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CHRONOUS, is applied to such vibrations of dicate the doctrine of fluxions from the ima pendulum as are performed in the same putation of uncertainty or obscurity, has space of time, as all the vibrations or swings illustrated this subject, which is considered of the same pendulum are, whether the as one of the most abstruse parts of this docarches it describes be longer or shorter : trine, by giving the resolution and composifor when it describes a shorter arch it movestion of these problemas by first fluxions so much the slower, and when a long one only; and in a manner that suggests a synproportionably faster.

thetic demonstration, serving to verify the ISOCHRONAL line, that in which a heavy solution. See Maclaurin's Fluxions. Mr. body is supposed to descend without any Crane also, in the Berlin Memoirs for 1752, acceleration.

has given a paper in which he proposes to M. Leibi z shows, that an heavy body, demonstrate, in general, what can be dewith a degree of velocity acquired by the monstrated only of regular figures in the descent from any height, may descend from elements of geometry, viz. that the circle the same point by an infinite number of is the greatest of all isoperimetrical figures, isochronal curves, all which are of the same regular or irregular. We shall now mention species, differing from one another only in a few of the properties of isoperimetrical the magnitude of their parameters, such figures. are all the quadrato-cubical paroboloids, 1. Of isoperimetrical figures, that is the and consequently similar to one another. greatest that contains the greatest number He shows also there, how to find a line in of sides, or the most angles, and consewhich a heavy body descending shall recede quently a circle is the greatest of all figures uniformly from a given point, or approach that have the same ambit as it has. uniforinly to it.

2. Of two isoperimetrical triangles, hav. ISOETES, in botany, a genus of the ing the same base, whereof two sides of Cryptogamia Filices class and order. Na- one are eqnal, and of the other unequal, tural order of Filices, or Ferns. Essential that is the greater whose two sides are character: male, anther within the base of equal. the frond: female, capsule two-celled, with Of isoperimetrical fionres, whose si

sides in the base of the frond. There are two,

are two are equal in number, that is the greatest species, viz. I. lacustris, common quillwort, which is equilateral and equiangular. From and 1. coromandelina, Coromandel quillo hence follows that common problem of wort, both natives of mountain lakes, and

making the hedging or walling that will in wet places that are inundated in the

wall in one acre, or even any determinate rainy season.

number of acres, u; fence or wall in any ISOPERIMETRICAL figures, in geo.

greater number of acres whatever, b. In metry, are such as have equal perimeters, order to the solution of this problem, let or circumferences.

the greater number, b, be supposed a Isoperimetrical lines and figures have

square ; let x be one side of an oblong, greatly engaged the attention of mathema. ticians at all times. The fifth book of Pap- whose area is a; then will be the other pus's Collections is chiefly upon this subject; where a great varieiy of curions and side ; and 2 + 2 x will be the ambit of the important properties are demonstrated,

oblong, which must be equal to four times both of planes and solids, some of which were then old in his time, and many new the square root of b; that is, 2 +2 x = 4 ones of his own. Indeed, it seems, he has

b. Whence the value of x may be easily

, here brought together into this book all the

had, and you may make infinite numbers of properties relating to isoperimetrical figures

squares and oblongs that have the same then known, and their different degrees of

ambit, and yet shall have different given capacity. The analysis of the general pro

areas. blem concerning figures, that, among all those of the same perimeter, produce maxi

Let b=d ma and minima, was given by Mr. James Bernoulli, from computations that involve the second and third fluxions. And several

a + 2 xx = 2 dx enquiries of this nature have been since pro

2 xx — 2dx=secnted in like manner, but not always

x x - dx with equal success. Mr. Maclaurin, to vin.

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xx-dit: dd=

ITEA, in botany, a genns of the Pen. +dd tandria Monogynia class and order. Natu

ral order of Rhododendra, Jussien. EssenI=V - tddtd t ial character: capsule two-celled, twoThus if one side of the sqnare be 10; and valved, many-seeded; stigma emarginate. one side of an oblong be 19, and the other There are two species, viz. I. virginica. 1 ; then will the ainbits of that square and Virginian itea; and I. cyrilla, entire-leaved oblong be eqnal, viz. each 40, and yet the itea. These are both shrubs. Linnæus re. area of the square will be 100, and of the marks, that the itea virginica has the apoblong bnt 19. .

pearance of the Padus ; that the leaves are ISOPYRUM, in botany, a genus of the petioled and the flowers in terminating Polyandria Polygynia class and order. Na. racemes. The stigma is headed in this spetural order of Multisilique. Ranunculaceæ, cies, whereas in the other it is bifidor Jussien. Essential character: calyx none; double; the former is a native of North petals five; nectary trifid, tubular; cap- America; the latter of Carolina and Ja. snle recurved, many-seeded. There are maica. three species.

ITTRIA. This earth was discovered by ISOSCELES triangle, in geometry, one Gadolin, a Swedish chemist, in a fossil, found that has two equal sides. See GEOMETRY. at Ytterby, in Sweden, which has since re

ISSUE, in law, has many significations, ceived the name of gadolinite, and in which sometimes being used for the children be- it is combined with silex and lime. The gotten between a man and his wife; some discovery was confirmed by Ekeberg, Klaptimes for protit growing from amerce- roth, and Vauquelin; and the same earth ments or fines; and sometimes for profits of has been discovered in some other fossils lands or tenements ; sometimes for that particularly combined with lantalium. In point of matter depending in a suit, when, several of its properties ittria resembles in the course of pleading, the parties in the glucine, particularly in forming salts of a case affirm a thing on one side, and deny it sweet taste, and in being soluble in carboon the other, they are then said to be at nate of ammonia ; but it differs entirely in issue; all their debates being at last con- others. tracted into a single point, which may be. The process followed by Vauquelin to. determined either in favour of the plain- obtain this earth from the gadolinite was to tiff or defendant.

dissolve it, with the assistance of heat, in Issues, in surgery, are little ulcers made diluted nitric acid, pouring off the solution designedly by the surgeon in various parts from the nndissolved silex. The liquor is of the body, and kept open by the patient then evaporated to dryness by which any for the preservation or recovery of his remaining silex and any oxide of iron is health.

separated from combination with the aITCH, a cutaneous disease, snpposed to eid. By redissolving the residuum in wabe caused by an insect, a species of the ter, the compound of nitric acid and ittria genus Acarus, riz. A. scabiei, whicl, when is obtained : if there are any traces of viewed by a good microscope, is white with iron, the liquor is either again evaporated reddish legs ; the four hind ones having a to dryness or a little ammonia is added ; long bristle. It is found in the small pellu- and after the separation of the oxide ot cid vesicles with which the hands and iron by yellow flakes, the solution is de. joints of persons infected with the itch are composed by ammonia, which precipitales covered. It appears to be not only the the new earth. (Philosophical Magazine, cause of the disorder, but the reason why it vol. viii. p. 369.) The process employed is so highly infectious.

by Klaproth is similar ; vitro-muriatic acid ' ITCHING, an uneasy sensation, which being employed; the iron being remov. occasions a desire of scratching the place ed by the action of succinate of soda; affected. It is frequently a troublesome and the ittria being precipitated by carbosensation, but more nearly allied to plea- nate of soda. (Analytical Essays, vol. ii. sore than pain. As pain is supposed to p. 47.) proceed from too great an irritation, so Ittria is obtained in the form of a white does itching proceed from a slight one. powder, and is heavier than any other Certain species of itching excites people to earth; its specific gravity according to many necessary actions, as the excretion of Ekeberg being 4.849. It is not fusible the feces and urine; coughing, sneezing, &c. alone, but with borax it forms a white glass, It is not soluble in water, but it retains conchoidal ; its hardness is such that it is that fluid with considerable force.

not scratched by the knife; ils specific Ittria combines with the acids; its salts, gravity is 4.2. It intumesces before the as lias been remarked, having generally a blow-pipe, but is not fused. With nitric sweetish taste. Several of them, too, are acid it forms a gelatinous solution. Accord. coloured, a property in which it differs ing to Klaproth it consists of ittria 59.75, from all the other earths.

silex 21.25, oxide of iron 17.5, argil 0.5, The sulphate of ittria crystallizes in water 0.5. The analysis of it by Ekeberg small brilliant grains, according to Klap- and Vauquelin give the proportion of ittria roth, of a rhomboidal form, and of a colour rather less, and of silex and iron somewhat inclining to an amethyst red. Their taste more. is sweet, becoming also astringent. They IVA, in botany, a genus of the Monoecia require from twenty-five to thirty parts of Pentandria class and order. Natural order water, and are not more soluble in hot wa- of Compositæ Nucamentaceæ. Corymbiter. Their specific gravity is 2.79. The feræ, Jussieu. Essential character : male, sulphuric acid is expelled by a red heat. calyx common, three-leaved; corolla of the Nitrate of ituria can scarcely be crystal. disk, one-petalled, five-cleft ; receptacle lized; it assumes a gelatinous consistence with hairs or linear chaffs : female, in the by evaporation, and becomes brittle when ray, five, or fewer; corolla none; styles this jelly cools. Its taste is similar to that two, long ; seeds naked, blunt. There are of the sulphate. The muriate is obtained two species, riz. I. annua, annual iva; and nearly in the same form. The phosphate I. frutescens, shrubby iva, or bastard Je. formed by complex affinity is insoluble. suits' bark tree. The acetite is a crystallizable salt of a pale JUBILEE, a time of public and solemn red colour.

festivity among the ancient Hebrews. This The salts of ittria are decomposed by the was kept every fiftieth year: it began about three alkalies, and by lime, astrontites, and the autumnal equinox, and was proclaimed barytes.

by sound of trumpet throughout all the Ittria is not dissolved by the liquid alka- country. At this time all slaves were relies, por do they redissolve it when added leased, all debts annihilated, and all lands, in excess, after having precipitated it from houses, wives, and children, however alieits solutions. This affords a distinguishing nated, were restored to their first owners. character between it and glucine. It is so. During this whole year all kind of agricul. luble in the alkaline carbonates, particu- ture was forbidden, and the poor had the larly in the carbonate of ammonia.

benefit of the barvest, vintage, and other Prussiate of potash throws down from its productions of the earth, in the same man. solution a granular precipitate, of a white ner as in the sabbatic, or seventh year, or pearl-grey colour. It is also precipitated As this was designed to put the Israelites in grey flocculi by the watery or spirituous in mind of their Egyptian servitude, and to infusion of galls; but very slightly by the prevent their imposing the like upon their pure gallic acid. It is not affected by sul brethren, it was not observed by the genpburetted hydrogen, or hydro-sulphuret of tile proselytes. ammonia added to its solutions.

The Christians, in imitation of the Jews, The great specific gravity of this earth, have likewise established jubilees, which its forming coloured salts, and being preci- began in the time of Pope Boniface VIII. pitated by the alkaline prussiates, and by in the year 1300, and are now practiseal tannin, from its solutions, in some mea every twenty-five years; but these relate stre connect it with the metals, and lead only to the pretended forgiveness of sins. to the suspicion that it may be a metallic and the indulgencies granted by the church oxide.

of Rome. The gadolinite is the only fossil that can JUDGE. The judges are the Muief ma. be considered as belonging to the genus of gistrates in the law, to try civil and criminal which this earth is the base, for the yttro causes. Of these there are twelve in Eng. tantalite contains it in small quantity only, land, riz. the Lord's Chief Justices of the and is properly a metallic fossil belonging Courts of King's Bench and Common Pleas: to the gems Tantalium. The gadolinite the Lord Chief Baron of the Exchequer. occurs massive, and disserpinated its colour; the three paisne or inferior judges of the is a deep greenish black. its internal lustre two former coasts, and the three puisne is resplendent, it is opaque; its fracture is barons of the latter. By statute 1 Ge. IL. c. 23, the judges are to continue in only intermediate, and doth not finally detheir offices during their good behaviour, termine or complete the suit; as upon dila. notwithstanding any demise of the crown tory pleas, when the judgment in many (which was formerly held immediately to cases is that the defendant shall answer vacate their seats) and their full salaries are over, that is, put in a more substantial plea. absolutely secured to them during the con- Final judgments are such as at once pnt an tinuance of their commissions, by which end to the action, by declaring that the means the judges are rendered completely plaintiff hath either entitled himself, or hath independent of the king, bis ministers, or not, to recover the remedy he sues for. his successors. A judge at his creation JUGLANS, in botany, walnut tree, a takes an oath that he will serve the king, genus of the Monoecia Polyandria class and and indifferently administer justice to all order. Natural order of Amentaceæ. Tere. men, without respect of persons, take no biutaceæ, Jussien. Essential character: bribe, give no counsel where he is a party, male, calyx one-leafed, scale-form ; corolla nor deny right to any, though the king or six-parted ; filaments eighteen: female, ca. any other, by letters, or by expressed words, lyx four-cleft, superior; corolla four-parted; command the contrary, &c. and in default styles two; drupe with a grooved nucleus. of duty, to be ans verable to the king in There are eight species, of which J. regia, body, land, and goods. Where a judge common walnut, is a very large and lofty has an interest, neither he nor his deputy tree, with strong spreading boughs. There can determine a cause, or sit in court, and are several varieties, but they all vary again if he do, a prohibition lies.

when raised from the seed, and nuts from Judges are punishable for wilful offences the same tree will produce different fruit : againt the duty of their situations; instances persons, therefore, who plant the walnut of which bappily live only in remembrance. for its fruit should make choice of the trees

A judge is not answerable to the king, or in the nurseries when they have their fruit the party, for mistakes or errors in his jndg- upon them. In France, Switzerland, &c. ment, in a matter of which he has jurisdic. the wood is in great request for furniture, tion.

as it was formerly in England, till the use JUDGMENT, among logicians, a faculty of mahogany superseded it; it is in great or rather act of the human soul, whereby it repute with the joiner, for the best grained compares its ideas, and perceives their and coloured wainscot; with the gun-smith, agreement or disagreement.

for stocks; with the coach-maker, for wheels JUDGMENT. The opinion of the judges and the bodies of coaches; with the cabinet. is so called, and is the very voice and final maker, for inlayings, especially the firm and doom of the law; and, therefore, is always close timber abont the root, which is adtaken for unquestionable truth; or it is the mirable for flecked and cambleted works. sentence of the law pronounced by the To render this wood the better colonred, court upon the matter contained in the joiners put the boards into an oven after record. Judgments are of four sorts, riz. the batch is out, or lay them in a warm 1. Where the facts are confessed by the stable ; and when they work it, polish it parties, and the law determined by the over with its own oil very hot, which makes court, which is termed judgment by de. murrer. 2. Where the law is admitted by the more estimable. The husks and leaves the parties, and the facts only are disputed, being macerated in warm water, and the as in judgment upon a demarrer. 3. Where liquor poured on grass walks and bowling. both the fact and the law arising thereon greens will infallibly kill the worms, withiare admitted by the defendant, as in case out endangering the grass. Not that there of judgment by confession or default. 4. is any thing peculiarly noxions in this decocWhere the plaintiff is convinced that fact tion; but worms cannot bear the applicaor law, or both, are insufficient to support tion of any thing bitter to their bodies, his action, and therefore abandons or with which is the reason that bitters, such as draws his prosecution, as in case of judg- gentian, are the best destroyers of worms ment upon a nonsnit or retraxit. See WARlodged in the bodies of animals. RANT of ATTORNEY.

JUGULAR, in anatomy, an appellation Judgments are either interlocutory or given to two veins of the neck, which arise final. Interlocutory judgments are such as from the subclavians. See ANATOMY. are given in the middle of a cause, upon JUGULARES, in natural history, an some plea, proceeding, or default, wlich is order of fishes according to the Linnæan system. The fishes of this order have their emarginate; antenne moniliform; two ventral bus situated before the pectoral feelers, filiform; body long, semi-cylindri. fins, and, as it were, under the throat. They cal, consisting of numerous transverse seg. are mostly inhabitants of the sea. Their ments; legs numerous, twice as many on body is sometimes covered with scales, each side as there are segments of the body, and sometimes not. With a very few ex There are fourteen species, of which we ceptions, they have spines in the dorsal and shall notice the J. indus, or great Indian anal fins, and their gills have bony rays. Of julus, which is six or seven inches long; this order there are the following genera: found in the warmer parts of Asia and Blenniuz Kurtus

America, inhabiting woods and other retir

ed places. It has 115 legs on each side, Callyonimus Trachinus

the body is ferruginous; legs yellow; the Gadus Uranoscopus.

last segment of the body is pointed. The JULIAN period, in chronology, a system most common species is the J. sabulosus, or period of 7980 years, found by multi- about an inch and a quarter lung; the co. plying the three cycles of the sun, moon, lour brownish black, except the legs, which and indiction into one another. See CHRO- are pale or whitish; it is an oviparous ani. NOLOGY.

mal; and the young when first hatched are This period was called the Julian, not be small and white, and furnished with only cause invented by Julius Cæsar; since the three pair of legs, situated near the head, Julian epocha was not received till the the remaining pairs, in all 120, do not make year 4669, but because the system consists their appearance till some time after. This of Julian years. This epocha is not his species inhabits Europe, and is found in torical bnt artificial, being invented only damp places and in nuts. The juli tribe for the use of true epochas; for Scaliger are nearly allied to the scolopendre, or considering that the calculation was very centipedes, but their body instead of being intricate in nsing the years of the creation, flattened, as in those insects, is nearly cy. the years before Christ, or any other lindrical, and every joint or segment is fur. epocha whatever, in regard that another nished with two pair of feet, the nnmber on person could not understand what year this each side doubling that of the segments, or that writer meant; to remove such but in the scolopendræ the number of joints doubts in the computation of time, he and of feet is equal on each side. The eyes thought of this period : which commencing of the juli are composed of hexagonal con. 710 years before the beginning of the world, vexities, as in most of the insect tribe, and the various opinions concerning other the mouth is furnished with a pair of den. epochas may commodiously be referred to ticulated jaws. When disturbed the juli roll it. See EPOCHA.

themselves up into a flat spiral: their geneThe most remarkable uses of the Jnlian ral motion is rather slow and undulatory. period are as follow: 1. That we can ex- JUNCUS, in botany, rush, a genus of the plain our mind to one another, for every Hexandria Monogynia class and order. Na.' year in this period has its peculiar cycles, tural order of Tripetaloideæ. Janci, Juswhich no other year in the whole period sien. Essential character; calyx six-leaved ; bas; whereas, on the contrary, if we reckon corolla none; capsule one-celled. There by the years of the world, we must first en- are twenty-nine species. The rushes have quire how many years any other reckons a simple grassy stem, without leaves of from the creation to the year of Christ, knots, or else knotty, with a sheathing leat which multiple-inquisition is troublesome at each knot; flowers terminating or lateand full of difficulties, according to the ral, coryinbed or panicled, with the branch. method of other periods. 2. That the three lets spathaceows at the base. cycles of the sun, moou, and indiction, are These plants agree with the grasses in easily found in this period. 3. That if it the glumes of their flowers, and the sheaths be kpown how the chronological characters of their leaves ; they differ in having the are to be found in this period, and how the stems filled with pith, whereas in grasses it years of any other epocha are to be con- is hollow. The rushes form an intermediate nected with the years of it, the same cha- link between the grasses and some of the racters also may, with little labour, be ap- liliaceous plants, as anthericum, &c. plied to the years of all other epochas. They form naturally two divisions, one

JULUS, in natural history, a genus of in- without leaves allied to scirpus, &c. and sects of the order Aptera. Lip crepate, the other with leafy stems. But all classical

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