OR A 



521 



O R A 



catoptrics, dioptrics, and perspective; 

 and considers the nature, composition, 

 and motion of light ; the whole doctrine 

 of colours, and all the circumstances of 

 yision ; the construction and management 

 of optical instruments, &c. 



OP'TIC, | Relating to optics or to vi- 



OP'TICAL. J sion. The optic nerves are 

 the second pair springing from the crura 

 of the medulla oblotigata, and passing 

 thence to the eye. The optic inequality of 

 a heavenly body is an apparent irregula- 

 rity which arises from the situation of 

 the eye of the observer, and not from any 

 real irregularity in the motion of the 

 moving body. The optic place of a star is 

 its place as seen by the eye. 



OP'TICAL SQUARE. An instrument used 

 in surveying, for laying out perpendicular 

 lines. It is made of brass, in the shape of 

 a circular box, and containing two prin- 

 cipal glasses of the sextant, viz. the index 

 and horizontal glasses, fixed at an angle 

 of 45, so that while viewing an object by 

 direct vision, any other, forming a right 

 angle with it, will appear by reflection at 

 the spot where the observer is situated. 



OP'TIMATES. Grandees, from optimtts, 

 best. A division of the Roman people, 

 opposed to populares, though it does not 

 certainly appear what were the charac- 

 teristic differences between these two 

 parties. 



OP'TIME. A scholar of the first class of 

 mathematics at Cambridge. 



OP'TIMISM, from optimiis, best. The 

 philosophical and religious doctrine which 

 maintains that this world, notwithstand- 

 ing its apparent imperfections, is the best 

 that could have been devised ; and that the 

 existing order of things in the universe 

 is that adapted to produce most good. 



OP'TION. At the Stock Exchange, a per- 

 centage given for the option of putting 

 or calling, i. e. selling or buying, stock in 

 time-bargains at a given price. 



OPTOM'ETER, from OVTIXI), vision, and 

 /u.iTgax, measure. An instrument to mea- 

 sure the limits of distinct vision, and de- 

 termine with exactness the comparative 

 strength of the sight. 



OPUN'TIA. The Indian fig-tree. A 

 species of cactus which grows abundantly 

 in the south of Europe, and takes its name, 

 ab opunte, from the city Opus, near which 

 it flourished. De Candollc makes it the 

 type of an extensive genus. 



OR. The French word for gold : used in 

 heraldry to express gold-colour or yellow, 

 represented in engraving by small' dots. 



O'RA. A Saxon coin, supposed to be 

 worth about one shilling and sixpence 

 sterling. 



OR'ACHE. In botany, the Atriplex sntiva, 

 used ofton as a substitute for spinach. 

 The wild orache belongs to the gonus 

 Chenopodium. 



OR'ACLE, Lat. oracttlum. The reply or 

 answer of a god, from oro, to utter: also, 

 by metonymy, the god who gave oral 

 replies to the inquiries of men. The most 

 celebrated of the ancient oracles were 

 those of Apollo at Delphi, and Jupiter Am- 

 mon at Thebes. These were consulted, 

 through the medium of priests and priest- 

 esses, on all momentous occasions, and 

 never failed to give suitable responses, 

 many of which are famous for their am- 

 biguity. The superstition indeed was 

 mainly supported, and it was kept up for 

 many centuries, by the ambidexterous 

 nature of the oracular saying, for which- 

 ever way the event happened, the oracle 

 was certainly correct in the revelation. 



OR'ANGE. The well-known fruit of the 

 orange-tree. The sweet orange is the 

 produce of the Citrus sinensis, or Citrus 

 nobilis, or Mandarin tree, and the bitter 

 or Seville orange is the produce of the 

 Citms aitrantium. The true orange is a 

 native of China, but was long since trans- 

 planted to other countries by the Portu- 

 guese. It now grows abundantly in the 

 south of Europe. 



OR'ANOEMEN. The name given by the 

 Catholics of Ireland to their Protestant 

 countrymen, on account of their adher- 

 ence to King William, (of the house of 

 Orange), while the former party sup- 

 ported the cause of James II. 



ORANG'-OUTANO'. The satyr or great 

 ape, the Simia satyrus, Lin., which of all 

 animals is considered as approaching 

 most nearly to man, in the form of his 

 head, height of forehead, and volume of 

 brain. The body is covered with coarse 

 red hair, the face bluish, and the hinder 

 thumbs very short, compared with the 

 toes. He inhabits only the most eastern, 

 countries, such as Malabar, Cochin-China, 

 and particularly the great island of Bor- 

 neo, whence he has been occasionally 

 brought to Europe by the way of Java, 

 He is mild and gentle, easily rendered 

 tame and affectionate, but his intelligence 

 does not appear to be much superior to 

 that of the dog. The popular name orang- 

 outang, ( often written ourang-outang), is 

 composed of two Malay words : orang, a 

 reasonable being, and outang, wild, or of 

 the woods: hence, "Wild Man of the 

 Woods." The orang-outang is very ge- . 

 nerally confounded with the chimpans6 

 (q. v.) ; and there is a monkey of Borneo, 

 known only by his skeleton, called the 

 Pongo, which is either of the species of, or 

 one closely allied to, the orang-outang. 

 He is the largest monkey known, and iu 

 size is nearly equal to man. 



OR'ATOR. In ancient Rome, the orator* 



were advocates for clients in the forum, 



I and before the senate and the people. 



! They were employed in causes of import - 



1 ance, instead of the patrons. In modern 



