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Bermuda grass

(Encyclopedia)Bermuda grass, perennial pasture, lawn, and hay grass (Cynodon dactylon) of the family Poaceae (grass family), native to Africa and Asia and now common in warm regions of both hemispheres. It is the s...

Centennial Exhibition, International

(Encyclopedia)Centennial Exhibition, International, held in Philadelphia from May to Nov., 1876, to celebrate the 100th anniversary of the Declaration of Independence. The buildings, in Fairmount Park, included the...

neoteny

(Encyclopedia)neoteny nēŏtˈənē [key], in biology, sexual maturity reached in the larval stage of some animals. Certain environmental conditions can inhibit the completion of metamorphosis; low temperature or l...

timberline

(Encyclopedia)timberline, elevation above which trees cannot grow. Its location is influenced by the various factors that determine temperature, including latitude, prevailing wind directions, and exposure to sunli...

Scoresby, William

(Encyclopedia)Scoresby, William skôrzˈbē [key], 1789–1857, English arctic explorer and scientist. He made yearly voyages (1803–22) to Greenland, at first on his father's whaler, later as captain on other shi...

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...

crucible

(Encyclopedia)crucible, vessel in which a substance is heated to a high temperature, as for fusing or calcining. The necessary properties of a crucible are that it maintain its mechanical strength and rigidity at h...

Challenger

(Encyclopedia)Challenger, U.S. space shuttle. It exploded (Jan. 28, 1986) 73 seconds into its tenth flight, killing all seven crew members, including the first civilian in space, schoolteacher Christa McAuliffe. Th...

analog circuit

(Encyclopedia)analog circuit, electronic circuit that operates with currents and voltages that vary continuously with time and have no abrupt transitions between levels. Generally speaking, analog circuits are cont...

delirium tremens

(Encyclopedia)delirium tremens trēˈmənz, trĕmˈənz [key], hallucinatory episodes that may occur during withdrawal from chronic alcoholism, popularly known as the DTs. An episode of delirium tremens is usually ...