was imported among timber used in re- CIMICIFUGA, in botany, a genus of the Polyandria Tetragynia class and order. Natural order of Multisiliquæ. Papaveracex, Jussieu. Essential character; calyx four or five-leaved; nectary four, urceolate; capsule four to seven. There is but one species; viz. C. fætida, a native of the distant parts of Siberia, flowering in July, and ripening its seeds in August. The whole plant has a strong virose smell, occasioning the head-ach. To this genus Pursh has referred Actea Racemosa, or black snake-root; called also rich-weed, cattle-weed, and squaroot. It is one of the medicines of the Indians of our country. CIMOLITE, in mineralogy, is of a light greyish white, inclining to pearlgrey; but by exposure to the air it acquires a reddish tint. It occurs in mass, forming large strata; its fracture is earthy, uneven, and its texture more or less slaty. It is opake, of a greasy lustre, and may be scraped with a knife. It adheres firmly to the tongue, stains the fingers in some degree, and, though soft, is very tough, and pulverized with difficulty. The specific gravity 2.0. When exposed to the action of the blow-pipe, it becomes at first of a dark grey colour; but afterwards recovers its whiteness with little or no alteration: with borax it forms a light brown glass. Its component parts are, Silex CIN dria Monogynia class and order. Natural order of Contorta. Rubiaceæ, Jussieu. There are nine species. See BARK. been supposed that a principle, analogous CINCHONIN, in chemistry: it has bles, particularly in the Peruvian bark : to animal gelatine, exists in some vegetathis has been denominated cinchonin. In this principle it has been supposed that the febrifuge power of the bark resided.· and some have gone so far as to recommend animal glue as a substitute for bark. CINERARIA, in botany, a genus of the Syngenesia Polygamia Superflua class Discoidea. Corymbiferæ, Jussieu. Esand order. Natural order of Compositæ leaved, equal; pappus simple; receptasential character; calyx simple, many cle naked. There are forty-one species, most of them natives of the Cape of Good Hope. CINNA, in botany, a genus of the Monandria Digynia class and order. Natural calyx glume two-valved, one-flowered; order of grasses. Essential character: corolla glume two-valved; seed one. nacea, a native of Canada, and many parts There is but one species, viz. C. arundiof the United States. of the genus Mercury, of which there CINNABAR, in mineralogy, a species are two sub-species, viz. the dark red, massive, disseminated, in blunt cornered and the bright red. The former occurs pieces, in membranes, amorphous,dendritic, and fruticose; it occurs also crystallized. The specific gravity is from 7 to 10, and the constituent parts are 63.00 Alumina 23.00 Oxide of iron 1.25 12.00 100 99.25 It abounds in the island of Cimola, and was in great request by the ancients for its detergent properties; at present its use is almost entirely confined to the inhabitants of the island. It produces the same effects as fuller's earth, but in a higher degree. CINCHONA, in botany, so named in honour of the Countess del Cinchon, lady of a Spanish viceroy, whose cure is said first to have brought the Peruvian bark into reputation, a genus of the Pentan Before the blow-pipe it is completely smoke which has the odour of sulphur. volatalized, giving a blue flame, and a Both species are found in Bohemia, Hungary, Transylvania, and many other parts mercury mines are those of Almadin in of the continent; but the most important Spain, which have been worked upwards that the greatest quantity of the mercury of two thousand years. It is from this ore of commerce is obtained. It is used also as a pigment, but not by any means equal to the artificial cinnabar. See the next article. CINNABAR, in chemistry, is a sulphuret of mercury, and is prepared by mixing one part of sulphur with seven or eight of mercury, and by applying such a heat as to make them combine. The black powder which they form is then exposed to heat sufficient to produce inflammation; after which the remaining mass is sublimed in close vessels. The sublimate is mercury in combination with sulphur: it is of a very fine red colour, and when levigated, is in common use as a pigment, under the name of cinnabar or vermilion. CINNAMON is the bark of the laurus cinnamomum, indigenous in some of the Eastern Islands, but an inferior kind, taken from the laurus cassia, is often sold for or mixed with it. Cinnamon is most grateful, aromatic, highly pungent, and yields a very fine cordial. The bark is used in many culinary preparations, and is generally taken from the tree by making an incision on the under side for the whole length of the branch, which causes the bark to curl, and to separate itself, almost voluntarily, when acted upon by the sun's heat. That from the smaller twigs is accounted the best: it should be thin, very brittle, and very hot to the tongue. What we use is the inner bark; the exterior rind being of no value. CINNAMON stone, in mineralogy, a species of the genus Zircon, found at Columbo, in the island of Ceylon. It is known in Holland under the name of kanelstein, which signifies cinnamon stone, probably from its resemblance in colour to that spice. CINNAMON tree. See LAURUS CINNA MOMUM. CINQUE PORTS, five havens that lie on the east part of England, towards France, thus called by way of eminence, on account of their superior importance, as having been thought by our kings to merit a particular regard for their preservation against invasions. Hence they have a particular policy, and are governed by a keeper, with a title of the lord warden of the Cinque Ports, which office belongs to the constable of Dover; and their representatives are called Barons of the Cinque Ports. They have various franchises, similar, in many respects, to those of the counties palatine, and particularly an exclusive jurisdiction before the mayor and jurats of the port, their warden having the authority of an admiral among them, and sending out writs in his own name; and the king's writs do not run there. However, on a judgment in any of the king's courts, if the defendant hath no goods, &c. except in the ports, the plaintiff may get the records certified into chancery, and from thence sent by mittimus to the lord warden to make execution. The Cinque Ports, it has been observed, are not "jura æqualia," like counties palatine, but are parcel of the county of Kent, so that if a writ be brought against one for land within the Cinque Ports, and he appears and pleads to it, and judgment is given against him in the Common Pleas, this judgment shall bind him, for the land is not exempted out of the county, and the tenant may wave the benefit of his privilege. These five ports are, Dover, Hastings, Romney, Hythe, and Sandwich; to which Winchelsea and Rye have been since added. CIPHER. See CYPHER. CIRCEA, in botany, a genus of the Diandria Monogynia class and order. Natural order of Aggregate. Onagræ, Jussieu. Essential character: corolla twopetalled; calyx two-leaved, superior; seed one, two-celled. There are two species; viz. C. lutetiana, common enchanter's nightshade, and C. alpina, mountain enchanter's nightshade. Both are natives of the United States. CIRCLE, the name of various astrononomical instruments for observing right ascensions, declinations, azimuths, altitudes, and likewise for the purposes of the most improved theodolite. Plate "Circular Instrument" is a representation of an instrument made by Mr. Troughton, and of which he liberally permitted our draughtsman to take a drawing. It is an instrument which measures both horizontal and vertical angles with great accuracy, and is equally adapted for astronomical purposes and surveying. The instrument is supported on three screws, two of which, x, y, are shewn in the figure; the three arms through which these pass meet in the centre, and hold a strong, vertical steel axis, truly turned, and very exactly fitted into two sockets, one at the top and the other at the bot. tom of a cone, A: upon this axis the upper part of the instrument turns. Bis the azimuth circle, laying upon the three arms of the tripod, and capable of turning round on the steel axis before mentioned: it is held by a screw, g, which moves the circles slowly round when turned: this motion is to adjust the circle, so that the plane of the vertical circle, P, shall be in the meridian when the index is set to zero. The circle is divided into degrees and every five minutes, and the microscope subdivides them into seconds. Another similar microscope is fixed diametrically opposite, upon the circular plate H, and turns round upon the vertical axis with the rest of the instrument. (For the constructions of these microscopes, see that article.) I, I, are two hollow conical pillars, screwed on the index plate to support the axis of the vertical circle, P, by means of two bars (one only of which can be seen, h,) screwed at the top of the pillars, and holding at their outer ends tubes, which contain angular bearings for the pivots of the axis: these bearings, or Y's, as they are called, from resembling that letter, can be elevated or depressed by screws e, beneath them, to bring the axis parallel to the plane of the azimuth circle. m, m, are two crooked hollow tubes, screwed to the upright pillars, holding two microscopes, n, n, reading divisions diametrically opposite to each other on the vertical circle P. The vertical circle is composed of two circles, each cut from a solid plate, and attached to two flanches on a hollow conical axis E; they are firmly braced together by short pillars, as in the figure; between the circles the telescope F is fixed, it is 30 inches long and 2 in diameter. Ois a thin plate of metal, screwed to the further main pillar, I, by its lower end, and its upper end supporting a clamp for fixing the circle, when set at any elevation, and a screw for moving it slowly a small quantity after clamping. Asimilar screw, for occasionally attaching the index plate, I, to the azimuth circle, B, is seen at p. a is a small roller pushed upwards by a spring, I: it acts against a ring upon the conical axis E, and its use is to support part of the weight of the circle and telescope, and take the bearing from the pivots at the end of the axis. R is a spirit level hung to the two horns m, m, and adjustable by a screw at its end. S is a telescope beneath the instrument, which is set to any distant object when the instrument is in use, and serves to shew that the instrument does not change its position. See OBSERVATORY and SUR VEYING. CIRCLE, in geometry, a plane figure comprehended by a single curve line, called its circumference, to which right lines or radii, drawn from a point in the middie, called the centre, are equal to each other. The area of a circle is found by multiplying the circumference by the fourth part of the diameter, or half the circumference by half the diameter: for every circle may be conceived to be a polygon of an infinite number of sides, and the semidiameter must be equal to the perpendicular of such a polygon, and the circumference of the circle equal to the periphery of the polygon : therefore half the circumference multiplied by half the diameter gives the area of the circle. Circles, and similar figures inscribed in them, are always as the squares of the diameters; so that they are in a duplicate ratio of their diameters, and consequently of their radii. A circle is equal to a triangle, the base of which is equal to the periphery, and its altitude to its radius: circles therefore are in a ratio compounded of the peripheries and the radii. To find the proportion of the diameter of a circle to its circumference. Find, by continual bisection, the sides of the inscribed polygon, till you arrive at a side subtending any arch, however small; this found, find likewise the side of a similar circumscribed polygon; multiply each by the number of the sides of the polygon, by which you will have the perimeter of each polygon. The ratio of the diameter to the periphery of the circle will be greater than that of the same diameter to the perimeter of the circumscribed polygon, but less than that of the inscribed polygon. The difference of the two being known, the ratio of the diameter to the periphery is easily had in numbers, very nearly, though not justly true. Thus Archimedes fixed the proportion at 7 to 22. Wolfius finds it as 10000000000000000 to 31415926535897932: and the learned Mr. Machin has carried it to one hundred places, as follows: if the diameter of a circle be 1, the circumference will be 3,14159, 26535, 89793, 23846, 26433, 83279, 50288, 41971, 69399, 37510, 58209, 74944, 59230, 78164, 05286, 20899, 86280, 34825, 34211, 70679 of the same parts. But the ratios generally used in practice are that of Archimedes, and the following; as 106 to 333, as 113 to 355, as 1702 to 5347, as 1815 to 5702, or as 1 to 3.14159. CIRCLE, the quadrature of the, or the manner of making a square, whose surface is perfectly and geometrically equal to that of a circle, is a problem that has employed the geometricians of all ages. Many maintain it to be impossible; Des Cartes, in particular, insists on it, that a right line and a circle being of different natures, there can be no strict proportion between them: and in effect we are at a loss for the just proportion between the diameter and circumference of a circle. re Archimedes is the person who has come nearest the truth; all the rest have made paralogisms. Charles V. offered a ward of 100,000 crowns to the person who should solve this celebrated problem; and the States of Holland have proposed a reward for the same purpose. CIRCLE, great, of the sphere, that which, having its centre in the centre of the sphere, divides it into two equal hemispheres; such are the equator, ecliptic, horizon, the colures, and the azimuths, See EQUATOR, ECLIPTIC, &c. &c CIRCLE, lesser, of the sphere, that which, having its centre in the axis of the sphere, divides it into two unequal parts: these are usually denominated from the great circles to which they are parallel, as parallels of the equator. CIRCLE of curvature, a circle, the curvature of which is equal to that of a certain curve at a given point. CIRCLE, horary, on the globe, a brazen circle fixed on every globe, with an index, to shew how many hours, and consequently how many degrees, any place is east or west of another. CIRCLE of perpetual apparition, one of the lesser circles, parallel to the equator, described by any point touching the northern point of the horizon, and carried about with the diurnal motion: all the stars included within this circle are always visible above the horizon. CIRCLE of perpetual occultation, another circle at a like distance from the equator, on the south, containing all those stars which never appear in our hemisphere. CIRCLES, diurnal, are immoveable circles, supposed to be described by the several stars and other points of the heavens, in their diurnal rotation round the earth; or, rather, in the rotation of the earth round its axis. CIRCLES of latitude, or secondaries of the ecliptic, are great circles perpendicular to the plane of the ecliptic, passing through the poles of it, and through every star and planet. They serve to measure the latitude of the stars, which is an arch of one of those circles intercepted between the star and the ecliptic. CIRCLES of longitude, are several lesser circles parallel to the ecliptic, still diminishing in proportion as they recede from it; on these the longitude of the stars is reckoned. CIRCLES of declination, on the globe, are, with some writers, the meridians on which the declination or distance of any star from the equinoctial is measured. CIRCLES, horary, in dialling, are the lines which shew the hours on dials, though these be not drawn circular, but nearly straight. CIRCLES, polar, are parallel to the equator, and at the same distance from the poles that the tropics are from the equator. See ARCTIC. CIRCLES of position, are circles passing through the common intersections of the horizon and meridian, and through any degree of the ecliptic, or the centre of any star, or other point in the heavens; and are used for finding out the situation or position of any star. CIRCLES, Druidical, a name given to certain ancient inclosures, formed by rude stones circularly arranged. These, it is supposed, were temples, or places for solemn assemblies for councils, or seats of judgment. These temples, though generally circular, occasionally differ in magnitude. The most simple were composed of one circle. Stonehenge consisted of two circles and two ovals, respectively concentric. One near St. Just, in Cornwall, is formed of four intersecting circles. In magnitude these differ very much : : some are formed of only 12 stones, while others, as Stonehenge and Abury, contained, the first 140, and the second 652, and occupied many acres of ground. These different numbers, measures, and arrangements, are supposed to have had reference, either to the astronomical divisions of the year, or some mysteries of the Druidical religion. CIRCUIT, in electricity, denotes the course of the electrical fluid from the charged surface of an electric body to the opposite surface on which the discharge is made. CIRCUIT, in law, signifies a longer course of proceedings than is needful to recover the thing sued for: in case a person grants a rent charge of 107. a year out of his manor, and afterwards the grantee disseises the grantor, who thereupon brings an assise, and recovers the land, and 201. damages; which being paid, the grantee brings his action for 10. of the rent, due during the time of the disseisin: this is termed circuity of action, because, as the grantor was to receive 201. damages, and pay 107. rent, he might only have received the 10. for the damages, and the grantee might have retained the other 10. for his rent, and by that means saved his CIRCUIT also signifies the journey, or CIRCULAR lines, in mathematics, such straight lines as are divided from the divisions made in the arch of the limb, such as sines, tangents, secants, chords, &c. CIRCULAR numbers, called also spherical ones, according to some, are such whose powers terminate in the roots themselves. Thus, for instance, 5 and 6, all whose powers do end in 5 and 6, as the square of 5 is 25, the square of 6 is 36, &c. CIRCULATION of the blood, the natu ral motion of the blood in a living animal, whereby that fluid is alternately carried from the heart to all parts of the body by the arteries, and returned from the same parts to the heart, by the veins. See PHYSIOLOGY. CIRCUMFERENCE, in a general sense, denotes the line or lines bounding a plane figure. However, it is generally used, in a more limited sense, for the curve line which bounds a circle, and otherwise called a periphery; the boundary of a right lined figure being expressed by the term perimeter. The circumference of every circle is supposed to be divided into 360 degrees. The angle at the circumference of a circle is double that at the centre. For the ratio of the circumference of a circle to its radius, see CIRCLE. CIRCUMFERENTOR, a mathematical instrument, used by land-surveyors for taking angles by the magnetic needle. It is an instrument (where great accuracy is not desired) much used in surveying, in and about woodlands, commons, harbours, seacoasts, in the working of coal-mines, &c. &c. where a permanent direction of the needle is of the CIR most material consequence in surveying. its most simple state, consists of the fol. The instrument is made of brass, and, in lowing parts; a brass compass box, about five inches diameter, or more; on the plate of the box are engraved and lettered the principal points of the compass, each, two of the quarters being figured divided into four quarters of 90 degrees from the south point, and terminated by 90 degrees at the east and west; and the other two quarters from the north point, terminating also at the east and west: on ring, divided into 360 degrees, numberthe circumference of the plate is fixed a therefore take his angles as bearing ed from 0 to 360; the observer may from the north and south towards the east and west; or, by that which is the most usual method, the whole circummencing from the north point: a magnetference of a circle of 360 degrees, comic needle of the usual kind turns upon an iron point, fixed in the centre of the is applied to the compass box, to throw compass plate; a stop and trigger wire the needle off its centre when not in the centre point: a glass and brass spring use, in order to preserve the fineness of ring covers the needle and closes the box; to the under side of the compass box, at the N. and S. points, is connected end, to each end of which is fixed a pera bar about 15 inches long, from end to long; each sight containing a long slit pendicular brass sight about five inches or perforation, and a sight line, so that the observer may take his line of sight, tion mark, at which end of the bar he or observation of the line upon the sta please's. CIRCUMSCRIBED, in geometry, is said of a figure which is drawn round another figure, so that all its sides or planes touch the inscribed figure. CIRCUMSCRIBED hyperbola, one of Sir CIRCUMSCRIBING, in geometry, de- cumvallation, in the art of war, is a trench |