DIG 2 



DI'ODON, the sun-fish. Placed by Cu- 

 vier in the family Gymnodontes, and thus 

 named from J/j, and odovs, a tooth, in 

 consequence of the jaws being undivided, 

 and formed of one piece above, and ano- 

 ther below. The skin is every where 

 armed with spines, so that when the fish 

 is inflated, and it has the power of swell- 

 ing itself like a balloon, it bears a close 

 resemblance in form to the burr of a 

 chestnut-tree. A number of species inha- 

 bit the seas of hot climates. 



DKE'CIA, from S/j,and oixo;,^ house. 

 The name of a class of plants in the sex- 

 ual system of Limurus, embracing such 

 as have barren or male flowers on one 

 individual, and fertile or female ones on 

 another of the same species. The poplar, 

 aspen, and willow, are examples. The 

 epithet for plants of this class is dioecious. 



DIOME'UEA, the albatross. A genus of 

 aquatic birds of gigantic size (See ALBA- 

 TROSS). They inhabit the South Seas. 

 Cuvier places them among the Longipen- 

 nes. The name is that of certain birds of 

 the Island of Diomedes, near Tarentum, 

 which were said to receive the Greeks 

 favourably, and to attack the barbarians. 



DIOPHAN'TINE ANALYSIS. \ In algebra, 



PROBLEMS. ) certain pro- 

 blems relating to square and cube num- 

 bers, right-angled triangles, &c. ; the 

 properties of which were first discussed 

 bjr Diophantes, in his " Arithmetic." 



DIOP'TRICS, from /<*, through, and 

 vrrofAcu, to see. That branch of optics 

 which treats of the laws of refraction, 

 and of the effects which the refraction 

 of light has on vision: called also ana- 

 elastics. 



DIOBA'MA, from &, and eeai^a, a view. 

 This name is given to those buildings in 

 which dioramic paintings are exhibited, 

 and also to the art of making such paint- 

 ings. Dioramic painting is a new art, 

 and is a decided improvement upon the 

 old panorama. It consists in uniting 

 transparent painting to the usual opaque 

 method, and causing the light to fall upon 

 the picture both before and behind. To 

 give life to the picture transparent blinds, 

 suspended both above and behind, are put 

 in motion by machinery, and now and 

 again modify and intercept the rays of 

 light, so as to fall at pleasure in graduated 

 tints upon all parts of the scene in succes- 

 sion. Uy the same means, figures are 

 made to appear where the spectators had 

 just beheld empty seats, &c. ; rocks to 

 tumble from mountains ; the dark thun- 

 der-cloud to overshadow the smiling 

 valley; or the avalanche to hurl destruc- 

 tion among the peaceful inhabitants of 

 th lowland village. 



DIGSCORE'A, a genus of perennial plants. 

 Dtcecia Hexandria. Named in honour of 



DIP 



Dioscorides. The esculent root called the 

 yam is afforded by three species, the alata, 

 bidbifera, and satira. They are natives of 

 both Indies, and the root is eaten promis- 

 cuously as the potato is with us. The 

 taste i more luscious than the potato. 



DIOS'MA, a genus of permanent plants 

 of about 50 species. PentandriaMonogy- 

 nia. Name from Aiof, Jove, and og-f&r,, 

 a smell, on account of its divine smell. 

 The smell, however, of some of this spe- 

 cies is so far from being divine that a di- 

 vision called Baroima has been formed to 

 include them. A bitter principle called 

 diosmine has been extracted from the 

 leaves of the D. crenata, the Buchu of the 

 natives. 



DIP, from Sax.dippan, to incline down- 

 wards. In geology and mining, the incli- 

 nation of a stratum, or the angle which 

 it forms with the horizon, is termed the 

 dip or angle of inclination. Mining work- 

 men also use the term dip for any inter- 

 ruption of a vein by a dike or fault, with- 

 out regard to the literal meaning of the 

 word. In magnetism, the depression of 

 one of the poles of a magnet, and the con- 

 sequent elevation of the other, is called 

 the dip of the magnet or needle. An ap- 

 paratus constructed to show the amount 

 of this depression is called a dipping- 

 needle (q.v.). For dip of the horizon, see 

 DEPRESSION. 



DIPETA'LOUS, from J.j , and -rsraXc*, a 

 petal ; having two flower-leaves or petals. 



DIPH'YOES, the name given by Cuvier 

 to a genus of zoophytes. Class Acalepha , 

 Order Hydrostatica ; from 5/j, and (f u -f,, 

 nature. Two different animals being al- 

 ways found together, the one encased in 

 a cavity of the other, but susceptible of 

 being separated without destroying the 

 life of either. They are gelatinous and 

 diaphanous. 



DIPHYL'LOUS, from S/j, and i/>.X*, a 

 leaf; two-leaved; applied to the perianth 

 of flowers when there are two calyces. 



DIP'LOE, from &jrAeai, to double; the 

 name given by anatomists to the cancel- 

 lated substance between the two plates of 

 the skull. 



DIPLO'MA, J/srA&i^ta. A writing which 

 confers some privilege, and especially the 

 instrument of licence given by colleges 

 to clergymen to exercise the ministerial 

 functions, and to physicians and surgeons 

 to practise physic and surgery: thus 

 named from tivrXou, to double, be- 

 cause usually written on parchment and 

 folded up. 



DIPLOM'ACY, from $nrXu t uct, a folded 

 letter (ancient meaning); the customs, 

 privileges, and rules of ambassadors, en- 

 voys, and other representatives of prince* 

 and state* at foreign courts. Minister! 



