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dredging
(Encyclopedia)dredging, process of excavating materials underwater. It is used to deepen waterways, harbors, and docks and for mining alluvial mineral deposits, including tin, gold, and diamonds. The Dutch at an ea...superconductivity
(Encyclopedia)superconductivity, abnormally high electrical conductivity of certain substances. The phenomenon was discovered in 1911 by Heike Kamerlingh Onnes, who found that the resistance of mercury dropped sudd...Everglades
(Encyclopedia)Everglades, marshy, low-lying subtropical savanna area, c.4,000 sq mi (10,000 sq km), S Fla., extending from Lake Okeechobee S to Florida Bay. Characterized by water, sawgrass, hammocks (islandlike ma...Erie Canal
(Encyclopedia)Erie Canal, artificial waterway, c.360 mi (580 km) long; connecting New York City with the Great Lakes via the Hudson River. Locks were built to overcome the 571-ft (174-m) difference between the leve...bossism
(Encyclopedia)bossism, in U.S. history, system of political control centering about a single powerful figure (the boss) and a complex organization of lesser figures (the machine) bound together by reciprocity in pr...dating
(Encyclopedia)dating, the determination of the age of an object, of a natural phenomenon, or of a series of events. There are two basic types of dating methods, relative and absolute. In relative dating, the tempor...lubrication
(Encyclopedia)lubrication, introduction of a substance between the contact surfaces of moving parts to reduce friction and to dissipate heat. A lubricant may be oil, grease, graphite, or any substance—gas, liquid...Andalusia, region, Spain
(Encyclopedia)Andalusia änˌdälo͞othēˈä [key], autonomous community, 33,821 sq mi (87,596 sq km), S Spain, on the Mediterranean Sea, the Strait of Gibraltar, and the Atlantic Ocea...Birmingham, city, England
(Encyclopedia)Birmingham bûrˈmĭngəm [key], city and metropolitan borough (2021 city pop. 2,606,374; met...birth control
(Encyclopedia)birth control, practice of contraception for the purpose of limiting reproduction. Although contraceptive techniques had been known in ancient Egypt, Greece, and Rome, the modern movement for birth ...Browse by Subject
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