Calah \'ka-b\ modern NimrQd \'nim- l rud\ Ancient city, Assyria. Lying south of modern Mosul, Iraq, it was founded in the 13th century bc by Shalmaneser I. It remained unimpor¬ tant until the 9th century bc, when Ashurnasirpal II made it the capital of Assyria. It was the site of a reli¬ gious building founded in 798 bc by Queen Sammu-remat (Semiramis of Greek legend). Excavations there have yielded thousands of carved ivories from the 9th-8th centuries bc.
Calais \ka-'le, ka-'la\ Seaport (pop.,
1999: 77,333) on the Strait of Dover, northern France. Originally a fishing village built on an island, it was improved by the count of Flanders in 997 and fortified by the count of Boulogne in 1224. Calais was taken in 1347 by Edward III of England, and after 1450 it was the only remaining English possession in France. The 2nd duke de Guise took Calais from the English in 1558. In World War II it was a main objective in the Ger¬ man drive to the sea in 1940. It is an important passenger port and is near the French terminus of the Channel Tunnel. The city is famous for its lace and embroideries.
Calamity Jane orig. Martha Jane Cannary (b. May 1, 1852?, near Princeton, Mo.?, U.S.—d. Aug. 1, 1903, Terry, near Deadwood, S.D.)
U.S. frontierswoman. She grew up in Montana and worked in mining camps, where she acquired riding and shooting skills. In 1876 she settled in Deadwood, S.D., site of new gold strikes; her pursuits there included hauling goods and machin¬ ery to the outlying camps and work¬ ing as a cook and a dance-hall girl.
There she probably first met Wild Bill Hickok, who would become her com¬ panion. In 1891 she married Charley Burke, and from 1895 she toured with Wild West shows in the Mid¬ west. Facts about her life were embellished by contemporary feature-magazine writers.
Calatrava \,ka-la-'tra-va. Order of Oldest military and religious order in Spain. It was founded in 1158 by two Cistercian monks who proclaimed a holy Crusade to defend the city of Calatrava against the Moors. By the 15th century the order had 200,000 members and became increasingly involved in Castilian domestic politics. In 1489 it was incor¬ porated into the crown by Ferdinand V and Isabella I, who deemed that all private armies had outserved their usefulness. It remained an honorary association of Spanish nobles until its dissolution in the 19th century.
calcedony See chalcedony
calcite Vkal-,slt\ Most common form of natural calcium carbonate (CaC0 3 ), a widely distributed mineral known for the beautiful develop¬ ment and great variety of its crystals. It occurs in stalagmites and stalac¬ tites and forms the structure of coral reefs. Calcite is the most important mineral in limestones and marbles used in the building, steel, chemical, and glass industries. Transparent crystals are called Iceland spar.
calcium Chemical element, one of the alkaline earth metals, chemical sym¬ bol Ca, atomic number 20. The most abundant metallic element in the human body, it is an essential part of bones and teeth and has many physi¬ ological functions (see calcium deficiency; tooth). It is the fifth most abun¬ dant element in Earth’s crust but does not occur naturally in the free state. In its compounds calcium has valence 2. It occurs in limestone, chalk, marble, dolomite, eggshells, pearls, coral, and many marine shells as calcium car¬ bonate, or calcite; in apatite as calcium phosphate; in gypsum as calcium sul¬ fate; and in many other minerals. It is used as an alloying agent and in other metallurgical applications; its alloy with lead is used in cable sheathing and grids for batteries. Calcite is used as a lime source, a filler, a neutralizer, and an extender; in pure form it is used in baking powder and as an antacid and calcium supplement. Calcium oxide (lime) and its product after water addi¬ tion, calcium hydroxide (slaked lime), are important industrially. Other sig¬ nificant compounds are calcium chloride (a drying agent), calcium hypochlorite (a bleach), calcium sulfate (gypsum and plaster of Paris), and calcium phosphate (a plant food and stabilizer for plastics).
calcium deficiency Inadequate supply or metabolism of calcium, the main structural element of bones and teeth. Its metabolism is regulated by vitamin D, phosphorus, and hormones (see parathyroid gland). Calcium in the blood has roles in muscle contraction, nerve-impulse transmission, blood clotting, milk production, hormone secretion, and enzyme function, for which calcium is pulled from the bones if deficiency develops. Chronic deficiency may be a factor in the development of osteoporosis or osteo¬ malacia (softening of bone) and may contribute to hypertension and colon cancer. Severe calcium deficiency (hypocalcemia), usually the result of a metabolic problem rather than a dietary deficiency, causes numbness, tin¬ gling, and painful muscle aches and spasms.
calcium oxide See lime
calculator Machine for performing arithmetic operations and certain mathematical functions automatically. Blaise Pascal devised a digital arith¬ metic machine in 1642. By the late 19th century, such machines had become smaller and easier to use, and desktop machines appeared in the early 20th century. Electronic data-processing systems in the mid-1950s led to the obsolescence of mechanical calculators. Miniature solid-state
Winged bull of alabaster, guardian of a gate of the palace of Ashurnasirpal II at Nimrud; in the Metropolitan Museum of Art, New York City.
COURTESY OF THE METROPOLITAN MUSEUM OF ART, NEW VORK, GIFT OF JOHN D. ROCKEFELLER, JR, 1932
© 2006 Encyclopaedia Britannica, Inc.
312 I calculus ► calendar
devices ushered in calculators that could perform mathematical functions in addition to basic arithmetic, and also store data and instructions in memory registers, providing programming capabilities similar to those of small computers.
calculus Field of mathematics that analyzes aspects of change in pro¬ cesses or systems that can be modeled by functions. Through its two pri¬ mary tools—the derivative and the integral —it allows precise calculation of rates of change and of the total amount of change in such a system. The derivative and the integral grew out of the idea of a limit, the logical extension of the concept of a function over smaller and smaller intervals. The relationship between differential calculus and integral calculus, known as the fundamental theorem of calculus, was discovered in the late 17th century independently by Isaac Newton and Gottfried Wilhelm Leibniz. Cal¬ culus was one of the major scientific breakthroughs of the modem era.
Calcutta See Kolkata
Caldecott Vkol-do-kotV, Randolph (b. March 22, 1846, Chester, Cheshire, Eng.—d. Feb. 12, 1886, St. Augustine, Fla., U.S.) British graphic artist and watercolourist. While working as a bank clerk, he began drawing for periodicals such as London Society, and, after he moved to London, Punch and Graphic. He developed a gently satirical style and achieved success with illustrations for Washington Irving’s books The Sketch Book (1875) and Bracebridge Hall (1876). Caldecott is best known as an illustrator of children’s books, including William Cowper’s John Gilpin (1878) and Oliver Goldsmith’s Elegy on a Mad Dog (1879). Always frail in health, he died at age 39 in Florida, where he had gone to improve his condition. Since 1938 the Caldecott Medal has been awarded annually to the illustrator of the most distinguished U.S. picture book for children.
Colder Vkol-dorX, Alexander (Stirling) (b. July 22, 1898, Lawnton, Pa., U.S.—d. Nov. 11, 1976, New York, N.Y.) U.S. sculptor. He was the son and grandson of sculptors, and his mother was a painter. He studied mechanical engineering, and in 1923 attended the Art Students League, where he was influenced by artists of the Ash Can school. In 1924 he con¬ tributed illustrations to the National Police Gazette. In 1926 he moved to Paris and began making toylike ani¬ mals and circus figures of wood and wire; from these he developed his famous miniature circus. In the 1930s he became well known in Paris and the U.S. for his wire sculp¬ tures, as well as for portraits, continuous-line drawings, and abstract, motor-driven constructions.