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reciprocal trade agreement
reciprocal trade agreement international commercial treaty in which two or more nations grant equally advantageous trade concessions to each other. It usually refers to treaties dealing with tariffs. For example, one nation may grant another a special schedule of tariff concessions in return for ...
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crank
crank mechanical linkage consisting of a bar attached to a pivot at one of its ends in such a way that it is capable of rotating through a complete circle about the pivot. One of the principal uses of a crank is to turn reciprocating, or back and forth, motion into rotary motion or vice versa. A be...
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parsec
parsec [ par allax + sec ond], in astronomy, basic unit of length for measuring interstellar and intergalactic distances, equal to 206,265 times the distance from the earth to the sun, 3.26 light-years, or 3.08 × 10 13 km (about 19 million million mi). The distan...
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rotary engine
rotary engine internal-combustion engine whose cycle is similar to that of a piston engine, but which produces rotary motion directly without any conversion from reciprocating motion. A major problem associated with engines of this type is preventing the leakage of combustion gases. The only type o...
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compressor
compressor machine that decreases the volume of air or other gas by the application of pressure. Compressor types range from the simple hand pump and the piston-equipped compressor used to inflate tires to machines that use a rotating, bladed element to achieve compression. The four basic types o...
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pump
pump device to lift, transfer, or increase the pressure of a fluid (gas or liquid) or to create a vacuum in an enclosed space by the removal of a gas (see vacuum pumps under vacuum ). The centrifugal pump, the most common kind, consists basically of a rotating device, called an impeller, inside a ...
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Manuel Ávila Camacho
Manuel Ávila Camacho , 1897-1955, president of Mexico (1940-46). As a young man, Ávila Camacho joined the revolutionary forces. Later he became brigadier general. Under Lázaro Cárdenas he became (1938) minister of national defense. As president he followed a middle-of-t...
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compressed air
compressed air air whose volume has been decreased by the application of pressure. Air is compressed by various devices, including the simple hand pump and the reciprocating, rotary, centrifugal, and axial-flow compressors . Compressed air exerts an expansive force that can be controlled and used ...
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William Stevens Fielding
William Stevens Fielding 1848-1929, Canadian statesman, b. Halifax, N.S. A newspaper editor in Halifax, he entered the provincial legislature in 1882 and was provincial prime minister (1884-96). He then entered the House of Commons, and for 15 years (1896-1911) he was Wilfrid Laurier's minister of ...
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Rio Treaty
Rio Treaty (Inter-American Treaty of Reciprocal Assistance), signed Sept. 2, 1947, and originally ratified by all 21 American republics. Under the treaty, an armed attack or threat of aggression against a signatory nation, whether by a member nation or by some other power, will be considered an att...
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