation from c. 1000. The word was first used in the 15th or 16th century when Europeans became interested in the Islamic arts, but the motif itself was derived from Hellenistic crafts¬ men in Asia Minor. Arabesques were also applied to the decoration of illu¬ minated manuscripts, walls, furni¬ ture, metalwork, pottery, stonework, majolica, and tapestry from the Renaissance to the 19th century.

Arabia See Arabian Peninsula

Arabian Desert Desert region,

Arabian Peninsula. It covers about 900,000 sq mi (2,330,000 sq km), occupying nearly the entire penin¬ sula. It lies largely within Saudi Ara¬ bia but large portions extend into Jordan, Iraq, Kuwait, Qatar, the United Arab Emirates, Oman, and Yemen. Its relief is broken by a num¬ ber of mountain ranges, with eleva¬ tions reaching as high as 12,000 ft (3,700 m), and it is bounded on three sides by high escarpments. At least one-third of the desert is covered by sand, including the Rub' al-Khali, considered to have one of the most inhospitable climates on Earth. There are no perennial bodies of water, though the Tigris-Euphrates river system lies to the northeast and the Wadi Hajr is located to the south, in Yemen. Humans have inhabited the area since Pleistocene times.

Arabian horse Earliest improved breed of horse, valued for its speed, stamina, beauty, intelligence, and gentleness. Its long history has been obscured by legend, but it was developed in Arabia by the 7th century ad. It has contributed its qualities to most modern breeds of light horses. It is compact and relatively small, with a small head, protruding eyes, wide nostrils, marked withers, and a short back. Its average height is about 15 hands (60 in. [152 cm]), its average weight 800-1,000 lbs (360-450 kg). Though many colours are possible, gray is the most common.

Arabian Nights' Entertainment See The Thousand and One Nights

Arabian Peninsula or Arabia Peninsular region, southwest Asia. With its offshore islands, it covers about 1 million sq mi (2.6 million sq km). Constituent countries are Bahrain, Kuwait, Oman, Qatar, United Arab Emirates, Yemen, and, the largest, Saudi Arabia. It is generally arid and is covered almost entirely by the Arabian Desert. The modem economy is dominated by the production of petroleum and natural gas. The world’s largest proven reserves of those minerals are in the Arabian Peninsula. Its political consolidation was begun by the Prophet Muhammad, and it was the centre of the orthodox caliphate until 661, when that office passed to the Umayyad dynasty in Damascus. After 1517 much of the region was dominated by the Ottoman Empire, though the peninsula’s people, who had remained largely tribal and nomadic, revolted repeatedly until the World War I (1914-18), when the Ottoman Empire dissolved. Thereafter, indi¬ vidual nation-states followed their own histories, though many maintained close ties with European powers such as the United Kingdom.

Arabian religions, ancient Polytheistic religions of Arabia prior to the rise of Islam. Most of the deities of the Arab tribes were sky gods, associated with heavenly bodies such as the Sun and Moon, and they had the power to ensure fecundity, protection, or revenge. At the head of the southern Arabian pantheon was 'Athtar, a god of thunderstorms and rain. Each kingdom also had a national deity, of whom the nation called itself the progeny. Sanctuaries were carved in rock on high places and held a baetyl (“raised stone”) or statue of the god in an open-air enclosure, accessible only to ritually clean persons. In northern Arabia they included a walled enclosure with a covered or enclosed altar, similar to the Mus¬ lim Ka'bah. Libations, animal sacrifices, and other offerings were made to the gods, and priests interpreted oracles and performed divination. Wor¬ shipers made yearly pilgrimages to important shrines, participating in rites that included purification, the wearing of ritual clothing, sexual absti¬ nence, abstention from shedding blood, and circuits performed around the sacred object.

Arabian Sea Northwestern part of the Indian Ocean, lying between India and the Arabian Peninsula. It has an area of about 1,491,000 sq miles (3,862,000 sq km) and an average depth of 8,970 feet (2,734 m). The Gulf of Oman connects it with the Persian Gulf via the Strait of Hormuz, while the Gulf of Aden connects it with the Red Sea via the Strait of Mandeb. The Indus is the principal river draining into the Arabian Sea. Socotra, Lakshadweep, and other islands lie within it. Chief ports are Mumbai (Bom¬ bay), India; Karachi, Pak.; and Aden, Yemen. The sea has been part of the principal trade route between Europe and India for centuries.

Arabic alphabet Script used to write Arabic and a number of other languages whose speakers have been influenced by Arab and Islamic cul¬ ture. The 28-character Arabic alphabet developed from a script used to write Nabataean Aramaic. Because Arabic had different consonants than Aramaic, diacritical dots came to be used to eliminate ambiguous read¬ ings of some letters, and these remain a feature of the script. Arabic is written from right to left. The letters denote only consonants, though the symbols for w, y, and (historically) the glottal stop do double duty as vowel letters for long u, i, and a. Additional diacritics, representing short vowels (or the lack thereof), case endings, and geminate (duplicate) con¬ sonants, are normally employed only for the text of the Qur’an, for prim¬ ers, or in instances where the reading might otherwise be ambiguous. Because Arabic script is fundamentally cursive, most letters have slightly different forms depending on whether they occur in the beginning, middle, or end of a word. Non-Semitic languages for which some version of the Arabic alphabet has been or is used include Persian, Kurdish, Pashto, Urdu, some Turkic languages, Malay, Swahili, and Hausa. The Maltese language is the only form of Arabic to be written in the Latin alphabet.

Arabic language Ancient Semitic language whose dialects are spoken throughout the Middle East and North Africa. Though Arabic words and proper names are found in Aramaic inscriptions, abundant documentation of the language begins only with the rise of Islam, whose main texts are written in Arabic. Grammarians from the 8th century on codified it into the form known as Classical Arabic, a literary and scribal argot that dif¬ fered markedly from the spoken vernacular. In the 19th-20th centuries, expansion of Classical Arabic’s stylistic range and vocabulary led to the creation of Modern Standard Arabic, which serves as a lingua franca among contemporary Arabs. However, Arabic speakers, who number roughly 200 million, use an enormous range of dialects, which at their furthest extremes are mutually unintelligible. Classical Arabic remains an important cultural and religious artifact among the non-Arab Islamic com¬ munity. See also Arabic alphabet.

Arabic literary renaissance (19th-century) Movement to develop a modern Arabic literature. Inspired by contacts with the West and a renewed interest in classical Arabic literature, it began in Egypt with Syr¬ ian and Lebanese writers who sought the freer environment there, and it spread to other Arab countries as a result of the dismemberment of the Ottoman Empire after World War I and the coming of independence after World War II. Its success in altering the direction of Arabic literature is related to the spread and modernization of education and the emergence of an Arabic press.

Arabic philosophy or Islamic philosophy Doctrines of the Ara¬ bic philosophers of the 9th-12th century who influenced medieval Scho¬ lasticism in Europe. The Arabic tradition combines Aristotelianism and Neoplatonism with other ideas introduced through Islam. Influential think¬ ers include the Persians al-KiNDi, al-FARABi, and Avicenna, as well as the

Arabesque decoration on the dome of the Madar-i-Shah madrasah ("school") built by Husayn I, early 18th century, at Esfahan, Iran

RAY MANLEY-SHOSTAL ASSOC./EB INC.

© 2006 Encyclopaedia Britannica, Inc.

94 I Arachne ► Aramaic

Spaniard Averroes, whose interpretations of Aristotle were taken up by both Jewish and Christian thinkers. Muslims, Christians, and Jews par¬ ticipated in the Arabic tradition and separated themselves according to philosophic rather than religious doctrines. When the Arabs dominated Spain, the Arabic philosophic literature was translated into Hebrew and Latin; this contributed to the development of modern European philoso¬ phy. In Egypt around the same time, the Arabic tradition was developed by Moses Maimonides and Ibn Khaldun.

Arachne \o-'rak-ne\ In Greek mythology, the daughter of the dyer Idmon of Colophon. She was a weaver who acquired such skill that she ventured to challenge Athena to a contest. Athena wove a tapestry showing the gods in majesty, while Arachne depicted them in their amorous adventures. Enraged at the perfection of her rival’s work, Athena tore it to shreds, whereupon Arachne hanged herself. Out of pity Athena loosened the rope, which became a cobweb, and Arachne was changed into a spider.

arachnid \o-'rak-nid\ Any member of the class Arachnida, primarily carnivorous arthropods having a well-developed head, a hard external skeleton, and four pairs of walking legs. Spiders and scorpions have a seg¬ mented body, but daddy longlegs, ticks, and mites do not. Arachnids range in size from tiny mites (0.003 in. [0.08 mm] long) to the 8-in. (21-cm) black scorpion of Africa. As arachnids grow, they molt several times (see molting). Most are unable to digest food internally; instead, they inject their prey with digestive fluids and suck the liquefied remains. Arachnids are found worldwide in nearly every habitat. Most groups are free-living, but some mites and ticks are parasitic and can carry serious diseases of animals and humans. Venomous spiders and scorpions also may pose a danger to humans. However, most arachnids are harmless and prey on insect pests.

Arachosia X.ar-o-'ko-zhoV Ancient province, eastern Persian empire. The province encompassed much of what is now southern Afghanistan in the area of the city of Kandahar. It was conquered by Alexander the Great c. 330 bc.

‘Arafat \,ar-9-'fat\, Yasir orig. Muhammad ‘Abd al-Ra’uf al-Qudwah al-Husaynl (b. August 1*929—d. Nov. 11, 2004, Paris, France) Palestinian leader. The date and place of his birth are disputed. A birth certificate registered in Cairo, Egypt, gives Aug. 24, 1929, but some sources support his claim to have been born in Jerusalem on Aug. 4, 1929. He graduated from the University of Cairo as a civil engineer and served in the Egyptian army during the 1956 Suez Crisis. That year, working as an engineer in Kuwait, he cofounded the guerrilla organiza¬ tion Fatah, which became the leading military component of the Palestine Liberation Organization (PLO), which he led from 1969. In 1974 the PLO was formally recognized by the UN, and 'Arafat became the first leader of a nongovernmental organization to address the UN. In 1988 he acknowledged Israel’s right to exist, and in 1993 he formally recognized Israel during direct talks regarding land controlled by Israel since the Six- Day War. In 1994 he shared the Nobel Prize for Peace with Israelis Yitzhak Rabin and Shimon Peres. In 1996 he became president of the new Pales¬ tinian Authority.

Aragon Var-9-,gan\ Spanish Aragon Autonomous community (pop., 2001: 1,204,215), northeastern Spain. Roughly coextensive with the his¬ torical kingdom of Aragon, it occupies an area of 18,425 sq mi (47,720 sq km). Its capital is Zaragoza (Saragossa). Mountains, including the Pyrenees, dominate the relief north and south of the Ebro River, which bisects Aragon. Established in 1035 by Ramiro I, the historical kingdom grew as land was retaken from the Moors: Zaragoza, the capital of the Almoravid kingdom, fell to Alfonso I of Aragon in 1118, and the recon¬ quest of present-day Aragon was completed by the late 12th century. In the 13th—15th centuries it came to rule Sicily, Sardinia, Naples, and Navarra. In the 15th century Ferdinand married Isabella of Castile, uniting the kingdoms of Aragon and Castile and forming the nucleus of modern Spain. The old kingdom of Aragon survived as an administrative unit until 1833, when it was divided into provinces. Agriculture, mining, and indus¬ try, the latter concentrated at Zaragoza, are economically important.

Aragon \a-ra-'go n \, Louis orig. Louis Andrieux (b. Oct. 3, 1897, Paris, Fr.—d. Dec. 24, 1982, Paris) French poet, novelist, and essayist. He was introduced by Andre Breton into avant-garde circles, and the two cofounded the Surrealist review Litterature in 1919. From 1927 he was increasingly a political activist and spokesman for communism, which resulted in a break with the Surrealists. Among his works are the novel tetralogy Le Monde reel, 4 vol. (1933-44), describing the class struggle

of the proletariat; the huge novel Les Communistes, 6 vol. (1949-51); novels of veiled autobiography; and volumes of poems expressing patrio¬ tism and love for his wife. He was editor of the communist weekly of arts and literature, Les Lettres frangaises, 1953-72.

aragonite Vs-'rag-o-.nlA A carbonate mineral, the stable form of calcium carbonate (CaC0 3 ) at high pressures. It is somewhat harder and has a slightly higher specific gravity than calcite. Aragonite is found in recent deposits formed at low temperatures near the surface of the earth, as in caves as stalactites, with ore minerals, in serpentine and other basic (see acid and basic rocks) rocks, and in sediments. Aragonite is the mineral nor¬ mally found in pearls, and it occurs in some animal shells. It is polymor¬ phous (same chemical formula but different crystal structure) with calcite and vaterite, and, with geologic time, changes to calcite even under nor¬ mal conditions.

Araguaia \,ar-9-'gwI-9\ River River, central Brazil. Rising in the Bra¬ zilian highlands, it flows north some 1,600 mi (2,600 km) to join the Tocantins River at Sao Joao do Araguaia. In midcourse it divides into channels on either side of Bananal Island, which is about 200 mi (320 km) long and the site of the National Park of Araguaia. Though the river drains a vast area of interior Brazil, it offers poor transportation because of its many falls.

arahant See arhat

Arai Hakuseki \a-r!-ha-ku-'sa-ke\ (b. March 24, 1657, Edo [Tokyo], Japan—d. June 29, 1725, Edo) Japanese scholar of Confucianism and gov¬ ernment official of the mid-ToKUGAWA period. Arai was tutor and later adviser to Tokugawa Ienobu, the sixth Tokugawa shogun. He wrote on such subjects as Japanese geography, philosophy, and legal institutions and is considered one of Japan’s greatest historians. Among his best- known works are Tokushi yoron, a history of Japan, and Koshitsu, a study of early document sources. See also Genroku period; Edo culture.

Arakcheyev \a-r9k-'cha-yif\, Aleksey (Andreyevich), Count

(b. Oct. 4, 1769, Novgorod province, Russia—d. May 3, 1834, Gruzino, Novgorod province) Russian soldier and statesman. Appointed inspector general of artillery in 1803, he reorganized that branch of the army, then served as minister of war (1808-10). In the Russo-Swedish War of 1808— 09, he personally compelled the reluctant Russian forces to cross the fro¬ zen Gulf of Finland to attack the Aland Islands, which ultimately resulted in Sweden’s cession of Finland to Russia. He was Alexander I’s chief military adviser in the Napoleonic Wars. After the wars, he supervised the management of Russia’s domestic matters with brutal and ruthless effi¬ ciency, which caused the period (1815-25) to be known as Arakcheyevsh- china, but also took part in the emancipation of serfs in the Baltic provinces and created a system of military-agricultural colonies.

Araks River See Aras River

Aral Sea Large salt lake between Kazakhstan and Uzbekistan. It once covered some 26,300 sq mi (68,000 sq km) and was the fourth largest inland body of water in the world, but diversion of the waters of the Syr Darya and Amu Darya rivers for irrigation has led to an overall reduction of its surface area by more than half since 1960. Its volume has been reduced drastically, which has led to an increase in salinity. The soil of the dried-up lake bed has been found to contain salts and other toxic sub¬ stances.

Aram \'ar-9m\ Ancient country, Middle East, southwestern Asia. It extended eastward from the Anti-Lebanon Mountains to beyond the Euph¬ rates River. It was named for the Aramaeans, who emerged from the Syr¬ ian desert to invade Syria and Upper Mesopotamia (c. 11th century bc) and who built numerous city-kingdoms, including Damascus. It lends its name to the Aramaic language.

Aramaean \,ar-9-'me-9n\ A member of any people belonging to a con¬ federacy of tribes that migrated from the Arabian Peninsula to the Fertile Crescent c. 1500-1200 bc. Among them were the biblical matriarchs Leah and Rachel, wives of Jacob. The Aramaic language and culture spread through international trade. They reached a cultural peak during the 9th- 8th centuries bc. By 500 bc, Aramaic had become the universal language of commerce, culture, and government throughout the Fertile Crescent and remained so through the time of Jesus and into the 7th century in some areas.

Aramaic \,ar-9-'ma-ik\ language Semitic language originally spoken by the ancient Aramaeans. The earliest Aramaic texts are inscriptions in

© 2006 Encyclopaedia Britannica, Inc.

Aramco ► arbitrage I 95

an alphabet of Phoenician origin found in the northern Levant dating from c. 850 to 600 bc. The period 600-200 bc saw a dramatic expansion of Aramaic, leading to the development of a standard form known as Impe¬ rial Aramaic. In later centuries, as “Standard Literary Aramaic,” it became a linguistic model. Late (or Classical) Aramaic (c. ad 200-1200) has an abundant literature, both in Syriac and in Mandaic (see Mandaeanism). With the rise of Islam, Arabic rapidly supplanted Aramaic as a vernacu¬ lar in South Asia. Modern Aramaic (Neo-Aramaic) comprises West Neo- Aramaic, spoken in three villages northeast of Damascus, Syria, and East Neo-Aramaic, a group of languages spoken in scattered settlements of Jews and Christians in southeastern Turkey, northern Iraq, and northwest¬ ern Iran, and by modern Mandaeans in the Shatt Al-'Arab. Since c. 1900 persecution has forced most contemporary East Neo-Aramaic-speakers, who number several hundred thousand, into diaspora communities around the world.

Aramco \3-'ram-ko\ in full Arabian American Oil Company Oil

company founded by the Standard Oil Co. of California (Chevron) in 1933, when the government of Saudi Arabia granted it a concession. Other U.S. companies joined after oil was found near Dhahran in 1938. In 1950 Aramco opened a pipeline from Saudi Arabia to the Mediterranean Sea port of Sidon, Leb. It was closed in 1983 except to supply a refinery in Jordan. A more successful pipeline, with a destination on the Persian Gulf, was finished in 1981. In 1951 Aramco found the first offshore oil field in the Middle East. In the 1970s and ’80s, control gradually passed to the Saudi Arabian government, which eventually took over Aramco and renamed it Saudi Aramco in 1988.

Aran Islands \'ar-an\ Islands (pop., 2001: 543), Galway Bay, western Ireland. The group of small islands, totaling about 18 sq mi (47 sq km), includes Inishmore (or Aranmore), Inishmaan, and Inisheer. Their main town is Kilronan on Inishmore. The islands contain impressive prehis¬ toric and early Christian forts. Novelist Liam O' Flaherty was born on Inish¬ more.

Arany \6r-'on y \ Janos (b. March 2, 1817, Nagyszalonta, Hung.—d. Oct. 22, 1882, Budapest) Hungarian epic poet. His main work is the tril¬ ogy of Toldi (1847), Toldi szerelme (1848-79), and Toldi esteje (1854). Recounting the adventures of a 14th-century youth of great physical strength, it was received with enthusiasm by a public craving a national literature of quality in a language all could grasp. Other notable works include a fragment of an epic poem, Bolond Istok (1850), and The Death of King Buda (1864), the first part of a projected Hun trilogy. The Osz- ikek, written just before his death, poignantly reflects his sense of unful¬ fillment and isolation. He is considered Hungary’s greatest epic poet.

arap Moi, Daniel See Daniel arap Moi

Arapaho \3-'ra-p9-,ho\ North American Plains Indian peoples living mostly in Oklahoma and Wyoming, U.S. They are believed to have once lived in permanent villages in the eastern woodlands. Their language is of Algonquian stock. Like other Plains groups, the Arapaho were nomadic, living in tepees and depending on the buffalo for subsistence. They split into northern and southern groups after 1830. They were highly religious and practiced the sun dance. Their social organization included age-graded military societies as well as men’s shamanistic societies. They traded with the Mandan and Arikara and were often at war with the Shos¬ hone, Ute, and Pawnee. A southern branch was long allied with the Chey¬ enne and fought with them against Col. George Custer at Little Bighorn in 1876. In the 2000 U.S. census some 7,000 people claimed sole Arapahoe descent.

Ararat \'ar-3-,rat\, Mount Turkish Agri Dagi Extinct volcanic mas¬ sif, eastern Turkey. Located in Ago province, near the Iranian border, Ararat has two peaks, Great Ararat, at 16,853 ft (5,137 m) the highest point of elevation in Turkey, and Little Ararat, almost 13,000 ft (4,000 m). Ararat is traditionally associated with the mountain where Noah’s ark came to rest at the end of the biblical Deluge. A village on its slopes at the site where Noah is said to have built an altar was destroyed in an earthquake in 1840.

Aras \a-'ras\ River or Araks \a-'raks\ River River in Turkey, Arme¬ nia, Azerbaijan, and Iran. It rises in the mountains south of Erzurum, Tur¬ key, and flows east to join the Kura River in Azerbaijan about 75 mi (120 km) from its mouth. Since a flood in 1897, a separate distributary of the Aras has also emptied into the Caspian Sea. Some 665 mi (1,070 km) long,

it forms the boundary between Armenia and Azerbaijan (north) and Tur¬ key and Iran (south). Located on an island from 180 bc to ad 50 was Armenia’s capital, Artaxata.

Aratus of Sicyon \3-'ra-t9s...'sis-e- 1 an\ (b. 271—d. 213 bc) Hellenis¬ tic Greek statesman, diplomat, and soldier. He democratized Sicyon (251) and, as leader of the Achaean League (in alternate years from 245), set up democracies in league cities and helped free Athens from Macedonia (229). Under him, the league opposed Sparta; with Macedonian help, it defeated Aetolia (217). Aratus nevertheless defied the anti-Roman policy of Philip V of Macedonia; his death, popularly linked to Philip, was more likely caused by tuberculosis.

Araucanian Va-.raii-'ka-ne-onzV South American Indian people who are now concentrated in the valleys and basins between the Bio Bio and Tolten rivers in south-central Chile. When the Spanish cONQUiSTADORes arrived in Chile, they encountered three Araucanian populations: the Picunche, who were accustomed to Inca control; the Huilliche, who were too few and scattered to resist the conquistadores; and the Mapuche, successful farm¬ ers and artisans. The first two were soon assimilated, but the Mapuche managed to resist Spanish and Chilean control for some 350 years. They were subdued in the late 19th century and were settled on reservations; they now live independently.

araucaria \ l ar-o- , kar-e-9\ Any pinelike coniferous plant (see conifer) of the genus Araucaria (family Araucariaceae). Found in South America, the Phoenix Islands, and Australia, araucaria trees are magnificent ever¬ greens, with whorled branches and stiff, flattened, pointed leaves. Com¬ mon species are the monkey puzzle tree and the Norfolk Island pine, often grown as a houseplant. Several species are cultivated on the Pacific coast of the U.S. and in southern Florida. See also pine.

Arawak \'ar-3-,wak\ American Indians of the Greater Antilles and South America. The Taino, an Arawak subgroup, were the first native peoples encountered by Christopher Columbus on Hispaniola. The island Arawak were wiped out by disease, but some mainland South American Arawak, who inhabited northern and western areas of the Amazon River basin, sur¬ vived conquest. At the turn of the 21st century, the Arawak lived mainly in Guyana, where they represented about one-third of the Indian population. Smaller numbers live in Suriname, French Guiana, and Venezuela.

Arawakan \,ar-3-'wa-k3n\ languages or Maipuran \ml-'pu-r9n\ languages Largest family of American Indian languages. The family comprises an estimated 65 known languages, of which at least 30 are now extinct. They stretch from the Caribbean coast of Central America to the Gran Chaco and southern Brazil, and from western Peru to the Guianas and central Brazil. Taino, a now-extinct Arawakan language of the Antil¬ les, was the first American Indian language encountered by Europeans. Arawakan languages that are still viable include Goajiro in Colombia and Venezuela; Amuesha, Machiguenga, and the Campa languages in Peru; and Terena in Brazil.

Arbenz \'ar-bans\ (Guzman), Jacobo (b. Sept. 14, 1913, Quezalt- enango, Guat.—d. Jan. 27, 1971, Mexico City, Mex.) Soldier and presi¬ dent of Guatemala (1951-54). The son of a Swiss emigre, Arbenz joined the leftist army officers who overthrew the dictator Jorge Ubico (1878— 1946) in 1944. Elected president in 1951, he made land reform his cen¬ tral project. His efforts to expropriate idle land owned by the United Fruit Co. and his alleged communist links led to an invasion sponsored by the U.S. Central Intelligence Agency. When the army refused to defend Arbenz against what appeared to be a superior force, he resigned and went into exile, and the CIA installed the leader of the proxy army. Col. Carlos Castillo Armas (1914-57), as president.

Arber, Werner (b. June 3, 1929, Granichen, Switz.) Swiss microbi¬ ologist. He has taught chiefly at the University of Basel. He shared a 1978 Nobel Prize with Daniel Nathans and Hamilton O. Smith for the discovery and use of restriction enzymes that break the giant molecules of DNA into pieces small enough to be separated for individual study but large enough to retain meaningful amounts of the genetic information of the original substance. He also observed that bacteriophages cause mutation in their bacterial hosts and undergo hereditary mutations themselves.

Arbiter, Gaius Petronius See Gaius Petronius Arbiter

arbitrage Var-bo-.trazhX Business operation involving the purchase of foreign currency, gold, financial securities, or commodities in one market and their almost simultaneous sale in another market, in order to profit

© 2006 Encyclopaedia Britannica, Inc.

96 I arbitration ► Arcaro

from price differentials existing between the markets. In the 1980s a form of speculation called risk arbitrage arose, in which speculators tried to identify companies targeted for takeover and buy blocks of their stock, to be resold at a profit when the takeover was announced and the compa¬ ny’s stock rose in value. See also insider trading; security.

arbitration Process of resolving a dispute or a grievance outside a court system by presenting it for decision to an impartial third party. Both sides in the dispute usually must agree in advance to the choice of arbitrator and certify that they will abide by the arbitrator’s decision. In medieval Europe arbitration was used to settle disputes between merchants; it is now commonly used in commercial, labour-management, and interna¬ tional disputes. The procedures differ from those used in the courts, espe¬ cially regarding burden of proof and presentation of evidence. Arbitration avoids costly litigation and offers a relatively speedy resolution as well as privacy for the disputants. The main disadvantage is that setting guide¬ lines is difficult; therefore the outcome is often less predictable than a court decision. See also mediation.

arbor Garden shelter providing privacy and partial protection from the weather, most commonly a lightweight, latticed framework (trellis) of wood or metal with interlaced branches of vines or climbing shrubs trained over it. If there is a distinction between an arbor and a bower, it is that the bower is an entirely natural recess whereas an arbor is only partially natural.

arboretum X.ar-bo-'re-tomV Place where trees, shrubs, and sometimes herbaceous plants are cultivated for scientific and educational purposes. An arboretum may be a collection in its own right or a part of a botanical garden. Important U.S. arboretums include the Arnold Arboretum of Har¬ vard University (Jamaica Plain, Mass.) and the U.S. National Arboretum in Washington, D.C.

arboriculture Var-bor-o-.kol-choA Cultivation of trees, shrubs, and woody plants for shading and decorating. Arboriculture includes all aspects of growing, maintaining, and identifying plants, arranging plant¬ ings for their ornamental values, and removing trees. The well-being of individual plants is the major concern of arboriculture, in contrast to such related fields as forestry and agriculture, in which the major concern is the welfare of a large group of plants as a whole.

arborvitae \,ar-b9r-'vl-te\ (Latin: “tree of life”) Any of six species (genus Thuja) of resinous, evergreen ornamental and timber conifers of the cypress family, native to North America and eastern Asia. Arborvitae trees or shrubs have thin, scaling outer bark and fibrous inner bark; hori¬ zontal or ascending branches; and flattened, spraylike branchlets with scalelike leaves. The Oriental, or Chinese, arborvitae ( T. orientalis ), a popular ornamental native to Asia, is a gracefully symmetrical shrub. Arborvitae wood is soft and lightweight but very durable, fragrant, and easily worked. The giant arborvitae ( T. plicata) is the most important timber-producing species, but the wood of the American arborvitae ( T. occidentalis) is also frequently used. False arborvitae ( Thujopsis dola- brata) is closely related.

arbovirus X.ar-bo-'vI-rosX Any of a large group of viruses that develop in arthropods (chiefly mosquitoes and ticks). The name derives from “arthropod-borne virus.” The spheroidal virus particle is encased in a fatty membrane and contains RNA; it causes no apparent harm to the arthro¬ pod host. Arboviruses are transmitted by bites to vertebrate hosts, in which they establish infections and complete their growth cycle; they include the agents responsible for yellow fever and equine encephalitis. See also TOGAVIRUS.

Arbus, Diane orig. Diane Nemerov (b. March 14, 1923, New York, N.Y., U.S.—d. July 26, 1971, New York City) U.S. photographer. The sister of the poet and critic Howard Nemerov, she worked as a fash¬ ion photographer in the 1950s. From about 1955 to 1957 she studied with documentary photographer Lisette Model. She published her first photo¬ essay, for Esquire, in 1960. In the 1960s she began to explore the sub¬ jects that would occupy her for much of her career: individuals living on the outskirts of society and “normalcy,” such as nudists, transvestites, dwarfs, and the mentally or physically handicapped. Her own evident intimacy with the subjects of her photos resulted in images that engage the sympathy and collusion of the viewer and elicit a strong response. During this period she mastered her technique of using a square format and flash lighting, which gives her work a sense of theatricality and sur¬ realism. In 1971 Arbus committed suicide.

Arbuthnot Var-'both-notV John (b. April 1667, Inverbervie, Scot.—d. Feb. 27, 1735, London, Eng.) Scot¬ tish mathematician, physician, and satirist. His satirical writings include a political allegory, The History of John Bull (1712), that established John Bull as a personification of England. He was a founding member of the famous Scriblerus Club, which aimed to ridicule bad literature and false learning. He was also chief contributor to and guiding spirit of the Memoirs of Martinus Scriblerus (written 1713-14), a mocking expo¬ sure of pedantry that was written by club members.

arbutus \ar-'byu-t3s\ Any of about 14 species (genus Arbutus) of broad¬ leaved evergreen shrubs or trees, in the heath family. Native to southern Europe and western North America, they are characterized by loosely clustered white or pink flowers and red or orange berries. A. menziesii (variously known as the madrona, Pacific madrona, laurelwood, and Oregon laurel) and A. unedo (the strawberry tree) are cultivated as orna¬ mentals. The trailing arbutus belongs to the genus Epigaea.

Arc de Triomphe \ , ark-do-tri- , o n f\ Largest triumphal arch in the world. A masterpiece of Romantic Classicism, it is one of the best-known monu¬ ments of Paris. It stands at the centre of the Place Charles de Gaulle, at the western terminus of the Champs-Elysees. Initiated by Napoleon, designed by Jean-Francois-Therese Chalgrin, and constructed in 1806-36, the monument is 164 ft (50 m) high and 148 ft (45 m) wide. Decorative relief sculptures celebrating Napoleon’s victorious military campaigns were executed on the arch by Francois Rude, Jean-Pierre Cortot, and An¬ toine Etex.

arc furnace Type of electric furnace in which heat is generated by an arc between carbon electrodes above the surface of the material (com¬ monly a metal) being heated. William Siemens first demonstrated the arc furnace in 1879 at the Paris Exposition by melting iron in crucibles; hori¬ zontally placed carbon electrodes produced an electric arc above the con¬ tainer of metal. The first commercial arc furnace in the U.S. (1906) had a capacity of four tons (3.6 metric tons) and was equipped with two elec¬ trodes. Modern furnaces range in heat size from a few tons up to 400 tons (360 metric tons), and the arcs strike directly into the metal bath from vertically positioned, graphite electrodes to remelt scrap steel or refine briquettes of direct-reduced iron ore.

arcade Series of arches, supported by columns or piers, joined together end to end in a row. When supporting a roof, an arcade may function as a passageway adjacent to a solid wall, a covered walkway that provides access to adjacent shops, or a transitional element surrounding an open internal court. See also colonnade.

Arcadia Ancient country, central Peloponnese, Greece. Mountainous and landlocked, it was not overrun by the Dorians during their occupation of Greece (1100-1000 bc). Its isolation and its pastoral character partly explain why it was represented as a paradise in Greek and Roman bucolic poetry. It was the scene of conflict during the War of Greek Independence (1821-29). The modem Greek department of Arkadhfa is nearly coex¬ tensive with the ancient country.

Arcadian League Confederation of ancient Greek city-states of Arca¬ dia. Arcadian towns had been forced to ally with Sparta by 550 bc, and most Arcadians remained faithful to Sparta during the Peloponnesian War (431^-04 bc). In an effort to contain Sparta, Epaminondas of Thebes founded the city-state of Megalopolis in 371-368 bc as the seat of the Arcadian League. The League united the Arcadians for a few decades until internal discord crippled their confederation.

Arcaro, Eddie orig. George Edward Arcaro (b. Feb. 19, 1916, Cincinnati, Ohio, U.S.—d. Nov. 14, 1997, Miami, Fla.) U.S. jockey. He became the first jockey to ride five Kentucky Derby winners (1938, 1941, 1945, 1948,1952) and the first to ride two Triple Crown champions (Whirl-

Arbuthnot, detail of an oil painting by W. Robinson; in the Scottish National Portrait Gallery, Edinburgh.

COURTESY OF THE SCOTTISH NATIONAL PORTRAIT GALLERY, EDINBURGH

© 2006 Encyclopaedia Britannica, Inc.

arch ► archer fish I 97

away, 1941; Citation, 1948). In 31 years of riding Thoroughbreds (1931— 61), he won 549 stakes events, a total of 4,779 races, and more than $30 million in purses.

arch Curved structure that spans the opening between two piers or col¬ umns and supports loads from above. The masonry arch provides the stepping stone from the post-and-beam system to the evolution of the vault, and was first widely used by the Romans. Its construction depends on a series of wedge-shaped blocks (voussoirs) set side by side in a semicir¬ cular curve or along two intersecting arcs (as in a pointed arch). The cen¬ tral voussoir is called the keystone, and the two points where the arch rests on its supports are known as the spring points. An arch can carry a much greater load than a horizontal beam of the same size and material, because downward pressure forces the voussoirs together instead of apart. The resulting outward thrust must be resisted by the arch’s supports. Present-day lightweight monolithic (one-piece) arches of steel, concrete, or laminated wood are highly rigid, and thereby minimize horizontal thrust. See illustration opposite.

archaebacteria \,ar-ke-,bak-'tir-e-3\ Group of bacteria whose mem¬ bers differ from the eubacteria in certain physical, physiological, and genetic features (e.g., cell-wall components). Archaebacteria are aquatic or terrestrial microorganisms that exhibit a diversity of shapes, including spherical, rod-shaped, and spiral forms. They survive in various extreme environments, including very hot or salty ones. Some require oxygen; some do not. Some produce methane as an end product; others depend on sulfur for their metabolism.

archaeology Scientific study of material remains of past human life and activities. These include human artifacts from the very earliest stone tools to the man-made objects that are buried or thrown away in the present day. Archaeological investigations are a principal source of mod¬ ern knowledge of prehistoric, ancient, and extinct cultures. The field emerged as an academic discipline in the late 19th century, following centuries of haphazard antiquarian collecting. Among the archaeologist’s principal activities are the location, surveying, and mapping of sites and the excavation, classification, dating, and interpretation of materials to place them in historical context. Major subfields include classical archae¬ ology, the study of ancient Mediterranean and Middle Eastern civiliza¬ tions; prehistoric archaeology, or general archaeology; and historical archaeology, the study of historic-period remains to augment the written record. See also anthropology; coin collecting; stone-tool industry.

archaeopteryx \ar-ke-'ap-t9-riks\ Oldest known fossil animal that is generally accepted as a bird (classified as genus Archaeopteryx). It flour¬ ished during the Late Jurassic period (159-144 million years ago). Fossil specimens indicate that archaeopteryx ranged in size from as small as a blue jay to as large as a chicken. Archaeopteryx shared anatomical char¬ acteristics with both birds (well-developed wings and birdlike skull) and theropod dinosaurs (well-developed teeth and a long tail).

Archangel See Arkhangelsk

archbishop In Christianity, a bishop who has jurisdiction, but not supe¬ riority, over the other bishops in a province as well as episcopal author¬ ity in his own diocese. Introduced as an honorary title in the Eastern churches in the 4th century, the office did not become common in West¬ ern churches until the 9th century. It is now most widely used in the Roman Catholic and Eastern Orthodox churches. It is more rarely used in Protestant denominations, though the Church of England has archbish¬ ops of Canterbury and York, and the Lutheran churches of both Sweden and Finland have an archbishop.

Archean \ar-'ke-on\ Eon or Archaean Eon or Archeozoic Eon

Older of the two divisions of Precambrian time. The Archean begins with the formation of the Earth’s crust c. 3.8 billion years ago and extends to c. 2.5 billion years ago, up to the start of the Proterozoic Eon, the second division of the Precambrian Period. The earliest and most primitive forms of life (bacteria and cyanobacteria) originated c. 3.5 billion years ago in the middle of the Archean Eon (the Archean’s alternative name, Archeo¬ zoic, means “ancient life”).

archer fish Any of five species (family Toxotidae) of Indo-Pacific fishes noted for their ability to knock their insect prey off overhanging vegetation by shooting it with drops of water expelled from their mouth. Archer fishes are elongated and have a relatively deep body that is almost flat from the dorsal fin forward. The head is pointed, the mouth is large, and the dorsal

crown

trefoil arch ogee arch

The arch supports a vertical load primarily by axial compression of its wedge- shaped voussoirs. As shown on the Roman arch, the first voussoir, or springer, rests on the impost, at the top of the abutment or pier. The haunch, rising from the impost to the crown (highest point), is defined by the inner curve, or intrados, and outer curve, or extrados. The Roman arch, with its semicircular intrados, has a rise exactly half the width of the span. Below it are shown examples of the curved arch (left) and the pointed arch (right). The stilted arch has vertical sides. A Moorish arch widens above the spring points. The trefoil arch's intrados has three indentations, or foils. A Gothic arch is a pointed arch usually having two haunches of equal radii of curvature. A Tudor arch has greater curvature near the springers than near the point. Each haunch of the ogee arch consists of a double curve.

© MERRIAM-WEBSTER INC.

© 2006 Encyclopaedia Britannica, Inc.

98 I archery ► Arctic Circle

and anal fins are placed toward the back of the body. Different species are spotted or vertically banded with black. Archer fishes live in both fresh and salt water, usually remaining near the surface. One well-known spe¬ cies (Toxotes jaculator, or jaculatrix ) grows to about 7 in. (18 cm) long.

archery Sport of shooting with bow and arrow. As the bow began to be replaced by the gun as the principal weapon of warfare and the hunt beginning in the 16th century, it increasingly became a sporting device. By the mid-19th century, many archery clubs had sprung up in England and the U.S. Competitions including target-shooting were held at the Olympic Games in the early 20th century, but were then suspended until 1972. Other varieties of archery include field archery, or roving (a simu¬ lation of hunting), and flight shooting (a distance event).

Arches National Park Preserve, eastern Utah, U.S. Located on the Colorado River north of Moab, the preserve was established as a national monument in 1929 and as a national park in 1971. Its area is about 120 sq mi (310 sq km). The park’s sandstone has been eroded into unusual shapes, including Courthouse Towers, Fiery Furnace, and Devils Garden, the site of Landscape Arch, at 306 ft (93 m) the longest freestanding natu¬ ral rock bridge in the world.

archetype \'ar-ki-,tlp\ Primordial image, character, or pattern of cir¬ cumstances that recurs throughout literature and thought consistently enough to be considered universal. Literary critics adopted the term from Carl Gustav Jung’s theory of the collective unconscious. Because arche¬ types originate in pre-logical thought, they are held to evoke startlingly similar feelings in reader and author. Examples of archetypal symbols include the snake, whale, eagle, and vulture. An archetypal theme is the passage from innocence to experience; archetypal characters include the blood brother, rebel, wise grandparent, and prostitute with a heart of gold.

Archimedean screw N.ar-ko-'med-e-sM or Archimedes' screw

Machine for raising water, said to have been invented by Archimedes for removing water from the hold of a large ship. One form consists of a cir¬ cular pipe enclosing a helix and inclined at an angle of about 45°, with its lower end dipped in the water; rotation of the device lifts the water in the pipe. Other forms consist of a helix revolving in a fixed cylinder or a helical tube wound around a shaft.

Archimedes V.ar-ko-'me-.dezX (b. c. 290-280 bc, Syracuse, Sicily—d. 212/211 bc, Syracuse) Legendary Greek inventor and mathematician. His principal discoveries were the Archimedes screw, an ingenious device for raising water, and the hydrostatic principle, or Archimedes' principle. His main interests were optics, mechanics, pure mathematics, and astronomy. Archimedes’ mathematical proofs show both boldly original thought and a rigour meeting the highest standards of contemporary geometry. His approximation of n was not improved on until after the Middle Ages, and translations of his works were important influences on 9th-century Arab and 16th- and 17th-century European mathematicians. In his native city, Syracuse, he was known as a genius at devising siege and countersiege weapons. He was killed by a Roman soldier during the storming of the city.

Archimedes' principle Law of buoyancy, discovered by Archimedes, which states that any object that is completely or partially submerged in a fluid at rest is acted on by an upward, or buoyant, force. The magni¬ tude of this force is equal to the weight of the fluid displaced by the object. The volume of fluid displaced is equal to the volume of the portion of the object submerged.

Archipenko X.ar-ko-'peq-koV Alexander (b. May 30, 1887, Kiev, Ukr.—d. Feb. 25, 1964, New York, N.Y., U.S.) Ukrainian-U.S. sculptor. In 1908 he moved to Paris to study at the Ecole des Beaux-Arts, and he soon became active in radical circles such as the Cubist movement. He began to explore the interplay between interlocking voids and solids and between convex and concave surfaces, forming a sculptural equivalent to Cubist paintings’ overlapping planes and, in the process, revolutionizing modern sculpture. About 1912 he introduced the concept of collage in sculpture, and he went on to further defy tradition in his “sculpto- paintings,” works in which he introduced painted colour to the intersect¬ ing planes of his sculpture. In 1923 he moved to New York City, where he worked and taught for most of his life.

architecture Art and technique of designing and building, as distin¬ guished from the skills associated with construction. The practice of archi¬ tecture emphasizes spatial relationships, orientation, the support of activities to be carried out within a designed environment, and the arrangement and visual rhythm of structural elements, as opposed to the

design of structural systems themselves (see civil engineering). Appropri¬ ateness, uniqueness, a sensitive and innovative response to functional requirements, and a sense of place within its surrounding physical and social context distinguish a built environment as representative of a cul¬ ture’s architecture. See also building construction.

archives Repository for an organized body of records. Archives are produced or received by a public, semipublic, institutional, or business entity in the transaction of its affairs and are preserved by it or its suc¬ cessors. The modern institution of archives and archival administration dates from the late 18th century, when national and departmental archives were established in France. In the U.S. the National Archives was estab¬ lished in 1934 to house the retired records of the national government; the Federal Records Act of 1950 authorized regional records repositories. Each U.S. state has its own archival agency. Archivists in the 20th cen¬ tury increasingly handled records involving new technologies, such as computer-kept records and motion pictures, as well as the records of busi¬ nesses, institutions, and individuals.

arch on In ancient Greece, the chief magistrate or magistrates in a city- state, from the Archaic period onward. In Athens, nine archons divided state duties: the archon eponymous headed the boule and Ecclesia, the polemarch commanded troops and presided over legal cases involving foreigners, the archon basileus headed state religion and the Areopagus, and the six remaining archons handled various judicial matters. At first only elected aristocrats could serve, and their term was for life; later, terms were limited to a year. Archons were chosen by a combination of elec¬ tion and lot. In the 5th century bc the authority of the archons declined as elected generals assumed most of their powers.

Archon \'ar-,kan\ In Gnosticism, any of various world-governing pow¬ ers created with the material world by the Demiurge. Because the Gnos¬ tics regarded the material world as evil or as the product of error, Archons were considered forces of evil. Seven or 12 in number, they were iden¬ tified with the seven planets of antiquity or the 12 signs of the ZODIAC. They were thought to have imprisoned the divine spark of human souls in material creation. The gnosis sent from the realms of divine light through Jesus enabled Gnostic initiates to pass through the spheres of the Archons into the realms of light.

archosaur Var-k3-,s6r\ Any of the various advanced reptiles in the sub¬ class Archosauria (“ruling reptiles”), including all thecodonts, pterosaurs, dinosaurs, birds, and crocodilians. The first known archosaurs appeared 242-227 million years ago during the Triassic Period. All early archosaurs possessed an ankle specialization that aided in upright posture, and most had long hindlegs and short forelimbs. Unlike the teeth of earlier reptiles, which were set in a shallow groove, the teeth of archosaurs were (and are) set in sockets.

Archytas \ar-'ki-tas\ (fl. 400-350 bc, Tarentum, Magna Graecia) Greek scientist, philosopher, and Pythagorean mathematician. Archytas is some¬ times called the founder of mathematical mechanics. Plato, a close friend, made use of his work in mathematics, and there is evidence that Euclid borrowed from Archytas for Book VIII of the Elements. An influential public figure, he served seven years as commander in chief of his city, Tarentum (now Taranto, Italy).

Arcimboldo V.ar-chem-'bol-doV Giuseppe (b. c. 1527, Milan—d. 1593, Milan) Italian painter. He began his career as a painter and designer of stained-glass windows for Milan Cathedral. In 1562 he moved to Pra¬ gue and became court painter to the emperors Ferdinand I and Rudolf II. He also painted scenery for the court theatre and became skillful at illu- sionistic imagery containing allegorical meanings, puns, and jokes. He is known for his eccentric and grotesque Mannerist compositions of fruits, vegetables, animals, landscapes, and implements arranged to resemble human forms. The style was regarded as being in poor taste until the Sur¬ realists revived the art of visual punning in the 1920s. See photograph on opposite page.

Arctic Archipelago Group of Canadian islands, Arctic Ocean. They lie north of the Canadian mainland and have an area of about 550,000 sq mi (1,424,500 sq km). The southeastern islands are an extension of the Canadian Shield; the balance consists of the Arctic lowlands to the south and the Innuitian Mountains to the north. The archipelago includes the large islands of Baffin, Ellesmere, Victoria, Banks, and Prince of Wales.

Arctic Circle Parallel of latitude approximately 66.5° north of the Equa¬ tor that circumscribes the northern frigid zone. It marks the southern limit

© 2006 Encyclopaedia Britannica, Inc.

Arctic fox ► Arendt I 99

of the area within which, for one day or more each year, the sun does not set or rise. The length of continuous day or night increases northward from the Arctic Circle, mounting to six months at the North Pole.

Arctic fox Northern fox ( Alopex lagopus ) found throughout the Arctic, usually on tundra or mountains near the sea. Its short, rounded ears and short muzzle reduce its body area exposed to heat loss, and it has fur- covered soles. It is 20-24 in. (50-60 cm) long (excluding the 12-in., or 30-cm, tail) and weighs 7-17 lbs (3-8 kg). It has two colour phases. Indi¬ viduals in the white phase are grayish brown in summer and white in win¬ ter; those in the blue phase (blue foxes of the fur trade) are grayish in summer and gray-blue in winter. The Arctic fox dwells in burrows and feeds on any available animal or vegetable material.

Arctic National Park, Gates of the See Gates of the Arctic National Park

Arctic Ocean Ocean centring approximately on the North Pole. Small¬ est of the world’s oceans, it is almost completely surrounded by the land- masses of Eurasia and North America, and it is distinguished by a cover of ice. Lands in it and adjacent to it include Point Barrow in Alaska, the Arctic Archipelago, Greenland, Svalbard, Franz Josef Land, and northern Siberia. The ocean covers about 5,440,000 sq mi (14,090,000 sq km) and reaches a maximum depth of about 18,000 ft (5,500 m). Its marginal seas include the Barents, Beaufort, Chukchi, East Siberian, Greenland, Kara, Laptev, and White seas. Areas within the Arctic Circle were first explored beginning in the 9th century by the Norse. In the 16th— 17th centuries explorers searching for the Northwest Passage reached the area; Martin Frobisher discovered the southern part of Baffin Island (1576-78), and Henry Hudson navigated the eastern coast of Hudson Bay (1610-11). Later explorers included Roald Amundsen, Fridtjof Nansen, Robert E. Peary, and Richard E. Byrd. Development of the area’s natural resources was spurred by the discovery of oil in Alaska in the 1960s. Virtually all of the Arctic has now been mapped. See map opposite.

Arctic tern Tern species {Sterna paradisaea ) that makes the longest annual migration of any bird. It breeds in the southerly reaches of the Arctic and winters in the Antarctic, making its migration a round-trip of nearly 22,000 mi (over 35,000 km). Its appearance—white with a black cap and grayish wings—is similar to that of the common tern (S. hirundo), its frequent companion.

Ardea \'ar-de-o\ Ancient town, Italy. Located south of Rome, Ardea was ruled by the Rutuli people and was an important center for the cult of Juno. In 444 bc the town signed a treaty with the Romans, who colonized it as a barrier against the Volsci. It declined in the Roman civil wars of the 1st century bc.

Arden, Elizabeth orig. Florence Nightingale Graham (b. Dec. 31, 1884, Woodbridge, Ont., Can.—d. Oct. 18, 1966, New York, N.Y., U.S.) Canadian-U.S. businesswoman who founded a chain of women’s salons. Graham moved to New York c. 1908, where she opened a beauty salon under the name Elizabeth Arden. She was instrumental in making cosmetics acceptable for respectable women. In 1915 she began to mar-

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ket her cosmetics products interna¬ tionally. At her death there were over 100 Elizabeth Arden salons through¬ out the world.

Arden, John (b. Oct. 26, 1930, Barnsley, Yorkshire, Eng.) British playwright. He studied architecture at Cambridge and the Edinburgh College of Art. His plays mix poetry and songs with colloquial speech in a boldly theatrical manner and involve strong conflicts purposely left unre¬ solved. Arden’s works include All Fall Down (1955), Serjeant Mus- grave’s Dance (1959), The Work- house Donkey (1963), Vandaleur’s Folly (1978), and the radio series Whose Is the Kingdom? (1988).

"Summer," painting on canvas by Giuseppe Arcimboldo, 1563; in the Kunsthistorisches Museum, Vienna

BY COURTESY OF THE KUNSTHISTORISCHES MUSEUM, VIENNA; PHOTOGRAPH, ERWIN MEYER

Ardennes \ar-'den\ or Forest of Ardennes Wooded plateau region, northwestern Europe. It covers over 3,860 sq mi (10,000 sq km) and

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includes parts of Belgium, Luxembourg, and the Meuse River valley of France; its average height is about 1,600 ft (488 m). Though half of it is covered with forests, the soil is generally unfertile and supports only heath. It is located in the middle of the heavily populated triangle of Paris, Brussels, and Cologne. During World Wars I and II, the area was the scene of severe fighting in 1914, 1918, and 1944 (see Battle of the Bulge).

Ardhanarisvara V.ar-do-na-'resh-vo-roX Composite male-female fig¬ ure of the Hindu god Shiva and his consort Parvati. In many Indian and S.East Asian sculptures, the right half is male and the left female. The figure symbolizes the inseparability of male and female principles.

Ards District (pop., 2001: 73,244), Northern Ireland. Formerly part of County Down, Ards was established as a district in 1973. Much of its land is devoted to crops and pasture. Newtownards, settled c. 1608 by Scots, is its administrative seat and manufacturing centre. Donaghadee is a popular resort town.

area See length, area, and volume

Arecibo \,ar-3-'se-bo\ Observatory Astronomical observatory near Arecibo, P.R., site of the world’s largest single-unit radio telescope (as opposed to multiple telescope interferometers such as the Very Large Array). The telescope dish, 1,000 ft (300 m) across, is built into a valley; celestial sources are tracked across the sky by moving secondary struc¬ tures suspended about 500 ft (150 m) above the dish. The observatory has produced detailed radar maps of the surface of Venus and near-Earth aster¬ oids (see Earth-crossing asteroid), made detailed studies of Earth’s iono¬ sphere, and made major contributions to studies of pulsars and hydrogen gas in GALAXIES.

arena stage See theater-in-the-round

Arendt \a-'rent\, Hannah (b. Oct. 14, 1906, Hannover, Ger.—d. Dec. 4, 1975, New York, N.Y., U.S.) German-bom U.S. political philosopher.

© 2006 Encyclopaedia Britannica, Inc.

100 I Areopagus ► Argentina

She studied philosophy at the Universities of Marburg, Freiburg, and Heidelberg, receiving a doctorate from the latter in 1928. While at Mar¬ burg she began a romantic relationship with her teacher Martin Heidegger. Following the Nazi takeover of Germany in 1933, Arendt, who was Jew¬ ish, fled to Paris, where she became a social worker, and then to New York City in 1941. Her major work, Origins of Totalitarianism (1951), traced totalitarianism to 19th-century anti-Semitism, imperialism, and the dis¬ integration of the traditional nation-state. Her highly controversial book Eichmann in Jerusalem (1963) argued that the Nazi war criminal Adolf Eichmann was not inwardly wicked or depraved but merely “thoughtless”; his role in the extermination of the Jews thus epitomized the fearsome “banality of evil” that had swept across Europe at the time. Resuming contact with Heidegger in 1950, she claimed that his involvement with the Nazis had been the “mistake” of a great philosopher. She taught at the University of Chicago (1963-67) and thereafter at the New School for Social Research in New York City.

Areopagus \,ar-e-'a-p9-g3s\ Supreme tribunal of ancient Athens. It was named for the Areopagus (“Ares’ Hill”), where it met. It began as the king’s council; by Draco’s code of law (c. 621 bc) it consisted of former archons, but Solon (594) opened candidacy to any citizen. It had broad judicial powers. Its prestige fluctuated from the mid 6th to the mid 4th century bc, after which its power revived and continued under Roman domination, when it reacquired extensive administrative duties.

Arequipa \,a-ra-'ke-pa\ City (pop., 1998 est.: 710,103), southern Peru. Located in the Andes Mountains at an elevation of 7,557 ft (2,303 m) at the foot of Misti Volcano (19,098 ft [5,821 m]), it has been subject to earthquakes, usually associated with volcanic activity, and was largely destroyed by an earthquake in 1868. In the Inca empire, Arequipa was an important point on the route from Cuzco to the seacoast. Modern Are¬ quipa is the commercial centre of southern Peru.

Ares \'ar-ez\ Greek god of war. Unlike his Roman counterpart, Mars, his worship was not extensive. From the time of Homer, he was one of the Olympian deities, the son of Zeus and Hera, but disliked by the other gods.

His worship occurred largely in northern Greece. He was associated from early times with Aphrodite, occasionally portrayed as his legiti¬ mate wife and at other times his lover. He was accompanied in battle by his sister Eris (strife) and by two of his children by Aphrodite, Phobos and Deimos (Panic and Rout).

Aretino \,a-ra-'te-no\, Pietro (b.

April 20, 1492, Arezzo, Republic of Florence [Italy]—d. Oct. 21, 1556,

Venice) Italian poet, prose writer, and dramatist. He was celebrated throughout Europe in his time for his bold and insolent literary attacks on the powerful. His fiery letters and dialogues are of great biographical and topical interest. His dramas, which are relatively free of venom¬ ous assaults, include five comedies and a tragedy, Orazia (1546), per¬ haps the best Italian tragedy of the 16th century.

Arevalo \,a-ra-'ba-lo\ (Berme- jo), Juan Jose (b. Sept. 10, 1904, Taxisco, Guat.—d. Oct. 6, 1990, Guatemala City) President of Guatemala (1945-51). Soon after earning his doctorate, he went to Argentina, where he held various academic posi¬ tions. After the overthrow of the Guatemalan dictator Jorge Ubico, he was elected president, receiving 85 percent of the vote. He established free¬ dom of speech and of the press, and his administration inaugurated a social security system, a labour code, and important education and health pro¬ grams. His policies favoured urban and agricultural workers and the indig¬ enous population. He stepped down voluntarily at the end of his term. A military coup prevented him from running again in 1963.

Argentina officially Argentine Republic Country, southern South America. Area: 1,073,400 sq mi (2,780,092 sq km). Population (2005 est.): 38,592,000. Capital: Buenos Aires. The people are mostly of Euro-

Catholic [official]; also Protestant); also Islam, Judaism. Currency: Argen¬ tine peso. Argentina can be divided into four general regions: the North, the Pampas, Patagonia, and the Andes Mountains. The subtropical plains in the northeast are divided by the Parana River into Mesopotamia to the east and Gran Chaco to the west and north. The Pampas, south and west of the Parana, is one of the world’s most productive agricultural areas and the country’s most populous region. Patagonia lies south of the Colorado River. The Argentine Andes include the continent’s highest peak, Mount Aconcagua. Argentina’s hydrology is dominated by rivers that include the Parana, Uruguay, and Pilcomayo, which drain into the Rio de la Plata. Argentina has a developing economy based largely on manufacturing and agriculture; it is Latin America’s largest exporter of beef and beef prod¬ ucts. It is a republic with two legislative houses; the head of state and government is the president. Little is known of the indigenous population before the Europeans’ arrival. The area was explored for Spain by Sebas¬ tian Cabot beginning in 1526; by 1580 Asuncion, Santa Fe, and Buenos Aires had been settled. Early in the 17th century it was attached to the Viceroyalty of Peru, but in 1776 it was included with regions of modem Uruguay, Paraguay, and Bolivia in the Viceroyalty of the Rio de la Plata, whose capital was Buenos Aires. With the establishment of the United Provinces of the Rio de la Plata in 1816, Argentina achieved its indepen¬ dence from Spain, but its boundaries were not set until the early 20th cen¬ tury. In 1943 the government was overthrown by the military; Col. Juan Peron took control in 1946. He in turn was overthrown in 1955. He returned in 1973 after two decades of turmoil. His third wife, Isabel,

Ares, classical sculpture; in the National Roman Museum, Rome

ANDERSON-AUNARI FROM ART RESOURCE

© 2006 Encyclopaedia Britannica, Inc.

Argerich ► Aries I 101

became president on his death in 1974 but lost power after another mili¬ tary coup in 1976. The military government tried to take the Falkland Islands (Islas Malvinas) in 1982 but was defeated by the British in the Falkland Islands War, with the result that the government returned to civilian rule in 1983. The government of Raul Alfonsin worked to end the human rights abuses that had characterized the former regimes. Hyperin¬ flation, however, led to public riots and Alfonsin’s party’s electoral defeat in 1989; his Peronist successor, Carlos Menem, instituted laissez-faire eco¬ nomic policies. In 1999 Fernando de la Rua of the Alliance coalition was elected president, and his administration struggled with rising unemploy¬ ment, heavy foreign debt, and government corruption.

Argerich \'ar-ger-ich\, Martha (b. June 5, 1941, Buenos Aires, Arg.) Argentine pianist. A prodigy, she began concertizing before she was 10. In 1955 she went to Europe, where her teachers included Arturo Bene- detti Michelangeli (1920-95). She won two prestigious competitions at age 16 and the Chopin competition in 1965. Her exceptionally brilliant technique, emotional depth, and elan won her an enthusiastic international following.

arginine \'ar-ja- l nen\ One of the essential amino acids, particularly abun¬ dant in histones and other proteins associated with nucleic acids. It plays an important metabolic role in the synthesis of UREA, the principal form in which mammals excrete nitrogen compounds. Arginine is used in medi¬ cine and biochemical research, in pharmaceuticals, and as a dietary supplement.

argon Chemical element, chemical symbol Ar, atomic number 18. Colourless, odourless, and tasteless, it is the most abundant of the noble GASes on Earth and the one most used in industry. It constitutes about 1 % of air and is obtained by distillation of liquid air. Argon provides an inert gas shield in welding and brazing, in lightbulbs and lasers, in Geiger counters, and in the production and fabrication of certain metals. Because a radioactive form of argon is produced by decay of a naturally occurring radioactive potassium isotope, it can be used to date rocks and samples more than 100,000 years old.

argon-argon dating See potassium-argon dating

Argonauts In Greek legend, a band of 50 heroes who went with Jason in the ship Argo to retrieve the Golden Fleece from the grove of Ares at Colchis. They had many adventures before arriving at Colchis, from which they were even¬ tually forced to flee, pursued by Medea’s father, Aeetes. The Argo eventually returned to Jason’s home kingdom (Iolcus) and was placed in a grove sacred to Poseidon; Jason died when its prow toppled as he was resting in its shadow.

Argos Ancient city-state, north¬ eastern Peloponnese, Greece. Under the Argive king Pheidon, it was the dominant city-state in the Peloponnese in the 7th century bc until the rise of Sparta. After suffer¬ ing incursions from Macedonia,

Argos joined the Achaean League in 229 bc. Later it came under Roman rule. The city flourished in Byzantine times but ultimately fell to the Otto¬ man Empire in the 16th century. During the War of Greek Independence (1821-29), the first free Greek Parliament was convened at Argos. The modern town (pop., 1991: 22,429) is an agricultural centre.

argument from design or teleological argument Argument for the existence of God. According to one version, the universe as a whole is like a machine; machines have intelligent designers; like effects have like causes; therefore, the universe as a whole has an intelligent designer, which is God. The argument was propounded by medieval Christian thinkers, especially St. Thomas Aquinas, and was developed in great detail in the 17th and 18th centuries by writers such as Samuel Clarke (1675— 1729) and William Paley. It was powerfully criticized by David Hume in his Dialogues Concerning Natural Religion. Immanuel Kant also rejected the

argument. In the late 20th century the argument was revived as the doc¬ trine of INTELLIGENT DESIGN. See also CREATIONISM.

Argun Var-'gun\ River Chinese Ergun He or O-erh-ku-na

Vo-'ar-'gii-'naV Ho River, northeastern Asia. Rising in the Da Hinggan (Greater Khingan) Range, it runs about 1,000 mi (1,600 km), forming part of the boundary between northeastern China and Russia and uniting with the Shilka River to form the Amur River. In its upper course it is called the Hailar.

arhat \'ar-hot\ or arahant Va-ro-hantX In Buddhism, one who has gained insight into the true nature of existence, has achieved nirvana, and will not be reborn. Theravada Buddhism regards becoming an arhat as the goal of spiritual progress. It holds that a seeker must pass through three ear¬ lier stages before being reborn in a heaven as an arhat. Mahayana Bud¬ dhism criticizes the goal of becoming an arhat as selfish and considers the bodhisattva to be a higher goal because the bodhisattva remains in the cycle of rebirths to work for the good of others. This divergence of opin¬ ion is one of the fundamental differences between Theravada and Maha¬ yana Buddhism.

Arhus or Aarhus Vor-.husX Seaport (pop., 2001: 286,688), eastern Jut¬ land, Denmark. It lies along Arhus Bay and has an extensive harbour. Its origins are unknown, but it became a bishopric in ad 948 and, with its many religious institutions, prospered during the Middle Ages. In mod¬ ern times, industrialization and harbour expansion have made it Den¬ mark’s second largest city.

aria Solo song with instrumental accompaniment in opera, cantata, or oratorio. The strophic or stanzaic aria, in which each new stanza might represent a melodic variation on the first, appeared in opera in Claudio Monteverdi’s Orfeo (1607) and was widely used for decades. The stan¬ dard aria form c. 1650-1775 was the da capo aria, in which the opening melody and text are repeated after an intervening melody-text section (often in a different key, tempo, and metre); the return of the first section was often virtuosically embellished by the singer. Comic operas never limited themselves to da capo form. Even in serious opera, from c. 1750 a variety of forms were used; Gioacchino Rossini and others often expanded the aria into a complete musical scene in which two or more conflicting emotions were expressed. Richard Wagner’s operas largely abandoned the aria in favour of a continuous musical texture, but arias have never ceased to be written.

Ariadne \,ar-e-'ad-ne\ In Greek mythology, the daughter of Pasiphae and King Minos of Crete. She fell in love with Theseus, who had promised to slay the Minotaur confined in Minos’s Labyrinth. She gave Theseus a ball of thread or glittering jewels that enabled him to mark his path and thus to escape the Labyrinth after killing the monster. Endings to the legend vary. In one, Theseus abandons Ariadne and she hangs herself; in others, he carries her to Naxos, where she either dies or marries the god Dionysus. See also Phaedra.

Arianism Christian heresy that declared that Christ is not truly divine but a created being. According to the Alexandrian presbyter Arius (4th century), God alone is immutable and self-existent, and the Son is not God but a creature with a beginning. The Council of Nicaea (ad 325) con¬ demned Arius and declared the Son to be “of one substance with the father.” Arianism had numerous defenders for the next 50 years but even¬ tually collapsed when the Christian emperors of Rome Gratian and The¬ odosius assumed power. The First Council of Constantinople (381) approved the Nicene Creed and proscribed Arianism. The heresy contin¬ ued among the Germanic tribes through the 7th century, and similar beliefs are held in the present day by the Jehovah's WiTNESSes and by some adherents of Unitarianism.

Arias Sanchez Var-e-as-'san-chas\, Oscar (b. Sept. 13, 1941, Heredia, Costa Rica) President of Costa Rica (1986-90). A moderate socialist born to wealth, Arias worked for the National Liberation Party from the 1960s. He became president at a time when much of Central America was torn by civil war. His 1987 Central American peace plan, signed by the leaders of El Salvador, Guatemala, Honduras, and Nicara¬ gua, included provisions for cease-fires, free elections, and amnesty for political prisoners. He was awarded the 1987 Nobel Peace Prize.

Aries (Latin: “Ram”) In astronomy, the constellation lying between Pisces and Taurus; in astrology, the first sign of the zodiac, governing approximately the period March 21-April 19. It is represented by a ram, which is sometimes identified with the Egyptian god Amon. In Greek

The Argonauts, detail of a painting by Lorenzo Costa in the Civic Museum, Padua, Italy

SCALA/ART RESOURCE, NEW YORK

© 2006 Encyclopaedia Britannica, Inc.

102 I Ariha > Arius

mythology Aries was identified with the ram that carried the prince Phrixus out of Thessaly to Colchis. Phrixus sacrificed the ram to Zeus, who placed it in the heavens as a constellation. Its golden fleece was later recovered by Jason.

Ariha See Jericho

aril \'ar-il\ Special covering of certain seeds that commonly develops from the seed stalk. It is often a bright-coloured fleshy envelope, as in such woody plants as the yews and nutmeg and in members of the arrow- root family, oxalis, and the castor-oil plant. Animals are attracted to arils and eat the seeds, dispersing them in their wastes. The aril of nutmeg is the source of the spice known as mace.

Arion \3-'ri-3n\ Semilegendary Greek poet and musician. He lived at Methymna on the island of Lesbos and is identified as the inventor of the dithyramb. He was sailing homeward after a performing tour when the sailors decided to kill him and steal his wealth. After singing a dirge for himself, he jumped overboard, but a dolphin charmed by his music car¬ ried him to shore. He reached Corinth before the ship; when the sailors arrived, the ruler Periander forced them to confess and punished them. Arion’s lyre and the dolphin were placed in the heavens as the constel¬ lations Lyra and Delphinus.

Ariosto V.ar-e-'o-stoV Ludovico (b. Sept. 8, 1474, Reggio Emilia, duchy of Modena [Italy]—d. July 6,

1533, Ferrara) Italian poet. His epic poem Orlando Furioso (1516) is regarded as the finest literary expres¬ sion of the Italian Renaissance. It enjoyed immediate popularity throughout Europe and was highly influential. He also wrote five com¬ edies based on Latin classics but inspired by contemporary life; though minor in themselves, they are among the first of the imitations of Latin comedy in the vernacular that would long characterize European comedy. He also composed seven satires (1517-25) modeled after those of Horace .

Aristagoras \,ar-9-'stag-9-r9s\ (d.

497) Tyrant of Miletus. He assumed his regency from his father-in-law,

Histiaeus (d. 494 bc), who had lost the trust of the Persian emperor, Dar¬ ius I. Possibly incited by Histiaeus, and with support from Athens and Eretria, Aristagoras raised the Ionian revolt against Persia. Defeated, he left Miletus to found a colony in Thrace, where he was killed by Thracians.

Aristarchus \,ar-3-'star-k3s\ of Samos (b. c. 310 bc —d. c. 230 bc) Greek astronomer. His advanced ideas on the movement of the Earth (which he asserted revolved around the Sun) are known from Archimedes and Plutarch. His only surviving work is the short treatise “On the Sizes and Distances of the Sun and Moon”; though the values he obtained are inaccurate, he showed that the Sun and stars are at immense distances. A peak in the centre of a lunar crater named for him is the brightest forma¬ tion on the Moon.

Aristide \,ar-i-'sted\, Jean-Bertrand (b. July 15, 1953, Port Salut, Haiti) First president of Haiti (1991, 1994-96, 2001-04) to be elected in free democratic elections. A priest in the Roman Catholic Salesian order, he aligned himself with the poor and opposed the harsh regime of Jean- Claude Duvalier, son of Francois Duvalier, often putting himself at odds with the church hierarchy and the military. Expelled by the Salesians in 1988, he formally requested that he be relieved of his priestly duties in 1994. In 1990 progressive-centre forces united behind Aristide and swept him into power. He initiated dramatic reforms but was ousted in a mili¬ tary coup after only seven months in office. Though restored to office in 1994 with the help of U.S. occupying troops, he received little aid with which to address his country’s endemic ills. Constitutionally prohibited from seeking a consecutive term, he stepped down in 1996 but remained Haiti’s most potent political figure. In 2000 he was reelected president

amid charges of electoral fraud. A coup against Aristide failed in 2001, but unrest with his rule increased until a full-scale rebellion in 2004 forced him to flee the country.

Aristides \,ar-3-'stI-dez\ (2nd century ad) Athenian philosopher, one of the earliest Christian Apologists. His Apology for the Christian Faith dis¬ cussed the harmony in creation and the nature of the divine being and stated that barbarians, Greeks, and Jews were all inadequate in their con¬ ception of the deity and their religious practices. Long considered lost, the Apology was reconstructed in the late 19th century.

Aristides the Just (fl. 5th century bc) Athenian statesman and general. He was ostracized in 482 bc, probably for opposing Themistocles but was recalled in 480 and helped defeat the Persians at the battles of Salamis and Plataea. In 478 he helped Sparta’s eastern allies form the Delian League; allied with Athens and based on Athenian naval power and the trust Aris¬ tides inspired, the league effectively became the Athenian empire.

aristocracy \,ar-3-'sta-kr9-se\ Originally, leadership by a small privi¬ leged class or a minority thought to be best qualified to lead. Plato and Aristotle considered aristocrats to be those who are morally and intellec¬ tually superior, and therefore fit to govern in the interests of the people. The term has come to mean the upper layer of a stratified group. Most aristocracies have been hereditary, and many European societies stratified their aristocratic classes by formally titling their members, thereby mak¬ ing the term roughly synonymous with nobility. See also oligarchy.

Aristophanes \ l ar-o- , sta-f3- l nez\ (b. c. 450— d. c. 388 bc) Greek play¬ wright. An Athenian, he began his career as a comic dramatist in 427. He wrote approximately 40 plays, of which 11 survive, including The Clouds (423), The Wasps (422), The Birds (414), Lysistrata (411), and The Frogs (405). Most of the plays typify the Old Comedy (of which they are the only extant representatives), in which mime, chorus, and burlesque were important features. His satire, wit, and merciless topical commentary made him the greatest comic dramatist of ancient Greece.

Aristotle (b. 384, Stagira—d. 322 bc, Chalcis) Greek philosopher and scientist whose thought determined the course of Western intellectual his¬ tory for two millenia. He was the son of the court physician to Amyntas III, grandfather of Alexander the Great. In 367 he became a student at the Academy of Plato in Athens; he remained there for 20 years. After Pla¬ to’s death in 348/347, he returned to Macedonia, where he became tutor to the young Alexander. In 335 he founded his own school in Athens, the Lyceum. His intellectual range was vast, covering most of the sciences and many of the arts. He worked in physics, chemistry, biology, zoology, and botany; in psychology, political theory, and ethics; in logic and meta¬ physics; and in history, literary theory, and rhetoric. He invented the study of formal logic, devising for it a finished system, known as syllogistic, that was considered the sum of the discipline until the 19th century; his work in zoology, both observational and theoretical, also was not surpassed until the 19th century. His ethical and political theory, especially his con¬ ception of the ethical virtues and of human flourishing (“happiness”), continue to exert great influence in philosophical debate. He wrote pro- lifically; his major surviving works include the Organon, De Anima (“On the Soul”), Physics, Metaphysics, Nicomachean Ethics, Eudemian Ethics, Magna Moralia, Politics, Rhetoric, and Poetics, as well as other works on natural history and science. See also teleology.

arithmetic Branch of mathematics that deals with the properties of numbers and ways of combining them through addition, subtraction, mul¬ tiplication, and division. Initially it dealt only with the counting numbers, but its definition has broadened to include all real numbers. The most important arithmetic properties (where a and b are real numbers) are the commutative laws of addition and multiplication, a + b = b + a and ab = ba; the associative laws of addition and multiplication, a + (b + c) = (a + b) + c and a{bc) = {ab)c\ and the distributive law, which connects addition and multiplication, a(b + c) = ab + ac. These properties include subtrac¬ tion (addition of a negative number) and division (multiplication by a FRACTION).

Arius \'ar-e-os\ (b. c. 250, Libya—d. 336, Constantinople, Byzantine Empire) Christian priest and heretic whose teachings gave rise to the doc¬ trine of Arianism. He was leader of a Christian community near Alexan¬ dria, Egypt, where he preached doctrines that combined Neoplatonism with a literal, rationalist interpretation of biblical texts. By asserting the abso¬ lute oneness and immutability of God, he called into question the divin¬ ity of Christ. His views were publicized through his major work, Thalia

Ariosto, woodcut after a drawing by Titian from the third edition of Orlando furioso , 1532.

© 2006 Encyclopaedia Britannica, Inc.

Arizona ► Arlington I 103

(c. 323). In 325 the Council of Nicaea declared him a heretic. He was striving to compromise his views and win readmission to the church when he died suddenly in Constantinople. The Arian heresy posed a threat to Christian orthodoxy for several centuries.

Arizona State (pop., 2000: 5,130,632), southwestern U.S. Bordered by Mexico and the U.S. states of Utah, New Mexico, California, and Nevada, it covers 113,999 sq mi (295,256 sq km). Its capital is Phoenix. Its high¬ est point is Humphreys Peak, at 12,633 ft (3,850 m). The site of Grand Canyon and Petrified Forest national parks, Arizona also contains much of America’s Indian tribal lands. Humans settled the area more than 25,000 years ago. Nomadic Apache and Navajo Indians arrived after the collapse of the Anasazi and Hohokam civilizations. They were followed in the 16th century by Spanish treasure seekers from Mexico, including Francisco Vazquez de Coronado, establishing Mexico’s claim to the area. In 1776 the Mexican army built a presidio at Tucson. After the Mexican War, Ari¬ zona was ceded to the U.S. as part of New Mexico in 1848; the Gadsden Purchase added to it in 1853. Organized as a territory in 1863, Arizona became the 48th state in 1912. Though still lightly populated, it has grown rapidly in population in recent decades, largely because of its climate. About one-fifth of the population is Spanish-speaking, while about 5% is American Indian, including Navajo, Hopi, Apache, Papago, and Pima. Its diverse economy includes agriculture, mining, aerospace, electronics, and tourism.

Arjan Vor-j9n\ (b. 1581—d. 1606) Fifth Guru of the Sikhs (1581-1606) and jts first martyr. He compiled the volume of Sikh scripture on which the Adi Granth is based, and he completed the Golden Temple at Amritsar, India. The first Guru to serve as both temporal and spiritual head of Sikhism, he built up Amritsar as a commercial centre and enlarged mis¬ sionary efforts. He was also a prolific poet and writer of hymns. He pros¬ pered under the tolerant Mughal emperor Akbar but was tortured to death by Akbar’s successor for not altering the Adi Granth to remove passages that gave offense to Hinduism or Islam.

Arjuna \'3r-ju-n9\ One of the five brothers who are the heroes of the Mahabharata. His reluctance to go into battle prompts Krishna, manifested as his friend and charioteer, to deliver the discourse on duty that consti¬ tutes the Bhagavadgita. An exemplar of skill, duty, and compassion as well as a seeker of true knowledge, Arjuna is a central figure in Hindu myth and theology.

Ark of the Covenant In Judaism and Christianity, the ornate, gold- plated wooden chest that in biblical times housed the two tablets of the Law given to Moses by God. The Levites carried the Ark during the Hebrews’ wandering in the wilderness. Following the conquest of Canaan, it was kept at Shiloh but was sometimes carried into battle by the Israelites. David took it to Jerusalem, and Solomon placed it in the Temple of Jerusalem, where it rested in the Holy of Holies and was seen only by the high priest on Yom Kippur. It is believed to have been captured when Jerusalem fell to the Babylonians in 586 bc, and its subsequent fate is unknown.

Arkansas State (pop., 2000: 2,673,400), south-central U.S. Bordered by Missouri, Tennessee, Mississippi, Louisiana, Texas, and Oklahoma, it covers 53,178 sq mi (137,730 sq km). Its capital is Little Rock, and its highest point is Mount Magazine, at 2,753 ft (839 m). The earliest inhab¬ itants were Indian bluff dwellers along the Mississippi River c. ad 500. Mound-building cultures later left burial mounds along the river. Spanish and French explorers traversed the region in the 16th- 17th centuries; the first permanent European settlement was founded at Arkansas Post in 1686. Acquired by the U.S. as part of the Louisiana Purchase, Arkansas Territory was established in 1819; the state’s current boundaries were fixed in 1828. Arkansas became the 25th state in 1836. It seceded in 1861 to join the Confederacy in the American Civil War; it was readmitted to the Union in 1868. Following Reconstruction, a rigid policy of segrega¬ tion lasted until 1957, when court-ordered desegregation of the schools was implemented. Once dominated by agriculture, the state’s economy now also includes mining and manufacturing. Tourism is promoted, espe¬ cially by the mineral springs at Hot Springs National Park and resorts in the Ozark Mountains.

Arkansas River River, rising in central Colorado, U.S. At 1,450 mi (2,333 km) long, it flows east through southern Kansas and southeast across northeastern Oklahoma and bisects Arkansas, where it empties into the Mississippi River. Navigable for 650 mi (1,046 km), its largest tributar¬ ies are the Canadian and Cimarron rivers. It is believed to have been

crossed by Francisco Vazquez de Coronado in 1541 near the site of Dodge City, Kan., and by Zebulon Pike in 1806.

Arkhangelsk \,3r-'kan-gilsk\ or Archangel City (pop., 2002: 355,500), northwestern Russia. Located near the mouth of Northern Dvina River, it has a large harbour kept open in winter by icebreakers. The area was settled by Norsemen in the 10th century ad. In 1553 it was visited by the English who were looking for the Northeast Passage. Founded in 1584 as a monastery of Michael the archangel, it became a trading station of the Muscovy Co. It was opened to European trade by Tsar Boris Godunov and flourished as the sole Russian seaport until St. Petersburg was built in 1703. Arkhangelsk was the scene of British, French, and U.S. support of the northern Russian government against the Bolsheviks in 1918-20. During World War II it received convoys of lend-lease goods from Britain and the U.S. (1941-45). It is a major timber-exporting port and has extensive shipbuilding facilities.

Arkona W. Slavic citadel-temple of the war-god Svantovit, built in the 9th-10th century ad and destroyed in 1168/69 by Christian Danes when they stormed the island of Riigen in the southwestern Baltic. According to Saxo Grammaticus, it was a log structure with red roof, surrounded by a yard and fence, carved and painted with symbols. The inner sanctum con¬ tained a statue of Svantovit with four heads and throats facing in opposite directions. Excavations in 1921 proved the temple’s actual existence.

arkose Yar-,kos, 'ar-,koz\ Coarse sandstone that has formed by the dis¬ integration of granite without appreciable decomposition. It thus consists primarily of quartz and feldspar grains. In the absence of stratification, arkose may bear superficial resemblance to granite, and it sometimes has been described as reconstituted granite, or granite wash. Like the granite from which it was formed, arkose is pink or gray.

Arkwright, Sir Richard (b. Dec. 23, 1732, Preston, Lancashire, Eng.—d. Aug. 3, 1792, Cromford, Derbyshire) British textile industrialist and inventor. His first spinning machine was patented in 1769 (see Lewis Paul). His water frame (so-called because it operated by waterpower) pro¬ duced a cotton yarn suitable for warp (see weaving), stronger than thread made on the spinning jenny, which proved suitable only for weft. He intro¬ duced all-cotton calico in 1773. He opened several factories equipped with machinery for carrying out the phases of textile manufacturing from card¬ ing through spinning (see drawing).

Arledge, Roone (b. July 8, 1931, Forest Hills, N.Y., U.S.—d. Dec. 5, 2002, New York City) U.S. television executive. He began work at ABC-TV in 1960 as a sports producer. He later became president of ABC Sports and group president of ABC News and Sports (1985-90). He cre¬ ated sports programs such as Wide World of Sports (from 1961) and Mon¬ day Night Football (from 1968) and produced television coverage of 10 Olympic games, making many technical and editorial innovations in sports coverage. As president of ABC News he developed several suc¬ cessful news shows such as Nightline (from 1980) and PrimeTime Live (from 1989).

Arlen, Harold orig. Hyman Arluck (b. Feb. 15, 1905, Buffalo, N.Y., U.S.—d. April 23, 1986, New York, N.Y.) U.S. songwriter. After working as a performer and arranger, in 1929 he began a collaboration with lyricist Ted Koehler (1894-1973) with the song “Get Happy”; until the mid-1930s they wrote many songs that were featured in shows at Har¬ lem’s Cotton Club. Arlen’ s scores for Broadway musicals include Bloomer Girl (1944) and St. Louis Woman (1946). For Hollywood films Arlen wrote the songs “It’s Only a Paper Moon,” “Let’s Fall in Love,” and “That Old Black Magic.” His most famous song is perhaps “Over the Rainbow” (lyrics by E.Y. Harburg) from The Wizard of Oz (1939).

Arles Varl, 'arlz\ City (pop., 1999: 50,453), southeastern France. Occu¬ pied and built up by the Romans in the 1st century bc, Arles became, through commerce, a leading city of the Roman Empire. In the 10th cen¬ tury ad it became the capital of Burgundy, known also as the kingdom of Arles. Portions of the Roman wall around the old town remain, and a Roman arena of the 1st century bc is still used for bullfights and plays. The city was home to Vincent van Gogh during one of his most produc¬ tive periods. Arles is still a river port, but its economy is based largely on tourism and agriculture.

Arlington Unincorporated settlement (pop., 2000: 189,453), northern Virginia, U.S. Lying across the Potomac River from Washington, D.C., it is the capital of Arlington county, which was part of Washington, D.C., from 1801 to 1847, when it was returned to Virginia. It is the site of

© 2006 Encyclopaedia Britannica, Inc.

104 I arm ► Armenia

Arlington National Cemetery (located on the former estate of Robert E. Lee), Ronald Reagan Washington National Airport, and numerous federal buildings, including the Pentagon.

arm Upper limb of a biped, particularly a primate. Primate arms have one long bone, the humerus, in the upper arm above the elbow, and two thinner bones, the radius and ulna, in the forearm. The triceps muscle straightens the forearm at the elbow joint; the brachialis and biceps muscles bend it. Forearm and small muscles in the hand move the hand and fingers. The term may also denote the limb or the locomotive or pre¬ hensile organ of an invertebrate (e.g., the ray of a starfish or the tentacle of an octopus).

Armada, Spanish Great fleet sent by Philip II of Spain in 1588 to invade England in conjunction with a Spanish army from Flanders. Philip was motivated by a desire to restore the Roman Catholic faith in England and by English piracies against Spanish trade and possessions. The Armada, commanded by the duke of Medina-Sidonia, consisted of about 130 ships. In the weeklong battle, the Spanish suffered defeat after the English launched fire ships into the Spanish fleet, breaking the ships’ for¬ mation and making them susceptible to the English ships’ heavy guns. Many Spanish ships were also lost during the long voyage home, and a total of perhaps 15,000 Spaniards died. The defeat of the Armada, in which Francis Drake played a principal role, saved England and the Neth¬ erlands from possible absorption into the Spanish empire.

armadillo Any of 20 species of armoured mammals (family Dasypo- didae) related to sloths and anteaters.

Armadillos are stout and short¬ legged, with strong, curved claws and a protective covering of pinkish to brown armour composed of bony plates covered with tough scales.

The plates are separated by flexible bands of tissue. One species lives in the U.S., the others in tropical and subtropical regions to the south, pri¬ marily in South America. Most inhabit open areas, but some can be found in forests. Species range in size from about 6 in. (16 cm) to 5 ft (1.5 m) long. They live alone, in pairs, or in small groups and feed on termites or other insects, vegetation, small animals, and carrion.

Armageddon \,ar-m9-'ged-3n\ In the New Testament, the place where the kings of the earth under demonic leadership will wage war on the forces of God at the end of history. Armageddon is mentioned only in the Revelation to John. The name may mean “Mountain of Megiddo,” a ref¬ erence to the city of Megiddo, which held strategic importance in Pales¬ tine. Other biblical references suggest Jerusalem as the battle site.

Armagh \'ar-,ma\ District (pop., 2001: 54,263), Northern Ireland. For¬ merly part of County Armagh, the district was established in 1973. It lies south of Lough Neagh. The northern part of the district is the island’s main fruit-growing region; the southern part, along the Irish border, was a hotbed of sectarian violence through the late 20th century. The district seat is Armagh town. According to tradition, St. Patrick established his principal Irish church here in the 5th century. The area was the leading intellectual centre of the Western world in the 5th-9th centuries. Taken by English Protestant forces in the 16th century, Armagh became a pros¬ perous centre for Protestant clergy and gentry, a circumstance reflected in its many Georgian monuments and buildings.

Armagnac \,ar-ma-'nyak\ Small territory in historical Gascony, south¬ western France. A portion was part of the Roman province of Aquitania (see Aquitaine). From c. 960 it was the separate countship of Armagnac, and it grew to occupy a buffer zone between lands controlled by the French kings (Toulouse) and those controlled by the English (Guyenne). It led the resistance to the English king Henry V’s invasion of France but suffered a setback at the Battle of Agincourt. It was first annexed to France in 1497, became a countship again, but finally, by descent through the rulers of Navarra, returned to the French crown in 1607. Again a count- ship from 1645, it was dissolved in 1789. The region produces the famous Armagnac brandy.

Armani \ar-'ma-ne\, Giorgio (b. July 11, 1934, Piacenza, Italy) Ital¬ ian fashion designer. He abandoned medical school and worked as a buyer

for a department store (1957-64) before training as a fashion designer. In 1974-75 he introduced his own label of ready-to-wear apparel for men and women. In 1980-81 he founded Giorgio Armani USA, Emporio Armani, and Armani Jeans, and in 1989 he opened shops in London. He was a leader in the move toward a pared-down, unstructured silhouette in menswear and was responsible for the wide-shouldered look for execu¬ tive women. His designs, often characterized by understated glamour and luxurious fabrics, introduced ease and streamlined modernity into late 20th-century dressing.

Armed Islamic Group French Groupe Islamique Armee (GIA) Algerian militant group. It was formed in 1992 after the govern¬ ment nullified the likely victory of the Islamic Salvation Front in 1991 leg¬ islative elections and was fueled by the repatriation of numerous Algerian Islamists who had fought in the Afghan War (1978-92). The GIA began a series of violent, armed attacks against the government and against for¬ eigners in Algeria and has been accused of civilian massacres—although it has been alleged that many such atrocities were committed by security- service infiltrators and special military units. It has also engaged in attacks abroad (particularly in France) and purportedly maintained links with militant Islamic groups throughout the world. Estimates of GIA strength have varied from hundreds to several thousand guerrillas.

Armenia officially Republic of Armenia Country, Transcaucasia, western Asia. Area: 11,484 sq mi (29,743 sq km). Population (2005 est.): 2,983,000. Capital: Yerevan. Armenians constitute nine-tenths of the popu-

dominantly Armenian Apostolic; also Roman Catholic); also Islam. Currency: dram. Armenia is a mountainous country with an average elevation of 5,900 ft (1,800 m). The Lesser Cau¬ casus ranges stretch across its northern portion, and Lake Sevan lies in the east-central part. Armenia has a dry and continental climate that changes dramatically with elevation. Though the country has become highly industrialized (as a result of the development of hydroelectric power during Soviet rule) and increasingly urbanized, agriculture is still important. The Republic of Armenia is a successor state to a historical region in Caucasia. Historical Armenia’s boundaries have varied consid¬ erably, but old Armenia extended over what are now northeastern Turkey and the Republic of Armenia. The area was equivalent to the ancient kingdom of Urartu, which ruled c. 1270-850 bc. It was later conquered by the Medes (see Media) and Macedonia and still later allied with Rome. Armenia adopted Christianity as its national religion c. ad 300. For cen-

Nine-banded armadillo (Dasypus novemcinctus).

APPEL COLOR PHOTOGRAPHY

© 2006 Encyclopaedia Britannica, Inc.

Armenia ► Armour I 105

turies the scene of strife among Arabs, Seljuqs, Byzantines, and Mongols, it came under the rule of the Ottoman Empire in 1514-16. Over the next centuries, as parts were ceded to other rulers, nationalism arose among the scattered Armenians; by the late 19th century it had caused widespread disruption. Fighting between Ottomans and Russians escalated when part of Armenia was ceded to Russia in 1828, and it continued through World War 1 (1914-18), leading to genocide against Armenians (see Armenian massacres). With the Ottoman defeat, the Russian portion became part of a Soviet republic in 1922. Armenia was established as a constituent repub¬ lic of the U.S.S.R. in 1936. The U.S.S.R. began to dissolve in the late 1980s, and Armenia declared its independence in 1991. In the years that followed, it fought Azerbaijan for control of Nagorno-Karabakh, a con¬ flict that continued despite attempts to settle it. Large numbers of Arme¬ nians left the country in the 1990s following an economic downturn, and many stayed away even after the economy began to improve.

Armenia, Little See Little Armenia

Armenian Armenian Hay plural Hayk or Hayq Member of an Indo-European people first recognized in the early 7th century bc when they moved into areas of Transcaucasia, Anatolia, and the Middle East that came to be known as Armenia. Armenian history has been one of nearly constant struggles for independence from foreign domination, first from the Medes and Persians, the Seleucid dynasty, and the Roman Republic and Empire and later from the Byzantine Empire, the SeuGq dynasty, the Otto¬ man Empire, the Safavid dynasty, and tsarist Russia. At the beginning of the 20th century most Armenians were driven from Anatolia or killed by Ottoman forces during the Armenian massacres. The Republic of Armenia was declared in 1990 after being part of the Soviet Union since 1922. More than 3.5 million Armenians live there, and there is an appreciable diaspora in other countries of Transcaucasia, in parts of the Middle East, and in the West. Armenian culture reached an apex in the 14th century, producing highly regarded sculpture, architecture, and fine art. Until the 20th century, Armenians were primarily agricultural; now they are highly urbanized. Traditionally they are either Orthodox or Roman Catholic Christians; Armenia was considered the first Christian state.

Armenian language Indo-European language of the Armenians. It is spoken by perhaps five to six million people worldwide. Armenian has undergone phonetic and grammatical changes that make it completely dis¬ tinct from other branches of Indo-European; its closest affinity may be with Greek, though this hypothesis has been vigorously disputed. Its long his¬ tory of contact with Iranian languages has resulted in the adoption of many Persian loanwords. According to tradition, the unique Armenian alphabet was created by the cleric Mesrop Mashtots in ad 406 or 407. Armenian of the 5th-9th centuries (Grabar, or Classical Armenian) was employed as the literary language into modern times. A 19th-century cultural revival led to the formation of two new literary languages: West Armenian, based on the speech of Istanbul Armenians, and East Armenian, based on the speech of Transcaucasian Armenians. Because of a long tradition of emigration and the massacres and expulsions during the last decades of Ottoman rule, most speakers of West Armenian live outside Anatolia. East Armenian is the lan¬ guage of the present-day Republic of Armenia.

Armenian massacres Murder and expulsion of Turkish Armenians by the Ottoman Empire under Abdulhamid II in 1894-96 and by the Young Turk government in 1915-16. In 1894, when the Armenians began agitat¬ ing for territorial autonomy and protesting against high taxes, Ottoman troops and Kurdish tribesmen killed thousands. In 1896, hoping to call attention to their plight, Armenian revolutionaries seized the Ottoman Bank in Istanbul. Mobs of Muslim Turks, abetted by elements of the gov¬ ernment, killed more than 50,000 Armenians in response. Sporadic kill¬ ings occurred over the next two decades. In response to Russia’s use of Armenian troops against the Ottomans in World War I (1914-18), the government deported 1.75 million Armenians south to Syria and Meso¬ potamia, in the course of which some 600,000 Armenians were killed or died of starvation.

Armenian Secret Army to Liberate Armenia See ASALA

Armistice (Nov. 11, 1918) Agreement between Germany and the Allies ending World War I. Allied representatives met with a German delega¬ tion in a railway carriage at Rethondes, France, to discuss terms. The agreement was signed on Nov. 11, 1918, and the war ended at 11:00 am that day (“the 11th hour of the 11th day of the 11th month”). The prin¬ cipal term was that Germany would evacuate Belgium, France, and Alsace-Lorraine. Negotiations formalizing the armistice were conducted

at the Paris Peace Conference. Later a “stab in the back” legend developed in Germany, asserting that the German military situation had not been hopeless and that traitorous politicians had done the Allies’ bidding by signing the Armistice.

Armory Show formally International Exhibition of Modern

Art Exhibition of painting and sculpture held in 1913 at the 69th Regi¬ ment Armory in New York City. Conceived by its organizers, the Asso¬ ciation of American Painters and Sculptors, as a selection of works exclusively by U.S. artists, it evolved into a comprehensive look at cur¬ rent European art movements, due in part to the advanced vision of asso¬ ciation president Arthur B. Davies. Of the 1,300 works assembled, one- third were European, tracing the evolution of modern art from Francisco de Goya to Marcel Duchamp and Vasily Kandinsky, with works representa¬ tive of Impressionism, Symbolism, Post-Impressionism, Fauvism, and Cubism. Perhaps the most controversial work was Duchamp’s nearly abstract Nude Descending a Staircase, No. 2 (1912). The U.S. artists featured were mainly members of the Ash Can school and The Eight. The show exposed the American public for the first time to advanced European art; Ameri¬ can art suffered by contrast. The exhibition traveled to Chicago and Bos¬ ton, establishing itself as a decisive event in the development of U.S. art and art collecting.

armour or body armour Protective clothing that can shield the wearer from weapons and projectiles. By extension, armour is also pro¬ tective covering for animals, vehicles, and so on. Prehistoric warriors used leather hides and helmets. Chinese warriors used rhinoceros skin in the 11th century bc, and Greek infantry wore thick, multilayered metal-and- linen cuirasses (armour covering the body from neck to waist) in the 5th century bc. Shirts of chain mail were worn throughout the Roman Empire, and mail was the chief armour of western Europe until the 14th century. Ancient Greeks and Romans used armour made of rigid metal plates, which reappeared in Europe around the 13th century. Plate armour domi¬ nated European design until the 17th century, when firearms began to make it obsolete. It began to disappear in the 18th century, but the hel¬ met reappeared in World War I and became standard equipment. Modern body armour (the bulletproof vest) covers the chest and sometimes the groin; it is a flexible garment reinforced with steel plates, fibreglass, boron carbide, or multiple layers of synthetic fabric such as Kevlar.

helmet

MERRIAM-WEBSTER INC.

Armour, Philip Danforth (b. May 16, 1832, Stockbridge, N.Y., U.S.—d. Jan. 6, 1901, Chicago, Ill.) U.S. entrepreneur and innovator. Armour’s first entrepreneurial success was in California mining endeav¬ ours. He vastly expanded his family’s Midwestern grain and meatpack-

© 2006 Encyclopaedia Britannica, Inc.

106 I armoured vehicle ► Arne

ing business in 1875, originating the use of byproducts and the sale of canned meat. When railcar refrigeration was introduced in the 1880s (see Gustavus Franklin Swift), he established distributing plants in eastern states and began exporting Armour meat products to Europe. His Armour & Co. enterprises helped make Chicago the meatpacking capital of the world.

armoured vehicle Motor vehicle with plating for protection against bullets, shells, or other projectiles that moves on wheels or tracks. The tank is the chief armoured vehicle for larger military forces. Other mili¬ tary types include infantry fighting vehicles, amphibious landing vehicles, and mobile weapons platforms such as self-propelled artillery and anti¬ aircraft guns. Infantry fighting vehicles, descended from the armoured personnel carriers of World War II and the Vietnam War, are armoured, tracked vehicles that transport infantry into battle but also serve as plat¬ forms from which soldiers can fight without dismounting. Armoured cars are wheeled civilian vehicles, ranging from commercial trucks to luxury sedans, that generally are equipped with armour and other amenities for securely transporting valuables and individuals over paved roads.

armoury practice Production system for the assembly of finished products, in this case arms. With the adoption of the Model 1842 mus¬ ket, the U.S. military achieved the large-scale assembly of weapons from uniform, interchangeable parts. By the mid-1850s arms makers around the world were beginning to copy this American System of manufacture, which contributed to the creation of the modern military small arm, especially after the introduction of percussion ignition and rifled barrels.

arms control Limitation of the development, testing, production, deployment, proliferation, or use of weapons through international agree¬ ments. Arms control did not arise in international diplomacy until the first Hague Convention (1899). The Washington Conference (1921-22) and the Kellogg-Briand Pact (1928) were broken without much fear of sanction. U.S.-Soviet treaties to control nuclear weapons during the Cold War were taken more seriously. In 1968 the two superpowers and Britain sponsored the Nuclear Non-proliferation Treaty (signed also by 59 other countries), which committed signatory countries not to promote the spread, or pro¬ liferation, of nuclear weapons to countries that did not already possess them. See also Nuclear Test-Ban Treaty; Strategic Arms Limitation Talks; Stra¬ tegic Arms Reduction Talks.

Armstrong, Edwin H(oward) (b. Dec. 18, 1890, New York, N.Y., U.S.—d. Jan. 31/Feb. 1, 1954, New York City) U.S. inventor. He studied at Columbia University, where he devised a feedback circuit that brought in signals with a thousandfold amplification (1912). At its highest ampli¬ fication, the circuit shifted from being a receiver to being a primary gen¬ erator of radio waves, and as such it is at the heart of all radio and television broadcasting. It earned him the Franklin Medal, the highest U.S. scientific honour. His 1933 invention of circuits that produced the carrier waves for frequency modulation (FM) made high-fidelity broadcasting possible.

Armstrong, Gillian (b. Dec. 18, 1950, Melbourne, Austl.) Australian film director. She first garnered international acclaim as the director of My Brilliant Career (1979), a feminist film about a young woman aspir¬ ing to be a writer in Victorian-era Australia. Her subsequent works include Australian films such as The Last Days of Chez Nous (1993) and Oscar and Lucinda (1997), as well as U.S. films such as Mrs. Soffel (1984), Little Women (1994), and Charlotte Gray (2001).

Armstrong, Lance (b. Sept. 18, 1971, Plano, Texas, U.S.) American cyclist and the first rider to win seven Tour de France titles (1999-2005). Armstrong began his professional cycling career in 1992 when he joined the Motorola team. He won stages of the Tour de France in 1993 and 1995 but withdrew from three of four Tours he attempted from 1993 to 1996. After the 1996 Tour, Armstrong fell ill, suffering from testicular cancer that had spread to his lungs and brain. Months of treatments fol¬ lowed before he could attempt his comeback. In 1998 he won the Tour of Luxembourg, and on July 25, 1999, he became the second American to win the Tour de France and the first to win it for an American team (three-time winner Greg LeMond had raced with European teams). In 2003 Armstrong won his fifth consecutive Tour de France, tying a record set by Miguel Indurain, and the following year he broke the record with his sixth consecutive win. After winning his seventh Tour in 2005, Arm¬ strong announced his retirement.

Armstrong, Louis (b. Aug. 4, 1901, New Orleans, La., U.S.—d. July 6, 1971, New York, N.Y.) U.S. jazz trumpeter and singer. As a youth in New

Orleans, he participated in marching, riverboat, and cabaret bands. A child¬ hood nickname, Satchelmouth, was shortened to Satchmo and used throughout his life. In 1922 he moved to Chicago to join King Oliver’s Cre¬ ole Jazz Band (see Dixieland). In 1924 he joined the Fletcher Henderson Orchestra in New York City; the fol¬ lowing year he switched from cornet to trumpet and began recording under his own name with his Hot Five and Hot Seven ensembles. In these recordings the prevailing emphasis on collective improvisation gives way to his developing strength as soloist and vocalist. By the time of his “West End Blues” (1928), Armstrong had established the preeminence of the virtuoso soloist in jazz. His vibrant melodic phrasing, inventive harmonic improvisation, and swinging rhyth¬ mic conception established the vernacular of jazz music. His powerful tone, great range, and dazzling velocity set a new technical standard. He also was one of the first scat singers, improvising nonsense syllables in the manner of a horn. He became something more than a jazz musician: solo attraction, bandleader, film actor, and international star.

Arndt, Ernst Moritz (b. Dec. 26, 1769, Schoritz bei Gartz, Swed.—d. Jan. 29, 1860, Bonn, Ger.) Swedish-born German prose writer, poet, and patriot. He rejected the Lutheran ministry at age 28 and eventually became a professor of history at Greifswald and Bonn. Among his important works is the huge Spirit of the Times, 4 vol. (1806-18), a bold call for political reforms that expressed German national awakening during the Napoleonic era. Not all of Arndt’s poems were inspired by political ideas; Gedichte (1804-18) contains many religious poems of great beauty.

Arne, Thomas Augustine (b. March 12, 1710, London, Eng.—d. March 5, 1778, London) British composer. Son of a London upholsterer, he secretly taught himself instrumental skills and composition with the help of an opera musician. Smitten by the opera, he had an early success with his own first opera, Rosamond (1733), and thereafter concentrated almost exclusively on the theatre. As composer to Drury Lane Theatre and London’s great pleasure gardens, he became Britain’s leading theat¬ rical composer and, after George Frideric Handel, possibly the finest Brit¬ ish composer of the century. Of his approximately 90 theatrical works, the best known are Comus (1738), The Judgment of Paris (1740), and Artaxerxes (1762). His song “Rule, Britannia” became an unofficial national anthem. His sister Susannah (1714-66) was the famous singer and actress known as Mrs. Cibber.

Louis Armstrong.

AP/WIDE WORLD PHOTOS

Armstrong, Neil (Alden) (b. Aug. 5, 1930, Wapakoneta, Ohio, U.S.) U.S. astronaut. He became a pilot at 16, studied aeronautical engineering, and won three Air Medals in the Korean War. In 1955 he became a civilian research pilot for the fore¬ runner of NASA. He joined the space program in 1962 with the sec¬ ond group of astronauts. In 1966, as command pilot of Gemini 8, he and David Scott completed the first manual space docking maneuver, with an unmanned Agena rocket. On July 20, 1969, as part of the Apollo 11 mission, he became the first per¬ son to step onto the Moon, proclaim¬ ing “That’s one small step for [a] man, one giant leap for mankind.”

army Large, organized force armed and trained for war, especially on land. The term may be applied to a large unit organized for independent action or to a nation’s or ruler’s over¬ all military organization for land warfare. The character and organization of armies have varied through history. At various times armies have been built around infantry soldiers or mounted warriors (e.g., cavalry) or men in machines, and have been made up of professionals or amateurs, of merce¬ naries fighting for pay or for plunder, or of patriots fighting for a cause. See also AIR FORCE, CONSCRIPTION, GUERRILLA, MILITARY UNIT, MILITIA, U.S. ARMY.

Neil Armstrong, 1969.

NASA

© 2006 Encyclopaedia Britannica, Inc.

Arnhem ► aromatic compound I 107

Arnhem Var-narrA Land Region, northeastern Northern Territory, Aus¬ tralia. It extends south from Van Diemen Gulf to the Gulf of Carpentaria and Groote Eylandt. Never fully explored, it has a total area of about 37,000 sq mi (96,000 sq km) and contains important bauxite and uranium mines. Occupied by Australian Aboriginals since the late Pleistocene, it was visited in 1623 by the Dutch explorer Jan Carstensz, who named it for his ship. The name now primarily refers to its large Aboriginal reserve.

Arnim, Bettina von orig. Elisabeth Katharina Ludovica Magdalena Brentano (b. April 4, 1785, Frankfurt am Main

[Germany]—d. Jan. 20, 1859, Ber¬ lin) German writer. Her best-known works are reworked records of her correspondence with Johann Wolf¬ gang von Goethe, Karoline von Gtin- derode, and her brother Clemens Brentano, much of it fictitious but written in a brilliantly vivid, unin¬ hibited style.

Arno River River, central Italy. It is 150 mi (240 km) long, flowing west from the Apennines through Flo¬ rence and into the Ligurian Sea below Pisa. Near Arezzo it is con¬ nected with the Tiber River by its cana¬ lized tributary, the Chiani. Subject to disastrous floods, in 1966 it inun¬ dated Florence and caused extensive damage.

Arnold, Benedict (b. Jan. 14,

1741, Norwich, Conn.—d. June 14,

1801, London, Eng.) American army officer and traitor. He joined the American Revolutionary army in 1775 and contributed to American victories at the Battle of Ticon- deroga, at Fort Stanwix, N.Y., and at the Battle of Saratoga, where he was seriously wounded. He was made a major general and placed in com¬ mand of Philadelphia, where he lived extravagantly and socialized with wealthy loyalist sympathizers, one of whom he married in 1779. Repri¬ manded for fiscal irregularities in his command, he began secret overtures to the British. After receiving com¬ mand of the fort at West Point, N.Y.

(1780), he offered to surrender it to the British for £20,000. The plot was uncovered after his British contact,

John Andre, was captured. Arnold escaped on a British ship to England, where he died penniless.

Arnold, Henry (Harley) known as Hap Arnold (b. June 25, 1886, Gladwyne, Pa., U.S.—d. Jan. 15, 1950, Sonoma, Calif.) U.S. air force officer. He attended West Point and initially served in the infantry. Vol¬ unteering as a flyer, he received instruction from Orville Wright. After World War I, with Billy Mitchell he became an eloquent advocate of an expanded air force. He rose through the ranks of the U.S. Army Air Corps to become its commander in 1938, and he commanded the Army Air Forces worldwide during World War II, overseeing a massive buildup and greatly influencing air bombardment strategy. He was named general of the army in 1944 and, after the National Defense Act of 1947 created an independent Air Force, general of the Air Force.

Arnold, Matthew (b. Dec. 24, 1822, Laleham, Middlesex, Eng.—d. April 15, 1888, Liverpool) English poet and literary and social critic. Son of the educator Thomas Arnold, he attended Oxford and then worked as an inspector of schools for the rest of his life. His verse includes “Dover Beach,” his most celebrated work; “Sohrab and Rustum,” a romantic epic; and “The Scholar Gipsy” and “Thyrsis.” Culture and Anarchy (1869), his central work of criticism, is a masterpiece of ridicule as well as a search¬

ing analysis of Victorian society. In a later essay, “The Study of Poetry,” he argued that, in an age of crumbling creeds, poetry would replace reli¬ gion and that therefore readers would have to understand how to distin¬ guish the best poetry from the inferior.

Arnold, Thomas known as Doctor Arnold (b. June 13, 1795, East Cowes, Isle of Wight, Eng.—d. June 12, 1842, Rugby, Warwickshire)

British educator. A classical scholar, he became headmaster in 1828 of Rugby School, which was in a state of decline. He revived Rugby by reforming its curriculum, athletics program, and social structure (in the prefect system he introduced, older boys served as house monitors to keep discipline among younger boys), becoming in the process the preeminent figure in British educa¬ tion. In 1841 he was named Regius Professor of Modern History at Oxford. In addition to several vol¬ umes of sermons, he wrote a three- volume History of Rome (1838—43).

He was the father of Matthew Arnold and grandfather of the novelist Mrs.

Humphry Ward (1851-1920).

Arnolfo di Cambio (b. c. 1245,

Colie di Val d’Elsa—d. 1301/10,

Florence) Italian sculptor and architect active in Florence. He studied under Nicola Pisano and assisted him on the pulpit for Siena Cathedral (1265-68). In 1277 he went to Rome, where he worked for Charles of Anjou, king of Sicily. He also designed and constructed monuments, including the tomb of Cardinal de Braye in San Domenico, Orvieto. In 1296 Arnolfo returned to Florence to undertake his most important com¬ mission, the design of the Duomo (the cathedral of Florence) and the carving of statues for its facade. Other buildings in Florence attributed to him include the Palazzo Vecchio and the church of Santa Croce. The structural and decorative elements of Santa Croce and the Duomo have a unity, balance, and a lightness of movement that demonstrate Arnolfo’s complete mastery of the late 13th-century Gothic architectural vocabu¬ lary. His works embody the transition between the late Gothic and Renais¬ sance architectural sensibilities.

Arnulf (d. Dec. 8, 899) King of Germany. Originally duke of Carinthia, he was elected king of the eastern Franks in 887, deposing his uncle, Charles the Fat. The western Franks, Burgundy, and Italy refused to rec¬ ognize Arnulf, thus dividing the Carolingian empire. He defeated the Vikings (891), ending their raids up the Rhine River, and maintained con¬ trol of Lotharingia (now Lorraine). He invaded Italy at the urging of Pope Formosus, captured Rome (895), and was crowned emperor in 896. Ill¬ ness forced him to return to Germany, however, and the previous emperor continued to rule. Arnulf s last years saw invasions by Magyars and Slavs and the collapse of his power.

aromatherapy Therapy using essential oils and water-based colloids extracted from plant materials to promote physical, emotional, and spiri¬ tual health and balance. Single or combined extracts may be diffused into inhaled air, used in massage oil, or added to bathwater. Inhaled molecules of these extracts stimulate the olfactory nerve, sending messages to the brain’s limbic system (the seat of memory, learning, and emotion) that are said to trigger physiological responses (e.g., eucalyptus relieves con¬ gestion, lavender promotes relaxation). Mainstream medical practitioners question the claim of independent physiological effects; they consider many of the benefits more likely due to the conditioned responses that odors can reinforce or help create. The oils and solutions used have been shown to have certain effects but are not standardized. The few risks involved include allergic reactions.

aromatic compound Any of a large class of organic compounds whose molecular structure includes one or more planar rings of atoms, usually but not always six carbon atoms. The ring’s carbon-carbon bonds (see bonding) are neither single nor double but a type characteristic of these compounds, in which electrons are shared equally with all the atoms around the ring in an electron cloud. The term was first applied c. 1860

Bettina von Arnim, engraving after Armgass von Arnim's copy of a minia¬ ture by an unknown artist.

COURTESY OF THE TRUSTEES OF THE BRITISH MUSEUM; PHOTOGRAPH, J.R. FREEMAN & CO. LTD.

Benedict Arnold, engraving by H.B. Hall, 1865.

LIBRARY OF CONGRESS, WASHINGTON, D.C.

Thomas Arnold, detail of an engraving by H. Cousins, 1840, after an oil painting by Thomas Philips.

COURTESY OF THE TRUSTEES OF THE BRITISH MUSEUM; PHOTOGRAPH, J.R. FREEMAN & CO. LTD.

© 2006 Encyclopaedia Britannica, Inc.

108 I Aron ► Arsacid

to a class of hydrocarbons isolated from coal tar and distinguished by odours much stronger than those of other classes of hydrocarbons. In modern chemistry, aromaticity denotes the chemical behaviour, especially the low reactivity, of this class of molecules related to their bonding. The parent compound of this class is benzene (C 6 H 6 ). See also hydrogenation.

Aron \ar-'o n \, Raymond (-Claude-Ferdinand) (b. 1905—d. 1983) French sociologist and historian. After receiving his doctorate from the Ecole Normale Superieure (1930), he taught at the University of Tou¬ louse until 1939. During World War II he joined the Free French and edited their newspaper (1940^44). He later taught at the Ecole Nationale d’Administration, the Sorbonne, and the College de France. He was also a columnist for Le Figaro (1947-77) and L’Express (1977-83). Aron upheld a rationalist humanism that was often contrasted with the Marxist existentialism of his great contemporary and former classmate Jean-Paul Sartre. A continuing theme in his writings was the subject of violence and war.

Aroostook \3-'ru-stuk\ War (1838-39) Bloodless conflict over the disputed boundary between the U.S. state of Maine and the British Cana¬ dian province of New Brunswick. As settlers from both countries moved into the disputed Aroostook area, officials and bands of men from both sides made arrests and took prisoners of “trespassers.” In 1839 U.S. and Canadian troops were ordered to the area. A truce allowed joint occupancy of the territory until 1842, when a satisfactory settlement was reached.

Arp, Jean known as Hans Arp (b. Sept. 16, 1887, Strassburg, Ger.—d. June 7, 1966, Basel, Switz.) French painter, sculptor, and poet. After studying in Weimar, Ger., and at the Academie Julian in Paris, he became involved in the most important movements of early 20th-century art: Der Blaue Reiter in Munich (1912), Cubism in Paris (1914), Dada in Zurich during World War I, Surrealism (1925), and Abstraction-Creation (1931). During these years he produced polychrome relief carvings in wood, cut-paper compositions, and, in the 1930s, his most distinctive sculptural works: abstract forms that suggest animals and plants. He also wrote poetry.

Arrabal \,ar-ra-'bal\, Fernando (b. Aug. 11, 1932, Melilla, Spanish Morocco) Spanish French Absurdist playwright, novelist, and filmmaker. He turned to writing in the 1950s, and in 1955 he began studying drama in Paris, where he remained. His early plays, in particular Picnic on the Battlefield , brought him to the attention of the French avant-garde. After the mid 1960s his plays evolved into what he termed Theatre Panique (“Panic Theater”); typical of this period is And They Put Handcuffs on the Flowers. His dramatic and fictional world is often violent, cruel, and por¬ nographic.

arrastra Vo-'ras-troX Drag-stone mill for pulverizing ores to isolate silver by the patio process, apparently used in pre-Columbian America. The silver ore was crushed and ground by mule power in the arrastras (shallow cir¬ cular pits paved with stone). Large blocks of stone attached by beams to a central rotating post were dragged around the arrastra, reducing the ore to a fine mud. Further steps resulted in the isolating of the silver.

arrest Restraint and seizure of a person by someone (e.g., a police officer) acting under legal authority. An officer may arrest a person who is committing or attempting to commit a crime in the officer’s presence. Arrest is also permitted if the officer reasonably believes that a crime has been committed and that the person arrested is the guilty party. A court or judicial officer may issue an arrest warrant on a showing of probable cause. Most states restrict or prohibit arrest in civil (noncriminal) cases; an example of occasionally permitted civil arrest is the taking into cus¬ tody of a debtor who might otherwise abscond. In the U.S., suspects must be warned of their rights when they are arrested (see Miranda v. Arizona ). An unlawful arrest is regarded as false imprisonment and usually invali¬ dates any evidence collected in connection with it. See also rights of the accused; grand jury; indictment.

Arrhenius \ar-'a-ne-9s\, Svante (August) (b. Feb. 19, 1859, Vik, Swed.—d. Oct. 2, 1927, Stockholm) Swedish physical chemist. His theo¬ ries on dissociation of substances in solution into electrolytes or ions, first published in 1884 as his Ph.D. thesis, were initially met with skepticism, but increasing recognition abroad gradually won over the opposition in Sweden. He also did important work on reaction rates; the equation describing the dependence of reaction rates on temperature is often called the Arrhenius law, and he was the first to recognize the greenhouse effect. After receiving the Royal Society of London’s Davy Medal (1902), he

became in 1903 the third recipient of the Nobel Prize for Chemistry. He is regarded as one of the founders of the field of physical chemistry.

arrhythmia \a-'rith-me-3\ Varia¬ tion from the heartbeat’s normal rate or rhythm, caused by problems in the heart’s pacemaker or in nerves con¬ ducting its signals. Occasional arrhythmias are normal. Tachycardia is a fast regular rhythm; bradycardia is a slow rhythm. Premature atrial or ventricular beats are extra contrac¬ tions in normal rhythm. Ongoing arrhythmia in some heart diseases can reduce the heart’s ability to sup¬ ply the body with blood and can lead to heart failure. Severe arrhythmias can trigger atrial fibrillation or ven¬ tricular fibrillation. Arrhythmias are detected by electrocardiography and treated by electric shock (often with an implanted pacemaker) or by drugs such as quinidine and digitalis.

arrow See bow and arrow

Arrow, Kenneth J(oseph) (b. Aug. 23, 1921, New York, N.Y., U.S.) U.S. economist. He received his Ph.D. from Columbia University and taught principally at Stanford and Harvard. Arrow’s books include Social Choices and Individual Values (1951). His most striking claim was that, under certain conditions of rationality and equality, a ranking of societal preferences will not necessarily correspond to the rankings of individual preferences, given more than two individuals and alternative choices. In 1972 he shared the Nobel Prize with John R. Hicks.

Arrow War See Opium Wars

arrowroot Any of several plant species of the genus Maranta (family Marantaceae), whose rhizomes yield an edible starch. Chief among these is the herbaceous perennial M. arundinacea, the source of genuine, or West Indies, arrowroot. The powder obtained from the harvested roots is almost pure starch; it is used in cookery as a thickener. Arrowroot is eas¬ ily digested and is used in diets requiring bland, low-salt, and low-protein foods. Its name is sometimes applied to starches obtained from other plants and used as substitutes for true arrowroot. Brazilian arrowroot, from the cassava plant, is the source of tapioca.

Ars Antiqua Vars-an-'te-kw3\ Latin "Ancient Art" Musical style of 13th-century France. The term was derived retrospectively to distinguish 13th-century music from that of the 14th century (Ars Nova). It is partly characterized by use of the six rhythmic modes, each being a rhythmic pat¬ tern that would recur throughout a piece, such as long-short (first mode) or short-long (second). Akin to the “feet” of poetry (see prosody), the relative lengths of long and short depended on the mode. The system broke down as composers began to use subdivisions of the short note. The musical genres of the Ars Antiqua included organum and the early motet.

Ars Nova \'ars-'no-v9\ Latin "New Art" Musical style of 14th- century Europe, particularly France. As composers began to use ever shorter notes in their music, the old system of rhythmic modes (see Ars Antiqua) ceased to be adequate to describe it. In his treatise Ars nova (1323), Philippe de Vitry (1291-1361) proposed a way of relating longer and shorter notes by a metrical scheme—the ancestor of time signatures— whereby each note value could be subdivided into either two or three of the next-shorter note. Though seemingly abstract, this innovation had a marked effect on the sound of music because composers were better able to control the relative motion of several voices, and 14th-century music consequently sounds much less “medieval” to modern ears. De Vitry and Guillaume de Machaut are the principal composers of the Ars Nova. The term is sometimes extended to describe all 14th-century music, including that of Italy. See also formes fixes.

Arsacid \ar-'sas-id\ dynasty (247 bc-ad 224) Persian dynasty. It was founded by Arsaces (r. c. 250-211? bc) of the Parni tribe, which origi¬ nally dwelt east of the Caspian Sea and entered Parthia after the death of Alexander the Great (323 bc), gradually extending control southward. Arsacid power reached its peak under Mithradates I (r. 171-138 bc). The

Svante Arrhenius, 1918.

BY COURTESY OF THE KUNGLIGA BIBLIOTEKET, STOCKHOLM

© 2006 Encyclopaedia Britannica, Inc.

arsenic ► Art Ensemble I 109

government was influenced by that of the Seleucid dynasty and tolerated the formation of vassal kingdoms. The dynasty legitimized its rule over former Achaemenian territories by claiming descent from the Achaeme- nian king Artaxerxes II. It controlled trade routes between Asia and the Greco-Roman world and used its resultant wealth to erect many build¬ ings. The dynasty was overthrown in 224 by the Sasanian dynasty.

arsenic poisoning Harmful

effects of arsenic compounds (in pesticides, chemotherapy drugs, paints, etc.), most often from insecticide exposure. Susceptibility varies. Arsenic is believed to combine with certain enzymes, interfering with cellular metabolism. Symptoms of acute arsenic poisoning include nausea and abdominal pain followed by circulatory collapse. Acute exposure to the gas arsine causes destruction of red blood cells and kidney damage; chronic exposure causes weakness, skin disorders, anemia, and nervous- system disorders. Arsenic in urine and hair or nails is the key to diagno¬ sis. Treatment involves washing out the stomach and promptly administering the antidote dimercaprol.

arson Crime commonly defined by statute as the unlawful damage or destruction of property by means of fire or explosion. In nearly all coun¬ tries (except Great Britain) an arsonist is guilty of murder if someone dies as a result of his action, even if he did not intend to kill. Germany and some U.S. states also impose serious penalties for arson when it is com¬ mitted to conceal or destroy evidence of another crime. Although fire caused by accident or ordinary carelessness is not arson, a person may be guilty of arson if he causes a fire in reckless disregard of the consequences of his actions.

art also called visual art A visual object or experience consciously created through an expression of skill or imagination. The term art encom¬ passes diverse media such as painting, sculpture, printmaking, drawing, decorative arts, photography, and installation. The various visual arts exist within a continuum that ranges from purely aesthetic purposes at one end to purely utilitarian purposes at the other. This should by no means be

taken as a rigid scheme, however, particularly in cultures in which every¬ day objects are painstakingly constructed and imbued with meaning. Par¬ ticularly in the 20th century, debates arose over the definition of art. Figures such as Dada artist Marcel Duchamp implied that it is enough for an artist to deem something “art” and put it in a publicly accepted venue. Such intellectual experimentation continued throughout the 20th century in movements such as conceptual art and Minimalism. By the turn of the 21st century, a variety of new media (e.g., video art) further challenged traditional definitions of art. See aesthetics; art conservation and restora¬ tion; drawing; painting; printmaking; sculpture; photography; decorative arts.

art brut V.art-'briit, ar-'brCet\ French "raw art" Art produced by people outside the established art world, particularly crude, inexperienced, or obscene works created by the untrained or the mentally ill. The term was coined by Jean Dubuffet, who regarded such works as the purest form of expression. See also naive art.

art collection Works of art accumulated by an individual or institution. Such collections were made in the earliest civilizations; precious objects were stored in temples, tombs, sanctuaries, and palaces. A taste for col¬ lecting per se developed in Greece (4th— 1 st century bc). The great art col¬ lections of the world grew out of private collections formed by royalty, aristocracy, and the wealthy. By the 18th century, collectors were donat¬ ing their holdings to the public and constructing buildings to house them (e.g., the Louvre Museum, Uffizi Gallery). Wealthy industrialists in the U.S. played a prominent role in the 19th-20th century, and an unprecedented flow of masterpieces from Europe soon filled U.S. museums.

art conservation and restoration Maintenance and preservation of works of art, their protection from future damage, deterioration, or neglect, and the repair or renovation of works that have deteriorated or been damaged. Research in art history has relied heavily on 20th- and 21st-century technical and scientific advances in art restoration. Modern conservation practice adheres to the principle of reversibility, which dic¬ tates that treatments should not cause permanent alteration to the object.

art criticism Description, interpretation, and evaluation of works of art, manifested in journal reviews, books, and patronage. Art criticism encom¬ passes a wide variety of approaches, from critical commentary to more subjective emotional reactions inspired by viewing works of art. Art criti¬ cism as a distinct discipline developed parallel to Western aesthetic theory, beginning with antecedents in ancient Greece and fully taking form in the 18th and 19th centuries. In the 20th century perceptive critics became champions of new artistic movements. Beginning in the 20th and con¬ tinuing into the 21st century, many critics used social and linguistic, rather than aesthetic, theoretical models. Prominent art critics include Roger Fry, Clive Bell, Clement Greenberg, Harold Rosenblum, Lawrence Alloway, Rosalind Krauss, and Donald Kuspit. See also aesthetics.

Art Deco \,M-'de-ko, ,ar-da-'ko\ or Style Moderne Vstel-mo-'dernN Movement in design, interior decoration, and architecture in the 1920s and ’30s in Europe and the U.S. The name derives from the Exposition Internationale des Arts Decoratifs et Industriels Modernes in Paris in 1925. Its products included both individually crafted luxury items and mass-produced wares, but, in either case, the intention was to create a sleek and antitraditional elegance that symbolized wealth and sophistica¬ tion. Influenced by Art Nouveau, Bauhaus, Cubist, Native American, and Egyptian sources, the distinguishing features of the style are simple, clean shapes, often with a “streamlined” look; ornament that is geometric or stylized from representational forms; and unusually varied, often expen¬ sive materials, which frequently include man-made substances (plastics, especially bakelite; vita-glass; and ferroconcrete) in addition to natural ones (jade, silver, ivory, obsidian, chrome, and rock crystal). Typical motifs included stylized animals, foliage, nude female figures, and sun rays. New York City’s Rockefeller Center (especially its interiors super¬ vised by Donald Deskey), the Chrysler Building by William Van Alen, and the Empire State Building by Shreve, Lamb & Harmon are the most monu¬ mental embodiments of Art Deco.

Art Ensemble of Chicago U.S. jazz ensemble. The group evolved from the Association for the Advancement of Creative Musicians (AACM), an experimental collective. Saxophonists Roscoe Mitchell and Joseph Jarman, trumpeter Lester Bowie, bassist Malachi Favors, and drummer Don Moye formed the group in 1969, combining freely chang¬ ing tempos, dynamics, and textures with an often comic theatricality of presentation. Their diversity of inspiration is expressed by their motto, “Great Black Music: Ancient to the Future.”

arsenic Nonmetallic to semimetallic chemical element, chemical symbol

As, atomic number 33. It exists uncombined in two stable (and sev¬ eral unstable) allotropes, one gray and one yellow, but is more often found in nature as the sulfide or oxide. The elemental form is used to form alloys of metals (especially lead), and certain semiconductors are made from crystals of gallium arsenide (GaAs). Arsenious oxide (arsenic trioxide or white arsenic, As 2 0 3 ) is used in pes¬ ticides, as a pigment, and as a preser¬ vative of hides and wood; this is the poisonous “arsenic” (see arsenic poi¬ soning) in detective stories. Arsenic pentoxide (As 2 0 5 ) is also used in insecticides, herbicides, metal adhe¬ sives, and pigments.

Arsenic (gray) with realgar (red) and orpiment (yellow)

BY COURTESY OF THE JOSEPH AND HELEN GUETTERMAN COLLECTION; PHOTOGRAPH, JOHN H. GERARD

Arsinoe \ar-'sin-o-e\ II (b. c. 316—d. July 270 bc) Queen of Thrace (300-281) and Egypt (277-270).

Daughter of Ptolemy I Soter, she mar¬ ried the king of Thrace (300) and tried to have her son made heir instead of Agathocles, the king’s son by an earlier marriage. Agathocles sought help from Seleucids, causing a war in which Arsinoe’s husband was killed in battle. Her half brother, who took power in Thrace and Mace¬ donia, cajoled her into marrying him and then promptly killed her two younger sons. She fled to Alexan¬ dria, ousted the wife of her brother Ptolemy II, and married him (c. 277); like the pharaohs, the two were called “Philadelphoi” (“Sibling- BY courtesy OF THE trustees OF THE BRITISH museum

Loving”). She wielded great power

and shared many honours with Ptolemy, including deification while alive.

Arsinoe II, coin, 270-250 bc; in the British Museum

© 2006 Encyclopaedia Britannica, Inc.

110 I art history ► artery

art history Historical study of the visual arts for the purpose of iden¬ tifying, describing, evaluating, interpreting, and understanding art objects and artistic traditions. Art-historical research involves discovering and collecting biographical data on artists to establish attribution; determin¬ ing at what stage in a culture’s or artist’s development an object was made; weighing the influence the object or artist had on the historical past; and documenting an object’s previous whereabouts or ownership (prov¬ enance). The analysis of symbols, themes, and subject matter is often of primary concern. In the 20th and 21st centuries art historians became increasingly concerned with the social and cultural context of artists and their work.

Art Institute of Chicago Museum in Chicago that houses European, American, Asian, African, and pre-Columbian art. It was established in 1866 as the Chicago Academy of Design and took its current name in 1882. In 1893 it moved to its present building, designed by the architec¬ tural firm of Shepley, Rutan, and Coolidge for the World’s Columbian Exposition, on Michigan Avenue. The Art Institute, which comprises both a museum and a school, is noted for its extensive collections of 19th- century French painting (Impressionist works and the work of Claude Monet in particular) and 20th-century European and American painting. Among its best-known works are Georges Seurat’s A Sunday Afternoon on La Grand Jatte—1884 (1884-86), Grant Wood’s American Gothic (1930), and Edward Hopper’s Nighthawks (1942).

Art Nouveau V.art-nii-'vo, .ar-nii-'voX Decorative style that flourished in western Europe and the U.S. c.

1890-1910. The term was derived in 1895 from a gallery in Paris called L’Art Nouveau. Characterized by sinuous, asymmetrical lines based on plant forms, the style was used in architecture, interior design, graphic art and design, jewelry, and glass. It was international in scope, with cel¬ ebrated exponents in England (Aubrey Beardsley), Paris (Alphonse Mucha), the U.S. (Louis Comfort Tif¬ fany), Scotland (Charles Rennie Mackintosh), Spain (Antonio Gaudi), and Belgium (Victor Horta). The style did not significantly survive the outbreak of World War I. See also Arts and Crafts Movement; Jugendstil.

Arta, Gulf of Inlet of the Ionian Sea, western Greece. It is 25 mi (40 km) long and 4-10 mi (6-16 km) wide. On its shores are the ruins of several cities important in ancient Greece. The seaport of Preveza, founded 290 bc, is to the north; the Battle of Actium took place near the gulf’s entrance.

Apollo. Accompanied by nymphs, she danced in mountains and forests. She both killed game and, as Mistress of Animals (see Master of the Animals), protected it. Stories of her nymphs’ love affairs may originally have been told of the goddess herself, but poets after Homer stressed her chastity. She was known for her unpitying wrath when offended. Artemis may have developed out of Ishtar in the East. Her Roman counterpart was Diana.

Artemisia \,art-9-'miz-e-3\ I (fl. 5th century bc) Queen of Halicarnas¬ sus and of the island of Cos c. 480 bc. She ruled under the Persian king Xerxes and helped him invade Greece (480^179). She commanded five ships in the Battle of Salamis; according to Herodotus, she advised Xerxes to retreat from Greece rather than risk another engagement.

Artemisia II (d. c. 350 bc) Sister and wife of King Mausolus (r. 377-353 bc) of Caria, southwestern Anatolia, and sole ruler for about three years after his death. She built his tomb, the Mausoleum, considered one of the Seven Wonders of the World.

arteriography See angiography

arteritis N.ar-ts-'rl-tosV Inflamma¬ tion of the arteries. It occurs in dis¬ eases including syphilis, tuberculosis, and lupus erythematosus. Varieties not closely associated with systemic dis¬ ease or disease of an organ outside the cardiovascular system have been described as temporal arteritis, poly¬ myalgia rheumatica, and polyarteri¬ tis nodosa.

artery Vessel that carries blood from the heart to other parts of the body (see cardiovascular system).

Arterial blood carries oxygen and nourishment to tissues; the one exception is the pulmonary artery, which conveys oxygen-depleted blood from the heart to the lungs for oxygenation and removal of excess carbon dioxide. Arteries are muscu¬ lar, elastic tubes that transport blood under the pressure of the heart’s pumping action, which can be felt as the pulse. Large arteries branch off from the aorta and give rise to smaller arteries, down to the threadlike arterioles, which branch into cap¬ illaries. An artery wall’s inner layer (tunica intima) consists of an endo¬ thelial (cellular) lining, a fine connective tissue network, and a layer of elastic fibres. The middle layer (tunica media) is mostly smooth muscle cells. The outer layer (tunica externa) contains supportive collagen fibres. See also capillary; vein.

"The Whiplash," Art Nouveau tapestry by Hermann Obrist, silk embroidered on wool, 1895; in the Munchner Stadt- museum, Munich.

COURTESY OF THE MUNCHNER STADTMUSEUM, MUNICH

Artemisia II, statue by an unknown art¬ ist; in the National Archeological Museum, Naples.

ANDERSON—AUNARI FROM ART RESOURCE

Artaud \ar-'to\, Antonin (b. Sept. 4, 1896, Marseille, France—d. March 4, 1948, Ivry-sur-Seine)

French poet, actor, and drama theo¬ rist. He wrote Surrealist poetry from 1925 and made his acting debut in Surrealist productions in Paris. He described his theory of drama in the Manifesto of the Theatre of Cruelty (1932; see Theatre of Cruelty) and The Theatre and Its Double (1938).

His own plays (including Les Cenci,

1935) were failures, but his theories exerted great influence on play¬ wrights of the Theatre of the Absurd.

Lifelong mental illness confined him periodically to asylums from 1936.

Artemis Var-to-mosV In Greek reli¬ gion, the goddess of wild animals, the hunt, vegetation, chastity, and child¬ birth. Artemis was the daughter of Artaud 1948.

Zeus and Leto and the twin sister of denise colomb-j.p. ziolo

artemisia V.ar-to-'mi-zhoV Any of a genus ( Artemisia ) of aromatic herbs and shrubs in the composite family. Examples include worm¬ wood, SAGEBRUSH, and TARRAGON.

Many species are valued as orna¬ mentals for their attractive silvery gray foliage, which is frequently used in horticultural plantings to cre¬ ate contrast or to smooth the transi¬ tion between intense colors. The leaves of common wormwood (A. absinthium ) have been used in medi¬ cines and beverages such as absinthe and vermouth. An extract from the Eurasian A. annua is used to treat quinine-resistant malaria.

Artemis as a huntress, classical sculp¬ ture; in the Louvre.

AUNARI/ART RESOURCE

© 2006 Encyclopaedia Britannica, Inc.

arthritis ► Arthur's Pass I 111

centipede class Chilopoda

subphylum Uniramia

subphylum Chelicerata

barnacle class Cirripeda

eye

telson

uropod

shrimp class Malacostraca

subphylum Crustacea

carapace

antennule

tail

(pygidium)

trilobite

subphylum Trilobita

eye

thorax

antenna

head

(cephalon)

Representative arthropods. Uniramia, the largest of the arthropod subphyla, contains mostly terrestrial insects and myriapods (including centipedes and millipedes). The insects, the largest arthropod class, differ from other arthropods in that they are usually winged and have only three pairs of legs. Members of the Crustacea subphylum are mostly marine-dwelling and include the shrimps, lobsters, crabs, and barnacles. The microscopic water fleas are chiefly found in fresh water and, along with other minute members of this subphylum, are part of the zooplankton. Most members of the Chelicerata subphylum are arachnids, including the spiders, scorpions, ticks, and mites. The trilobites (members of the Trilobita subphylum) are extinct marine arthropods that flourished during the Cambrian Period. Fossilized remains show a body having three lon¬ gitudinal lobes divided into three regions—head, thorax, and tail.

© MERRIAM-WEBSTER INC.

arthritis \ar-'thri-t9s\ Inflammation of the joints and its effects. Acute arthritis is marked by pain, redness, and swelling. The principal forms are osteoarthritis, rheumatoid arthritis, and septic arthritis. Several forms of arthritis are part of the symptom complexes of autoimmune diseases.

arthropod Any member of the largest phylum, Arthropoda, in the ani¬ mal kingdom. Arthropoda consists of more than one million known inver¬ tebrate species in four subphyla: Uniramia (five classes, including insects), Chelicerata (three classes, including arachnids and horseshoe crabs), Crus¬ tacea (crustaceans), and Trilobita (trilobites). All arthropods are bilaterally symmetrical and possess a segmented body covered by an exoskeleton containing chitin, which serves as both armour and a surface for muscle attachment. Each body segment may bear a pair of jointed appendages. The phylum includes carnivores, herbivores, omnivores, detritus feeders, filter feeders, and parasites (see parasitism) in nearly all environments, both aquatic and terrestrial. See illustration above.