D H A 



691 



D I A 





Dhalac. observes, " that the round harbour of Dobelew, and 

 ""■"V"""' its narrow entrance, are no where discoverable ; and the 

 town itself, instead of being tln - ee miles S. W. of the 

 harbour, is, in fact, on a parallel with the northern ex- 

 tremity of Irwee, which forms the harbour, and is an 

 island." 



At the distance of four and a half miles from Dobe- 

 lew stands Gerbeschid, which consists of about twenty 

 wretched huts, about tlu-ee miles distant from the sea. 

 A considerable quantity of cheese is exported from this 

 place to Loheia. The island of Irwee contains a small 

 village, which is visited by fishermen in catamarans. The 

 coast is low, with a few trees scattered up and down ; 

 and the sea between it and Dobelew is shallow, and full 

 of shoals. 



The inhabitants of this island are a simple and an 

 inoffensive people, and are employed almost solely in 

 working the vessels, which trade to the different parts 

 of the coast. Fish is the principal source of their sub- 

 sistence ; and in some of the villages, which are not vi- 

 sited by the Arabian boats, the inhabitants will some- 

 times live a whole year without tasting bread. The wo- 

 men are excellent fishers. They have, in general, a 

 brown complexion, but are sometimes of a reddish hue, 

 a little darker than the colour of new mahogany. The 

 language of the inhabitants is that of the " Shepherds," 

 though Arabic is also generally spoken. 



Dhalac is dependent on Massowah. A goat brought 

 every month from each of the twelve villages constitutes 

 the principal part of the revenue of the governor. Eve- 

 ry Arabian vessel also brings him a dollar or pataka ; 

 and every vessel from Massowah contributes a pound 



of coffee. Venetian glass beads are the only money cur- 

 rent in the island. 



The valuable fisheries for pearls and tortoise shells, 

 which were formerly carried on in the Red Sea, extend- 

 ed from Dhalac to nearly the latitude of 20° ; and the 

 divers and fishers were principally obtained from that 

 island. Under the Ptolemies, it was successfully car- 

 ried on. It was afterwards rented to the Basha of Sua- 

 ken ; but when it became dependent on the Basha of 

 Jidda, the Aga, whom he appointed, appropriated to 

 himself the provisions and salary which were allotted 

 for the fishery. The pearls found here are of the lar- 

 gest size, and of the finest kind ; and the tortoise shells, 

 which were carried to the East Indies and China, were 

 esteemed the finest in the world. See Bruce's Travels 

 in Abyssinia, vol. i. ; and Lord Valentia's Voyages and 

 Travels, vol. ii. chap. i. and v. (t) 



DHELLY. See Timour. 



DIABETES. See Medicine. 



DIADELPHIA. See Botany, p. 76. and 272. 



DIALIUM, a genus of plants of the class Diandria, 

 and order Monogynia. See Botany, p. 90. 



DIAL, an instrument generally so constructed as to 

 show the hour of the day by the solar shadow of some 

 opaque body falling on a system of lines traced on a 

 surface. Sometimes the surface is a horizontal plane, 

 and then the instrument is called a horizontal dial. The 

 surface of a dial, however, may be of any figure what- 

 ever, and may have any position ; and hence the vari- 

 ous kinds of dials, as horizontal, vertical, polar, equato- 

 rial, &c. the principal of which will be found explain- 

 ed in the article Dialling. (|) 



Dhelij 



II, 

 Dial. 



DIALLING. 



History k .Dialling, or the method of constructing sun di- 

 y_,- ,•_*■ als, is a branch of mixed mathematics, which depends 

 partly on the principles of geometry, and partly on 

 those of astronomy. 

 Definition. This branch of mathematical science was called by 

 the Greeks and Romans Gnomonica, also Sciaterica, 

 from Tvupuv an index, and g-kix a shadow. It has also 

 been called Photnsciaterica from <pug light, and h-kU a 

 shadow, because the hour is sometimes indicated by 

 the light of the sun, as when it passes through a small 

 hole, and falls on the dial. Again, it has been called 

 Horographia, because it is the art of writing the hours; 

 also Horologiagraphia, because sun dials were formerly 

 called Horologia ; they were also named Sciaterica. 

 History. 2. As the division of time is a matter of great im- 



portance, this branch of knowledge must have early 

 engaged the attention of mankind. It appears that the 

 ancient Jews had instruments for measuring time by 

 shadows ; for it is recorded in scripture, 2 Kings, chap. 

 xx. and Isaish, chap, xxviii. that, by a miracle, the 

 shadow went back ten degrees on the sun dial of Ahaz, 

 as a sign given to Hezekiah that he should recover 

 when he was " sick unto death." This happened 113 

 years before the Christian era. 



3. The nations of antiquity differed greatly from us 

 in their mode of reckoning time ; we know, that first 

 . the rising and setting of the sun were the circumstances 

 which determined the length of then day. The Baby- 

 lonians began the day at sunrise, and reckoned it to 

 continue until the next following sunrise. The Athe- 

 nians, again, considered the interval between any sun- 



set and the next following, as forming their day, which History, 

 they divided into two portions ; the natural night ex- •— "V"* 

 tending from sunset to sunrise, and the natural day origin of 

 from sunrise to sunset. It is probable that the Egypti- dialling. 

 ans reckoned time in the same manner ; but as they 

 cultivated astronomy long before the Greeks, they must 

 have earlier felt the inconvenience of this manner of 

 reckoning time, and thence have been led to begin the 

 day at noon. 



4. The Egyptians and Babylonians were the first 

 that could determine correctly the position of the meri- 

 dian. The former have shewn their skill in resolving 

 this problem, by placing the pyramids in the direction 

 of the cardinal points ; they are also reckoned to have 

 been the first who divided the day into 24 equal parts : 

 but it is certain that they were one of the earliest people 

 who divided the duration of the day into equal parts, 

 whether astronomically or mechanically, and this was 

 long before the Greeks had reached the same degree of 

 refinement in reckoning time. Although this last na- 

 tion employed the word 'flPA from the remotest anti- 

 quity, yet it did not indicate a division of the day, but 

 a season, an indeterminate portion of time. Until the 

 period that philosophy was cultivated among them, the 

 only circumstances of the day that they noted, were the 

 rising and setting of the sun, and the time of noon 

 found vaguely, as by the light of the sun falling upon, 

 or leaving the face of some edifice. As to midnight, it 

 could only be determined by a rough estimation. 



5. When Greece became enlightened by philosophy, 

 geometry, and astronomy, this last science furnished 



