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animal to be wholly formed in the egg; that, in lieu of an organical part of an animal cut off, another should aile perfectly like it: the fact, however, is too well attested to be denied. The legs of lobiters, &c. confift each of five articulations; now when any of the legs happen to break, by any accident, as by, walking, &c, which frequently happens, the fracture is always found to be at the future near the fourth articulation; and what they thus lofe, is exactly reproduced in fome time afterwards; that is, a part of the leg fhoots out, confifting of four articulations, the firft whereof has two claws, as before; fo that the lofs is entirely repaired.

If the leg of a lobster be broken off by defign at the fourth or fifth articulation, what is thus broke off is always reproduced. But, if the fracture be made in the first, fecond, or third articulation, the reproduction is not fo certain. And it is very furprizing, that, if the fracture be made at these articulations, at the end of two or three days, all the other articulations are generally found broke off to the fourth, which, it is fupposed, is done by the creature itself, to make the reproduction certain. The part reproduced is not only perfectly fimilar to that retrenched, but also, in a certain fpace of time, grows equal to it. Hence it is that we frequently fee lobsters, which have their two large legs unequal, in all proportions. And, if the part reproduced be broken off, a fecond will lucceed. REPTILES, in natural history, a kind of animals denominated from their creeping or advancing on the belly. Or reptiles are a genus of animals and infects, which, instead of feet, rest on one part of the body, while they advance forward with the reft.

Such are earthworms, fnakes, caterpil lars, &c. Indeed, moft of the class of reptiles have feet; only thofe very fmall, and the legs remarkably fhort in proportion to the bulk of the body. Naturalifts obferve a world of artful contrivance for the motion of reptiles. Thus, particularly in the earth-worm, Dr. Willis tells us, the whole body is only a chain of annular mufcles; or, as Mr. Derham fays, it is only one continued fpiral muscle, the orbicular fibres whereof being contracted, render each ring narrower and longer than before; by which means it is enabled, like the worm

of an augre, to bore its paffage into the earth. Its reptile motion might also be explained by a wire wound on a cylin der, which when flipped off, and one end extended and held fast, will bring the other near to it. So the earth-worm having fhot out and extended his body (which is with a wreathing) it takes hold by thefe fmall feet it hath, and fo contracts the hinder part of its body. Dr. Tyfon adds, that when the forepart of the body is ftretched out, and applied to a plane at a distance, the hind part relaxing and shortening is easily drawn towards it as a center.

Its feet are difpofed in a quadruple row the whole length of the worm, with which, as with fo many hooks, it fastens down fometimes this and fometimes that part of the body to the plane, and at the fame time stretches out or drags after it another.

The creeping of ferpents is effected after a fomewhat different manner; there being a difference in their structure, in that there last have a compages of bones articulated together.

The body here is not drawn together, but as it were complicated; part of it being applied on the rough ground, and the reft ejaculated and shot from it, which, being fet on the ground in its turn, brings the other after it. The fpine of the back variously wreathed has the fame effect in leaping, as the joints in the feet of other animals; they make their leaps by means of muscles, and extend the plica or folds.

REPTILE is alfo ufed, by fome botanical

writers, to fignify plants which creep upon the earth, unless fuftained by fome other plant, prop, &c. As cucumbers, melons, the vine, &c.

REPUBLIC, respublica, commonwealth, a popular ftate or government; or a nation where the people have the government in their own hands.

REPUBLIC of letters, a phrafe ufed collec tively of the whole body of the people of fludy and learning. REPUDIATION, repudium, in the civil law, the act of divorcing. See DIVORCE. REPULSION, repulfio, in phyfics, that property in bodies, whereby, if they are placed just beyond the fphere of each other's attraction of cohesion, they mutually fly from each other.

Thus if an oily fubitance, lighter than water, be placed on the furface thereof, or if a piece of iron be laid upon mer16 Ba cury,

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cury, the furface of the fluid will be depreffed about the body laid on it: this depreffion is manifeftly occafioned by a repelling power in the bodies, which hinders the approach of the fluid towards them. But it is poffible, in fome cafes, to prefs or force the repelling bodies into the fphere of one another's attraction; and then they will mutually tend toward each other, as when we mix oil and water till they incorporate.

Dr. Knight defines repulfion to be that caufe which makes bodies mutually endeavour to recede from each other, with different forces, at different times; and that fuch a caufe exifts in nature, he thinks evident for the following reasons, 1. Because all bodies are electrical, or capable of being made fo; and it is well known, that electrical bodies both attract and repel. 2. Both attraction and repulfion are very confpicuous in all magnetical bodies. 3. Sir Ifaac Newton has fhewn from experiments, that the furfaces of two convex glaffes repel each other. 4. The fame great philofopher has explained the elasticity of the air, by fuppofing its particles mutually to repel each other. 5. The particles of light are, in part at leaft, repelled from the furfaces of all bodies. 6. Laftly, it seems highly probable, that the particles of light, mutually repel each other, as well as the particles of air.

The fame gentleman afcribes the caufe of repulfion, as well as that of attraction, to the immediate effect of God's will; and as attraction and repulfion are contraries, and confequently cannot, at the fame time, belong to the fame sub. ftance, the doctor fuppofes there are in nature two kinds of matter, one attracting, the other repelling; and that thofe particles of matter which repell each other, are fubject to the general law of attraction in respect of other matter. A repellent matter being thus fuppofed, equally difperted through the whole universe, the doctor attempts to account for many natural phænomena by means thereof. He thinks light is nothing but this repellent matter put into violent vibrations, by the repellent corpufcles which compole the atmosphere of the fun and ftars; and that, therefore, we have no reason to believe they are gulphs of fire, but, like the reft of the heavenly bodies, inhabitable worlds. From the fame prinCiples, he attempts to explain the nature of file and heat, the various phænomena

of the magnet, and the cause of the variation of the needle: and, indeed, it is difficult, if not impoffible, by the doctrine of attraction alone, to account for all the phænomena obfervable in experiments made with magnets, which may now be folved by admitting this doctrine of a repellent fluid; but whether it will be fufficient to account for all the particular phænomena of nature, which are the proper tefts of an hypothesis, time and experience alone must determine.

The doctor alfo endeavours to fhew, that the attractions of cohefion, gravity and magnetifin are the fame, and that by thefe two active principles, viz. attrac tion and repultion, all the phænomena of nature may be explained; but as his ingenious treatife on this fubject is laid down in a series of propofitions, all connected together, it would be impoffible to do justice to his arguments, without transcribing the whole: we fhall therefore refer the curious to the book itself. According to 'sGravefande and others, when light is reflected from a polished fpherical furface, the particles of light do not strike upon the folid parts, and fo rebound from them; but are repelled from the furface, at a small distance before they touch it, by a power extended all over the faid polifhed furface. And Sir Ifaac Newton obferves, that the rays of light are also expelled by the edges of bodies, as they pafs near them; lo as to make their fhadows, in fome cafes, larger than they would otherwife be. See 'sGravefande's Introd. P. I. n° 40 to 44. and Sir Ifaac Newton's Optics, B. II. P. III. prop. 8. and B. III. P. I. where this repulfive force is illuftrated from other phæ

nomena.

REQUENA, a town of New Caftile, fortyfive miles weft of Valencia. REQUEST, in law, a fupplication or pe tition preferred to a prince, or to a court of justice; begging relief in fome confcionable cafes where the common law grants no immediate redress. Court of REQUESTS, an antient court of equity, inftituted about the nineteenth year of Henry VII. See Court. In the fortieth and forty-first years of queen Elizabeth, it was adjudged upon folemn argument, in the court of common-pleas, that the court of request was then no court of equity. REQUIEM, in the romifh church, a mass fung for the rest of the foul of a perion deceated. See the article Mass. RESAR

cates for mental refervations; yet are they real lyes, as including an intention to deceive.

RESARCELE'E, in heraldry, is where a flender cross is charged upon another, as reprefented in plate CCXXXI. fig. 4. RESCEIT, receptio, in law, an admithion or receiving of a third perfon to plead his right, in a cause formerly commenced between the other two. RESCHET, the capital of the province of Gilan, in Perfia, fituated on the fouthweft coaft of the Cafpian sea. RESCISSION, rescissio, in the civil law, an action intended for the annulling, or letting afide, any contract, deed, &c. RESCOUS, or RESCUE, in law, an illegal taking away and fetting at liberty a diftrefs taken, or a perfon arrefted, by process, or course of law. See the article DISTRESS, &c.

Refcous, in matters relating to treason, is deemed treason; and in inatters concerning felony, is felony. RESCRIPT, refcriptum, an answer delivered by an emperor, or a pope, when confulted by particular perfons, on fome difficult question, or point of law; to ferve as a decifion thereof,

RESEARCH, a fcrutiny, or diligent enquiry into any thing. RESEARCH, in music, is a kind of prelude or voluntary played on the organ, &c. wherein the performer feems to fearch or look out for the ftrains and touches of harmony, which he is to ufe in the regu: lar piece to be played afterwards. See the article PRELUDE. RESEARCHING, in sculpture, the repairing of a caft figure, &c. with proper tools; or the finishing it with art and exactness, so as the minuteft parts may be well defined.

RESEDA, BASE-ROCKET, in botany, a genus of polyandria-trigynia clafs of plants, the corolla of which confifts of certain unequal petals, fome one of which is always femitrifid; and its fruit is a gibbofe and angulated capfule, containing one cell, with numerous kidneyfhaped feeds.

RESERVATION, in law an action or claufe whereby fomething is referved, or fecured to one's self.

Mental RESERVATION, a propofition which ftrictly taken, and according to the natural import of the terms, is falfe; but, if qualified by fomething concealed in the mind, becomes true,

Mental reservations are the great refuge of religious hypocrites, who use them to accommodate their confciences with their interefts; the jefuits are zealous advo

RESERVE, in law, the fame with reserva, tion. See the article RESERVATION. Body of RESERVE, or corps de RESERVE, in military affairs, the third or iaft line of an army, drawn up for battle; fo called because they are referved to sustain the reft, as occafion requires; and not to engage, but in case of neceflity. RESERVOIR, a place where water is collected and reserved, in order to be conveyed to distant places through pipes, or fupply a fountain, or jet d'eau. RESET, in law, the receiving or harbouring an outlawed perfon. See the article OUTLAWRY.

RESIDENCE, in the canon and common law, the abode of a perfon, or incumbent, upon his benefice; and his affiduity in attending on the fame.

RESIDENT, a public minifter, who ma nages the affairs of a kingdom or state, at a foreign court.

They are a clafs of public minifters inferior to ambaffadors or envoys; but, like them, are under the protection of the law of nations.

RESIDENTIARY, residentiarius, a canon inftalled into the privileges and profits of refidence.

RESIDUAL FIGURE, in geometry, the figure remaining after fubtracting a leffer from a greater.

RESIDUAL ROOT, in algebra, a root compofed of two parts or members, connected together by the fign-.

Thus x-y is a refidual root, so called, because its value is no more than the difference between its parts x and y.. RESIDUE, refiduum, the remainder or balance of an account, debt, or obligation. RESIGNATION, in the canon law, the furrendering a benefice into the hands of the collator, or bishop.

RESIGNEE, in law, the perfon to whom a thing is refigned.

RESIN, in natural hiftory, a vifcid juice ouzing either spontaneously, or by incifion, from feveral trees, as the pine, fir, &c. For the difference between refins and gums, fee the article GUM.

Natural refins are either folid or fluid. Of the folid refins, fome are used more frequently in medicine, as ftorax, Lenjamin, maftich, olibanum, elmi, lac, dragons-blood, and camphor; and others more rarely, as anime, copal, caranna, tachamahaca, laudanum, fandarach, &c.

See

1

See the articles STORAX, Benjamin, &c. The liquid raisins, used in medicine, are lefs numerous, viz. balfam of gilead, of *peru, of tolu, of capivi, turpentine, liquid amber, and liquid ftorax. See the articles BALSAM, TURPENTINE, SC. All refins are ufed, more or less, in all officinal plafters; both as being ripeners and drawers, and because they give a due confiftence and tenacity.

The refins of vegetables may be prepared nearly in the fame manner as extracts, by using rectified fpirit of wine instead of water for fuch a spirit is the only proper menftruum that will diffolve the groffer refinous matter of vegetables, as water is of the mucilaginous and saline parts; yet these principles are so intimately combined in almost all plants, that whichever of thefe liquors is applied at firft, it will take up a portion of what is directly foluble only in the other : hence fundry vegetables, extremely refinous, and whofe virtues confift chiefly in their refin, afford nevertheless very useful extracts with water, though not equal to those obtained by a prudent application of fpirit. See EXTRACT,

The indiffolubility of pure refins in aqueous fluids, and their tenacions quality by which they flick to the coats of the inteftines, occafion gripes and other inconveniencies; fo that it is not safe to give them alone: the better way of fit. ting them for internal ufe, is by tritu rating them with the teftaceous powders, or with almonds, into the form of an emulfion; or by diffolving them in spirit of wine, and mixing the folution with a proper quantity of fyrup. Six or eight grains of the raifin of jalap, or scammony, managed in this manner, prove powerfully cathartic without griping, or greatly difordering the body.

For the preparation of the refins, fee the articles, JALAP, SCAMMONY, &c. RESISTANCE, or RESISTING FORCE,

in philofophy, denotes, in general, any power which acts in an oppofite direction to another, fo as to deftroy or diminish its effect.

Hence the force wherewith bodies, moving in fluid mediums, are impeded or re. tarded, is the refiftance of thofe fluids. See the article FLUID.

Authors have eftablished it as a certain rule, that, whilft the fame body moves in the fame medium, it is always refifted in the duplicate proportion of its velocity; that is, if the refifted body move in one

part of its track, with three times the velocity with which it moved in some other part, then its refiftance to the greater velocity will be nine times the resistance to the leffer: if the velocity in one place be four times the velocity in another, the refiftance to the greater velocity will be fixteen times the refiitance to the leffer, and so on. This rule, though exceffively erroneous, when taken in a general sense, is yet undoubtedly very near the truth, when confined within certain limits.

In order to conceive the resistance of fluids to a body moving in them, Mr. Robins diftinguishes between thofe fluids, which being compressed by some incumbent weight, perpetually close up the fpace deferted by the body in motion, without permitting, for an inftant, any vacuity to remain behind it; and those fluids in which, they being not fufficiently compreffed, the fpace left behind the moving body remains for fome time empty. Thefe differences, in the refifting fluids, will occafion very remarkable varieties in the laws of their refistance, and are abfolutely neceffary to be confidered in the determination of the action of the air in fhot and fhelis; for the air partakes of both these affections, according to the different velocities of the projected body.

If a fluid was so conftituted that all the particles compofing it were at fome diftance from each other, and there was no action between them, then the resistance of a body moving therein, would be eafily computed from the quantity of motion communicated to these particles: for inftance, if a cylinder moved in fuch a fluid in the direction of its axis, it would communicate to the particles it met with a velocity equal to its own, and in its own direction, fuppofing that neither the cylinder, nor the parts of the fluid were elaftic; whence, if the velocity and diameter of the cylinder be known, and alfo the density of the fluid, there would thence be determined the quantity of motion communicated to the fluid, which (action and re action being equal) is the fame with the quantity loft by the cylinder, confequently the refiftance would be hereby ascertained.

In this kind of discontinued fluid, the particles being detached from each other, every one of them can pursue its own motion in any direction, at least for fome time, independent of the neighbouring ones; wherefore, if instead of a cy

the fame cylinder would undergo, if it moved with the fame velocity, in a fluid, conftituted in the manner we have defcribed in our firft hypothefis, each fluid being fuppofed to be of the fame density. But again, it is not only in the quantity of their refiftance that these fluids differ, but likewife in the different manner in which they act on folids of different forms moving in them.

We have fhewn, that in the difcontinued fluid, which we firft described, the obliquity of the foremost furface of the moving body would diminish the refiftance; but in compreffed fluids this holds not true, at least not in any confiderable degree; for the principal refiftance in compreffed fluids arifes from the greater or leffer facility, with which the fluid, impelled by the forepart of the body, can circulate towards its hindermoft part; and this being little, if at all, affected by the form of the moving body, whether it be cylindrical, conical, or spherical, it follows, that while the tranfverse section of the body, and confequently the quantity of impelling fluid is the fame, the change of figure in the body will fcarcely affect the quantity of its refiftance.

linder moving in the direction of its axis, a body, with a furface oblique to its direction, be fuppofed to move in such a fluid, the motion the parts of the fluid will hereby acquire, will not be in the direction of the refifted bolly, but perpendicular to its oblique furface; whence the refiftance to such a body will not be eftimated from the whole motion communicated to the particles of the fluid, but from that part of it only which is in the direction of the refifted body. In fluids then, where the parts are thus difcontinued in each other, the different obliquities of that furface, which goes foremoft, will occafion confiderable changes in the resistance; although the fection of the folid, by a plain perpendicular to its direction, fhould in all cafes be the fame. And Sir Ifaac Newton has parcularly determined, that in a fluid thus conftituted, the refiftance of a globe is but half the resistance of a cylinder of the fame diameter, moving in the direction of its axis with the fame velocity. But though the hypothefis of a fluid, thus conftituted, be of great ufe in explaining the nature of refiftances; yet, in reality, no fuch fluid does exift within our knowledge: all the fluids with which we are converfant are so formed, that their particles either lie contiguous to each other, or at least act on each other in the fame manner as if they did; confequently, in thefe fluids, no one particle, contiguous to the refifted body, can be moved, without moving at the fame time a great number of others, fome of which will be distant from it; and the motion thus communicated to a mafs of the fluid will not be in any one determined direction, but will in each particle be different, according to the different manners in which it lies in contact with those, from which it receives its impulse; whence, great numbers of the particles, being diverted into oblique directions, the refiftance of the moving body, which will depend on the quantity of motion communicated to the fluid in its own direction, will be hereby different in quantity, from what it would be in the preceding fuppofition, and its estimation becomes much more complicated and operofe. Sir Ifaac Newton, however, has determined, that the refiftance to a cylinder, moving in the direction of its axis in fuch a compreffed Auid as we have here treated of, is but one fourth part of the refiftance, which

The refiftance of bodies of different figures, moving in one and the fame medium, has been confidered by Mr. J. Bernouli in the A&ta Lipfienf. for May, 1693; and the rules he lays down, on this fubject are the following: 1. If an ifofceles triangle be moved in the fiuid according to the direction of a line which is normal to its bafe; firft with the vertex foremost, and then with its bafe; the refiitances will be as the legs, and as the fquare of the bafe, and as the fum of the legs. 2. The refiftance of a fquare moved according to the direction of its fide, and of its diagonal, is as the diagonal to the fide. 3. The refiftance of a circular fegment (lefs than a femi-circle) carried in a direction perpendicular to its bafis, when it goes with, the base foremost, and when with its vertex foremoft (the fame direction and celerity continuing, which is all along supposed) is as the fquare of the diameter to the fame, lefs one third of the fquare of the bafe of the fegment. Cor. Hence the refiliances of a femicircle, when its bafe, and when its vertex go foremost, are to one another in a felquialterate ratio. 4. A parabola moving in the direction of its axis, with its

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