DUO 



DUR 



ly possess the latter in such perfection, 

 that nothing' rther is necessary, in order 

 to make them aiticulate, than to teach 

 them how to use these organs. This, in- 

 deed, is no easy task ; but experience 

 shews that it is p'raciicable. Mr. Thomas 

 Braidwood, late of Edinburgh, was per- 

 haps the first who ever brought this sur- 

 prising art to any degree of perfection. 

 He began with a single pupil in 1764, 

 and since that period has taught great 

 numbers of people born deaf to speak 

 distinctly, to read, to write, to under- 

 stand figures, the principles of religion 

 and morality, &c. 



But a new and different method, equal- 

 ly laborious and successful, we under- 

 stand, is practised by the Abbe de 1'Epee 

 of Berlin. We are informed that he be- 

 gins his instructions, not by endeavouring 

 to lorm the organs of speech to articulate 

 sounds, but by communicating ideas to 

 the mind by means of signs and charac- 

 ters : to effect this, he writes the names 

 of things ; and, by a regular system of 

 signs, establishes a connection between 

 these words and the ideas to be excited 

 by them. After he has thus furnished 

 his pupils with ideas and a medium of 

 communication, he teaches them to ar- 

 ticulate and pronounce, and renders 

 them nut only grammarians, but logicians. 

 In tins manner he has enabled one of his 

 pupils to deliver a Latin oration in public, 

 and another to defend a thesis against the 

 objections of one of his fellow pupils in 

 a scholastic disputation; in which the ar- 

 guments of each were communicated to 

 the other, but whether by signs or in 

 writing is not said. 



DUMOSA,(from Dumus, abush) bushy 

 plants ; the name of the forty -third order 

 in Linnaeus's Fragments of a Natural Me- 

 thod; consisting of a number of shrubby 

 plants, which are thick, set with irregular 

 branches, and bushy. 



DUNG, in husbandry, is of several 

 sorts, as that' of horses, cows, sheep, 

 hogs, pigeons, geese, hens, &c. See Au- 



B1CULTUKE. 



DUNGEON, in fortification, the high- 

 est part of a castle built after the ancient 

 mode ; serving as a watch-tower, or place 

 of observation ; and also for the retreat 

 of a garrison, in case of necessity, so 

 that they may capitulate with greater ad- 

 vantage . 



DUO, in music, a song or composition 

 to be performed in two parts only, one 

 sung, the other played on an instrument, 

 or by two voices. 



Duo is also when two voices sing dif- 



ferent parts, accompanied with a third* 

 which is a thorough bass. It is seldom 

 that unisons and octaves are used in duos, 

 except at the beginning and end. 



DUODENUM, the first of the small 

 guts, so called from its length, which is 

 about twelve fingers breadth. It has its 

 origin at the pylorus, or right orifice of 

 the stomach; from which ascending a 

 little, it afterwards descends again, and 

 towards its end re-ascends, and runs 

 transversely towards the left kidney : at 

 the distance of three or four fingers 

 from the pylorus it receives, at one pro- 

 minent hiatus or mouth, the choledo- 

 chic and pancreatic ducts, which dis- 

 charge their respective liquors into it. 

 See ANATOMY. 



DUPLICATE, among lawyers, denotes 

 a copy of any deed, writing, or account. 

 It is also used for the second letters pa- 

 tent, granted by the Lord Chancellor iij 

 a case wherein he had before done the 

 same. Also a second letter, written and 

 sent to the same party and purpose as 

 the former, for fear of the first's miscarry- 

 ing, is called a duplicate. 



DUPLICATE proportion, or ratio, is a ra. 

 tio compounded of two ratios: thus, the ' 

 duplicate ratio of a to b, is the ratio of a a 

 to b b, or of the square of a to the square 

 of b. Hence the duplicate ratio ought to 

 be well distinguished from double. 



In a series of geometrical proportion- 

 als, the first term to the third is said to 

 be in a duplicate ratio of the first to the 

 second : thus in 2, 4, 8, 16, &c. the ratio 

 of 2 to 8 is duplicate of that of 2 to 4, or 

 as the square of 2 to the square of 4. Du- 

 plicate ratio is therefore tiie proportion 

 of squares, as triplicate is of cubes, 8tc. 

 and the ratio of 2 to 8 is said to be com- 

 pounded of that of 2 to 4, and of 4 to 8. 



DUPLICATION, in general, signifies 

 the doubling of any thing, or multiplying 

 of it by 2 : also the folding of any thing 

 back again on itself. See CUHE. 



DUKA mater, one of the membranes 

 which surround the brain. See A NATO - 



Mf. 



DURANTA, in botany, So called in 

 honour of Castor Durantes, a genus of 

 the Didynamia Angiospermia class and 

 order. Natural order of Personals. Vi- 

 tices, Jussieu. Essential character : ca- 

 lyx five-cleft, superior ; berry four-seed- 

 ed; seeds two-celled. There are three 

 species. These are shrubs with quad- 

 rangular branches; the flowers are in 

 loose spikes, either from the axils, or at 

 the ends of the branches. They have 

 generally axillary spines; and they are 



