DI A 



274 



DI A 



DET, the title of the supreme governor 

 of Algiers, Tunis, and the other States of 

 Barbary. 



D.F., for defensorfidei, defender of the 

 faith. 



D. G., for Dei r/ratia,\yy the grace of God. 



DIAB'ETES, 'b'ioc.Z-f,TY,;- A morbid copi- 

 ousness of urine, a disease of which there 

 are two species, the D. insipidus, in which 

 the urine has its usual taste, and the D. 

 mellitus in which it contains a great 

 quantity of sugar. Both species are at- 

 tended with great thirst, voracious appe- 

 tite, and emaciation. 



IJIACAC'STIC, from diotxctvu, to burn ; 

 applied to a double convex lens or burn- 

 ing glass. The diacaustic curve is a spe- 

 cies of the caustic curves formed by re- 

 fraction. 



DIACH'YLO.V, Sxt/X<wy. The name 

 given by the Greeks to a plaister coin posed 

 of the juices of herbs, from 5/ and %t>Af, 

 juice. In modern pharmacy two diachy- 

 lon plaisters are known, the simple or 

 white diachylon or lead-plaister, and the 

 yellow diachylon or diachylon with gum, 

 made by adding galbanum, turpentine, 

 and frankincense, to simple diachylon. 



DIACOTJ'STICS, from / and aixovca, to 

 hear : the doctrine of refracted sounds, 

 called also diaphonics (q. v.). 



DIACRIT'IC MARKS, tt*x,%iv*, to distin- 

 guish. Marks used to distinguish let- 

 ters, between the forms of which much 

 similarity exists. 



DIADEL'PHIA, &?, twice, and otb&Qn, 

 a brotherhood ; the name of a class in the 

 sexual system of plants, embracing those 

 the flowers of which are papilionaceous 

 or hermaphrodite, and have the male 

 organs united below (generally) into two 

 sets of cylindrical filaments. The fruits 

 are leguminous. The pea and bean are 

 examples. 



DI'ADEM, $ia$v[*oc, diadema. 1. The 

 head-band anciently worn by kings as a 



badge of royalty. 2. The regal crown, 



hence figuratively supreme power. 3. 



In heraldry, a circlet enclosing the crown 

 of a prince. 4. In surgery, a sort of 

 bandage for the head in cases of relaxa- 

 tion of the sutures. 



DIJE'EESIS, from J/agea/, to divide. 1. 

 In grammar, the division of one syllable 

 into two, usually denoted by two points 



over a letter, as in aulai for auks. 2. In 



surgery, a solution of continuity, as an 

 ulcer. 



DIAGNO'SIS, from 'btot.'yivuffxca, to know 

 vhoroughly ; the art of distinguishing one 

 disease from another by the symptoms 

 presented, called also diacrisis. 



DIAGNOS'TIC, Siatyvoo-nzei, character- 

 istic ; the diagnostics of a disease are the 

 igns or symptoms by which it is recog- 



nised and distinguished from others. 

 These are of two kinds, the adjunct when 

 the symptoms are common to several dis- 

 eases, and the pathognomic when they at- 

 tend only one disease, and serve to distin- 

 guish it from all others. 



DIAG'OSAL, from ?<, through, and 

 yiattot,, a corner- in an angular direction. 



A rieht line, as A B drawn across an 

 equilateral figure from one ansle to 

 another, is by some called the diameter, 

 by others the diametral, but generally 

 the diagonal of the figure. 



DIA'GRAM, from 'bui'yeai.Qca, to delineate ; 

 a geometrical delineation for the purpose 

 of demonstrating the properties of any 

 figure, as a square, triangle, &c. The 

 'oict.'yocifjLfjiM of the Greeks was a sort of 

 musical scale, a proportion of measures 

 distinguished by certain notes. 



DIA'GRAPH, Sty, and yaoiQa, to describe ; 

 an instrument recently invented in 

 France, used in perspective. 



DI'AL, an instrument serving to mea- 

 sure time by the shadow of the sun, called 

 therefore tautologically, a sun-dial. The 

 word is formed from dies, day, because 

 indicating the hour of the day. The an- 

 cients called it sciathericum, from its doing 

 it by the shadow. There are many kinds 

 of dials, the diversity arising from the 

 different situations of the plane, and from 

 the different figures of the surfaces upon 

 which they are described, as the horizontal, 

 the equinoctial, vertical, polar, direct, erect, 

 declining, inclining, reclining, &c., and 

 there are several kinds called universal, 

 because they serve for all latitudes. De- 

 scriptions of several of these will be found 

 in Jones's Instrumental Dialling. The 

 miner's compass is sometimes erroneously 

 called a dial by the workmen. 



DIA'LECT, from 5/a and Xiytu, to speak ; 

 the form or idiom of a language peculiar 

 to a province, a kingdom, or a state, as 

 the Attic dialect spoken by the Athe- 

 nians in contradistinction to the Ionic, 

 Doric and ^Eolic dialects. Many lan- 

 guages which are regarded as distinct, 

 are dialects of one common language 

 locally accommodated to circumstances. 



DIAL'LING GLOBE, an instrument of brass 

 or wood, with a plane fitted to the hori- 

 zon, and an index so contrived as to give 

 a clear illustration of the scientific prin- 

 ciples on which dials are constructed. 



DIAL'LINU LISES, \ Graduated line* 



DIAL'LING SCALES. ) placed on rulers, 

 the edges of quadrants and other instru- 

 ments, for the construction of <iial. 



