Columbia Encyclopedia

Search results

500 results found

nuclear reactor

(Encyclopedia)CE5 Power reactor system nuclear reactor, device for producing controlled release of nuclear energy. Reactors can be used for research or for power production. A research reactor is designed to pr...

air pollution

(Encyclopedia)air pollution, contamination of the air by noxious gases and minute particles of solid and liquid matter (particulates) in concentrations that endanger health. The major sources of air pollution are t...

power, electric

(Encyclopedia)power, electric, energy dissipated in an electrical or electronic circuit or device per unit of time. The electrical energy supplied by a current to an appliance enables it to do work or provide some ...

Moore, Henry

(Encyclopedia)Moore, Henry, 1898–1986, English sculptor. Moore's early sculpture was angular and rough, strongly influenced by pre-Columbian art. About 1928 he evolved a more personal style which has gained him a...

rectifier

(Encyclopedia)rectifier, component of an electric circuit used to change alternating current to direct current. Rectifiers are made in various forms, all operating on the principle that current passes through them ...

Bedlington terrier

(Encyclopedia)Bedlington terrier, breed of long-legged, lithe terrier developed in the eastern Border districts of England in the 19th cent. It stands about 16 in. (40.6 cm) high at the shoulder and weighs from 22 ...

schipperke

(Encyclopedia)schipperke skĭpˈərkē [key], a breed of small nonsporting dog developed in Belgium several hundred years ago. It stands about 13 in. (33 cm) high at the shoulder and weighs from 14 to 18 lb (6.4–...

cube

(Encyclopedia)cube, in geometry, regular solid bounded by six equal squares. All adjacent faces of a cube are perpendicular to each other; any one face of a cube may be its base. The dimensions of a cube are the le...

tympanum

(Encyclopedia)CE5 Tympanum (west pediment, temple of Aphaia at Aegina) tympanum tĭmˈpənəm [key]. In architecture, the triangular space of a pediment, or low-pitched gable, above a portico, door, or window. ...

porphyry, igneous rock

(Encyclopedia)porphyry pôrˈfərē [key], igneous rock composed of large, conspicuous crystals (phenocrysts) and a groundmass in which the phenocrysts are embedded. Some authorities consider the expression “porp...