ORT 



seeded; gland under the base of the germ' 

 There are fourteen species. 



OROBUS, m botany, bitter vetch, a ge- 

 nus of Uie Diadelphia Decandria class 

 and order. Natural order of Papiliona- 

 ceae, or Leguminosx. Essential charac- 

 ter : calyx blunt at the base ; the upper 

 teeth deeper and shorter; style linear. 

 There are sixteen species. 



ORONTIUM, in botany, a genus of the 

 Hexandna Moriogynia class and order. 

 Natural order of Piperitse. Aroideae, Jus- 

 sieu. Essential character: spadix cylin- 

 drical, covered with florets ; corolla six- 

 petalled, naked ; style none ; follicles one- 

 seeded. There are two species, viz. O. 

 aquaticum, and O. japonicum. 



ORPHAN. In the city of London 

 there is a court of record established 

 for the care and government of orphans. 

 ORPIMENT is a fine yellow powder, 

 formed from a solution ot the white oxide 

 of urser-ic in muriatic acid, to which is 

 added a solution of sulphuretted hydro- 

 gen in water. It may also be obtained 

 by subliming arsenic and sulphur by a 

 heat not sufficient to melt them. It is 

 likewise found native in many parts of 

 Germany and Italy, composed of plates 

 that have a considerable degree of flexi- 

 bility. Its specific gravity is 5.3. It is 

 used as a pigment. The Chinese fash- 

 ion vessels of different shapes, and their 

 pagodas, of the mineral. 



ORRERY, a curious machine for re- 

 presenting the motions and appearances 

 of the heavenly bodies. See PLANETA- 

 RIUM. 



ORTEGIA, in botany, so named in ho- 

 nour of Joseph Ortega ; a genus of the 

 Triandria Monogynia class and order. 

 Natural order of Caryophyllese. Essen- 

 tial character : calyx five-leaved ; corolla 

 none ; capsule one-celled ; seeds very 

 many. There are two species, viz. O. 

 Hispanica, Spanish ortegia, and O. dicho- 

 toma, forked ortegia, natives of Spain and 

 Italy. 



ORTHOGRAPHIC projection of the 

 sphere, that wherein the eye is supposed 

 at an infinite distance ; so called, because 

 the perpendiculars from any point of the 

 sphere will all fall in the common inter- 

 section of the sphere with the plane of the 

 projection. 



ORTHOGRAPHY, that part of gram- 

 mar which teaches the nature and affec- 

 tions of letters, and the just method of 

 spelling or writing words with all the pro- 

 per and necessary letters, making one of 

 the four greatest divisions or branches of 

 grammar. 



ORY 



ORTHOGRAPHY, in geometry, the art 

 of drawing or delineating the fore-right 

 plan ot any object, and of expressing the 

 heights or elevations of each part. It is 

 called orthography, from its determining 

 things by perpendicular lines falling on 

 the geometrical plane. 



ORTHOGRAPHY, in architecture, the ele- 

 vation of a building. This orthography is 

 either external or internal The external 

 orthography is taken for the delineation 

 of an external face or front of a building ; 

 or, as it is by others denned, the model, 

 platform, and delineation of the front of a 

 house, that is contrived, and to be built, 

 by the rules of geometry, according to 

 which pattern the whole fa'oric is erected 

 and finished. This delineation or plat- 

 form exhibits the principal wall, with its 

 aperlures, roof, ornaments, and every 

 thing visible to an eye placed before the 

 building. Internal orthography, which is 

 also called a section, is a delineation or 

 draught of a building, such as it would 

 appear were the external wall removed. 



ORTHOGRAPHY, in perspective, is the 

 fore-right side of any plane, i. e. the side 

 or plane that lies parallel to a straight 

 line, that may be imagined to pass 

 through the outward convex points of the 

 eyes, continued to a convenient length. 



ORTHOGRAPHY, in fortification, is the 

 profile or representation of a work ; or a 

 draught so conducted, as that the length, 

 breadth, height, and thickness, of the 

 several parts are expressed, such as they 

 would appear if perpendicularly cut from 

 top to bottom. 



ORYCTOLOGY is the science which 

 teaches the natural history of those ani- 

 mal and vegetable substances which are 

 dug out of the earth, in a mineralized 

 state. In the following slight sketch of 

 the history of these substances it will be 

 seen, that the remarkable situations in 

 which they have been found, and the ex- 

 traordinary changes which they have un- 

 dergone, have led to the adoption of va 

 rious contradictory and absurd notions re- 

 specting their nature and origin ; which 

 have been corrected, as just ideas have 

 been obtained respecting the formation 

 of the earth itself. Xenophahes, more 

 than 400 years before Christ, was led to 

 the belief of the eternity of the universe, 

 by discovering the remains of different 

 marine animals imbedded in rocks, and 

 under the surface of the earth. Hero- 

 dotus ascertained the existence of fossil 

 shells in the mountains of Egypt, and 

 was thereby induced to conclude, that 

 the sea must have once covered those 



