EVA 



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EUFHRA'SIA, the Eyebright; a genus of 

 hardy annual plants. Didynamia Angio- 

 spermia. The name is corrupted from 

 lu^txrvvvi, from tu$iuv, joyful, because it 

 exhilarates the spirits. Europe. Its Eng- 

 lish name is derived from its supposed 

 efficacy in ophthalmic diseases. 



EURI'PUS, a space, in ancient architec- 

 ture, which separated the seats of the cir- 

 cus from the arena. 



EURITH'IMY. In architecture, &C. See 

 ECRITHMY. 



EC'IUTHMY, iv^iBfjiM, from w, good, and 

 ti9[Mt, harmony; that agreeable har- 

 mony between the breadth, length, and 

 height of the rooms of a fabric, which sud- 

 denly, where it is, taketh every beholder, 

 toy the secret power of proportion. The 

 word is used also in painting and sculp- 

 ture to imply ease, dignity, and elegance 

 combined, and arising from just propor- 

 tions in the composition. 



EUROC'LYDON, from uiftf, wind, and 

 xXv^cav, a wave; a tempestuous wind 

 Which drove ashore, on Malta, the ship in 

 which Paul was sailing to Italy, Acts xxviL 

 EUSTA'CHIAN. In anatomy, an epithet 

 for the tube which forms a communica- 

 tion between the posterior nares and the 

 ear, discovered by Eustachius. 



EUSTA/THIA..XS, a sect of heretics of the 

 fourth century. 



EL-'STYLE, from tu, beautiful, and 

 rrvXo;, column; an intercolumniation of 

 2i diameters, which is one of the most 

 beautiful arransements that can be given 

 to a row of columns. 



EUTER'PE, vj and rtgirtu, 1 delight. In 

 mythology, the muse which presided over 

 wind instruments. 



ECT-VCH'IAJJS, an ancient sect, who sup- 

 posed the human nature of Christ to be 

 merged in the divine. 



EVAN'TES, priests of Bacchus. 

 EVAPORATION, from e and rapour ; con- 

 version of any liquid into vapour. As an 

 artificial operation, it is usually per- 

 formed by applying heat to the substance, 

 but it differs from distillation in its ob- 

 ject, which chiefly consists in preserving 

 the more fixed matters, while the -vola- 

 tile parts are dissipated and lost. The ves- 

 sels accordingly differ also ; evaporation 

 being commonly performed in shallow 

 vessels, and distillation in apparatus 

 nearly closed from the external air. Eva- 

 poration, as a natural process, is of vast 

 importance in the economy of nature. 

 When a liquid is exposed to a free atmo- 

 sphere, vapour rise continually from it, 

 and the liquid at length disappears ; and 

 as very considerable portions of the 

 earth's surface are covered with water, 

 vast quantities of it are perpetually being 

 converted into vapour, which, being 



lighter than atmospheric air, ascends. n1 

 afterwards, by partial condensation 

 forms clouds, to be subsequently preci 

 pitated in rain, &c. 



EVAPOROM'ETBR, from evaporo and fiirto*, 

 a hygroscope (q. v.). 



EV'ATES. Strabo divides the British 

 and Gaulish philosophers into three sects, 

 Bards, Evates, and Druids. The bards 

 were the poets and musicians, the evates 

 the priests and naturalists, and the Druids 

 were moralists as well as naturalists. 



EVEC'TION, from eveho, to carry away, 

 a term in astronomy for one of the most 

 considerable lunar irregularities caused 

 by the action of the sun upon the moon. 



E'VEN KEEL, a ship is said to be on an 

 even keel when she draws the same abaft 

 as forward. 



EV'OLUTE, from evolvo, a particular 



species of curve first proposed by Huy- 



v gens. Thus, if 



f/ a thread be 



/ ""---... wound round 



p,: ^the curve ABC, 



'v/ fixing one end 

 at C, and car- 

 rying the other 

 round to A ; and 

 if this thread be 

 now unwound, 

 keeping it tight 

 upon the con- 

 vexity of the 

 curve, its end 

 A will describe another curve, ADE, 

 passing further and further from the 

 former curve, AB C, as the thread un- 

 winds, till it reaches the point C, where 

 it is supposed to be fixed. If carried fur- 

 ther to F, the arc EF will be part of 

 a circle. The primary curve round which 

 the thread was wound is the evolute, and 

 the secondary curved formed by unwind- 

 ing the thread is termed an involute. The 

 term evolvent is by some used for involute, 

 as being the curve evolved by the opening 

 of the evolute. 



EVOLTJ'TION, from evolvo. 1. In mili- 

 tary tactics, the motion made by a body 

 of men in changing their position or form 



of drawing up. 2. In geometry, the 



equable evolution of the periphery of a 

 circle, or other curve, is such a gradual 

 approach of the circumference to recti- 

 tude, as that all its parts do meet to- 

 gether, and equally evolve or unbend. 



3. In algebra, &c., the extraction of 



roots, being thus opposed to involution. 



4. In natural history, the theory of evolu- 

 tion supposes that the germs of all plants 

 and animals were really all formed within 

 the first of their respective kinds, and 

 are not evolved by the process of genera- 

 tion : opposed to Epigencsis. 



E'VOVJE. In music, the vowels used with 

 the ending notes of the ecclesiastical tone* 



