Chad officially Republic of Chad Country, north-central Africa. Area: 495,755 sq mi (1,284,000 sq km). Population (2005 est.): 9,157,000. Capi¬ taclass="underline" N'Djamena. The Sara are the largest ethnic group, making up about
single ethnic group. Languages: French,
Arabic (both official), Fula, Sara. Religions: Islam, Christianity, tradi¬ tional beliefs. Currency: CFA franc. The landlocked country’s terrain is a shallow basin that rises gradually from the Lake Chad area in the west. The basin is rimmed by mountains, including the volcanic Tibesti Massif
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to the north, rising to 11,204 ft (3,415 m) at Mount Koussi. The lowest elevation, 573 ft (175 m), is in the Djourab Depression. Chad’s river net¬ work is limited to the Chari and Logone rivers and their tributaries, which flow from the southeast into Lake Chad. The economy is agricultural; gold, uranium, and petroleum reserves have not been fully exploited. Chad is a republic with one legislative body; its chief of state is the president, its head of government the prime minister. About ad 800 the kingdom of Kanem was founded, and by the early 1200s its borders had expanded to form a new kingdom, Kanem-Bornu, in the north. Its power peaked in the 16th century with its command of the southern terminus of the trans- Sahara trade route to Tripoli. About this time the rival kingdoms of Bagu- irmi and Ouaddai (Wadai) evolved in the south. In the years 1883-93 all three kingdoms fell to the Sudanese adventurer Rabih al-Zubayr, who was overthrown in 1900 by a local ruler under French protection. Extending their power, the French in 1910 made Chad a part of French Equatorial Africa, and it was made an overseas territory in 1946. The country achieved independence in 1960 but has had decades of civil war despite frequent intervention by France and Libya, resulting in political instabil¬ ity and a lack of economic development.
Chad, Lake Lake, west-central Africa. Located at the juncture of the boundaries of Nigeria, Niger, Chad, and Cameroon, the lake covered 9,900 sq mi (25,600 sq km) in the mid-20th century. Its water level has since dropped—owing to severe drought, the desertification of the sur¬ rounding Sahel region, and irrigation projects—and, by the beginning of the 21st century, the lake had shrunk to 580 sq mi (1,500 sq km). The lake is fed by the Chari River.
Chaeronea \ l ker-9- , ne-o\ Ancient city, eastern Greece. Its ruins are located in western Boeotia southeast of Mount Parnassus, near Orchomenus. Philip II of Macedon won the Battle of Chaeronea there in 338 bc. In 86 bc it was the scene of a victory of Sulla over Mithradates VI of Pontus. Plutarch was bom there c. ad 46.
Chaeronea, Battle of (338 bc) Battle in Boeotia, central Greece, in which Philip II of Macedonia defeated Thebes and Athens. The victory, partly credited to Philip’s young son Alexander the Great, gave Macedonia a foothold in Greece and represented a start toward Alexander’s eventual empire.
Chafee \'cha-fe\, Zechariah, Jr. (b. Dec. 7, 1885, Providence, R.I., U.S.—d. Feb. 8, 1957, Boston, Mass.) U.S. legal scholar. He graduated from Harvard Law School and joined its faculty in 1916. Concerned about the restrictions on freedom of speech imposed in World War I, he wrote Freedom of Speech (1920), which became a leading text of U.S. libertar¬ ian thought. Chafee became recognized as an expert on civil liberties (see civil liberty), influencing Louis Brandeis and Oliver Wendell Holmes, Jr. He was also an authority on equity, nego¬ tiable instruments, and antitrust law.
chafer Any of several species of scarab beetle (most in the subfamily Melolonthinae). Adult leaf chafers (genus Macrodactylus ) eat foliage; the female deposits her eggs in the soil, and the larvae live underground for years, feeding on plant roots. The well-known rose chafer, a tan, long- legged beetle, feeds on the flowers and foliage of grapes, roses, and other plants. Poultry that eat rose- chafer grubs may be poisoned.
chaffinch Songbird ( Fringilla coelebs) that breeds in gardens and farmlands of Europe and northern Africa to central Asia (and, by intro¬ duction, South Africa). It is the most common finch in western Europe.
The 6-in. (15-cm) male has a bluish crown, rust-brown back, greenish rump, and pinkish to rust face and breast; the female is greenish brown.
The Canary Islands, or blue, chaffinch (F. teydea ) is similar.
Chagall \sha-'gal\, Marc (b. July 7, 1887, Vitebsk, Belorussia, Rus¬ sian Empire—d. March 28, 1985, Saint-Paul, Alpes-Maritimes, France) Belarusan French painter, printmaker, and designer. After studying paint¬ ing in St. Petersburg, he moved to Paris in 1910. During the next four years he mixed with the avant-garde there and created what is often con¬ sidered his best work in the style he would explore for the next 60 years. Often the principal figure in his fantastical works is the painter himself, and memories of Jewish life and folklore in Belarus and themes from the Bible are main sources of imagery. The often whimsical figurative ele¬ ments in his works are frequently depicted upside down and distributed on the canvas in an arbitrary fashion. In the 1920s he launched a career in printmaking, producing hundreds of etchings for special editions of books. In 1941 he left for New York City, where he designed sets and costumes for Igor Stravinsky’s ballet The Firebird. He later produced stained-glass windows and murals for public buildings in Jerusalem, Paris, and the U.S.
Chagos Archipelago Ycha-gssX Island group, central Indian Ocean. Located about 1,000 mi (1,600 km) south of the tip of the Indian sub¬ continent, it has a total area of 23 sq mi (60 sq km). Acquired by Britain from France in 1814, it was originally administered by Britain as a depen¬ dency of Mauritius; since 1976 it has been the sole member of the Brit¬ ish Indian Ocean Territory. Strategically situated at the centre of the Indian Ocean, its chief island, Diego Garcia, was developed as an air and naval refueling station by the U.S. and Great Britain in the mid 20th century, over the strong opposition from the region’s coastal and island states.
C hag res \'cha-gros\ River River, Panama. Rising in central Panama, it is part of the Panama Canal system and flows southwest where it is dammed to form Gatun Lake. It drains northwest out of the lake and into the Caribbean Sea.
Chaikin Vcha-konV, Joseph (b. Sept. 16, 1935, Brooklyn, N.Y., U.S.) U.S. stage director, actor, and writer. He was a member of the Living The¬ atre before founding the Open Theatre (1963), which became an influen¬ tial force in experimental theatre. His celebrated productions, the results of intense collaboration between writer, director, and actors, included America Hurrah (1966), The Serpent (1969), Terminal (1970), The Muta¬ tion Show (1971), and Nightwalk (1973). He published his ideas about theatre in The Presence of the Actor (1972). He later collaborated with Sam Shepard on a number of plays, including The War in Heaven (1984) and When the World Was Green (1996). In 1977 he received the first lifetime-achievement Obie Award.
Chain, Sir Ernst Boris (b. June 19, 1906, Berlin, Ger.—d. Aug. 12, 1979, Ire.) German-born British biochemist. With Howard Walter Florey he isolated and purified penicillin and performed the first clinical trials of the antibiotic. For their pioneering work, Chain, Florey, and Alexander Fleming
shared a 1945 Nobel Prize. In addi¬ tion to his work on antibiotics, Chain studied snake venoms, the spreading factor (an enzyme that aids the dis¬ persal of fluids in tissue), and insulin. He was knighted in 1969.
chain drive Device widely used for the transmission of power where shafts are separated at distances greater than that for which gears are practical. In such cases, sprockets (wheels with teeth shaped to mesh with a chain) take the place of gears and drive one another by means of a chain passing over the sprocket teeth. The chains used in conveyor belts are commonly block chains, and consist of solid or laminated blocks connected by side plates and pins. The blocks engage with teeth on sprocket wheels. Depending on the material being moved, buckets, hooks, or other devices are con¬ nected to the blocks.