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Humboldt, Alexander, Freiherr von

(Encyclopedia)Humboldt, Alexander, Freiherr von hŭmˈbōlt, Ger. älĕksänˈdər frīˈhĕr fən ho͝omˈbôlt [key], 1769–1859, German naturalist, inventor, explorer, and author, the most eminent scientist of ...

engineering

(Encyclopedia)engineering, profession devoted to designing, constructing, and operating the structures, machines, and other devices of industry and everyday life. Until the Industrial Revolution there were only t...

Oxford, University of

(Encyclopedia)Oxford, University of, at Oxford, England, one of the oldest English-language universities in the world. The university was a leading center of learning throughout the Middle Ages; such scholars as Ro...

Cenozoic era

(Encyclopedia)Cenozoic era sēnəzōˈĭk, sĕn– [key], last major division of geologic time (see Geologic Timescale, tablegeologic timescale, table) lasting from 65 million years ago to the present. The Cenozoic...

Frémont, John Charles

(Encyclopedia)Frémont, John Charles, 1813–90, American explorer, soldier, and political leader, b. Savannah, Ga. He taught mathematics to U.S. naval cadets, then became an assistant on a surveying expedition (18...

crater

(Encyclopedia)crater, circular, bowl-shaped depression on the earth's surface. (For a discussion of lunar craters, see moon.) Simple craters are bowl-shaped with a raised outer rim. Complex craters have a raised ce...

silver

(Encyclopedia)silver, metallic chemical element; symbol Ag [Lat. argentum]; at. no. 47; at. wt. 107.8682; m.p. 961.93℃; b.p. 2,212℃; sp. gr. 10.5 at 20℃; valence +1 or +2. Pure silver is nearly white, lustrou...

parrot

(Encyclopedia)parrot, common name for members of the order Psittaciformes, comprising nearly 400 species of colorful birds, pantropical in distribution, including the parakeets. Parrots have large heads and short n...

San Diego

(Encyclopedia)San Diego săn dēāˈgō [key], city (1990 pop. 1,110,549), seat of San Diego co., S Calif., on San Diego Bay; inc. 1850. San Diego includes the unincorporated communities of La Jolla and Spring Vall...

Jurassic period

(Encyclopedia)Jurassic period jərăsˈĭk [key] [from the Jura Mts.], second period of the Mesozoic era of geologic time, lasting from 213 to 144 million years ago. At the start of the Jurassic most of the contine...