25 



REPUBLICATIOtf. 



RESCUE. 



possess the entire sovereign power. Dr. Johnson, in his dictionary, 

 defines a republic to be " a state in which the power is lodged in more 

 than one." Since a republic is a political community in which several 

 persons share the sovereign power, it comprehends the two classes of 

 aristocracies and democracies, the differences between which are ex- 

 plained under ARISTOCRACY and DEMOCRACY. 



The word republic is sometimes understood to be equivalent to 

 dimixracy, and the word republican is considered as equivalent to 

 democrat ; but this restricted sense of the words appears to be in- 

 accurate ; for aristocratic communities, such as Sparta, Rome in early 

 times, and Venice, have always been called republics. 

 REPUBLICATION. [WILL AND TESTAMENT.] 

 REPULSION is that power by which bodies or the particles of 

 bodies are made to recede from one another. Both attraction and 

 repulsion exist in all the particles of material substances, and seem to 

 be properties by which those particles act upon one another when not 

 in contact. The cause of these actions will probably be for ever 

 unknown to us ; and the terms are only applied in conformity to the 

 phenomena exhibited. At all sensible distances, bodies, small and 

 great, except in certain states with respect to electricity or magnetism, 

 attract one another ; and the intensity of the attraction varies inversely 

 as the square of the distance between the bodies. But the phenomena 

 of light, and of elasticity in general, show that at distances which are 

 not appreciable by the eye (perhaps such as are less than ^^ inch) 

 both attractions and repulsions take place. [ATTRACTION.] 



In his researches concerning the phenomena of light, Newton, having 

 brought at one time a hair, and at another the edge of a knife, near a 

 small beam of light in a darkened room, found that the particles of 

 light were made to deviate from the rectilinear direction, as if attracted 

 by a force which diminished with the distance of the ray from the hair 

 or knife. The shallow of the latter was bordered with three coloured 

 binges, of which the nearest to it was formed by inflected rays passing 

 at a distance rather greater than ,.' inch from the knife-edge ; and the 

 second and third fringes by rays inflected respectively at greater 

 distances. (' Optices,' lib. iii) [DIFFRACTION OF LICIIT.] From these 

 phenomena Newton waa led to the opinion (which he proposes as 

 query) that all material bodies might be assemblages of particles in 

 '|uilil.ri It-twvfii their mutual attractions and repulsions. He 

 imagined also that a subtle ether, pervading material bodies, was the 

 immediate agent in producing such attractions or repulsions, together 

 with all the circumstances of cohesion, and also those of chemical, 

 magneticnl, and electrical actions. The phenomena of nature seem to 

 justify the supposition than an ether pervades all bodies; but it must 

 be admitted that the hypothesis of Newton only removes the difficulty 

 concerning the actions of the particles of bodies a step further, since 

 we are equally at a loss to account for the existence of the powers in 

 those particles, and in the ether itself. 



The reality of a distance between the particles of bodies, whether 

 solid, fluid, or gaseous, admits of no question ; for the differences in 

 the densities of these classes of bodies can only be conceived to arise 

 fi"m the different extent of the intervals between the particles. 

 [HEAT.] By the process of cooling, all bodies, with certain exceptions 

 in particular cases, become contracted in volume ; and the mixing of 

 two given volumes of different fluids (as water and sulphuric acid) pro- 

 duces a volume less than the sum of the two separate volumes. These 

 effects manifestly depend upon the approach of the particles to one 

 another, and are therefore inconsistent with the supposition that they 

 were originally in contact. 



It is natural to ask if there be such a thing as mathematical contact 

 in nature, and it may be answered that we have no evidence of such a 

 condition. [COHESION.] Besides the continual diminution of volume 

 produced in the cooling of bodies, the Newtonian experiment of 

 pressing a convex lens of glass upon the surface of a glass mirror 

 affords evidence that the Inn, .-it the point of nearest approach, and 

 under a very great pressure, is not in contact with the mirror ; and it 

 has been supposed that the distance Ixitween them, at that place, is then 

 not less than }& inch. (Robison, ' Median. Phil.') It seems to follow 

 that a vast force of repulsion must be in action between the particles 

 of bodies when they are as near together as mechanical power can 

 bring them ; and it can be easily conceived that such repulsive force 

 may be the immediate cause of the sensation of touch. 



It has been said that the mixture of certain different fluids produces 

 a diminution of volume; but it must be observed that a contrary effect 

 frequently takes place. Some of the metals, when mixed together in a 

 melted state, produce a volume greater than the sum of the component 

 volumes,; and melted metals, on becoming solid, like water on being 

 frozen, expand in volume. The latter effect may arise from the crystals, 

 on being formed, placing themselves across one another so as to leave 

 comparatively large intervals ; but the other can only be caused either 

 by a diminution of the attractive power which the particles exert on 

 one another, or by its being changed into a power of repulsion. One 

 of these latter circumstances must also be the cause of the great 

 augmentation of volume which takes place when the components of 

 some bodies are disengaged from each other. It is said that if the 

 parts of olefiant gas were separated, the sum of the separate volumes 

 would be four times as great as the volume of the compound ; that w, 

 two volumes of hydrogen and two of carbon vapour are condensed in 

 olefiant gaa into the space of one- volume. 



It is right to observe that the word repulsion is often applied to 

 phenomena which are in reality the results of attraction. A small 

 quantity of quicksilver being laid on a glass plate assumes a spherical 

 form, instead of spreading over it in a thin surface ; and this was once 

 supposed to arise from a repulsive power in the glass, whereas it is 

 owing to the attraction of the particles of quicksilver for one another 

 being greater than the attraction of the glass for the quicksilver. 

 Again, when a small sewing-needle is placed on the surface of water, it 

 remains there without sinking, and the water is depressed about the 

 needle as if it were repelled by the steel ; in fact, however, the trough 

 is caused by the weight of the needle, which displaces the particles of 

 water, but is not great enough to overcome their attraction for each 

 other. Also, when two balls, one of them of glass, which is capable of 

 attracting water, and the other of burnt cork, which is not, or only in 

 a very small degree, are placed near one another in water, the latter 

 seems to be repelled from the former ; but the cause of the pheno- 

 menon is that the ring of elevated water about the glass assumes on 

 the exterior a conical surface, so that when the cork ball is brought 

 near enough to the other to be partly on the slope, it immediately 

 slides off by its gravity. 



The elasticity of bodies is a result either of attractive or repulsive 

 powers, or both. For example, when a steel rod is bent, the particles 

 on one side will be forced towards, and on the opposite they will be 

 drawn from one another ; in recovering itself, a force of attraction will 

 be exerted on the latter side, and of repulsion on the other ; and this 

 may be considered as an evidence that in the insensible spaces between 

 the particles of bodies attractions and repulsions prevail according as 

 the distances between those particles are varied. While the change of 

 figure in the rod is small, so that the displacement of any two particles 

 is but a small part of their whole distance from one another, the 

 attractions and repulsions exerted by the force applied are proportional 

 to that force ; and upon this principle depends the observed isochro- 

 nism in the oscillations of a watch-balance, whatever be the extent of 

 the arcs of vibration. The expansions of solids and fluids by heat, and 

 the elastic powers of gas at different temperatures, are consequences of 

 the repulsions residing in the particles of caloric, or induced by the 

 latter in those of the bodies with which they are combined. [ELAS- 

 TICITY ; GAS ; HEAT.] The repulsive power existing in the air which 

 is condensed in nitre, produces, on being combined with heat, a velocity 

 of expansion equal to about 7000 feet per second ; and the force of 

 pressure resulting from it is thought to be equal to 2000 times the 

 pressure of the atmosphere. (Hutton, ' Tracts.') The repulsive force 

 which produces some of the electric explosions in the atmosphere is 

 supposed to be much greater. But the forces both of attraction and 

 repulsion by which the particles of light are deflected from their course 

 wfcen they impinge on a refracting or reflecting surface are enormous ; 

 and Sir John Herschel computes that they exceed the force of gravity 

 in the ratio of 2 x 10" to 1. This is on the hypothesis of radiation ; 

 and that philosopher observes that on the undulatory hypothesis the 

 numbers are equally high. 



The circumstances of electrical attractions and repulsions are shown 

 in the article ELECTRICITY ; and the results of experiments prove that 

 the intensities of these forces in the electric, galvanic, and magnetic 

 fluids, like that of general attraction, vary inversely as the squares of 

 the distances of the bodies. 



Boscovich has ingeniously represented the series of alternate 

 attractions and repulsions supposed to be experienced by a particle 

 of matter within the very small -distances between that particle and 

 another, by a curve consisting of several bends crossing and recrossing 

 an axis in points at various distances from the origin, which may be 

 supposed to be the place of the second particle above mentioned. The 

 ordinates of this curve on one side of the axis represent attractions, and 

 those on the other side repulsions ; the places of crossing being sup- 

 posed to be those at which the first particle would be at rest. Beyond 

 the small distance above mentioned, this axis becomes an asymptote to 

 the curve, and the ordinates of the curve here represent the general 

 law of attraction (the inverse square of the distances). Near the origin 

 of the axis the ordinaten represent repulsions; and these ordinates 

 constantly increase till they become infinite, so that a right line drawn 

 through the place of the second particle, perpendicular to the axis, is 

 an asymptote to this branch of the curve. 



REQUEST, COURTS OF (sometimes called Courtt of Conscience), 

 were local tribunals, founded by Act of Parliament to facilitate the 

 recovery of small debts from any inhabitant or trader in the district 

 defined by the Act : they have been altogether superseded by the 

 COCSTY COURTS. 



REQUIEM (Re>juui, Lat., rett), the name of a mass sung in the 

 Romish Church for the repose of the dead, beginning Jiequiem 

 atcrnam, and in the Roman Catholic liturgy called Missajrro Defunctis. 



KEREDOS. [RETABLE.] 



RESCUE, in Law (' rescous,' from the old French word rescouner, 

 ' to recover '), is tho unlawful and forcible setting at liberty a person or 

 goods, in lawful custody. A rescue may be either a criminal offence 

 or a civil injury, according to the circumstances under which it is 

 effected. The character of the criminal offence is determined by the 

 character of the offence committed by the person rescued. If, for 

 instance, a party has rescued a traitor or a felon, he has committed the 

 offence of treason or felony ; but as the treason or felony of the person 



