Columbia Encyclopedia

Search results

359 results found

Lombard League

(Encyclopedia)Lombard League, an alliance formed in 1167 among the communes of Lombardy to resist Holy Roman Emperor Frederick I when he attempted to assert his imperial authority in Lombardy. Previously the commun...

relay

(Encyclopedia)relay, electromechanical switch operated by a flow of electricity in one circuit and controlling the flow of electricity in another circuit. A relay consists basically of an electromagnet with a soft ...

feather star

(Encyclopedia)feather star, common name of a class of echinoderms that, as juveniles, are attached to the sea bottom by a stalk with rootlike branches; the mouth side faces upward. In the adult stage they break awa...

Gregory XVI

(Encyclopedia)Gregory XVI, 1765–1846, pope (1831–46), an Italian named Bartolomeo Alberto Capellari, b. Belluno; successor of Pius VIII. In 1783 he became a Camaldolite and was (1825) created cardinal. Gregory ...

pneumothorax

(Encyclopedia)pneumothorax no͞omōthôrˈăks [key], collapse of a lung with escape of air into the pleural cavity between the lung and the chest wall. The cause may be traumatic (e.g., gunshot or stab wound), spo...

Grenville, Sir Richard

(Encyclopedia)Grenville, Sir Richard, 1542?–1591, English naval hero. His cousin, Sir Walter Raleigh, gave him command of the fleet of seven vessels carrying the first colonists to Roanoke Island in 1585. In 1591...

Warshel, Arieh

(Encyclopedia)Warshel, Arieh, 1940–, Israeli-American chemist, b. Kibbutz Sde Nahum (in what is now Israel), Ph.D. Weizmann Institute, 1969. He has been a professor at the Univ. of Southern California since 1976....

thermostat

(Encyclopedia)thermostat, automatic device that regulates temperature in an enclosed area by controlling heating or refrigerating systems. It is commonly connected to one of these systems, turning it on or off in o...

phenylketonuria

(Encyclopedia)phenylketonuria fĕnˌəlkētˌəno͝orˈēə [key] (PKU), inherited metabolic disorder caused by a deficiency in a specific enzyme (phenylalanine hydroxylase). The absence of this enzyme, a recessive...

avalanche

(Encyclopedia)avalanche, rapidly descending large mass of snow, ice, soil, rock, or mixtures of these materials, sliding or falling in response to the force of gravity. Avalanches, which are natural forms of erosio...