REP 



RET 



7, that number must be subtracted, and 

 the remainder shows that the next day 

 was the first of the Paschal moon.— Sir 

 H. Nicolas. 



RE'GULUS {rex, regis, a king). The 

 name given by the alchemists to the 

 metallic matters which were separated 

 from other substances by fusion, from 

 their expecting to find gold, the king of 

 metals, at the bottom of the crucible. 

 The term has since been applied to some 

 metals when extracted from their ores, 

 as regulus of antimony, &c. 



RE'GULUS (in Astronomy). A star 

 of the first magnitude in the zodiacal 

 constellation Leo. It is also called a 

 Leonis, or Cor Leonis. By Ptolemy and 

 other Greeks it was called /SaatXia-Kot, 

 whence is derived the Latin name Regu- 

 lus, the diminutive of Rex. 



RELATIVE and CORRELATIVE. 

 The nature of relative terms has been 

 explained under the article Absolute and 

 Relative. Terms are correlative to each 

 other, which denote objects related to 

 each other, and viewed as in that rela- 

 tion. Thus, though a king is a ruler of 

 men, "king" and "man" are not cor- 

 relative, but king and subject are. 



REPEATING CIRCLE. An astro- 

 nomical instrument, invented by Borda, 

 by which the error of graduation may be 

 diminished to any degree, and, prac- 

 ticaJly speaking, annihilated. By this 

 instrument the observer is enabled to 

 repeat or multiply the observation, by 

 reading it oiF successively on different 

 parts of the graduated limb. A number 

 of values being thus found, the mean of 

 the whole is taken as the correct result. 



REPETE'ND {repetendus, to be re- 

 peated). The part of a circulating deci- 

 mal which is perpetually repeated. It 

 is called simple, when the figures are the 

 same ; and compound, when they vary. 



REPLUM. A leaf of a door. In Bo- 

 tany, the framework formed by the sepa- 

 ration of the two sutures of a legume 

 from its valves. 



REPTATRI'CES {repo, to creep). 

 Creepers ; an order of Climbing birds, 

 which have the three fore toes more or 

 less united at the base, and spreading 

 little. They are thus distinguished from 

 the Scandrices, or Climbers, in which the 

 outer toe is directed outwards or back- 

 wards. 



REPTI'LIA {repo, to creep). The 

 third class of Vertebrate animals, con- 

 sisting of reptiles, most of which are 

 terrestrial. They are characterized by 

 287 



cold-bloodedness, oviparous reproduction, 

 the absence of metamorphosis, and the 

 protection of the skin by means of hard 

 plates or scales. 



REPULSION {repello, to drive back). 

 That property of natural bodies, by 

 which, under certain cir(;umstances, they 

 repel, or fly oflT from, each other, It is 

 an eflect of caloric, by which the par- 

 ticles of a body, into which it enters, are 

 removed from each other. It is the op- 

 posite of that form of attraction which is 

 termed cohesion. 



Repulsion, in Electricity. The law by 

 which light bodies fly off from an elec- 

 trified surface, after contact. 



RESI'DUAL. An expression which 

 gives the remainder of a subtraction, as 

 a — h. A residual phenomenon is that 

 part of a phenomenon which remains 

 when every part which is capable of ex- 

 planation has been removed. 



RESIN. A volatile oil, rendered con- 

 crete by combination with oxygen. 



RESrSTANCE. A term applied, in 

 Physics, to any power by which motion, 

 or a tendency to motion, is impeded or 

 prevented. Thus, the atmosphere offers 

 resistance to the path of a projectile, the 

 water to the passage of a ship, inequality 

 of surface to the movement of bodies on 

 one another, &c. 



RESOLUTION OF FORCES. This 

 term denotes, in physics, the finding of 

 several forces, their directions, and in- 

 tensities, which by their joint action have 

 moved a body, exactly as it would have 

 been moved by a single force of deter- 

 minate intensity and direction. See 

 Force. 



RE'SONANCE (resono, to sound 

 again). That property of sonorous bodies 

 by which they acquire the same vibra- 

 tions as are possessed by a body emitting 

 a sound; they thus vibrate with it, and 

 strengthen the original note. A tuning- 

 fork emits a louder sound when its 

 handle is placed on a table ; the notes of 

 a musical box are louder when the box 

 is placed upon a table. 



RESU'LTANT. A term applied in 

 physics to ^\xch a. single force &% is equi- 

 valent to the effects of all the moving 

 forces in any compound motion ; in other 

 words, it is the force which results from 

 the composition of two or more forces 

 acting upon a body. See Forces, Com- 

 position of. 



RETI'CULUS RHOMBOIDA'LIS. A 

 modern southern constellation, consist- 

 ing of ten stars. 



