662 



DIADEM DIAL. 



and the morbid state of the skin, but where tin 

 urine does not contain sugar. 



There is much obscurity respecting the origin oi 

 diabetes : it has been attributed to improper diet, to 

 the use of spirituous liquors ; to large quantities oi 

 wjitrry fluids ; to exposure to cold during perspira- 

 tion ; to violent exercise ; and, in short, to anything 

 which might be supposed likely to weaken the sys- 

 tem generally, or the digestive organs in particular. 

 It does not, however, appear that any of these cir- 

 ( uiiistances so commonly precede the disease, as to 

 mtitle it to be regarded as the cause, although many 

 of them may contribute to aggravate it, or to bring 

 it into action, when the foundation is laid in the con- 

 stitution. The proximate has been no less the sub- 

 ject of controversy than the exciting cause ; and on 

 this point two hypotheses have divided the opinions 

 of pathologists ; some liave ascribed it to a primary 

 affection of the stomach and the function of assimila- 

 ion, und others to a primary disease of the kidney. 

 With respect to the treatment which may aflbrd 

 the best diance of success, or which may possibly 

 remove the complaint in its incipient state, we should 

 recommend that a moderate bleeding be premised, 

 and that a diet be employed, of which vegetable 

 matter should form only a small proportion ; at the 

 same time we may administer vegetable tonics, and 

 may endeavour to restore the natural action of the 

 skin by diaphoretics and t lie warm bath. 



DIADEM ; a band of silk or woollen, invented, 

 according to some, by Bacchus, to relieve the head- 

 ache produced by excessive drinking. It more pro- 

 bably belonged to him as coming from the East (the 

 Indies.) It afterwards became the distinguishing 

 ornament of royalty. The diadem of the Egyptian 

 deities and kings bore the symbol of the sacred ser- 

 pent. Among the Persians, it was twined about the 

 tiara of the kings, and was purple and white. The 

 diadem of Bacchus, particularly of the Indian Bac- 

 chus, as seen in very old representations, consisted 

 of a broad, plaited band, encircling the forehead and 

 temples, and tied behind, with the ends hanging 

 down. When unfolded, it formed, in fact, a veil ; 

 and, for this reason, it was often called, by the 

 Greeks, calyptra, i. e., a veil. It was afterwards at- 

 tributed to other deities, and finally became the badge 

 of kings. In the earliest times, it was very narrow. 

 Alexander the Great adopted the broad diadem of 

 the Persian kings, the ends of which hung over his 

 shoulders ; and this mark of regal dignity was re- 

 tained by his successors. On coins we see queens 

 also, with the diadem, with the addition of a veil. 

 The early Roman emperors abstained from this orna- 

 ment, to avoid giving offence to the people. Con- 

 stantine the Great was the first who used it, and he 

 added new ornaments to it. After his time, it was 

 set with a single or double row of pearls and other 

 precious stones, so that it was somewhat similar to a 

 Turkish turban. 



DIOECIOUS, in botany ; plants which have their 

 stamens on one individual and their pistils on another. 

 The willow, the ash, the poplar, &c., are diaecious, 

 DIAGLYPHON (Lat. ; $/yXty, Gr.); in an- 

 cient sculpture ; the name by which the Greeks de- 

 signated works in sculpture when sunk in with the 

 chisel. Among the most celebrated of these were 

 the buckler and pedestal of a colossal statue of 

 Minerva at Athens. When it was in relief, the work 

 was called anaglyphic. See Anaglyphic. 



DIAGNOSIS, in medicine ; the distinction of 

 one disease from others resembling it, by means of a 

 collected view of the symptoms. 



DIAGNOSTIC symptoms are the leading symp- 

 toms, or those which are most characteristic of any 

 particular form or seat of disease. 



DIAGONAL, DIAGONAL LINE; a straight 

 line, joining two angles not adjacent, in a rectilinear 

 figure, having more than three sides. Every rectili- 

 near figure may be divided by diagonals into as many 

 triangles as it lias sides, minus two. 



DIAGRAM : a figure or geometrical delineation, 

 applied to the illustration or solution of geometrical 

 problems, or a description or sketch in general. 

 Anciently, it signified a musical scale. Among the 

 Gnostics, the name diagram was given to a figure 

 formed by the superposition of one triangle on another, 

 and inscribed with some mystical name of the Deity, 

 and worn as an amulet. 



DIAL, SON. This instrument lias been known 

 from the earliest times : the Egyptians, Chaldeans 

 and Hebrews (Isaiah xxxvii. 8) were acquainted 

 with the uses of it. The Greeks derived it from their 

 eastern neighbours, and it was introduced into Rome 

 during the first Punic war. A dial constructed for 

 the latitude of Catana was carried off from that city 

 and placed in the forum by Valerius Messana ; but, 

 as there was a difference of 4 of latitude between 

 the two cities, it could not, of course, indicate the 

 true time at Rome. Before this period, the Romans 

 ascertained the hour by the rude method of observing 

 the lengths of shadows, or, in the absence of the sun, 

 by the clepsydra (q. v.), which a slave was employed 

 in tending. 



The complete investigation of the theory of the 

 formation ot dials would require the application of the 

 higher mathematics ; but the leading principles of 

 dialling may be made intelligible to general readers 

 by the following simple illustration : 



Let P B D represent the earth as a hollow trans- 

 parent sphere, having an axis P E p, of which P and 

 p are the poles. Let the equator be divided into 

 twenty-four equal parts, and through these divisions 

 draw the meridians a, b, c, d, &c. Let one of these 

 meridians pass through any given place, for which a 

 dial is required to be made, and where that meridian 

 cuts the equator, let it be numbered XII. The 

 opposite meridian must likewise be numbered XII., 

 the other meridians being numbered as shown in the 

 cut. This being done, these meridians will be the 

 liour circles of the place on the first meridian ; so that 

 if the axis P E p were opaque, the sun in his (ap- 

 parent) motion round the earth in twenty-four hours, 

 will pass from one meridian to another in one hour, 

 and cause the shadow of the axis to fall or. the hour 

 on the plane D C B A. This diagram has been 

 drawn for the latitude of Glasgow 55 52', and the 

 plane in its present position would form a horizontal 

 dial for that place ; but we may suppose it capable 



