618 



DEBURE DECIPHERING. 



DEBURE, GUILLACMK and GUILLAUME FRAN- 

 gois ; two cousins, distinguished bibliographers. 

 The former prepared the first division of the cata- 

 logue of the excellent library of the duke de la Val- 

 liere (1783, 2 vols.). The latter, a bookseller, born 

 1731, and died 1782, opened a new path for biblio- 

 graphers, by reducing to a system what liad before 

 been left merely to tact, in his Bibliographic instruc- 

 tu-i; on Traite tie la Connaissance den Livres rares et 

 singvliers (Paris, 1763 68, 7 vols.). Lemercier and 

 others attacked the work severely ; yet it must be 

 . onsklered of much value. (Seo Ebert's Bibliogra- 

 phische* Lexicon, vol. i. p. 452.y Among his other 

 works is to be mentioned Supplement d la Bibliogra- 

 phic instructive, ou Catalogue des Livres du Cabinet 

 de M. Uaignat (Paris, 1769, 2 vols.). To these two 

 works, tliat of Nee de la Rochelle, Table destinee d 

 faciliter la Recherche dea Livres anonymes, etc. 

 ( 1782), forms a tenth volume. The sons of Debure, 

 advantageously known in the world of letters as 

 Debure Freres, have distinguished themselves as 

 bibliographers by the catalogue of the rich and 

 valuable library of count Mac-Carthy Reagh, 

 (1817.) 



DECADE, (Lat. decas, from the Greek &x) is 

 sometimes used for the number ten, or for an aggre- 

 gate of ten, and decades for an enumeration by tens. 

 The books of Livy are divided into decades. In the 

 French revolution, decades took the place of weeks, 

 in the division of the year. (See Calendar.) In the 

 French system of weights and measures, the Greek 

 word Six is used to increase the value of the desig- 

 nations tenfold ; thus decagramme (a weight of ten 

 grammes), decalitre (ten litres), decametre (ten me- 

 tres), decare (ten ares.). 



DECAGON, (decagonum), in geometry; a figure 

 of ten sides and angles. 



DECALOGUE, (from Si*, ten, and x'y, the 

 word) ; the ten commandments, which, according to 

 Exod.,chap. xx.,and Deut., chap, v., were given 

 on two tables, by God to Moses. The Jews call 

 them, by way of eminence, the ten words; hence 

 their name, Decalogue. Jews and Christians Iiave 

 divided the ten commandments differently ; and, in 

 some Catholic catechisms, the second commandment 

 has been united, in an abridged form, with the first, 

 and the tenth has been divided into two. Cate- 

 chisms generally contain the ten commandments, not 

 verbally as they stand in the Bible, but abridged. 



DECAMERON (Greek ; fromSjxa, ten, and fifiifu, 

 day) ; a book in which the author relates the events, 

 &c., of ten days. The Decameron of Boccaccio 

 (q. v.) is the history of a gay company of ten per- 

 sons, who, on ten different days, relate ten tales 

 each day. The Decameron of Dibdin treats of bib- 

 liographical curiosities. 



DECAPITATION. See Capital Punishment. 



DECANDRIA, in botany; the tenth class of 

 plants, with hermaphrodite flowers, and ten stamina, 

 or male parts, in each. 



DECAPOLIS, in ancient geography ; a country 

 of Palestine, wlu'ch contained ten principal cities, 

 some on this, some on the other side of Jordan, 

 whence its name. Pliny eimmerates the following : 

 Scythopolis, Philadelphia, Raphanae, Gadara, Hip- 

 pos, Dion, Pella, Gerasa, Canatha, and Damascus. 

 Others reckon them differently. They were chiefly 

 inhabited by Gentiles, though some of them might 

 be within the region of Judea. 



DECCAN, or the COUNTRY OF THE 

 SOUTH; an extensive country of Hindostan, 

 bounded N. by the Nerbuddah, and S. by the Kist- 

 nali, extending across the peninsula, from sea to sea. 

 During the. reign of the great mogul Aurungzebe, 

 i. e. in the latter half of the seventeenth century 



this country was annexed to the kingdom of Delhi, 

 and divided into six governments Candeish, Amed- 

 nagur, Beeder, Golconda, Bejapore, and Benin The 

 capitals were Burliampour, Aurungabad, Hulberga, 

 Bejapore, and Hyderabad. 



DECEM (Latin, ten) ; a word which is found in 

 several compound and derivative words in English ; 

 as December, to decimate, decimal fractions, &c. 



DECEMBER, the twelfth month of our year, 

 from the Latin decent, ten, because in the Roman 

 year instituted by Romulus, it constituted the truth 

 month, the year beginning with March. In De- 

 cember the sun enters the trophic of Capricorn, and 

 passes our winter solstice. This month was under the 

 protection of Vesta. 



DECEMVIRS. See Appius Claudius. 



DECIMAL ARITHMETIC ; a kind of calcula- 

 tion hi which no other fractions are used tlian 

 tenths, hundredths, thousands, &c., which are conse- 

 quently called decimal fractions. Joh. Regiomon- 

 tanus first made use of it in his Tables of the Sines. 

 It affords great facilities in calculation. As, in our 

 system of notation, the values of figures are deter- 

 mined by their places, so that the figure on the left 

 is always of' ten times more value tlian the next at 

 the right hand ; so in decimal fractions, which must 

 be considered as an extension of the decimal system 

 (described in the article Notation), the place of the 

 numerator determines the value of the denominator 

 of the fraction, which need not, therefore, be ex- 

 pressed. The integers are separated from the frac- 

 tional numbers by a period, so tiiat this period, placed 

 between several numbers,is the characteristic sign of a 

 decimal fraction. For instance 5-36 is 5 whole numbers 

 3 tenths, and 6 hundredths, or 36 hundredths ; 5-009 

 is 5 whole numbers, and 9 thousandths. If the di- 

 visions of money and measures be in a decimal ratio 

 as is the case with those adopted during the French 

 revolution, the ease of calculation is greatly increas- 

 ed, almost all operations being reduced to addition, 

 and subtraction. 



DECIMAL MEASURE; the division of the unit 

 of measure (whatever it be, as a foot, a rod, &c.) 

 into ten equal parts. The quadrant of a circle has 

 also been divided into ten equal parts. In this case 

 the tenth part of such a quadrant is called a decimal 

 degree. The French mathematicians, however, call 

 the hundredth part of such a quadrant a decimal de- 

 gree, and the hundredth part of such a degree a de- 

 cimal minute* 



DECIMATE; to exact the tithe. The collection 

 or the payment of the tithe is called decimation. 

 In war, decimation signifies the selection of the 

 tentli man of a corps, t>y lot, for punishment, as in 

 case of revolt. It was early practised by the Ro- 

 mans. Sometimes every tenth man is executed ; 

 sometimes only one man of each company, the tenth 

 in order, as was the case when the Saxons revolted 

 against Bluecher, before the battle of Waterloo. 



DECIPHERING, ART OF; the art of discovering 

 the contents of a writing in which secret characters 

 are used (often ciphers; hence the term decipher- 

 ing). First, the vowels must be determined. This is 

 done in the following way : 1. All the words of two 

 letters are selected and written down together ; then 

 those words are selected which are divided at the 

 end of a line, so that only two letters of the word re- 

 main, one of which must necessarily be a vowel. 

 Then the five (or whatever may be the number of the 

 vowels in a language) letters are taken which occur 

 the most frequently. 2. It is necessary to see if some 

 one of these five letters is contained in every word 

 of the secret writing. If there is any word in which 

 none of them is contained, the signs of the vowels 

 are not yet all discovered, and it remains to make 



