DES 



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D E T 



DERMATOL'OGY, ) from 5Eua. the skin, 



DERMOL'OGY, J and Ao^aj, discourse; 

 a discourse or treatise on the skin. 



DEHMES'TES, a genus of coleopterous 

 insects named popularly the leather- 

 eaters, because they destroy furs, leather, 

 &C-, &c. ; dissectors by De Geer, because 

 they devour and reduce to skeletons the 

 dead bodies of animals. Cuvier places 

 the dermestes among the davicornes, 



DEROO'ATORY CLAUSE. In wills, a sen- 

 tence or secret character, inserted by the 

 testator, of which he reserves the know- 

 ledge to himself, with a condition that no 

 will which he may hereafter make shall be 

 valid, unless this clause be inserted word 

 for word. This is done as a precaution to 

 guard against later wills being extorted 

 by violence or other improper means. 



"DBR'RICK. In navigation, a tackle used 

 at the outer quarter of the mizen-yard ; 

 also a prop or support to shears, &c. 



DER'VISE, a Persian name given to all 

 Mohammedan monks, though of various 

 orders. 



DES'CANT. In old music, from Ital. des- 

 eanto, Lat. canto, to sing; the art of com- 

 posing music in several parts. Plain 

 descant consists in the orderly disposition 

 of concords, and is the foundation of 

 musical composition. Figurative or florid 

 descant is that part of an air in which 

 some discords are concerned. Double 

 descant is when the parts are so contrived 

 that the base may become the treble and 

 the treble the base. 



DESCEX'SION, from de and scando, to 

 Climb ; a going downwards. Applied in 

 astronomy} 1. Right descension is an arc 

 of the equator which descends with the 

 star or sign below the horizon in a right 



sphere. 2. Oblique descension is an arc 



of the equator which descends with a 

 star or sign below the horizon in the 

 oblique sphere. The difference between 

 the right and oblique descension of any 

 heavenly body is called the descensional 

 difference. 



DESCENT', "Lat. descensus, the tendency 

 of a body from a higher to a lower place. 

 1. In mechanics, the descent of bodies is 

 their motion or tendency towards the 

 centre of the earth either in a direct or 

 In an oblique direction. The line of swift- 

 est descent is that which a body falling by 

 the action of gravity, describes, in the 

 shortest time possible, from one given 

 point to another ; and this line is the arc 

 of a cycloid when the one point is not 

 perpendicularly over the other (see BRA- 

 CHYSTOCHRONE). In law, descent is the 

 title by which an individual on the death 

 of his ancestor acquires his estate by right 

 <* representation as his heir at law. In 

 Iteraldry, descent expresses the position of 

 an animal in the act of descending, as a 



lion in descent with his heels upwards, a 

 in the act of leaping down from an emi- 

 nence. 



DESCRI'BENT. In geometry, from de and 

 scribo, to write; the line or surface, from 

 the motion of which a figure or body is 

 supposed to be generated or described. 



DESI'OS, Fr. dessein,a.plnn or represen- 

 tation of anything by an outline or sketch. 

 In painting, the design is the first idea of 

 a large work drawn roughly and on a 

 small scale, with the intention of being 

 executed and finished in large. In textile 

 manufactures, design expresses the draw- 

 ings which the workman copies by va- 

 rious contrivances into the fabric upon 

 which he is employed. In architecture, 

 &c., the plan of an intended building pro- 

 jected according to the rules of art, with 

 taste and judgment, is called a design : it 

 includes plans, sections, and elevations. 

 In music, design means both the invention 

 and execution of the subject in all its 

 parts. 



DESIG'NATOR. Anciently, a master of 

 the ceremonies, whose duty it was to as- 

 sign to each person his proper place in 

 the theatres and at the other public spec- 

 tacles. 



DESMOL'OOY, from dwtM>s, a ligament, 

 and Xo"/og, discourse; the anatomical de- 

 scription of the ligaments of the body. 



DESPUMA'TION , from de and spuma, froth ; 

 the clarification of a liquid, or the sepa- 

 ration of the spume, froth,-or scum from it. 



DESOUAMA'TION, from de and squama, a 

 scale ; the separation of scales from the 

 skin or bones : in the case of the bones 

 the word exfoliation is commonly used. 



DESTEM'PER, Fr. dttrempe. In painting, 

 a preparation of opaque colour, ground 

 up with size and water, used in scene- 

 painting. 



DKSTRCC'TIVE DISTILLATION, th,e distil- 

 lation of organic products at a high tem- 

 perature, whereby the elements enter 

 into new combinations, as in distilling 

 coal for the production of gas, and wood 

 for the formation of vinegar. 

 DBS' c ETUDE, from desuetudo, to cease from 

 any practice ; discontinuance of any cus- 

 tom, law, &c. Words are lost, and laws 

 are virtually abrogated, by desuetude. 



DE'SUNT CJS'TERA (Lat.) , " the rest want- 

 ing;" put at the end of any chasm or de- 

 ficiency in an imperfect or mutilated 

 work. 



DETACHED. In painting, is said of figures 

 when they stand free and disengaged from 

 each other. 



DETACH'SD PIECES. In fortification, out- 

 works at i distance from the body of a 

 place, as -'emilunes, ravelins, &c. 



DETA'II? (of a plan), drawings or de- 

 lineations 'or the use of workmen, other- 

 wise callt> working drawings. In Uw 



