COM

And sat like Patience on

ment, Smiling at Grief."

COMPARTMENT,

or

a monu

COMPARTI

MENT, in general, is a design composed of several different figures, disposed with symmetry, to adorn a parterre, a ceiling, &c.

A compartment of tiles, or bricks, is an arrangement of them, of different colours, and varnished, for the decoration of a building. Compartments, in gardening, are an assemblage of beds, plats, borders, walks, &c. disposed in the most advantageous manner that the ground will admit of. Compartments in heraldry are otherwise called partitions.

COMPASS, or mariner's compass, an instrument whereby the ship's course is determined. See MAGNETISM.

COMPASS is also an instrument in surveying of land, dialling, &c. whose structure is chiefly the same with that of the mariner's compass; and,like that, consists of a box and needle; the principal difference being this, that instead of the needle's being fitted into the card, and playing with it on a pivot, it here plays alone.

See SURVEYING.

on a centre.

tical.

COMPASSES, caliber. See the article CA

LIBER.

COMPASSES,clockmakers', are joined, like the common compasses, with a quadrant or bow, like the spring compasses; only of different use, serving here to keep the instrument firm at any opening. They are made very strong, with the points of their legs of well-tempered steel, as being used to draw lines on pasteboard or copper.

COMPASSES, elliptic, consist of a cross with grooves in it, and an index which is fastened to the cross by means of dovetails that slide in the grooves; so that when the index is turned about, the end will describe an ellipsis, which is the use of these compasses.

COMPENSATION, in horology, is a contrivance in the pendulum of a clock, by means of which, while the expansion from increase of temperature depresses the centre of gravity of some of the vibrating parts, other parts are made to ascend nearer the centre of suspension, or else to draw up the pendulum, so as to preserve the centre of oscillation of the compound pendulum at an invariable distance; and in consequence to keep all the vibrations to the same time.

Compensation pendulums have the part which expands upwards made either of brass or zinc, or some very expansible metal, while the descending parts are usually iron or steel, and some of these have leaves or machinery in their construction in others the compensationpart does not vibrate, but serves to alter the length of a simple pendulum; and in others a fluid is used, most commonly mercury. See HOROLOGY and PENDU

LUM.

COMPENSATION balance. See Ho

ROLOGY.

COMPLEMENT, in astronomy, the distance of a star from the zenith: or the arch comprehended between the place of the star above the horizon and the zenith.

COMPLEMENT, in geometry, is what remains of a quadrant of a circle, or of 90° after any certain arch has been taken away from it. Thus, if the arch taken away be 40°, its complement is 50: beThe sine of the cause 50+40= 90. complement of an arch is called the cosine, and that of the tangent, the cotangent, &c.

COMPLEMENT of the course, in navigation, is the number of points the course wants of 90°, or eight points, viz. of a quarter of the compass.

:

COMPLEMENT of life, in the doctrine of annuities, denotes the difference, according to M. De Moivre's hypothesis, between the age of any given life and 86 years. Thus the complement of a life of 45 years is 41 of 30 it is 56. According to this hypothesis, the probabilities of life, through every period of existence, are supposed to decrease in an arithmeti cal progression, so that out of 86 persons just born, one is supposed to die every year, till at the end of 86 years, which is considered as the utmost limit of human life, the last survivor becomes extinct. On this supposition, the number of years that a person has an equal chance of surviving, is made to be the same with the expectation which M. De Moivre finds to be equal to half the complement of life; so that if the age be 4, the expecta.

the expectation will be

4 2

2; while the

to be considered as distinct, single be ings, they are called a compounded idea, whether these united ideas be simple or complex. Complex ideas, however compounded and recompounded, though their number be infinite, and their variety endless, may be all reduced under these three heads, modes, substances, and relations.

COMPLEX proposition, is either that which has at least one of its terms com. plex, or such as contains several members, as causal propositions; or it is several ideas offering themselves to our thoughts at once, whereby we are led to affirm the same thing of different objects, or different things of the same object. Thus, "God is infinitely wise, and infinitely powerful." In like manner, in the proposition, "Neither kings nor people are exempt from death.

COMPLEXION, a term technically denoting the temperament, habitude, and natural disposition of the body; but popularly signifying the colour of the face and skin. Few subjects have engaged the attention of naturalists more than the diversities among the human

41 82

years is and the chance that a person

aged 82 survives 2 years is 2. Since each of these fractions is , it follows that the one has an equal chance of living 41, and the other of living 2 years. But by tables founded on observation, the expectation of these lives are 402 and 34, while the chance of the younger living 402 years is 464, and the chance of the elder living 3 is 53: that is, in the first instance the chance is less, and in the second greater than an even one, that a person lives such a number of years as shall be equal to his expectation, which proves the incorrectness of M. De Moivre's hypothesis.

COMPLEMENTS, in a parallelogram, are the two smaller parallelograms made by drawing two right lines through a point in the diagonal, and parallel to the side of a parallelogram. In every parallelogram these compliments are equal.

COMPLEX, terms, or ideas, in logic, are such as are compounded of several simple ones.

Complex ideas are often considered as single and distinct beings, though they may be made up of several simple ideas, as a body, a spirit, a horse, a flower; but when several of these ideas of a different kind are joined together, which are wont

most remarkable. The great differences in this respect have given occasion to several authors to assert, that the whole human race have not sprung from one original: but that as many different species of men were at first created, as there are now different colours to be found among them. It remains, in reality, a matter of no small difficulty, to account for the remarkable variations of colour that are to be found among different nations. Dr Hunter, who considered the matter more accurately than has commonly been done, determines absolutely against any specific difference among mankind. He introduces his subject by observing, that when the question has been agitated, whether all the human race constituted only one species or not, in which the term species has been much confusion has arisen from the sense adopted. He therefore thinks it neces

term. He includes under the same spesary to set out with a definition of the cies all those animals which produce issue capable of propagating others resembling the original stock from whence they sprung.. This definition he illustrates by having recourse to the human species as an example. And in this sense of the term he concludes,that all of them are to be considered as belonging to the same species. And as, in the case of plants, one species comprehends several

varieties, depending upon climate, soil, culture, and similar accidents; so he considers the diversities of the human race to be merely varieties of the same species, produced by natural causes.

Upon the whole, colour and figure may be styled habits of the body. Like other habits, they are created, not by great and sudden impressions, but by continual and almost imperceptible touches. Of habits, both of mind and body, nations are susceptible as well as individuals. They are transmitted to the offspring, and augmented by inheritance. Long in growing to maturity, national features, like national manners, become fixed only after a succession of ages. They become, however, fixed at last; and if we can ascertain any effect produced by a given state of weather or of climate, it requires only repetition, during a sufficient length of time, to augment and impress it with a permanent character. The sanguine countenance will, for this reason, be perpetual in the highest latitudes of the temperate zone; and we shall for ever find the swarthy, the olive, the tawny, and the black, as we descend to the south.

COMPOSER, in music, a practical musical author; so called, in contradistinction to one who merely speculates in acoustics, and writes on the laws of harmony and melody, but does not concern himself with their practical application in composition.

:

COMPOSITE numbers, are such as can be measured exactly by a number exceed ing unity as 6 by 2 or 3, or 10 by 5, &c. so that 4 is the lowest composite number. Composite numbers, between them. selves, are those which have some common measure besides unity; as 12 and 15, as being both measured by 3.

COMPOSITE order, in architecture, the richest of the five orders, being a combination of the Ionic capital, with the bell and foliage of the Corinthian. Its cornice has simple modillions or dentils. See

ARCHITECTURE.

To composition belong both the artful joining of the words, whereof the stile is formed, and whereby it is rendered soft and smooth, gentle and flowing, fall and sonorous, or the contrary; and the order, which requires things first in nature and dignity to be put before those of inferior consideration.

COMPOSITION, in painting, consists of two parts, invention and disposition; the first whereof is the choice of the objects which are to enter into the composition of the subject the painter intends to execute, and is either simply historical or allegorical. The other very much contributes to the perfection and value of a piece of painting.

COMPOSITION, in commerce, a contract be tweenan insolvent debtor and hiscreditors, whereby the latter accept of a part of the debt.in compensation for the whole, and give a general acquittance accordingly.

COMPOSITION, in printing, commonly termed composing, the arranging of several types or letters in the composingstick, in order to form a line; and of several lines ranged in order in the galley, to make a page; and of several pages to make a form,

COMPOSITION of motion, is an assemblage of several directions of motion, resulting from several powers acting in different, though not opposite directions. MECHANICS.

See

COMPOSITION of proportion, is the comparing the sum of the antecedent and consequent with the consequent, in two equal ratios; as, suppose, 4: 8:: 3:6, they say, by composition of proportion 12: 896.

COMPOST, in husbandry and gardening, several sorts of soils or earthy matter mixed together, in order to make a manure for assisting the natural earth in the work of vegetation, by way of amendment or improvement.

COMPOUND flower, in botany, a flower formed of the union of several fructifications, or lesser flowers, within a common calyx; each lesser flower being furnished with five stamina, distinct at bottom, but united by the anthers into a cylinder, through which passes a style considerably longer than the stamina, and crowned by a stigma or summit, with two divisions that are rolled backwards. These are the essential characters of a compound flower. Compound flowers, which make up four classes in Tournefort's system, are all reduced to the class Syngenesia, which see. See BOTANY.

COMPOUND interest. See INTE

REST.

COMPOUND motion, that affected by the concurring action of several different powers. Thus, if one power act in the direction of, and with a force proportional to the end of a parallelogram, and another act in the direction of, and with a force proportional to its side, the compound motion will be in the direction of, and proportional to, the diagonal of the said parallelogram.

COMPOUND numbers, those which may be divided by some other number besides unity, without leaving any remainder: such are, 18, 20, &c. the first being measured by the numbers 2, 6, or 9: and the second by the numbers 2, 4, 5, 10.

COMPRESS, in surgery, a bolster of soft linen cloth, folded in several doubles, frequently applied to cover a plaster, in order not only to preserve the part from the external air, but also the better to retain the dressing. See SURGERY.

COMPRESSION, the act of pressing or squeezing some matter, so as to set its parts nearer to each other, and make it possess less space.

Water was, during a very long period, considered as a fluid perfectly unelastic: that is, unyielding, or incompressible; and this opinion was corroborated by an experiment of the Academy del Cimento in Italy. About a century and a half ago, the members of that academy endeavoured to ascertain whether water was capable of being compressed in any degree. For this purpose they filled a hollow metallic sphere with that fluid, and stop. ped the aperture very accurately. This ball then was pressed in a proper ma chine, but no contraction could be observed; nor, indeed, was the apparatus capable of manifesting small degrees of compression. Hence they concluded that water was not capable of compression. This opinion prevailed until the year 1761, when the ingenious Mr. Canton discovered the compressibility of water, and of other liquids, which he immediately made known to the Royal Society. He took a glass tube, having a ball at one end, filled the ball and part of the tube with water, which he had deprived of air as much as it was in his power; then placed the glass thus filled under the receiver of an air-pump; and on exhausting the receiver, which removed the pressure of the atmosphere from over the water and the glass vessel which contained it, in consequence of which the water rose a little way into

"In

the tube, viz. expanded itself. He then placed the apparatus under the receiver of a condensing engine, and on forcing the air into it, which increased the pressure upon the water, a diminution of bulk evidently took place; the water descending a little way within the tube. this manner," Mr. Canton says, "I have found by repeated trials, when the heat of the air has been about 50°, and the mercury at a mean height in the barometer, that the water will expand and rise in the tube by removing the weight of the atmosphere, one part in 21740, and will be as much compressed under the weight of an additional atmosphere. Therefore the compression of water by twice the weight of the atmosphere is one part in 10870." "Water has the remarkable property of being more compressible in winter than in summer, which is contrary to what I have observed both in spirits of wine and oil of olives." By the same means, and in the same circumstances, Mr. Canton ascertained the property of being compressed in some other fluids, and the results are as in the following table :

COMPTONIA, in botany, so called in honour of Henry Compton, Lord Bishop of London, a genus of the Monoecia Triandria class and order. Essential character: male ament. calyx two-leaved; corolla none; anthers two.parted. Female ament. calyx six-leaved; corolla none; styles two nut. ovate. There is but one species, viz. C. asplenifolia, fernleaved Comptonia, a native of North America. It is an astringent, and is in considerable estimation as a remedy for fluxes. It is brought to the Philadelphia market abundantly for this purpose.

COMPUTATION of a planet's motion.

See PLANET.

COMPUTATION, in law, is used in respect of the true account or construction of time, so understood as that neither party to an agreement, &c. may do wrong to the other; and that the determination of time be not left at large, or taken otherwise than according to the judg ment and intention of law.

If a lease is ingrossed, bearing date January 1, 1808, to have and to hold for

three years from henceforth, and the lease is not executed till the second of January; in this case the words from henceforth shall be accounted from the delivery of the deed, and not by any computation from the date. And if the lease be delivered at four o'clock in the afternoon on the said second day, it shall end the first day of January, in the third year; the law, in such computations, rejecting all fractions or divisions of the day.

CONCAVE, an appellation used in speaking of the inner surface of hollow bodies, but more especially of spherical ones.

CONCAVE glasses, such as are ground hollow, and are usually of a spherical figure, though they may be of any other, as parabolical, &c. All objects seen through concave glasses appear erect and diminished.

CONCENTRATION, in chemistry, the act of increasing the strength of fluids, which are rendered stronger by abstracting a portion of the mere menstruum. This is generally effected by evaporation, where the menstruum is driven off at a lower heat than is required to drive off the substance with which it is united. Thus, dilute sulphuric acid may be considered as a mixture of the real acid with water; and by applying a certain heat the water may be evaporized, leaving the acid behind in a state of concentration. When concentrated as much as possible, its specific gravity is about twice as great as that of water; but it can rarely be ob

tained denser than 1.85. When concentrated to 2.000 it contains a considerable

portion of water, as has been proved by combining it with barytes or potash, in which case water remains behind, and does not enter into the combination. Again, vinegar consists of an acid and water, and brandy of alcohol and water; and in proportion as the acid and alcohol are freed from the water, they are said to be more or less concentrated. This may be performed, (1.) either by simple distillation, in which case the acid or spirit comes over first, leaving the water behind; or, (2,) by exposing the vinegar or brandy to severe frost, when the water will be frozen, and the acid or alcohol will be found in a state of concentration in the middle of the ice; the greater the cold the higher the state of concentration. M. Lowitz

has found that the acid, however concentrated, congeals at 22°. Sulphuric acid, on the other hand, exposed to a much less severe cold, crystallizes, and to effect this

it must not be greatly concentrated. (3.) Another mode of concentrating the acetic acid is by distilling acetate of copper reduced to a powder in a retort. At first there comes over a liquid nearly colourless, and almost insipid, and afterwards a highly concentrated acid, tinged with green; but being distilled a second time in a moderate heat, it is colourless, transparent, exceedingly pungent, and concentrated. (4.) The most perfect method of obtaining this acid in a concentrated state was discovered by Mr. Lowitz, of Petersburgh. It is thus: distil a mixture of three parts of acetate of potash, and four parts of sulphuric acid, till the acetic acid has come over into the receiver. To separate it from the sulphuric acid, with which it is slightly contaminated, it must be distilled over a portion of acetate of barytes.

CONCENTRIC, in mathematics, something that has the same common centre with another: it stands in opposition to eccentric. Concentric is chiefly used in speaking of round bodies and figures, or circular and elliptical ones, &c. but may be likewise used for polygons, drawn parallel to each other upon the same centre. The method of Nonius, for graduating instruments, consists in describing with the same quadrant 45 concentric arches, dividing the outermost into 90 equal parts, the next into 89, &c.

CONCEPTION, in logic, is the simple apprehension or perception which we have of any thing, without proceeding to affirm or deny any thing about it. There are rules by which we may guide and regulate our conceptions of things, which is the main business in logic: for most of our errors in judgment, and the weakness, fallacy, and mistakes of our argumentation, proceed from the darkness, confusion, defect, or some other irregularity, in our conceptions. rules are these: 1. To conceive of things clearly and distinctly in their own natures. 2. Completely in all their parts. 3. Comprehensively in all their properties and relations. 4. Extensively in all their kinds. 5. Orderly, or in a proper method.

The

CONCESSION, in rhetoric, a figure whereby something is freely allowed that yet might bear dispute, to obtain something that one would have granted to him, and which he thinks cannot fairly be denied, as in the following conces sion of Dido, in Virgil: