ROB 6 



at the intersection of the nave and tran- 

 sept of a church, which covered the rood- 

 loft. 



HOOF, Sax. wrof. The top covering 1 of a 

 house or other building, in which sense it 

 comprises the timber-work, slate, tile, 

 lead, with whatever else is necessary to 

 form and complete the whole. The parts 



are AA, the tie-beam ; B, the kingpost ; 

 CC, the principal rafters or principals; 

 1)D, the struts: BE, the purlines ; and 

 without are the common rafters. 

 HOOK. 1. Sax rhoc. A bird, the Corvtis 



frugilegus, Lin. 2. Ital. rocco, a bishop's 



staff ; a common man at chess. 



ROOT. 1. In arithmetic and algebra, a quan- 

 tity which being multiplied into itself a 

 certain number of times, produces ano- 

 ther quantity called a power, and of which 

 power the original quantity is the root. 

 Thus la is the square root of 4aa, or 2 V ; 

 the cube root of 8 aaa, or 2 *n ; the fourth 



root of 16 aaaa, or 2 *a", &c. 2. In 60- 



tany, the descending fibres of a plant, 

 whose function is to attract liquid food 

 from the soil in which it is imbedded. 



ROPE, Sax. rap. Ropes are made of 

 hemp, hair, &c. spun into a thick yarn, of 

 which several strings are twisted together 

 by means of a wheel. Very small ropes 

 are termed cords, and very thick ones 

 cables. See CABLE. 



ROPE-ROLL. A hollow cylinder fixed on 

 an axle, around which either single or 

 endless ropes or bands are passed, for the 

 purpose of communicating motion to other 

 parts of the machine. See DRUM. 



ROPE-TARN. Yarn for ropes, consisting 

 of a single thread ; the threads are twisted 

 into strands, and the strands into ropes. 



ROSA. ROSE. A very extensive genus 

 of trees and shrubs. IcosandriaPoly- 

 gynia. Rosa is the Latin name, derived 

 from the Celtic rhiis, allied to rhuz, red 

 Don enumerates 29 British species, and 

 .about as many varieties of the rose, and 

 in all 89 species, all of which, with a very 

 few exceptions, are natives of temperate 

 climates. 



Ros.v'ctc ACID. A peculiar acid depo- 

 sited from the urine of persons labouring 

 under gout and inflammatory fevers. It 

 is of a rose colour, and sometimes forms 

 reddish crystals. 



ROSARY, Lat. rotarium, a rose-bed. A 



3 RO8 



Roman Catholic devotional practice, con 

 sisting in reciting a number of times the 

 Lord's Prayer and the Ave Maria. As the 

 computation is aided by means of beads, 

 the string of beads has acquired also the 

 name of a rosary. 



ROSE-ENGINE. In mechanics, an appen- 

 dix to the turning-lathe, by which a sur- 

 face of wood or metal is engraved with a 

 variety of curve lines. 



ROSE-NOBLE. An ancient English gold 

 coin, stamped with the figure of a rose : 

 first struck in the reign of Edward III., 

 and current at 6s. 8d. (according to John- 

 son 16s.). 



ROSES, FESTIVAL OF. An annual rural 

 festival of some parts of France, in 

 which the best-behaved maiden of the 

 town or village is crowned with roses 

 in the church, to which she is conducted 

 with great pomp by the villagers. 



ROSET'TA STONE. A celebrated stone, 

 found at Rosetta in Egypt, the subject -jt 

 much hieroglyphic research. 



ROSE-WINDOW. A circular window, 

 with compartments of mullions or tracery, 

 branching from a centre ; sometimes 

 called a Catharine-wheel, or marigold- 

 window. 



ROSE-WOOD. A beautiful wood, pro- 

 duced in Brazil, the Canary Islands, Siam, 

 and some other places. It is the produce 

 of a large tree, not, however, well knows 

 to botanists: Don calls it the Polysoca- 

 lymnia floribunda. It takes its name from 

 its irregular knotty grain, as if studded 

 over with small roses, together with its 

 fragrant smell, and purple red ground. It 

 is highly valued for cabinet work, in 

 which, from its great price, it can only 

 be used for veneering ; price in bond from 

 120Z. to IZM. per ton; duty 101. per ton. 

 (formerly 20Z-). 



ROSICRTJ'CIANS. A sect or cabal of her- 

 metical philosophers, (rather fanatics), 

 who sprung up in Germany, in the 14th 

 century, and made great pretensions to a 

 knowledge of science. Among other 

 things they pretended to be masters of 

 the secret of the philosopher's stone. They 

 took their name from ros, dew, and crux , 

 cross : dew being the most powerful dis- 

 solvent of gold, according to their notions, 

 and cross an emblem of light. 



RO'SIN. This is the name given to the 

 resin which the different species of tur- 

 pentines leave when they are deprived of 

 their volatile oil by distillation. After 

 this process it is melted with about J o!" 

 its weight of galipot, placed upon a straw 

 filter, and a little water sprinkled on the 

 melted mass. Thus prepared, it is com- 

 mon rosin : when it has a golden-yellow 

 colour, it is called Burgundy-pitch. It 

 has a deep brownish-yellow colour, is 

 translucent and brittle, and is liquifte 

 by a temperature of 2' 5 P. 



