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Cerro Tololo Inter-American Observatory

(Encyclopedia)Cerro Tololo Inter-American Observatory sāˈrō tōlōˈlō [key], astronomical observatory located on Cerro Tololo peak, Chile, with offices in La Serena, about 40 mi (64 km) to the west. Funded by ...

ceilometer

(Encyclopedia)ceilometer sēlŏmˈĭtər [key], in aviation and meteorology, automatic instrument used to record ceiling, i.e., the altitude of the lowest cloud layer covering more than half of the sky. The ceilome...

ultimatum

(Encyclopedia)ultimatum ŭlˌtĭmāˈtəm [key], in international law, final, definitive terms submitted by one disputant nation to the other for immediate acceptance or rejection. Since refusal to accept the terms...

spectroscope

(Encyclopedia)spectroscope, optical instrument for producing spectral lines and measuring their wavelengths and intensities, used in spectral analysis (see spectrum). When a material is heated to incandescence it e...

tone

(Encyclopedia)tone. In music, a tone is distinguished from noise by its definite pitch, caused by the regularity of the vibrations which produce it. Any tone possesses the attributes of pitch, intensity, and qualit...

bolometer

(Encyclopedia)bolometer bōlŏmˈətər, bə– [key], instrument for detecting and measuring radiation, e.g., visible light, infrared radiation, and ultraviolet radiation, in amounts as small as one millionth of a...

Piazzolla, Ástor Pantaleón

(Encyclopedia)Piazzolla, Ástor Pantaleón, 1921–92, Argentinian composer and player of the bandoneón (a large accordionlike instrument), b. Mar del Plata. He spent much of his childhood in New York, returned (1...

commonwealth

(Encyclopedia)commonwealth, form of administration signifying government by the common consent of the people. To Locke and Hobbes and other 17th-century writers the term meant an organized political community simil...

Christian, Charlie

(Encyclopedia)Christian, Charlie (Charles Henry Christian), 1916–42, African-American jazz guitarist, b. Bonham, Tex. The son of a singer-guitarist father and pianist mother, he grew up in Oklahoma City, where he...

Essen

(Encyclopedia)Essen ĕsˈən [key], city, North Rhine–Westphalia, W Germany, on the Ruhr River. The major...