courfe north by Mentz, &c. After entering the Netherlands at Skenkinchans, it is divided into leveral channels, the two Jarget whereof obtain the names of the Lech and the Waal, which running through the United-provinces difcharge themfelves into the German Sea, below Rotterdam.

tution is fanguineous they fhould all be avoided, and the part covered carefully with the bed-cloaths; but if there is a thick, cold, itagnating humeur in the part, and a fenfe of cold, with a fticture of the pores, then frictions may be ufed with rough warm cloths, and afterwards cupping with fearifications. If the part becomes itiff and inflexible, with a numbness, which is called a parefis, then take human or canine axungia, two ounces; balfam of Peru, and oil of cloves, each two drams; with which make a liniment for the port: this has been known to have a wonderful effect. Arbuthnot fays that cream of tartar in water-gruel, taken for feveral days, will abate the pains and fwellings confiderably by its acidity, correcting the alkaline falts of the blood.

Cheyne fays, that the hot and inflammatory rheumatisms have all the symptoms of the gout, and, like it, change from place to place, and by over violent evacuations may be tranflated upon the noble organs.

RHEXIA, in botany, a genus of the octandria-monogynia clafs of plants, the corolla whereof confifts of four roundifh patent petals inferted into the calyx; the fruit is a roundifh capfule, formed of four valves, containing four cells, and inclofed in the belly of the cup; the feeds are roundish and numerous. RHEXIS, among oculifts, denotes a rupture of the cornea of the eye. See the article EYE.

RHIME, in poetry. See RHYME.、 RHINANTHUS, YELLOW-RATTLE, in botany, a genus of the didynamia-angiofpermia clats of plants, the corolla whereof is a ringent lingle petal; the tube is almoft cylindric, and of the length of the cup; the limb is dehifcent, and compreffed at the bafe; the upper lip is galeated, compreffed, emarginated and narrow; the lower one is patulous, plane and femitrifid: the fruit is an orbiculated, erect, compreffed, bilocular and bivalved capfule: the fecds are numerous and compreffed.

RHINE, a great river rifing in the country

of the Grilons, in Switzerland, and, running north, continues its courfe till it forms the lake of Conftance; from whence it turns weft, and having visited Bafil, runs north, dividing Suabia from Alfatia; from thence it runs through the Palatinate, and receiving the Neckar, the Maine and the Mofelle, continues its

RHINE lower circle confifts of the Palatinate of the Rhine and the three ecclefiaftical electorates, viz. those of Cologn, Mentz, and Triers.

RHINE upper circle confifted of the Landgraves of Alfatia and Heffe, comprehending the Wetteraw: but only Heffe can be accounted a part of Germany at prefent, Frauce having united Alface to that kingdom.

RHINEBURG, a town of Germany, in the circle of the lower Rhine and electorate of Cologn, fituated fifteen miles east of Gelder.

RHINEFIELD, the name of two towns of Germany, one whereof is fituated in the circle of Suabia, on the Rhine, eight miles east of Bafil; the other is the capital of the county of Rhinefield, fituated in the circle of the Upper Rhine, fixteen miles north-west of Mentz. RHINE-LAND-ROD, in fortification, &c. a measure of two fathoms, or twelve feet, ufed by the Dutch and German engineers, &c.

RHINOBATUS, in ichthyology, a fpecies of the raja, with only a fingle row of prickles in the middle of the back. See the article RAja,

RHINOCEROS, in zoology, an order of the jumenta, having eleven fore-teeth in each jaw; there are no canine teeth; the nofe is ornamented with a fingle or double horn, which is permanent. This, of all quadrupeds, approaches nearest to the elephant in fize, the body being nearly as bulky, but the legs much fhorter. A full grown rhinoceros is fourteen feet high, and the legs are fo fhort with all this height, that the belly comes near the ground; the head is very large and oblong, of an irregular figure, broad at top and depreffed towards the fnout; the ears resemble thofe of a hog: the eyes are very fmall, and fituated at a fmall distance from the extremity of the fnout : on the upper part of the fnout, near the extremity, ftands the horn, growing to about two feet and a half in length, bent a little back, of a black colour, and vaftly firm and hard: the fkin is remarkably thick and hard, fo that the

creature could not turn its body in any direction but for the joints and folds in it: the tail is short, and furnished with fome long and extremely thick black hairs. See plate CCXXXII. fig. 2, which reprefents a young rhinoceros with a fhort obtufe horn; there being fome fpecies which have the horn much longer. RHINOCEROS BIRD, a large bird about the fize of the european raven, which it greatly refembles: it is fo called from a true horn, which, rifing from the root of the heak, bends upwards. See plate CCXXXII. fig. 6.

There are other two varieties of this horn brought from the East-Indies, all belonging to different fpecies of hydrocorax. See HYDROCORAX. RHIZOPHORA, in botany, a genus of the dodecandria-monogynia clafs of plants, called, by Plumier, mangles: the flower is erect, being compofed of a single petal, divided into four fegments; the feed is fingle, very long, and of a clavated figure, pointed at the end.

RHODES, the capital of an island of that

name, fituated in the Mediterranean-fea, in east long. 28°, and between 30° and 37° north lat.

RHODIOLA, or RHODIA, in botany, a genus of the polygamia-dioecia clafs of plants, which produces two kinds of flowers, viz. hermaphrodite and female ones; both which are composed of four petals, only much longer in the hermaphrodite than in the female flowers: the fruit confifts of four corniculated capfules, containing numerous round:fh feeds. RHODIUM LIGNUM, RHODIAN WOOD, in botany, the fame with afpalathus. See the article ASPALATHUS. Jamaica affords a wood, called, by the people there, rofe-wood; which, though n the rhodium of the fhops, has nevertheless much of its fmell: it is described by Sir Hans Sloane to be a tree growing to twenty or more feet in height, and thick enough to afford the largest segments we ever meet with of it; and poffibly an adulteration of the true rhodium with this wood may be the true caufe why the rhodium is not allowed to be the root, but a fpecies of cytifus, as Hoffman affirms.

The flowers of the Jamaica rofe-wood are fmail and white, confifting of three petals, and ftanding in clusters: the fruit is a berry of the size of a pepper corn; and the leaves of the tree are pinnated. RHODODENDRUM, in botany, a genus

of the decandria - monogynia clafs of plants, the calyx of which is a permanent perianthium, divided into five fegments; the corolla is a wheel haped, funnelfhaped, fingle petal: the fruit is an oval angular capfule, containing five cells, in which are a great many very small feeds. RHODON, in pharmacy, an appeliation given to several compofitions, on account of roles being the chief ingredient in them; as the diarrhodon, rhodofaccia. rum, &c. See DIARRHODON and Rose. RHOMBOIDES, in geometry, a quadrilateral figure whofe oppofite fides and angles are equal, but is neither equilateral nor equiangular; as the figure NOPQ, plate CCXXXII. fig. 5.

RHOMBOIDES, in anatomy, a thin, broad, and obliquely quare A thy muscle, fituated between the basis of the feapula and the fpina dorfi; fo called from its figure. Its general ufe is to draw, backward and upward, the fubfpinal portion of the bafis fcapulæ.

RHOMBOIDIA, in natural history, the name of a genus of fpars, given them from their being of a rhomboidal form. They owe this figure to an admixture of particles of iron, and confift of fix planes. Of this genus there are only two known fpecies. 1. A white, thin one, with very thin crufts; and, 2. A whitish brown thick one, with thicker crufts. These are both found in the foreft of Dean in Gloucestershire, and in other places where there are iron ores.

RHOMBUS, in geometry, an obliqueangled parallelogram, or a quadrilateral figure whole fides are equal and parallel, but the angles unequal, two of the oppofite ones being obtufe, and the other two acute, as ABCD, plate CCXXXII. fig. 4.

To find the area of a rhombus, upon CD, affumed as a bafe, let fall the perpendicular Ae, which is the altitude of the figure; then multiply the bafe by the altitude, the product will be the area. RHOMBUS, the PEARL FISH, in ichthyology, a fpecies of pleuronectes, with the eyes on the left fide: it is a moderately large fpecies, but is not fo thick and Behy as the turbot, nor is its flesh fo well talted. See the articles PLEURONECTES and TURBOT.

RHONE, one of the largest rivers in France, which rifing in one of the Alps of Switzerland, pafles through the lake of Geneva, vifits that city, and then runs fouth-west to Lyons, where joining 16 E a

the river Soane, it continues its course due fouth, paffing by Orange, Avignon, and Arles, and falls into the Mediter ranean a little weftward of Matfeilles. RHOPALIC VERSES, in antient poetry, a kind of verfes, which beginning with monofyllables, were continued in words growing gradually longer and longer to the last. RHOPOGRAPHI, in antiquity, painters who confined themfelves to low fubje&ts, as animals, plants, landskips, &c. Ste the article PAINTING. RHUBARB, rhabarbarum, in pharmacy, a thick root, of an oblong figure, large at the head, and tapering pretty fuddenly as it extends in length. It is fometimes fingie, but more ufually divided into two or three parts at the lower end, We frequently meet with it in pieces of four, five, or fix inches long, and three or four in diameter at the top; it is of a tolerably fmooth and even furface, and externally of a faint yellow colour, with a large admixture of brown; it is moderately heavy but not hard; it cuts through very freely and easily with a knife, especially if the blade of it has been rendered a little un&tuous fift, by drawing it over an almond or any other fatty fubftance, When fresh cut it is found to be of a marbled or variegated appearance; its colours are a pale but bright yellow, and a faint reddifh. The yellow is the ground-colour, and the red is difpofed in thort irregular veins, much in the manner of the darker colour in the common nutmeg. It is of a fomewhat lax and fpongy texture; it has an agreeable and aromatic fmell, and a bitterish, aftringent, and subacid taste, upon the whole not difagreeable: it tinges the fpittle to a fine bright yellow on being held fome time in the mouth. Rhubarb is to be chofen fresh, tolerably hard and moderately heavy, and fuch as does not duft the fingers in handling; fuch as infufed a few minutes in water gives it a fine yellow, and, when bruised in a mortar, has a reddish colour with the yellow. Rhubarb is not fo often adulterated as damaged; care is to be taken that it be not wet, nor rotten; much of it is fubject, after steeping too long, to be worm-eaten and full of holes on the furface. There are certain traders in this drug, who have a way of filling up thefe holes with the powder of fome of the worst and most decayed pieces; but this

is easily discovered, and fuch rhubarb ought always to be rejected.

The antients were not acquainted with the true rhubarb : their rhubarb appears to be the rheum, or raphontic plant which, tho' Linnæus makes it the fame with the rhubarb, is yet very different in quality if not in characters. See RHEUM. The rhubarb is brought to us from Ruffia, and from the Eaft Indies. It is produced in great plenty on the confines of China and Tartary, and in many parts of Tartary itself: the mountains of Tibet abound with it, and a very confiderable part of what is fent into Europe grows there.

It was long before the rhubarb was known in Europe, but of late it has been fent fram Ruflia to the gardens of Paris and Chelfea, in both which it thrives extremely well, and ftands the fevereft colds unhurt. Other authors make it the lepathum bardanæ folio undulato glabro: and as there are fufficient proofs that we now have the true rhubarb among us, it will be eafy to propagate a quantity of it, in order to try whether its virtues, when produced with us, will be the fame with tho e it poffeffes as brought from its native climate. See LAPATHUM. The root of the native rhubarb plant is long, thick, and perennial; its bark, while growing, is of a brownish red colour; but under this the fubftance of the root is of the true colour of dried rhubarb, only deeper, of the right nutmeggrain, marbled with red and yellow, and has the true smell and taste of rhubarb, especially about the upper part of the root: it has a vifcofity indeed in the mouth, tho' rhubarb, as we meet with it in the fhops, has not; but this may only be the difference of the faine root fresh and dried.

Rhubarb poffeffes the double virtue of a cathartic and an aftringent; it readily evacuates particularly the bilious hu mors, and afterwards gently aftringes and ftrengthens the stomach and inteftines, It is given with great fuccefs in all obftructions of the liver, in the jaundice, in diarrhoeas, and in the fluor albus and gonorrhoeas; it is alfo an excellent remedy againft worms. It is fometimes given as a purgative, fometimes as only an alterant; and, which ever way it is taken, it is an excellent medicine, agreeing with almost all ages and conftitutions. The only cafes in which its ufe is

to

to be avoided, are thofe in which the blood and vifcera are too hot. Fallopius fays it is never to be given to people who have disorders of the kidneys or bladder, as it is apt to occafion an extraordinary beat in thofe parts; and Simon Pauli tells us of vertigoes brought on by a too free and continued use of it.

Rhubarb is given in powder in infufion, and in its own crude folid ftate; the chewing it perhaps being the best way of giving it of all others, when it is intended to strengthen the ftomach and affift digeftion; the quantity of twentyfive grains, or thereabout, fhould be chewed daily on thofe occafions, an hour before eating; this is alfo by much the best way of taking it againft obftructions of the vifcera. Its dofe in powder is from half a fcruple to two fcruples; in infufion, about a drachm of it will purge gently; but the dofe may be increafed to two drachms. It is obfervable, that neither the infufion, nor the decoction, nor even the extract of rhubarb, purge near fo briskly as the root itself in powder.

The preparations of rhubarb in use in the fhops are, 1. The tincture in fpirit. 2. The tincture in wine: and, 3. The extract; though, the last is but little ufed.

Monk's RHUBARB, rhaponticum. See the article RHAPONTICUM.

White RHUBARB, a name given to mecho

acan. See the article MECHOACAN. RHUMB, RUMB, or RUM, in navigation, a vertical circle of any given place, or the interfection of fuch a circle with the horizon; in which laft fenfe thumb is the fame with a point of the compaís. See the article COMPASS. RHUMB LINE, loxodromia, is also used for the line which a fhip defcribes when failing in the fame collateral point of the compafs, or oblique to the meridians. Now that fuch rhumb-lines are spirals, which continually approach to the pole but never fall into it, as Abcdefg, plate CCXXXII. fig. 7. is evident for the following reafons. In any place on the furface of the globe, the rhumb running north and fouth, coincides with the meridian of that place; the east and west rhumbs are perpendicular to the meridian, and the other thumbs are oblique to it: but this obliquity is the fame under every meridian; and therefore all the rhumbs, except the north and fouth, cut the meridians at equal angles. When

right lines are parallel to each other, a right line will cut them at equal angles but not fo when they are inclined to one another therefore feveral inclining lines cannot be cut at equal angles, but by a curve line bending towards the place where thofe lines would meet. Now the meridians being inclined to each other, and meeting in the poles, the oblique thumbs must be curve-lines continually approaching the poles. But, in every latitude, an oblique rhumb runs between the prefent parallel and the pole; and a line cannot cut feveral other lines at equal angles in the fame point: confequently the rhumb-lines are spirals, which continually wind round the poles without ever falling into them.

Again, that thefe fpiral rhumbs, on the globe, are of the fame kind with the proportional fpiral, will appear hence: let PABC, &c. (ibid.) be the ftereogra phic projection of part of the fphere, on the plane of the equator; where ABC DEF is part of the equator; P the pole; PA, PB, PC, &c. are meridians; and the fpiral Abcdefg, one of the rhumbs. Now, in fuch a projection, the lines interfecting each other, form angles equal to the angles on the fphere which they reprefent: therefore the projection of the rhumb, Abcd, &c. cuts the radii, or meridians, PA, PB, PC, &c, at equal angles; and as this is a property of the proportional spiral, the spiral rhumbs mult be analogous to the proportional fpiral. Hence the differences of longitude AB, AC, AD, &c. are the logarithms of the intercepted parts of the meridians, Pb, Pc, Pd, &c.

RHUS, SUMACH, in botany, &c. the name given by Linnæus to a plant calJed COTINUS by other authors, and already defcribed under that name. See alfo the article SUMACH.

RHYME, RHIME, RYME, or RIME, in poetry, the fimilar found, or cadence and termination of two words which end two verfes, &c. Or rhyme is a fimilitude of found between the latt fyllable or fylJables of a verse, fucceeding either immediately or at a distance of two or three lines.

Rhymes are either single, double, or triple, though the two latt are much dif ufed. Single rhymes are divided into perfect or whole rhymes, and imperfe&t or half hymes. A whole or perfect rhyme is where there is a fimilitude of found without any difference: an imperf&

Thyme

shyme is where there is a fimilitude of found, with a difference either in respect of the pronunciation or orthography, but chiefly the former. Single rhymes are again divided into feminine and mafculine rhymes: the feminine rhyme is that where the last fyllable of the rhyme ends with an e mute and the mafculine rhymes are thofe of all other words. Double rhymes are thofe where two words terminate alike through the whole two last fyllables. Plain rhymes are those where the two rhyming verfes fucceed immediately to each other: and cross rhymes are thofe where the verses are fo difpofed as that the first rhymes with the third, and the fecond with the fourth,

There is no rule in poetry, fays Du Bos, whofe obfervance cotts fo much trouble, and is productive of lefs beauties in verfe, than that of rhyming. Rhyme frequently maims and almoft always enervates the fenfe of the difcourfe, for one bright thought which the paffion of hyming throws in our way by chance, is, without doubt, every day the caufe of a hundred others that people would blush to make ufe of were it not for the richness or novelty of the rhyme with which thefe thoughts a

attended.

And yet the allurement of rhyme has nothing in it worth comparing to the charms of numbers and harmony. The terminating of a fyllable with a particu lar found is no beauty in itself. The beauty of a rhymne is only a relative one, which confifts in a conformity of termination between the two Jaft or two correfponding verfes. This ornament therefore, which is of so short a duration, is perceived only at the end of two verses, and after having heard the laft word of the fecond verte, which rhymes to the firft. One is not even fenfible of this pleafure, but at the end of three or four verfes, if the mafculine and feminine rhymes are interwoven, fo that the first and fourth be masculines, and the fecond and third feminines: a mixture which is very much ufed in feveral kinds of poetry. But even in thofe verfes where the richness thereof difcovers itself at the end of the fecond verfe, it is the greater or leffer conformity between the two laft words of these verfes, which forms its elegance. Nor, for the most part, do people upon hearing the fecond rhyme, recal the first diftinctly enough to be charmed with their perfection. Their merit is known rather by reflection than

、

fenfation, fo trifling is the pleasure by which it tickles the ear. Numbers and harmony are a light which throws out a conftant luftre; but,rhyme is a mere flash, that difappears after having given only a fhort-lived fplendor. See the articles NUMBER, METRE, &c.

Rhyne owes its origin to the barbaroufnels of our ancestors. The people from whom the modern nations are defcended, and who fubverted the roman empire, had their poets, who being ignorant, and the languages in which they wrote not sufhciently improved to bear a handling according to the rules of metre, they fancied there would be fome ornament in terminating with the fame found two confecutive or relative parts of a discourse, both of which were to be of an equal extent. Thus, in all probability, it was that rhyme firft rofe in Europe. These new-born languages were not only forced to fubmit to the flavery of rhyming, but it paffed even to the latin tongue, the use of which was ftill retained by a particular fet of people. The practice of leonine verfe was introduced as early as the VIIIth century, and prevailed at the time the folJowing ones were made,

Fingitur hac fpecie bonitatis odore refertus, Ifius ecclefia fundator rex Dagobertus. Thefe leonine verses disappeared upon the rifing of that light, whole dawn appeared in the XVth century.

Since the reltoration of learning in the XVIth century, attempts have been made to banish rhyme out of the modern poetry, and to fettle the english and french verfes on the footing of the antient greek and latin ones, by fixing the quantities of fylJables and trufting wholly to thofe, and to the numbers and measure. This Milton has done with great fuccefs, and after him Philips, Additon, Thomfon, Young, and fome others. Verfes of this kind are called blank verfes. The French have attempted the fame, but not with equal fuccefs; which has convinced the world, that this kind of measure is inconfiftent with the french tongue.

RHYPTICS, puntua, in medicine, detergent remedies. See DETERGENTS. RHYTHM, ¡ubu, in mufic, the variety in the movement, as to the quickness or flowness, length or fhortness of the notes. Or it may be defined more generally, the proportion which the parts of the motion have to each other. See the next article. Ariltides, among the antient musicians, applies the word rhythmus three ways,