cornelian \kar-'ne-le-on\ or cornelian Translucent, semiprecious variety of the silica mineral chalcedony that owes its red to reddish brown colour to the incorporation of small amounts of iron oxide. A closely related variety of chalcedony, sard, differs only in the shade of red. Car- nelian was highly valued and used in rings and signets by the Greeks and Romans, some of whose intaglios have retained their high polish better than those made from harder stones. Carnelian is mined principally in India, Brazil, and Australia. Its physical properties are those of quartz.
Carniola Region, western Slovenia. It is located northeast of the head of the Adriatic Sea and includes a mountainous area. Its chief town is Ljubljana. It was part of the Roman province of Pannonia in ancient times and was occupied by the Slovenes in the 6th century ad. In the 13th cen¬ tury it became part of the Holy Roman Empire. In 1335 it became a pos¬ session of the Austrian Habsburgs, who held it as a duchy until 1849, when it was recognized as an Austrian crown land (1849-1918). After World War I it was divided between Italy and the new Kingdom of Serbs, Croats, and Slovenes (later Yugoslavia); it was incorporated entirely into Yugo¬ slavia by a 1947 treaty. When Yugoslavia was fragmented in the 1990s, Carniola was included in Slovenia.
carnival Final celebration before the fasting and austerity of Lent in some Roman Catholic regions. The most famous and probably most exu¬ berant carnival is that of Rio de Janeiro, which is celebrated with masked
balls, costumes, and parades; the best-known U.S. celebration is Mardi Gras in New Orleans. The first day of carnival season varies with local traditions, but carnival usually ends on Shrove Tuesday, the day before the start of Lent.
carnivore Any meat-eating animal, but especially any member of the order Carnivora, consisting of 12 families of primarily predatory mam¬ mals: Canidae (e.g., dogs), Ursidae (bears), Procyonidae (raccoons), Mus- telidae (weasels), Mephitidae (skunks), Viverridae (civets), Herpestidae (mongooses), Hyaenidae (hyenas), Felidae (cats), Otariidae and Phocidae (seals), and Odobenidae (the walrus). Though most carnivores eat only meat, some rely heavily on vegetation (e.g., the panda). Most have a com¬ plex tooth structure and a lower jaw that can move only vertically but can exert great power. The earliest carnivores, which probably evolved from an insectivorous ancestor, appeared during the Paleocene Epoch (about 65-55 million years ago). Carnivores are highly intelligent.
carnivorous plant Any of about 400 diverse species of plants spe¬ cially adapted for capturing insects and other tiny animals by ingenious pitfalls and traps and for digesting the nitrogen-rich animal proteins to obtain nutrients. These adaptations are thought to enable such plants to survive under otherwise marginal or hostile environmental conditions. The conspicuous trapping mechanism (a leaf modification) draws the prey’s attention to the plant. More than half the species belong to the family Lentibulariaceae, most being bladder worts. The remainder belong to several families composed of the pitcher plants, sundews, and flytraps (see Venus's-flytrap). Most are found in damp heaths, bogs, swamps, and muddy or sandy shores where water is abundant and where nitrogenous materials are often scarce or unavailable because of acid or other unfavourable soil conditions. The smallest Drosera species are often hid¬ den among the moss of a sphagnum bog; most carnivorous plants are small herbaceous perennials. Some become large shrubby vines.
carnosaur Any of the large carnivorous dinosaurs, a branch of thero- pod dinosaurs that evolved into predators of large herbivorous dinosaurs. Carnosaurs were massive animals with short necks, large skulls, and wide, gaping mouths equipped with formidable teeth. They walked on two legs. Tyrannosaurs were the largest of all carnosaurs. The carnosaurs became extinct at the end of the Cretaceous period (65 million years ago).
Carnot \kar-'no\, Lazare (-Nicolas-Marguerite) (b. May 13,
1753, Nolay, Burgundy, France—d. Aug. 2, 1823, Magdeburg, Prussian Saxony) French statesman and administrator in successive governments of the French Revolution. He entered the army as an engineer (1773) and was elected to the Legislative Assembly in 1791. As a leading member of the Committee of Public Safety and the Directory, he helped mobilize the Revolutionary armed forces and materiel, and he was lauded as the “Orga¬ nizer of Victory.” During the Coup of 18 Fructidor he fled France to escape arrest. He returned after Napoleon rose to power and served him in vari¬ ous offices, including minister of the interior during the Hundred Days.
Carnot \kar-'no\, (Nicolas-Leonard-) Sadi (b. June 1, 1796, Paris, France—d. Aug. 24, 1832, Paris) French scientist, known for describing the Carnot cycle. Son of Lazare Carnot, he was an army officer most of his life. Convinced that Britain’s advanced steam engines and France’s inadequate use of steam were factors in Napoleon’s downfall, he wrote a nontechnical essay on steam engines (1824). He subsequently developed a theory of heat engines, predicting that efficiency depends only on the temperature of the hottest and coldest parts and not on the substance (steam or any other fluid) that drives the mechanism. Though adopted slowly, his theory was eventually incorporated into the general theory of THERMODYNAMICS.
Carnot, (Marie-Francois-) Sadi (b. Aug. 11, 1837, Limoges, France—d. June 24, 1894, Lyon) French politician. Grandson of Lazare Carnot and son of Sadi Carnot, he worked as a government engineer before turning to politics. After serving as minister of public works (1880— 81) and finance (1885-87), he was elected in 1887 as fourth president of the Third Republic. He competently handled the plots by Georges Boulanger, anarchist agitation, and the Panama Canal scandals, and retained his popu¬ larity through 10 different governments but was assassinated in 1894 by an Italian anarchist.
Carnot cycle In heat engines, the ideal cycle of changes of pressures and temperatures of a working fluid, such as steam or ammonia, conceived by Sadi Carnot. It is the standard of performance of all heat engines oper¬ ating between a high and a low temperature. In the cycle, the working
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340 I Carnuntum ► carpal tunnel syndrome
fluid undergoes four successive changes: (1) the fluid receives heat, expanding at high temperature; (2) it delivers work during the reversible adiabatic expansion (it changes in volume or pressure without losing or gaining heat); (3) it rejects heat (to the heat sink) during compression at low temperature; and (4) it receives work during the reversible adiabatic compression. The efficiency is determined by the difference between the temperatures of the heat source and the heat sink divided by the tempera¬ ture of the heat source. See also Rankine cycle.
Carnuntum Ancient town, Roman Empire. Located in northern Pan- nonia on the Danube River, it was an important Roman post from the time of Tiberius. It was used as a base by Marcus Aurelius in his campaign against the Marcomanni (ad 172-174); there he wrote the second book of his Meditations. The camp was finally destroyed by the Germans in the 4th century.
carob Leguminous evergreen tree ( Ceratonia siliqua) native to the east¬ ern Mediterranean region and cultivated elsewhere. It is sometimes known as locust, or St. John’s bread, in the belief that the “locusts” on which John the Baptist fed were carob pods. The tree, about 50 ft (15 m) tall, bears compound, glossy leaves with thick leaflets. Its red flowers are fol¬ lowed by flat, leathery pods that contain 5-15 hard brown seeds embed¬ ded in a sweet, edible pulp that tastes similar to chocolate.