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AC of the star; whence, as the earth changes the direction of its motion in going round the sun, the direction of the aberration will also change.

3. That we have committed an error in supposing the lines a σ and Ba to be parallel, since they meet at the star; which error, on account of the star's enormous distance, will be imperceptible.

4. That AB is not properly the spectator's motion round the sun only, but compounded of that and his motion round the earth's axis; the latter, however, being at most not one-third of a mile in a second while the former is nineteen miles per second, the maximum effect of the diurnal aberration amounts to only a fraction of a second of space. 5. The real direction Ac of the light may be considered as the same at every part of the earth's orbit, on account of the distance of

the star.

6. The aberration always throws the star apparently nearer to the earth's course, that is, a a is always within the angle CA B.

7. The aberration is greater or less according as the angle CAB is nearer to, or further from, a right angle, and is greatest when CAB is a right angle. This result may readily be proved by those who understand trigonometry, if they recollect that A B and a ▲ are given, being the velocity of the earth and the apparent velocity of light, and that

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Let us suppose, which will be exact enough for our purpose, that the earth moves in a circle (the ecliptic), of which the sun is in the centre. The line s A, perpendicular to the plane of the ecliptic, looks towards the pole of the ecliptic. Let SB be the direction of a star, PS Q perpendicular in the plane of the ecliptic to s B, and RST perpendicular to PSQ in the same plane. When the earth is at E, it is moving in the direction E M, perpendicular to s E, and the star, from its great distance, is in the direction EC parallel to SB. Hence the aber Fig. 3.

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ration takes place in the plane CEM, that is, the star is a little lowered towards EM, and appears in the direction ED. Let the needle SN move round the circle with the earth, so as always to indicate the direction in which the earth is moving, that is, s N is always parallel to EM, and perpendicular to s E. The plane BSN being parallel to the plane CEM, is the plane in which aberration would appear to take place if the spectator were at s, and s was moving; but as the spectator does not perceive his own motion, let us suppose him placed at s, and the same aberration to take place in the plane BSN, which really does take place in CEM. By what has been said, the aberration is greatest when the needle points to Q or P, that is, when the earth is at T or R; and least, when the needle points to T or R, that is, when the earth is at P or Q; because the angle BSN is a right angle when N is at P or Q, and differs most from a right angle when N is at T or R. Hence the aberration increases as the earth moves from P to T, diminishes from T to Q, increases from 9 to R, and decreases again from R to P. The line in which the star appears, moves round 8 B in the course of a year, and describes a cone, while the star appears to describe a small oval or ellipse about B, the greater axis of which is parallel to PQ, and the lesser to RT; such as prqt, in which p is the apparent place when the earth is at P, and so on. This deviation is completed in the course of a year.

When the star itself is in the pole of the ecliptic, or is seen in the direction sa, the angle a S N, is always a right angle, the aberration is always of the same magnitude, and the apparent path of the star is a circle. As we take stars in which SB is more inclined to the ecliptic, the oval becomes flattened in proportion to its length, so that when the star is in the ecliptic, it appears to vibrate backwards and forwards in a straight line, going and returning once in each year.

If the star be on the solstitial colure, the points P and Q will be the equinoxes, and R and м the solstices. The aberration will consequently be greatest at the solstices, and least at the equinoxes. We shall refer to this case presently.

The stars appear to us to lie on a large sphere, of which we are at the centre. [SPHERE.] We may represent the phenomenon on a common globe, by drawing a small ellipse or oval round the star, the major axis of which is parallel to the ecliptic, and the figure of which is more or less flattened, as the star is nearer to, or further from,

the ecliptic. The major axis will always be an arc of 41", and the minor axis will be 41" multiplied by the sine of BSM or the star's latitude.

Previously to entering upon the quantity of aberration, we shall give some account of the discovery, which is one of the most remarkable in the history of science. The arguments for the motion of the earth, though tolerably conclusive, were yet principally derived from the great simplicity of this hypothesis in comparison with others, since all the phenomena then observed could be equally well explained upon the supposition, that the other planets moved round the sun, at the same time that the sun moved round the earth. It remained, therefore, to find some experimentum crucis, some phenomenon, which admitted of no other explanation except what could be derived from the earth's motion. The first idea which suggested itself to astronomers was, that if the earth really moved, the stars would appear to change their places; though they did not count much upon this, since they knew that the distance of the stars might be so great, that the whole diameter of the earth's orbit would be too small a change of position to cause any perceptible change of place. [PARALLAX.]

However, the great improvements effected in practical astronomy towards the close of the 17th century, enabled astronomers to detect certain small changes in the apparent places of the stars, which had hitherto escaped observation, but which could not be satisfactorily explained by the parallax depending on the annual motion of the earth. Hooke, indeed, from observations of y Draconis, made with a zenith sector of his own construction, was led to assign a parallax of sensible magnitude to that star, but the result at which he arrived was not generally admitted by astronomers. About the same time Picard remarked that the apparent place of the pole star was subject to a variation of which he could give no satisfactory account. Flamsteed, who independently detected the same phenomenon, attributed it to the effects of annual parallax, but Cassini showed that the direction in which the displacement occurred, was not in accordance with the effect which would result from the annual motion of the earth.* It may be mentioned also that Römer, a contemporary of Flamsteed, remarked certain changes in the declinations of the stars which, according to his pupil Horrebow ('Basis Astronomiæ,' p. 66) he was unable to explain either by parallax or refraction.

In the year 1725, Bradley, Savilian Professor of Astronomy at Oxford, and afterwards Astronomer Royal, and Molyneux, the son of Locke's well-known friend of that name, resolved to verify Hooke's observations of y Draconis. This star had been selected by Hooke for his researches on annual parallax, because it passed very near the zenith of Gresham College, London, the place where his observations were made, and therefore would not be sensibly affected by refraction. The star manifestly offered the same facility of investigation to Bradley and Molyneux, whose observations were originally made at Kew. The instrument with which their observations were made was also a zenith sector, which, indeed, at that time was the most correct instrument for measuring very small angles [ZENITH SECTOR]; and a very large one, having a telescope 24 feet long, made by Graham, one of the most celebrated artists this country has produced, was erected at the place just mentioned, under the direction of Molyneux. Before proceeding further let us consider what would be the effect produced on the apparent place of y Draconis by the aberration of light. This star happens to be situate within about 16° of the pole of the ecliptic; it will, therefore, in accordance with the preceding account of aberration, appear to describe nearly a small circle about the place it would have if the earth had no motion, which is called its mean place. In the maps of the stars, published by the Useful Knowledge Society, the little circle, which represents y Draconis, will do well enough to give an idea of the path which it describes every year. By measuring the star's zenith distance when on the meridian, its polar distance was also measured, since the zenith and pole are both points of the meridian, distant from one another by the colatitude of the place [COMPLEMENT]; in other words, by adding the difference between 90° and the latitude of Kew to the meridional zenith distance of the star at that place, we obtain its polar distance. In fig. 4, s represents the mean place of the star and v saw the small ellipse, nearly a circle, described by the star in one year. The reader must imagine this circle placed in the heavens, and the line PS bent over his head, so that z is his zenith and P the pole. We must now show how to find the points of the ellipse v s a w, answering to the four principal periods of the year

namely, the solstices and equinoxes. Referring back to fig. 3, in which we finally placed the spectator at s, the sun will appear to describe the circle which the earth really describes; that is, as the earth moves from Q to R, the sun will appear to move from P to T. Hence, when the earth is at Q, the aberration, throwing the apparent place of the star towards 8 R, 90° before the earth, throws it also towards a line 90° behind the sun's apparent place. Let E, fig. 5, be

The displacement remarked by Flamsteed was evidently due to aberration. This has recently been established beyond doubt by Dr. Peters, who, by a discussion of Flamsteed's observations of the pole star, found the maximum value of aberration to be 20"-676, with a probable error of 1"11. The close agreement of this result with the mean of the most trustworthy values of the same element hitherto obtained, furnishes a favourable proof of the accuracy of Flamsteed's observations,

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The circle which rounds the whole figure is the solstitial colure, and as the star y Draconis is very nearly on that colure, we will suppose it to be at s. Let z be the spectator's zenith; that is, let him be on such a part of the earth that the plumb-line falls in the direction z E, the point z will, by the motion of the earth, be carried round the dotted circle. The meridian is the moving circle passing through P and z, and as the figure stands, the real star and the pole of the ecliptic are on the meridian. First, let the time be the vernal equinox, or let the sun appear at v; then the point w being 90° behind v, the star will appear to be thrown towards w, and its apparent place is v. Similarly, s, a, and w are the apparent places corresponding to s, A, and w, the dotted part of the ellipse being supposed to be bent over on the other side of the sphere. Fig. 4 is taken from fig. 5, and is the course of the star, as it will appear to the spectator at E, S Q P being bent, so that z is over his head, and P behind him. Let us now suppose him in the situation of Bradley, with an instrument capable only of measuring changes in the polar distance, the time being the winter solstice. As the star appears to move from w to v, which takes place between this and the vernal equinox, the polar distance will increase from day to day; after the vernal equinox it will decrease, and continue to do so until the autumnal equinox; after which, it will increase again till the winter solstice. This is precisely the phenomenon observed by Bradley, who clearly perceived that it could not be attributable to the annual parallax of the star. To illustrate this, let us suppose that when the earth is at Q (fig. 3), we look at the star in the direction Q G, and when it is at P we look at it in the direction P F. Draw PH parallel to QG: the spectator, who imagines himself at rest, will, if he observes the star at these two epochs, see the difference of position corresponding to the angle HP F, at least if the distance of the star be not so great as to render that angle imperceptible to his instruments. This however will take place in the plane passing through the star and PQ, whereas, the effect observed by Bradley took place in a direction perpendicular to that plane.

The displacement of y Draconis, observed by Bradley at Kew, was confirmed by subsequent observations which he made at Wanstead, in Essex, with an instrument of similar construction. The question now occurred, to what was the phenomenon attributable? At first he suspected that it arose from some irregularity in the instrument, or deviation of the plumb line, and afterwards from some nutation, or conical motion of the earth's axis. These, however, he found would not account for the observed displacement of the star. "At last, when he despaired of being able to account for the phenomenon which he had observed, a satisfactory explanation occurred to him all at once when he was not in search of it. (Thomson,' History of the Royal Society, p. 346.) He accompanied a pleasure-party in a sail upon the river Thames. The boat in which they were was provided with a mast which had a vane at the top of it. It blew a moderate wind, and the party sailed up and down the river for a considerable time. Dr. Bradley remarked, that every time the boat put about, the vane at the top of the boat's mast shifted a little, as if there had been a slight change in the direction of the wind. He observed this three or four times without speaking; at last he mentioned it to the sailors, and expressed his surprise that the wind should shift so regularly every time they put about. The sailors told him that the wind had not shifted, but that the apparent change was owing to the change in the direction of the boat, and assured him that the same thing invariably happened in all cases." * While pondering on the circumstance, it occurred to him that the velocity of light, combined with the motion of the earth in its orbit, must produce a similar minute change in the apparent places of the stars, and thus he was led to his great discovery of aberration. The greatest aberration, as we have observed, is parallel to the ecliptic, and is the greatest semi-diameter of the apparent annual ellipse of a star. This ought to be the same for all stars, if the rays which come from them move with the same velocity. Hitherto it

The original authority for this account is said to be Dr. Robison ('Natural Philosophy,' vol. iv. p. 629), who probably received it from Bradley himself.

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has not been discovered that the greatest aberrations of different stars differ by more than may reasonably be imputed to instrumental errors; we must therefore conclude that, as far as we know, the light of every star moves with the same velocity.

Bradley, in the early period of his researches, fixed the maximum value of aberration at 20" 25, but ultimately he adopted 200 as the most probable value. Delambre, from observations of the eclipses of Jupiter's satellites, determined it to be 20"-255. Bessel, by a discussion of Bradley's observations (Fundamenta Astronomiæ,' 1818) found the maximum value to be 20"-7080, but in the Tabula Regiomontana' (1830), he has adopted Delambre's result. In recent times various astronomers have investigated the value of the constant of aberration, and have obtained results which generally fluctuate between these two extremes. In the Introduction to the British Association Catalogue of Stars' (1844), Mr. Bailey has compared together all the most trustworthy determinations, and hence deduces 20 4192 as the most probable value. The result generally adopted by astronomers in the present day is due to M. Struve, Director of the Imperial Observatory of Pulkowa, who has found the maximum aberration to amount to 20"-445 by a discussion of observations recently made at that observatory with a transit instrument placed in the prime vertical. [TRANSIT INSTRUMENT.] This result agrees very nearly with that obtained about the same time by Dr. Peters, who, from observations made at the Pulkowa observatory with a vertical circle by Ertel [CIRCLE], determined the maximum value of aberration to be 20 481.

The aberration of light has furnished astronomers with what has been always regarded a desideratum since the establishment of the true system of the universe by Copernicus-an incontrovertible proof of the annual motion of the earth. In recent times, M. Foucault, an eminent French physicist, has given two distinct demonstrations of the diurnal motion, founded on the doctrine of rotation. [GYROSCOPE; PENDULUM.] It is well known that solar light is composed of several colours, which admit of separation from one another. The light of the stars is also compounded of several colours; for though different tinges predominate in different stars, no one gives a perfectly pure colour. The phenomenon of aberration proves that these different lights move with the same velocity; for two lights, moving with different velocities from the same star, would give different quantities of aberration; that is, would make differently coloured images of the star in different places, that image being nearest to the real place of the star, the colour of which moves with the greatest velocity. But as no indication of such an appearance is observable in the very best telescopes, we are, therefore, bound to conclude, that all the different coloured light of which white light is composed, moves with the same velocity. For the determination of the velocity of light from the aberration, see LIGHT. We have hitherto considered only the case of a star which has no motion of its own; let us now take that of a planet, comet, or the moon, which moves while the earth moves. Let the planet move from A to a, and the earth from E to e, in the time which it takes the light to move from the planet to the earth. Then, by what has been said, the earth at e receives the ray Ae, which is imagined to be in the direction Be; and if the planet had remained fixed at A, ACB would have been the aberration, or the angle contained between its true and its apparent direction. But in the meanwhile the planet has moved to a, and if light were transmitted instantaneously would appear in the direction ea. Hence E

a e B is the aberration; that is, to the former angle, the planet's motion round e, during the passage of the light, must be added or subtracted, according as the earth and planet move in the contrary or same directions. The greatest aberration of Mercury is nearly one minute; that of the moon, only two-thirds of a second. To the sun, which has no motion of its own, the rule for a star in the ecliptic may be applied; recollecting, however, that as a line drawn from the sun to the earth is always at right angles, or very nearly so, to the direction of the earth's motion, the aberration is always at its greatest value, or nearly so, and is nearly 201'.

In the preceding account we have omitted two circumstances, which would only have perplexed the reader. Firstly, every star changes its place on account of the precession of the equinoxes. [PRECESSION.] This was known to Bradley, who was therefore obliged to allow for this change, before he could pretend to assign that arising from any other phenomenon; secondly, the motion of the earth not being perfectly circular, but slightly elliptical, the quantity of aberration must be a little modified on that account. The effect of this will be seen in the article REDUCTION.

ABERRATION, in Optics. The most perfect mirror, or lens, which could be made, would be one in which all the rays which come from one point should be reflected or refracted to another point. Owing to the practical difficulties in the way of forming such a mirror or lens, the spherical form is adopted, of which it can only be said, that instead of returning to a point all the rays coming from a point, it condenses so many of them near a particular point, that an apparent image is formed at that point. The point near which most rays are collected is called the focus, and the distance at which a ray cuts any line passing through the focus is called its aberration with respect to that line. For a discussion of this subject, see LENS. Again, when light is refracted through any transparent medium, its different colours have

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different foci; for the cause and phenomena of which see ACHROMATIC. The aberrations arising from these two causes are generally known by the names of spherical aberration and chromatic aberration.

ABETTOR. The etymology of this word is somewhat uncertain; it may be derived from the Saxon betan, to push forward, or incite. An abettor is an instigator or setter on-one that procures another to commit a crime. If an abettor, or, as he is then usually termed, aider and abettor, be present at the time of committing the crime, he is treated as a principal; if absent, he becomes an accessary before the fact. [ACCESSARY.] ABEYANCE is a legal term, derived from the French bayer, which, says Richelet, means to "look at anything with mouth wide open." Coke ('Co. Litt.' 342, b.) explains the term thus, " En abeiance, that is, in expectation, of the French bayer, to expect. For when a parson dieth, we say that the freehold is in abeyance, because a successor is in expectation to take it; and here note the necessity of the true interpretation of words. If tenant pur terme d'autre vie dieth, the freehold is said to be in abeyance until the occupant entereth. If a man makes a lease for life, the remainder to the right heirs of J. S., the fee-simple is in abeyance until J. S. dieth. And so in the case of the parson, the fee and right is in abeyance, that is, in expectation, in remembrance, entendment or consideration of law, in consideratione sive intelligentia legis; because it is not in any man living."

The expression that the freehold or the inheritance of an estate is in abeyance, therefore, means that there is no person in whom the freehold or inheritance is vested at the moment, and that the freehold or inheritance is waiting or expecting for an owner who is to be ascertained. This doctrine of the suspense of the freehold or inheritance is repugnant to the general principles of the tenure of land in England. By the old law, it was necessary that some person should always be in existence as the representative of the freehold, for the discharge of the feudal duties, and to answer the actions which might be brought for the fief; and thus the maxim arose that the freehold could never be in abeyance. The case of glebe lands belonging to parsons, and of lands held by bishops and other corporations sole were scarcely exceptions, for the corporation always existed, although the individual parson or bishop was not yet named.

Titles of honour are also sometimes said to be in abeyance, which occurs when the persons next in inheritance to the last possessor are several females or co-parceners. In this case, the title is not extinct, but is said to be in abeyance; and may be called out of abeyance at any time by the crown. Several instances of the exercise of this prerogative are on record both in ancient and modern times. (Camoys's Case, 5 Bing. N. C. 754; Coke upon Littleton, 165; Cruise, Digest, vol. i. pp. 52, 55; Report of Committee of House of Lords, Segg. 1858.)

ABIB, the first month of the Hebrew year, now more generally known by the Chaldee name Nisan. [NISAN.] ABIETINE (Formula unknown), a neutral resin, extracted from Canada balsam and Strasbourg turpentine. It is inodorous and tasteless; soluble in alcohol, concentrated acetic acid, ether, and naphtha, but insoluble in water. It fuses on being heated, and assumes the form of a crystalline mass on cooling. Caustic potash has no action upon it. (See Journ. de Pharm.,' xvi. 436.)

ABJURATION OF THE REALM signifies a sworn banishment, or the taking of an oath to renounce and depart from the realm for ever. By the common law of England, if a person guilty of any felony, excepting sacrilege, fled to a parish church or churchyard for sanctuary, he might, within forty days afterwards, go clothed in sackcloth before the coroner, confess the full particulars of his guilt, and take an oath to abjure the kingdom for ever, and not to return without the king's licence. Upon making his confession and taking this oath, he became attainted of the felony; he had forty days from the day of his appearance before the coroner to prepare for his departure, and the coroner assigned him such port as he chose for his embarkation, to which he was bound to repair immediately with a cross in his hand, and to embark with all convenient speed. If he did not go immediately out of the kingdom, or if he afterwards returned into England without licence, he might suffer death as a felon, unless he happened to be a clerk, in which case he was allowed the benefit of clergy. This practice, which has obvious marks of a religious origin, was by several regulations in the reign of Henry VIII., in a great measure discontinued, and at length, by statute 21 James I. c. 28, the privilege of sanctuary was entirely abolished. In the reign of Queen Elizabeth, however, Roman Catholics and Protestant Dissenters convicted of having refused to attend the divine service of the Church of England, might be required to abjure the realm, and if they refused to swear, or to depart, or returned without licence after their departure, they were to be adjudged felons, and to suffer death without benefit of clergy. The punishment inflicted by stat. 35 Eliz. c. 2, was thus more severe than that imposed for a return after adjuration at the common law, for in the latter case the felon had the benefit of clergy; in the former, it was expressly taken away; but the circumstances which called for the act must not be forgotten. Protestant Dissenters were exempted from this statute by the Toleration Act, 1 Win. III. c. 18; but Popish recusants convict continued liable to be called upon to abjure the realm for their recusancy, until the statute 31 Geo. III., c. 32 (1791),

ARTS AND SCI. DIV. VOL. I.

relieved them from that and many other penal restrictions, upon their taking the oaths of allegiance and abjuration.

ABJURATION, OATH OF, is an oath which asserts the title of the present royal family to the crown of England. It was first imposed by 13 & 14 Will. III., c. 6; altered by 1 Anne, st. 1. c. 22, and amended again by 1 Geo. I., stat. 2, c. 13. The person taking the oath recognised the right of the king under the Act of Settlement, engaged to support him to the utmost of the juror's power, promised to disclose all traitorous conspiracies against him, and disclaimed any right to the crown of England by the descendants of the Pretender. The juror next declared that he rejected the opinion that princes excommunicated by the Pope might be deposed and murdered; that he did not believe that the Pope of Rome or any other foreign prince, prelate, or person, had or ought to have jurisdiction, directly or indirectly, within the realm. Persons required to take the oath of abjuration were generally obliged to take at the same time the oaths of allegiance and supremacy. All these oaths have now been simplified and reduced to one form by the statute 21 & 22 Vict., c. 48. The form of oath to be taken by a Roman Catholic is given in 10 Geo. IV., c. 7 (the Roman Catholic Relief Act). The first part of the oath is similar in substance to the form required by 6 Geo. III. c. 53. The taker disclaims, disavows, and solemnly abjures any intention to subvert the present Church Establishment as settled by law within the realm; and solemnly swears that he will never exercise any privilege to which he is or may become entitled to disturb or weaken the Protestant religion or Protestant government in the United Kingdom; and solemnly, in the presence of God, professes, testifies, and declares that he makes this declaration, and every part thereof, in the plain and ordinary sense of the words of the oath, without any evasion, equivocation, or mental, reservation whatever. The word abjuratio does not occur in classical Latin writers, and the verb abjurare, which often occurs, signifies to deny a thing falsely upon oath. ABLATIVE CASE, a term borrowed from the grammatical system of the Latin language, and occasionally employed in teaching our own, In the English Language there are many little words, such as with, in, to, at, &c., which are called prepositions, because they are preposed or prefixed to the words with which they are connected. The name however is an unfortunate one, as they are sometimes found postponed or placed after such words, especially in the older specimens of our language. We say with which or wherewith, in which or wherein, from which or wherefrom. So, in the Latin language, a certain set of little words, with the force of prepositions, were tacked on to the end of their nouns thus, while the three letters, reg, meant king (whence our word reg-al), reg-is meant of or from a king-reg-i, with, in, or near a king-reg-em, to a king. Thus the three little words, is, i, em, were equivalent to prepositions. It pleased the grammarians however, who are fond of multiplying names, to call these words reg-is, reg-i, &c., by the name of cases. The meaning of the endings of these words was not always definite enough. Thus with the case in i for instance, it was found necessary to mark the relation of place more precisely by the addition of other words, as in, in-pro, before—cum, with. Thus they would have, in regi, in the king; pro regi, before the king; cum regi, with the king. Now, as in, pro, cum, were much more definite than the termination i, it became unnecessary to make the i distinctly heard. It was no longer necessary to the meaning, and might therefore be slurred over: hence the pronunciation was reduced to in rege (the last e very faintly pronounced), pro rege, cum rege. But we have so far dealt only with those cases where the so-called ablative grew out of a case in i, commonly called the dative. There was, however, another case-ending, of different form and very different power, which in the end got similarly corrupted. This, in old Latin, had a final d, as Gnaivod patre prognatus, afterwards Cnaco, &c., sprung from a father Cnaeus. In Sanscrit this d is represented by a t, as mat, from me, trat, from thee. Bopp indeed (V. G. § 340) regards the original suffix of the Sanscrit as tas, afterwards reduced to a t, and further holds that this tas corresponds on the one hand to the Homeric ev of eueÛev, σeder, and on the other to the Latin tus, as seen in caelitus, from heaven. Be this as it may, it seems pretty certain that in the so-called ablative of the Latin there are blended what were originally two distinct cases; first, a true ablative, once ending in d with the sense of from, so as to justify the use of the case after prepositions of removal, as ex rege, ab rege, de rege, as well as Corintho fugit, he fled from Corinth; secondly, what was more properly a dative, or rather locative, answering to the question where, as in the examples already given with the prepositions of rest, cum, with, pro, before, in, in. The fact that two independent cases have slipped into an identity of form is not rare in language. We have an example of such confusion in one of our own pronouns, as in he gave him a book, where him is a dative, corresponding to the German ihm; and he gave him to the constable, where him is an accusative, corresponding to the German ihn.

ABLUTION, literally a washing away-a religious ceremony, consisting in bathing the body, or a part of it, in water, which has been practised more or less extensively by the disciples of almost every form of faith. Among outward types, none can be conceived more natural or appropriate as a sign or attempted representation of mental purity. The custom, particularly in the warm climates where it was first introduced, had also the further advantage of being highly conducive to

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health; and this circumstance no doubt contributed powerfully to recommend it to the authors of many of the religions by which it was sanctioned and enjoined. Ablutions, or lustrations, as they are more commonly called, even constituted a part of the Mosaic ceremonial, and were practised among the Jews on various occasions both by the priests and by the people. They occupy an important place in the Brahminical and other religions of India, where the waters of the Ganges are considered as having so purifying a power, that even if a votary, who cannot go to that river, shall call upon it to cleanse him, in prayer, while bathing in another stream, he will be freed from any sin or pollution he may have contracted. But the religion by which ablutions have been enjoined most punctiliously, and in the greatest number, is the Mohammedan. According to the precepts of the most rigid doctors of that faith, it may almost be said that scarcely the most ordinary or trifling action can be rightly performed without being either preceded or followed by an entire or partial lustration. The rules laid down upon the subject by these writers are minute and tedious, to a degree scarcely to be believed. The simple ceremony of Christian baptism may be regarded as an adoption of this natural type by the Author of our faith. Although, however, that is the only instance in which dipping in or sprinkling with water has been enjoined under the dispensation of the New Testament, the early Christians appear to have been also in the habit of undergoing ablution with water before partaking of the communion. The sprinkling with holy water, in use in the Roman Catholic church, may be considered as a species of ablution; and as a liturgical term it is applied in that church to the wine and water used by the priest to cleanse his fingers, and the chalice, after having administered the sacrament. In the Greek church, ablution sometimes means the wine and water given to the communicant, the better to be enabled to swallow the holy wafer. ABORTION. [INFANTICIDE.]

ABRAHAM MEN. To sham Abraham' is a well-known cant expression, which has reference to the practices of a large class of vagabonds and cheats who were once common in this country. An Abraham Man was an impostor who personated a 'Tom of Bedlam,'an unhappy being who was turned out of a lunatic asylum to subsist upon casual alms, incurable but harmless, without a home, but still maintained by public sympathy. This class of persons was so numerous at a period when there was very insufficient provision for the cure or mitigation of the greatest of human calamities, that the charity of the kind-hearted inhabitants of the small towns and villages was largely taxed for their support; and the appeal thus made to the feelings by a poor creature, fantastically clothed in tawdry rags, and singing snatches of old songs, was so irresistible, that it became a profitable trade to imitate such an unfortunate being. In Decker's English Villainies,' written more than two centuries ago, there are many curious particulars of the habits of this class of impostors; these details, in great part, agree with the rich description which Shakspere has given in his 'Lear,' (Act. ii. scene 3,) of a pretended 'Poor Tom,' who has put on

"The basest and most poorest shape,

That ever penury, in contempt of man, Brought near to beast."

ABSCESS, (from a Latin word, Abscedo, implying separation,) is so called, because parts which were in contact have become separated. An abscess consists of a collection of the matter termed pus, in some tissue, or organ of the body. Purulent matter, or pus, is formed out of the lymph separated from the blood during the process of inflammation. The production of pus during the progress of inflammation is called suppuration. [INFLAMMATION.]

The purulent matter constituting an abscess, properly so called, is always confined within a definite space the means by which it is confined vary. Sometimes the purulent matter is effused into the substance of an organ; in this case some portion of that part of the blood which is called fibrin, or coagulable lymph, is effused with it; this fibrin coagulates into a firm solid membrane, encloses the pus, and so prevents its diffusion. Sometimes the effused fibrin, or coagulable lymph, becomes organised; in this case it forms a new membrane, which is called an adventitious membrane, and the pus is completely enclosed in this new membrane as in a bag, or shut sac or cyst: an abscess of this kind is called an encysted abscess, and the internal surface of this cyst is always endowed with the properties both of absorption and of secretion; for large collections of matter, enclosed in bags of this kind, occasionally disappear without any external opening; and on the other hand, when such a bag has been completely emptied of its contents, it is sometimes rapidly refilled with pus. When an opening is formed in an abscess, and purulent matter continues to be discharged from it, it loses the name of abscess, and takes that of ulcer.

Purulent matter is poured out from the blood in other modes, and forms other collections of pus; but these latter collections are never called abscesses. Sometimes, for example, the pus, as it is secreted from the blood, is diffused through the substance of the inflamed organ. This is the case especially with the lung during the progress of inflammation. This diffusion of purulent matter through the substance of an inflamed organ is termed INFILTRATION and, instead of containing an abscess, the organ is said to have pus infiltrated through it. This is also seen in phlegmonous erysipelas.

There are few tissues of the body, and still fewer organs, in which abscesses may not form. They are found in the brain, the lungs, the heart, the liver, the spleen, the uterus, the ovaria, the cellular membrane, and the joints. In some of these organs the disease is highly dangerous, in others certainly fatal, in others comparatively unimportant. [INFLAMMATION.]

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ABSCISSA, or LINEA ABSCISSA, a line cut off, is a mathematical term, used as follows: If any two right lines A B, C D, be given, meeting in o, the position of any point, P, in the plane of those lines, is known when we know, first, within which of the four angles, BOC, COA, A OD, DOB, it lies, and, secondly, what is its distance from each line, measured on a line parallel to the other; or, in other words, what are the sides of the parallelogram o M P N. Either of these sides being called the abscissa, the other is called the ordinate; both are called co-ordinates; the straight lines, A B and C D, are called the axes, and o is called the origin. It is customary to denote the lengths of the abscissa and ordinate by the letters x and y respectively. Thus o M being the abscissa of the point P, P M is its ordinate. All points in the line P M have the same abscissa; all those in P N the same ordinate. [CO-ORDINATES.]

ABSENTEE. This is the first subject, in alphabetical order, that comes under our notice in the science of political economy. In the whole compass of that science there is no subject which presents more difficulties in the way of popular explanation, if we view it purely as a scientific question. An absentee, as the term is now used, is a person who derives his income from one country, but resides in another country where he expends that income. The common voice of mankind says that this is an evil and an injustice. It points to lands imperfectly cultivated, to labourers inadequately employed, to ruined cottages, to uneducated children, and it proclaims that these things would not be if the proprietor resided upon his estates. He does not choose to reside upon his estates; he would rather derive less from his estates, having the liberty to spend the revenue as he pleases. There is no law to prevent him but the great law of moral obligation, which he may obey or not. The public inconveniences of a positive law to bind his person to his property would far outweigh its public good. But the common sense of mankind is right; and the day of retribution comes when neglect goes forward into general destitution. Then the capital which has been abstracted from its fertilising local influence, is forcibly driven back, to prevent misery becoming utter ruin. Such results have been shown in large districts of Ireland. The political economists of every class cannot shut their eyes to these facts; but some say that these facts lie beyond the boundaries of their science; they belong to the moralist to explain. They consent only to look at the absentee in his abstract capacity of a capitalist; they admit that it would be better for his own local connections and dependants that he should not be an absentee; but they are prepared to prove that it is a matter of indifference to the country in general; that the wealth of the country is neither increased nor diminished whether he spend his rents in Dublin or in London-in London or in Rome. Even in this point of view these economists have few supporters. Popular opinion, without pointing to the extreme moral evils of a non-resident landed proprietary, maintains that the amount of revenue which the landlord spends in a foreign country is so much clear loss to the country from which he derives his property, and so much encouragement withdrawn from its industry; and that he ought therefore to be compelled to stay at home, instead of draining his native land for the support of foreign rivals. Some political economists reply, that this is a popular delusion, and that, in point of fact, the revenue spent by the landlord in a foreign country has precisely the same effect upon the industry of his own country as if his consumption took place at home. The truth perhaps lies between these counter opinions. The argument of the economists runs thus: all consumers residing in their own country, and landlords amongst the number, purchase many articles of foreign production which have been exchanged for the productions of their own country. In purchasing such foreign productions they stimulate native industry: in taking from foreigners what they produce cheaper and better than we can, and in sending them in exchange what we can produce cheaper and better than they can, we develop a wider field of industry for our native productions, and obtain a larger store of commodities for our home necessities. The consumption of an English resident in a foreign state, they go on to say, produces, in principle, the same indirect effects upon English industry, as his partial or entire consumption of foreign goods in England. His consumption of foreign goods abroad is equivalent to an importation of foreign goods into England; and that consumption, it is said, produces a correspondent exportation of English goods to the foreigner. For why? There must be an export of English goods to some country to the amount of the foreign goods which he consumes, otherwise his remittances could not be made to him. For example, England owes half a year's rent to the resident at Brussels; he draws a bill upon England, which a banker discounts, and sells to a merchant at Antwerp, who wants the bill to pay for goods which Antwerp owes to England; and so, say the economists, England keeps the rent after all; and it stimulates industry as much as if it had been spent in England at first. It does little, they say, to stimulate

industry in either case, for it is equally unproductive consumption. It has been a notion amongst a class of political economists, which is fast yielding to sounder notions, that all expenditure is unproductive unless it be incurred directly in the aid of further production. The truth is becoming apparent, that it is impossible to limit productive expenditure by such narrow laws-to say that the man who spends 100%. in clothes is an unproductive consumer, whilst the tailor who spends 50%. in cloth and labour for the clothes is a productive consumer. The one could not exist without the other. The one has enabled the other to make a profit upon the clothes, and part of that profit may become accumulation as certainly as if the buyer of clothes had been satisfied with half his wardrobe [CAPITAL]; and this shows the fallacy that lies at the bottom of the absentee argument. The absentee withdraws the local profit of those who have a natural claim to supply his wants. It may be true, that the foreigner requires some additional goods from England in consequence of the domiciliation of the English absentee; but does he require as large an amount of English goods as the total sum which the Englishman expends? Unquestionably not. There are large differences between the exchanges of commerce and the smaller exchanges of domestic life. The profit of the foreign retailers, of the foreign domestic servants, of the foreign landlord of the absentee's house, remain at any rate to the foreign country, and are so much abstracted from the absentee's country. By abstracting the profit of these smaller transactions, the surplus that becomes accumulation remains in the shape of new capital to the foreign country. New capital in a country is created by the slow aggregation of minute individual profit. Profit is like the nitrogenous substances in the food of men. Individuals may exist feebly and miserably without profit from their labour-that is, their labour may replace what they consume, and leave no surplus-as individuals may drag on existence upon the innutritious root which imperfectly replaces their ordinary exhaustion, and leaves nothing for development or extraordinary exertion. But the wealth of nations cannot be sustained without surplus produce-without profit; as the health of communities cannot be sustained without the food which builds up the body as well as keeps alive the animal heat. Rent is really profit under another name. It is, in most cases, the largest portion of the sarplus produce of the soil. It is that surplus which constitutes a natural fund for social improvement. The absentee who withdraws that fund from its local appropriation to make it the source of new profit to a foreign country, even if it be only the profit of supplying his domestic necessities, and not the profit of commercial exchange, to a certain extent must take away what he ought to contribute to the accumulation of his own district and his own country.

(The arguments which deny the injurious effects of absenteeism, merely regarded as a question of political economy, may be seen in Mr. M'Culloch's evidence before the Select Committee on the 'State of Ireland, 1825, Fourth Report,' and his evidence before the Committee on the State of the Poor in Ireland, 1830.' The contrary argument may be found in 'Lectures on Political Economy,' by J. A. Lawson, LL.B., Lecture V. 1843.)

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ABSINTHINE (Formula, C., H2, O), the bitter principle of the Artemisia absinthium. To prepare it, the dried leaves of wormwood are extracted with alcohol of 80 per cent., the extract evaporated to a syrupy consistence and treated with ether; the supernatant ethereal layer must be decanted, and the treatment of the residue with ether repeated until the ethereal extract no longer tastes bitter. This ethereal solution, evaporated on the water bath, leaves a residue composed of absinthine and a resinous body, which latter may be dissolved out by very dilute ammonia. The residual absinthine must be digested with dilute hydrochloric acid, washed with water, and then dissolved in alcohol; to the alcoholic solution acetate of lead must be added until the liquid becomes milky. After filtration, the excess of lead must be removed by sulphuretted hydrogen, and the alcoholic solution, slightly diluted with water, allowed to evaporate spontaneously in a warm place. Yellow resinous drops of absinthine gradually separate, and these finally solidify to a confusedly crystalline mass. Absinthine has a slight odour of wormwood, and an exceedingly bitter taste. It is very slightly soluble in water, more so in ether, and very soluble in alcohol, and also in concentrated acetic acid. Ammonia dissolves it in very small quantity only, but potash somewhat more freely. It possesses a decidedly acid reaction.

ABSOLUTION, a religious ceremony in use in different Christian communities, by which the priest declares an individual, on repentance and submission to the requisite penance, to be absolved either from his sin, or from the ecclesiastical punishment or deprivation to which it had rendered him liable. It is contended by many theological writers, that down to the twelfth century the priest in this act only used the words "May God, or may Christ, absolve thee;" thus refraining from claiming any authority to remit the sin himself. Since then, nowever, the formula used in the Roman Catholic church has been Ego te absolvo a peccatis tuis (I absolve thee from thy sins), accompanied with the sign of the cross. The Council of Trent has expressly condemned the doctrine that the priest has not power of himself to absolve from the guilt of sin. (Session xiv. Canon 4.) The Church of England employs in the Order for the Visitation of the Sick, words nearly the same with those employed in the Roman Catholic communion, "I absolve thee from all thy sins." It is, however, main

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tained by the highest authorities that the absolution thus bestowed is only declaratory, while that pronounced by the Roman Catholic priest is professed to be absolute, and to proceed solely from himself. Hooker, Ecclesiastical Polity,' B. VI. § 12; who winds up his comparison of the doctrine of his own church with that of the Church of Rome, by saying, "Wherefore the further we wade, the better we see it still appear, that the priest doth never in absolution, no not so much as by way of service and ministry, really either forgive the act, take away the uncleanness, or remove the punishment of sin: but if the party penitent come contrite, he hath by their own grant absolution before absolution; if not contrite, although the priest should ten thousand times absolve him, all were in vain." (Ibid. B. VI. § 13.) In the Greek church the formula is merely declaratory; that is to say, it is of the nature of a prayer to heaven that the sins of the penitent person may not be visited with their due punishment. It is so also in the Protestant Church of Scotland; and there the term absolution is commonly used to denote simply the declaration of the Kirk-Session or other judicatory, expressed by the mouth of its president, that the party is released from the ecclesiastical interdict to which his delinquency had subjected him.

In the early church there were held to be five kinds of absolution: by baptism; by the eucharist; declaratory, by word of mouth and doctrine; precatory, by imposition of hands and prayer; judicial, by relaxation of church censures.

The Absolution as it now stands in the order for Morning and Evening Prayer was first inserted in the Second Book of Edward VI. On a subsequent revision the word minister was changed into priest. The other two absolutions are coeval with the reformed Prayer Book. ABSORPTION (from absorbeo, to suck up) is the process by which rays of heat are made to disappear. The surfaces of different bodies vary greatly in absorbing power, and even in the same body the power varies with the state of the surface as to colour, roughness, &c. The subject will be considered in its proper place under HEAT.

ABSORPTION OF LIGHT is that process which takes place when light enters an imperfectly transparent medium, in virtue of which a portion of the light is continually stifled, or spent in producing some physical effect, while the remainder is either directly transmitted, or emerges after one or more internal reflections.

A body absorbing all the light incident upon it would appear black, and would be wholly invisible; though, in point of fact, the blackest body actually existing reflects some light from its surface; while a body absorbing none, but reflecting light of all kinds indifferently from a multitude of irregularly placed surfaces, would appear white like snow. In general, the different component parts of white light are absorbed with unequal energy, and thus the light which escapes absorption is coloured, as not containing the colours of the spectrum in the proper proportion to form white light. In the great majority of cases the colours of natural bodies are occasioned in this way.

When light of any one kind enters a homogeneous medium, its intensity decreases in geometric progression as the length of its path within the medium increases in arithmetic in progression. This readily follows from the fact that in any given case the quantity of light lost by absorption is a given fraction of the quantity originally incident. (See Herschel on Light, 'Encyclopædia Metropolitana,'art. Absorption.) Accordingly, in being transmitted directly across a stratum of the medium of thickness t, the intensity is reduced in the ratio of 1 to r, where r is a fraction less than 1, or at most equal to 1. The quantityr varies from one medium to another, and for the same medium from light of one refrangibility to light of another. If r 1 for light of all kinds, the medium is colourless and transparent, like water, which for ordinary purposes may be regarded as such. If r were less than 1, but the name for light of all kinds, the medium, in a stratum of sufficient thickness, would cease to transmit light, without becoming coloured in smaller thicknesses; but no such media are known to exist. When r is less than 1, it always varies more or less with the kind of light, and therefore the transmitted light is coloured.

If a, a', a"... denote the original intensities of the various kinds of light of which white light is made up, r, r', r" . . . the different values of the fraction r for those kinds of light, the intensities after transmission will be reduced to art, a'r1, a" r The relative proportions of these latter will determine the tint of the transmitted light. It is to be remarked, that this tint will change, not only with a change in the absorbing medium, but even while the medium remains the same, with a change in the thickness t. While the total quantity of light transmitted continually decreases as the thickness of the stratum looked through is increased, the colour generally becomes purer and purer, those colours for which r is least becoming more and more predominant. Sometimes however the change of tint with an increase on thickness is very remarkable. Thus, solutions of the chrome salts in general are green in small thickness, and passing through a sort of neutral tint, become red when the thickness is sufficiently increased. The reason of this is easily explained according to the principles just laid down. The green, and a comparatively small quantity of red, are the colours which chiefly escape absorption at an early stage; but as the absorption goes on, the red, being absorbed less rapidly than the green (r being less for a portion of the red than for the green), becomes at length the predominant colour.

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