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chart

(Encyclopedia)chart, term referring to maps prepared for marine navigation and for air navigation. All charts show, in some convenient scale, geographic features useful to the navigator, as well as indications of d...

amplifier

(Encyclopedia)amplifier, device that accepts a varying input signal and produces an output signal that varies in the same way as the input but has a larger amplitude. The input signal may be a current, a voltage, a...

Morse code

(Encyclopedia)CE5 Morse code [for S. F. B. Morse], the arbitrary set of signals used on the telegraph (see code). It may also be used with a flash lamp for visible signaling. The international (or continental) M...

Dyson, Sir Frank Watson

(Encyclopedia)Dyson, Sir Frank Watson dīˈsən [key], 1868–1939, English astronomer, b. Ashby-de-la-Zouch, grad. Cambridge. He was astronomer royal of Scotland (1905–10) and of England (from 1910). As director...

Al-Biruni, Abu Rayhan Muhammad ibn Ahmad

(Encyclopedia)Al-Biruni or Al Beruni, Abu Rayhan Muhammad ibn Ahmad äbo͞oˈ rīhänˈ məhămˈĭd ĭbˈən äˈməd ăl-bēro͞oˈnē, ăl bĕro͞oˈnē [key], b. 973, d. after 1050, Central Asian scientist. His...

color index

(Encyclopedia)color index, in astronomy, difference in an object's brightness as recorded between any two well-defined bands of the electromagnetic spectrum by using optical filters of different colors. If blue and...

Chaldaea

(Encyclopedia)Chaldaea or Chaldea both: kăldēˈə [key], properly the southernmost portion of the valley of the Tigris and the Euphrates rivers. Sometimes it is extended to include Babylonia and thus comprises al...

atlas, in geography

(Encyclopedia)atlas, in geography, collection of maps or charts. It usually includes data on various features of a country, e.g., its topography, natural resources, climate, and population, as well as its agricultu...

opposition

(Encyclopedia)opposition, in astronomy, alignment of two celestial bodies on opposite sides of the sky as viewed from earth. Opposition of the moon or planets is often determined in reference to the sun. Only the s...

Bailly, Jean Sylvain

(Encyclopedia)Bailly, Jean Sylvain zhäN sēlvăNˈ bäyēˈ [key], 1736–93, French astronomer and politician. His works on astronomy and on the history of science (notably the Essai sur la théorie des satellite...