chain mail or mail Form of body armour worn by European knights and other medieval warriors. An
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368 I chain reaction ► Chalkis
early form, made by sewing iron rings to fabric or leather, was worn in late Roman times and may have originated in Asia. Medieval armourers interlaced the rings, which were closed by welding or riveting. In the 8th century, mail was a short coat with a separate sleeve for the sword arm. By the Norman Conquest (1066), the coat was long and fully sleeved; a hood, usually fitting under a helmet, covered the head and neck. By the 12th century, mail was fitted to hands, feet, and legs. The addition of plates to increase chest and back protection gradually evolved in the 14th cen¬ tury into complete plate armour, displacing mail.
chain reaction Process yielding products that initiate further processes of the same kind. Nuclear chain reactions are a series of nuclear fissions initiated by neutrons produced in a preceding fission. A critical mass, large enough to allow more than one fission-produced neutron to be captured, is necessary for the chain reaction to be self-sustaining. Uncontrolled chain reactions, as in an atomic bomb, occur when large numbers of neu¬ trons are present and the reactions multiply very quickly. Nuclear reac¬ tors control their reactions through the careful distribution of the fissionable material and insertion of neutron-absorbing materials.
chain silicate See inosilicate
chair Seat, usually with four legs and a back, intended for one person. It is one of the most ancient forms of furniture, dating to the 3rd Egyp¬ tian dynasty (c. 2650-2575 bc). Various styles were developed through¬ out Europe. In the 16th century, many chairs began to be covered with upholstery over padding and decorated with elaborate wood carving. U.S. chairs adapted versions of English styles from the late 17th century.
Chajang Yulsa Vja-'yaq-'yul-'saV (fl. 7th century, Korea) Korean Bud¬ dhist monk who attempted to make Buddhism the state religion. He went to Tang-dynasty China in 636 for seven years of study and practice and returned with some of the supposed remains of the historical Buddha. Appointed to the highest Buddhist post in Silla, he erected a tower to house the remains and asserted Silla’s leadership over the other kingdoms of Korea. He sought China’s aid in wars against them. He built the Tongdo Temple to uphold monastic austerity as a model for the nation and sought to make Buddhism a unifying force in Korean society.
chakra Vcha-kroN In Hinduism and Tantra, any of 88,000 focal points in the human body where psychic forces and bodily functions can merge and interact. In Hinduism there are seven and in Tantra four major chakras, each associated with a colour, shape, sense organ, natural element, deity, and mantra. The most important are the heart chakra, the chakra at the base of the spine, and the chakra at the top of the head.
chakravartin or cakravartin N.cho-kro-'var-UnV Ancient Indian conception of the world ruler. Buddhist and Jain sources distinguish three types of secular chakravartin s: cakravala cakravartin, ruler over all four of the continents of Indian cosmography; dvipa cakravartin, ruler of one continent; and pradesa cakravartin, a ruler of part of a continent. The chakravartin was considered a secular counterpart to a buddha.
Chakri dynasty Thailand’s ruling family. Phraphutthayotfa Chulalok (1737-1809) founded the dynasty and ruled as Rama I (r. 1782-1809). He reorganized Siam’s defenses to successfully repel numerous Burmese attacks. His descendants have reigned in an unbroken line ever since. Rama III (r. 1824-51) increased trade with Europe and negotiated a treaty with the British East India Co.; King Mongkut (Rama IV; r. 1851-68) and King Chulalongkorn (Rama V; r. 1868—1910) helped modernize the gov¬ ernment along Western lines and thereby avoided colonial rule. King Vajiravudh (Rama VI; r. 1910-25) instituted social reforms and restored the nation’s fiscal autonomy (lost to the West under Rama IV). Bhumibol Adulyadej (Rama IX) has reigned since 1946 as Thailand’s ceremonial head of state.
Chalcedon Vkal-so-.danV, Council of (451) Fourth ecumenical coun¬ cil of the Christian Church, held in Chalcedon (modern Kadikoy, Tur.). Called by the emperor Marcian, it approved the creeds of Nicaea (325) and Constantinople (381; later known as the Nicene Creed). It also approved the Tome of Pope Leo I confirming the two distinct natures in Christ and rejecting the Monophysite heresy. The council then explained these doctrines in its own confession of faith. The council disciplined clergy and declared Jerusalem and Constantinople patriarchates.
chalcedony or calcedony \kal-'se-d 3 n-e\ Very fine-grained variety of the silica mineral quartz. A form of chert, it occurs in a great variety of colours, usually bluish white, gray, yellow, or brown. Other physical
properties are those of quartz. For centuries, chalcedony has been the stone most used by gem engravers, and many varieties are still cut and polished as ornamental stones. See also agate; carnelian; onyx.
Chalcis See Chalkis
chalcocite Vkal-ko-.sfiA Sulfide mineral, Cu 2 S, that may be an important ore of copper. It belongs to a group of sulfide minerals formed at rela¬ tively low temperatures. Chalcocite alters to native copper and other cop¬ per minerals. Valuable deposits occur in Nevada and Arizona, where other components of the original rock have been dissolved away; chalcocite is also found with bornite in sulfide veins in Montana and Namibia.
chalcopyriteV.kal-ko-'pI-.ritXMost common copper mineral, a copper and iron sulfide (CuFeS 2 ), and a very important copper ore. It typically occurs in ore veins deposited at medium and high temperatures, as in parts of Spain, Japan, Montana, and Mis¬ souri. Chalcopyrite is a member of a group of sulfide minerals, and it crys¬ tallizes in the tetragonal crystal system. Its atomic structure is related to that of SPHALERITE.
Chaldea \kal-'de-o\ Ancient region, on the headwaters of the Euphrates River and adjacent to the Persian Gulf. It was originally the southern part of Babylonia; the name Chaldea also has been used (especially in the Bible) to describe all of Babylonia after it was occupied by the Chaldeans, who established a Chaldean (or neo-Babylonian) dynasty c. 625 bc. Under Nebuchadrezzar II, the empire expanded, subduing Judaea and capturing Jerusalem. It fell to the Persian Achaemenian dynasty in 539 bc.
Chaleur \sha-'loer\ Bay Inlet of the Gulf of St. Lawrence, southeastern Canada. It extends about 90 mi (145 km) between northern New Brun¬ swick and the Gaspe Peninsula. It receives many rivers, including the Res- tigouche. The bay is famous as a fishing ground, especially for mackerel. It was navigated and named in July 1534 by Jacques Cartier.
Chalgrin \shal-'gra n \, Jean-Francois-Therese (b. 1739,, Paris, Fr.—d. Jan. 21, 1811, Paris) French architect. He was trained by Etienne- Louis Boullee and won the Academy of Architecture’s Grand Prix de Rome at age 19. His Saint-Philippe-du-Roule (1764), Paris, was influential in reviving the basilica plan as a standard for European churches; it is char¬ acterized by a simplicity of design in stark contrast to the complex inte¬ riors of existing Gothic and Renaissance churches of the time. Chalgrin died before finishing his masterpiece, the Arc de Triomphe.
Chaliapin Vsho-'lya-pinX, Feodor (Ivanovich) or Fyodor Shalyapin (b. Feb. 13, 1873, near Kazan, Russia—d. April 12, 1938, Paris, France) Russian singer. Born a peasant, he received little early musical training, but his talent led to his taking leading roles with a tour¬ ing opera company in his teens. Coached by Dimitri Usatov (1847-1913), he had debuts in St. Petersburg (1894) and Moscow (1896), where he played Boris Godunov, the role he would be most associated with. These led to his triumphant 1901 La Scala debut as Mefistofele. His imposing stage presence and fine acting gave him a popularity second only to that of Enrico Caruso.