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aphid

(Encyclopedia)aphid or plant louse, tiny, usually green, soft-bodied, pear-shaped insect injurious to vegetation. It is also called greenfly and blight. Aphids are mostly under 1⁄4 in. (6 mm) long. Some are wingl...

diesel engine

(Encyclopedia)diesel engine, type of internal-combustion engine invented by the German engineer Rudolf Diesel and patented by him in 1892. Although his engine was designed to use coal dust as fuel, the diesel engin...

hertz

(Encyclopedia)hertz hûrts [key] [for Heinrich R. Hertz], abbr. Hz, unit of frequency, equal to 1 cycle per second. The term is combined with metric prefixes to denote multiple units such as the kilohertz (1,000 Hz...

Nevin, Ethelbert Woodbridge

(Encyclopedia)Nevin, Ethelbert Woodbridge, 1862–1901, American pianist and composer, b. Edgeworth, Pa., studied in Boston and in Germany. He made his debut as a pianist in Pittsburgh in 1886 but devoted most of h...

Snodgrass, W. D.

(Encyclopedia)Snodgrass, W. D. (William DeWitt Snodgrass), 1926–2009, American poet and translator, b. Wilkinsburg, Pa., grad. Univ. of Iowa, 1959. He is particularly known for his debut book, Heart's Needle (195...

Stirling engine

(Encyclopedia)Stirling engine, an external combustion reciprocating engine having an enclosed working fluid that is alternately compressed and expanded to operate a piston, thus converting heat from a variety of so...

Boccaccino, Boccaccio

(Encyclopedia)Boccaccino, Boccaccio bōk-kätˈchō bōk-kätchēˈnō [key], c.1465–1525. Italian artist, b. Cremona. He probably made several trips to Venice, for his numerous paintings of the half-length Madon...

Schnitzler, Arthur

(Encyclopedia)Schnitzler, Arthur ärˈto͝or shnĭtsˈlər [key], 1862–1931, Austrian dramatist and novelist. The son of a prominent Jewish Viennese physician, he studied and practiced medicine until he attracted...

sunspots

(Encyclopedia)sunspots, dark, usually irregularly shaped spots on the sun's surface that are actually solar magnetic storms. The spots are darker because the temperature of the spots is lower than that of the surro...

rotary engine

(Encyclopedia)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...