for preservation and arrangement, is Stonehenge on Salisbury Plain in Wiltshire. Here we find stones, some of very large dimensions, placed upright in the ground, and forming a series of concentric circles. They are not merely rude masses, like those of Avebury near Silbury Hill, but they have evidently undergone some shaping and rubbing down so as to form tolerably regular parallelopipedons. We here observe also two stones placed upright, like posts or pillars, and another large stone placed over them like an architrave or lintel: the lintel is also secured by means of mortises and tenons: all this indicates certainly a regular principle of construction. But, with the exception of a few inquirers who are, perhaps, disposed to over-value Celtic remains, can any careful antiquarian trace the forms of our oldest churches and other ancient edifices, to the rude masses of the British monuments in this island? It is an historical fact, that the Romans introduced into England their own principles of building; and it is equally demonstrable that, with the exception, probably, of the arch, Roman architecture, as it is known to us, both from existing specimens and written books, is a modification and adaptation of Grecian architecture; it was probably introduced among the Romans by Greeks, and certainly generally practised by them even under the emperors. If we then trace the progress of architectural construction from the Greeks, through the Romans, to its introduction into western Europe, we may fairly assert that the term architecture, in its strictest historical sense, implies the adaptation of Grecian models to the buildings of our own times. A building may be well arranged for all purposes of mere convenience, but if this is all it is not an architectural construction. To possess an architectural character it must combine internal convenience and fitness with beauty of external form, and with durability. If the external arrangement of a building should be compounded of those of several nations, such as Hindoo, Egyptian, and Greek, we should not admit this to be an architectural construction, even if the external form gave pleasure, which, however, is hardly a possible result; for it is essential to the character of an architectural structure, that the general arrangement and ornaments should have a unity of character and be referable to some one model. Architecture arose, in fact, from the combination of sculpture with construction. Building may be older than sculpture, but sculpture combined with building produced architecture. From the Homeric poeins we deduce only very vague ideas as to the structure of temples and palaces; we find no distinct indication of the arrangement of columns, which are the very essence of Greek architecture. But the arts of design, and even the arts of working in metal, had attained some excellence. (See in the Iliad,' book 18, the description of the shield of Achilles.) We find epithets derived from metal applied to the house of Alcinous and other buildings, from which we infer that they were structures of wood, and that the decorations were of metal; but we find no trace of columnar arrangement, or of an edifice of stone. (Odyss.' vii. 84, &c.; iv. 45, &c.) Even in the time of Pausanias (x. 5, 11) there still existed at Lacedæmon the temple of Minerva, called the house of copper,' from which it would appear, that this and other ancient temples were mainly of wood, and ornamented with metal. That the oldest material of sculpture was wood, is a fact in itself probable enough, and attested by the authority of Pausanias (viii. 17). Many of these wooden statues of high antiquity remained after the wooden temple itself had been exchanged for a more substantial edifice of stone. The ornamental parts of the stone structure, even in their simplest form, were no doubt derived from the art of the sculptor. The sculptor and the architect, in fact, were often united in the same person; and even when it became usual to separate these arts into two distinct branches, we can have no doubt that the skill of the architect, and the taste, at least, of the sculptor, were generally combined in the same individual. This was the case also with the medieval architects, and not least with those of England, who frequently not only adapted the exterior forms of their edifices for the reception and display of sculpture, but had good taste enough to take care that these ornaments were in harmony with the whole design, and worthy of the edifice which was to receive them. Further it is worthy of remark, though it seems to have escaped the observation of many writers, that the nation to which Europe is indebted for the elements of its architecture is also the nation to which we are indebted for our knowledge of geometry. That law of the mind which gave birth to the simple forms of the triangle, the circle, and the square, gave to man the elements of all his works of art. We are not aware of any nation that has had a system of architecture which has not also had a style of sculpture; nor do we know of any nation that has carried architecture to perfection, or even to a degree of excellence in its kind, that has not also had a system of geometry and arithmetic. We have endeavoured briefly to show, what we believe to be strictly demonstrable, that the term architecture, historically explained, is the mode of constructing edifices which we have received from the Romans and the Greeks. But with the establishment of Christianity, and its diffusion over western Europe, a gradual modification was made in the forms of buildings devoted to religious worship: for it must be observed, that it is principally in the religious edifices of a nation that we find the essential principles of its architecture exhibited and preserved. This remark applies with equal truth to all nations that have left behind them examples of some definite style of building. The great ecclesiastical structures of western Europe now exhibit a character in appearance very different indeed from the models of Greek and Roman buildings. They gradually deviated from the heavy and rounded Norman arch, the type of which is undoubtedly the Roman arch, to the pointed and light constructions generally denominated the Gothic. That foreign ornaments of a barbarous or at least incongruous style were occasionally mingled with them by the numerous architects of the middle ages, cannot be denied; but still in the early ecclesiastical, and also in many of the civil structures of Italy, Germany, France, Flanders, and England, a distinct and new character of architecture may be seen; and this distinction became again so marked in the several countries of Europe, that the Gothic or pointed styles of England and various Continental countries have each a distinctive character, though they may all have had a common origin. The architecture of a people is an important part of their history. It is the external and enduring form of their public life; an index of the state of knowledge and social progress. Architecture, therefore, to be understood aright, must be considered historically; must be con sidered, that is, in connection with the whole public and social life of the several nations in which it has been practised, and the particular times and circumstances in which it flourished. The architecture of the ancient Greeks, or that of the various European nations during the middle ages, would be very imperfectly understood if the architec tural remains were studied apart from the external and inner history of the countries in which they are found. On the other hand, the existing edifices serve to illustrate and elucidate much that would, without their assistance, be but imperfectly comprehended. No national architecture has ever been self-originated or invented. The architecture of every age and country where true architecture has existed, has grown out of some previous architecture. The architecture of Greece, the purest architecture which the world has ever seen, may be traced back to Assyria and Egypt. The architecture of Rome was derived immediately from Greece. The Oriental imagination transformed this into Byzantine; the Occidental into Romanesque; and borrowing something from both of these, the mind of the 13th century produced the Pointed or Gothic style, which the architects of Italy, Germany, France, and England, modified to suit the wants and characters of their respective countries. But always it was a modification, adaptation, or development of a previous system, not a reproduction of it. No true architecture has ever been merely mimetic. Though the architecture of Greece derived its germ from Egypt and Assyria, it developed into its perfect beauty and suitableness only by the free influence of the Greek mind. So that of Rome owed whatever of beauty and fitness it possessed to its departure from, not to its conformity with the Greek type. So whatever there is of grandeur and glory in the wondrous Gothic of the middle ages, dates from its emancipation from the classic form. No imported architecture has ever been lasting. In our own country we have tried this, and the failure is palpable. Our architects have erected copies of the temples of Greece and Rome, alike for churches, museums, and town-halls: and, however much they may have been admired whilst the fashion lasted, and scholars imbued with classic ideas gave tone to public opinion, almost before they were finished, the fashion passed away, and they are now regarded with general dissatisfaction. To the Greek succeeded the Gothic, and though the passion for it be still fervid, the opinion is evidently fast gaining ground, that Gothic reproduction is as essentially vicious and untrue as that which it has supplanted. In fact, we may hope that we are in this country coming to understand that whilst an absolutely new style is a thing neither to be desired nor looked for, and that an eclectic style is an absurdity, the architecture of every age as well as every country, to be a true living architecture, must be a product of that age and country-adapted to its special wants, and circumstances, and character: developed out of some previously existing architecture, but adapted with perfect freedom to present purposes, and embodying to the fullest possible extent the scientific knowledge and artistic feeling of the present time. And if this be so, the question of style will eventually, perhaps at no very distant day, settle itself. It will be felt that in every building there is a matter to be determined antecedent to all considerations of style. The first grand requisite is, as Vitruvius long ago pointed out, that a building shall be designed so as to answers perfectly as possible the purpose for which it is erected: shall, in other words, possess the greatest attainable convenience and stability. When that is arrived at, the feeling for beauty and grandeur in the architect who has rightly studied his art, will suggest a style-an outward and visible clothing of the actual body-which shall be as evidently in conformity with it, and the most beautiful, because the most suitable, for it-be as properly adapted to the purpose it has to fulfil, and the locality in which it is placed-as the form and clothing and colour of an animal or a flower are recognised to be the most beautiful as well as the most suitable with which it could have been endowed. Ornament then is an essential part of architecture. Without ornament there is no true architecture, only building. But it is a misconception of the true purpose of art to say that an edifice is erected for the sake of ornament. Architecture consists of construc- to see what is in it. Hence also Archivum and Arcanum, that is, a tion and ornament. But ornament must not be a thing extraneous thing kept secret, from which people are excluded (arc-entur)." to the construction, a something added to it merely to please the eye. The Temple of Saturn, built in the time of the Republic, was the True ornament is the expression of the idea of a building. Equally chief repository of the archives as well as of the public treasure of with the building itself the ornament must possess unity, proportion, ancient Rome. In England the archives are kept in various and too congruity; be a well considered whole, to which every part conduces, often inconvenient places, but a Record Office has been partly comand of which every part is a part. pleted in Fetter Lane, London, where some have been transferred. The history of the several great styles of architecture will be given Some pains have also been taken to classify them, and make them and their distinctive characteristics be pointed out, under the names of more generally useful. Under the direction of the Record Commisthe countries in which they flourished, or the terms by which they are sioners, with the active assistance of Sir J. Romilly, the Master of the best known, as EGYPTIAN, GRECIAN, ROMAN ARCHITECTURE, &c.; or Rolls, several volumes of detailed catalogues of these papers have been BYZANTINE, GOTHIC, RENAISSANCE ARCHITECTURE, &c. The great published, and more are in preparation. The building was intended architectural features will be found under their respective heads, as for the reception of all the archives, but the portion at present erected ARCH, ARCHITRAVE, COLUMN, &c. Some of the more important will contain only a very small part, and the work has for a considerable classes of buildings will also be separately described, as AMPHI-time been discontinued. The national archives of France are preserved THEATRE, Triumphal Arch [ARCH, TRIUMPHAL], CHURCH, TEMPLE, in the Hôtel Soubise at Paris; those of the Courts of Justice, in La THEATRE. Constructive architecture will likewise be found fully Sainte Chapelle at the Palais de Justice. treated of in a distinct series of articles. [ARCH; HOUSE; ROOF, &c.] ARCHITRAVE, from a Greek word and a Latin one, meaning, when put together, the principal beam, is the lower part of any structure supported by pillars, or the lower beam which rests upon the columns ARCHIVOLT, or ARCHIVAULT, means, literally, the principal turning, or arch, and is applied to any ornamented band or moulding which runs round the lower part of all the voussoirs of an arch. When this part of the arch is plain, with square edges, as in arches of the Romanesque style, it is called a soffit. ARCH-LUTE, a large lute, or double-stringed theorbo (THEORBO), formerly used by the Italians for the base parts, and for accompanying the voice. In the early editions of Corelli's Sonatas,' the principal and joins them together, on which the whole entablature (or ornamental part which comes immediately above the columns) rests. It was also called by the Greeks and Romans epistylion, or that which is on the columns. Thus, when pillars support an arch, the voussoirs, or wedgeshaped stones which form the arch [ARCH], supply the place of an architrave, by which name they are sometimes called. In the same way the flat beam, or row of stones coming immediately above a door or window, is called the architrave. The architrave may have only one face or two, that is, may appear as one beam, resting on and joining the contiguous columns (as in the temple of Pastum), or as two beams, the upper of which projects a little in front of the lower, as at a in the preceding cut. [COLUMN.] ARCHIVE, or ARCHIVES, a chamber or apartment where the public papers or records of a state or community are deposited: sometimes, by a common figure, applied to the papers themselves. By some the word archive is supposed to have been derived from the Greek 'Apxea (archeia), a term used by Josephus in the sense of public registers, and considered to have been transmitted to us through the Latin of the middle ages. The Greek archeion seems, in its primary signification, to mean a council-house or state-house,' or 'a body of public functionaries,' as the Ephori at Sparta. (See Aristot. 'Polit.' book ii.; and Pausan. iii. 11.) Others derive it from arca, a chest;' such being, in early times, a usual depository for records. So Isidorus, 'Orig.' lib. xx. c. 9-" Archa dicta, quod arceat visum atque prohibeat. Hinc et archivum, hinc et arcanum, id est secretum, unde cæteri arcentur." "It is called Archa, because it does not allow (arc-eat) is base staff is assigned to the violone (double base) or arcileuto. Accord ing to Kircher (Musurgia,' lib. vi.), this instrument had fourteen notes, the highest whereof was A, the fifth line in the base, the lowest the double G below; and possessed considerable power. It was about five feet in extreme length, and proportionally large in the body. At the commencement of the last century this instrument (invented, as is supposed, in the 16th century) was much in use; Handel employed it in many of his early operas. The office of Lutenist still continues as part of the establishment of the Chapel-royal, though the place has been a sinecure for nearly a century. A'RCHON, a Greek word written in Roman characters, signified originally one who had rule or command, either civil or military. In modern usage it is known only as the title of certain magistrates of the Athenians, of whom we propose to give some account in this article. On the abolition of regal government at Athens, on the death of Codrus, the chief power was still intrusted to a single magistrate, or archon, without the title of king (Baoteus), which was more directly associated with the idea of arbitrary rule. The new office was heredi tary; at least it is said to have been enjoyed successively by lineal descendants of Medon, the first archon, who was himself a son of Codrus, the last king. The Athenians were fond of attributing to Theseus the origin of their democracy; by which probably they meant that many of his regulations had a popular tendency, and that his general reformation of the state, which was favourable to that part of the population which had possessed no political rights, was accompanied by a permanent relaxation of regal authority. (Plut., ' Vit. Thes.' c. 25.) The prerogative of the archon was still further limited; for he was made responsible to his fellow citizens for the acts of his government. (Paus. iv. 5, 10.) Tradition told of thirteen hereditary archons, after whom, about B.C. 752, the chief magistrate was appointed to his office for ten years, but was still at first taken from the Medontidæ, or descendants of Medon. We have the name of Charops and of six others after him as decennial archons; but in B.C. 714 the archonship was thrown open to all the order of nobles, and the last three of the decennial archons were not of the family of Medon. (Vell. Paterc. 1, 8.) Another revolution, which is placed by Mr. Grote B.C. 683, limited the duration of the office to a single year, at the same time dividing the charge of administration between the chief magistrate and eight others, thus forming a council of state, which consisted of nine magistrates or archons. Hence they are sometimes mentioned by the Greek writers under the general designation of The Nine. These officers had their distinguishing titles and duties, of which we shall presently speak, when we have carried a little farther the general history of this new constitution. We have seen that the first archon was, like his royal predecessor, the head of the government. The decennial archons had doubtless the same place and character, and the annual magistrates for a time exercised collectively the political power before vested in a single ruler. Their names and number, and in great measure the particular civil duties assigned to them, remained unaltered whilst Athens continued to possess an independent government; but the course of events wrought a most important change as to their position in the state. This change, to which in earlier times there was a gradual approximation, was effected mainly by the increased activity of the ecclesia, or popular assembly, which received its first impulse from the regulations of Solon, about B.C. 594, was urged on more effectually by the reformation of Cleisthenes (B.C. 509), and was confirmed by the consequences of the Persian war, by which the thetes, or lowest class of citizens, which supplied the naval strength of Athens, were taught to know their power. (Aristot., Polit.' 2, 9, 4.) From the time that the ecclesia interfered habitually and directly with the government of the republic, the actual minister of state was the person who enjoyed the confidence of the people, which neither the office of archon nor any other office could procure. The inevitable consequence was, that the archons sunk from ministers of state into municipal officers of high rank. We have thought it worth while to point attention to this fact, from having had occasion to observe that young students of Athenian history are sometimes perplexed by the apparent inconsistency of the accounts given them of the first appointment of archons with the little notice bestowed upon these magistrates in the general history of the republic. They read of important public measures, and of the persons who originated and executed them, whilst the name of archon seldom occurs in Grecian history, except as marking the year in which certain events took place. (See Thucyd. ii. 2.) Pericles, without the office of archon, to which it was not his chance ever to attain, enjoyed a degree of power which was not possessed during the freedom of the republic by any other citizen. Perhaps no one who read with the least attention would find the difficulty, if he were not in some measure led to it by popular works on Grecian antiquities, which too commonly present an accumulation of facts and authorities without sufficiently discriminating the times to which the different statements refer. The annual archons, from their first appointment down to the time of Solon, were taken from the eupatridae, or nobles, to which class all political power seems to have been confined. This is rather assumed from what we know of the progress of civil and political society at Athens, than asserted on any authority of much weight. The establishment by Solon of a timocracy, or government in which political power was distributed with reference to property, put an end to the claims of noble blood; but since the archons were by this regulation taken from the wealthiest class of citizens (oi tevтakoσioμédiμvo), the noblest families probably still continued chiefly to supply the archons for each year, till the celebrated law of Aristeides, enacted about B.C. 479, threw open the offices of state to the whole body of the people. (Plut., Vit. Arist.' c. 1, and c. 22.) From this time no qualification was requisite in an Athenian citizen for the office of archon but fair fame and freedom from bodily defect. The mode of appointment presents some difficulties, from the want of precise information. It appears that the archons were originally elected by suffrage, and the elective franchise was probably confined to the noble class from which they were taken. By Solon, eligibility to the office, and perhaps the right of suffrage, were enlarged, but the mode of appointment remained the same. In after times, and even as early as the first Persian invasion of Greece, the appointment was by lot. The case of Aristeides seems to have been an exception to the general rule, and may be attributed perhaps to his high character and eminent services. (Aristot. Polit.' 2, 9, 2; Herod. 6, 109; Plut. Vit. Arist.' c. i., p. 481, ed. Reisk, compared with p. 479.) We have no information which enables us to fix the time when the change was effected. It has been attributed, with some probability, to Cleisthenes, but we know only with certainty that they were at one time elected and at some subsequent period appointed by lot. It must not be supposed that all the citizens were eager to avail themselves of the double opportunity offered by the new mode of appointment and the law of Aristeides. It seems that the poorest of them declined the hazard of the lot, which might throw upon them a burdensome honour. (Xen. Rep. Athen.' 1, 3.) Of the nine archons, one, usually termed the archon, was chief, and had the title of epónymus (èñávvuos), or name-giver, because the year in which he served the office was called by his name, as among the Romans the year was distinguished by the names of their consuls. Thus his name appears at the head of all public decrees (see Dem. 'De Cor. ;' Thucyd. 5, 19), and generally in all solemn records of state. The list, from the time of Creon, the first annual archon, is nearly complete and trustworthy. Of the remaining eight, one was called the king (Baotλevs), another the polemarch, and the last six had the general title of thesmotheta. Before admission to their office, they were subjected, like other public officers, to the examination called dokimasia (that is, trial or examination), for the purpose of ascertaining that they were Athenians of pure blood, whole of limb, and without blemish in their characters. With reference to the last point, they were asked if they had treated their parents kindly. When once invested with their office and adorned with the chaplet, the distinguishing mark of it (Esch. contra. Tim.' p. 3, 33), they were especially protected by the laws from all insult and outrage, and were exempted even from those public burdens which were not included in the general exemption granted to their most favoured citizens, the descendants of Harmodius and Aristogeiton. (Dem. 'contra. Lept.' p. 462, 20; and p. 465, 17.) There is reason to believe that they were members of the council of Areopagus by virtue of their office. [AREOPAGUS.] It is certain that they passed from their annual magistracy to a permanent seat in that council. 6 Their public duties had reference for the most part to the administration of justice. In some courts, and in certain causes, they were the presiding judges. On some occasions they had the execution only of the sentence pronounced by other judges; but it seems to have formed a large if not the most considerable part of their legal duties to bring causes into court (eiodyew, Dem. 'contra Lacr.' p. 940, 5–20) to be tried before the proper tribunal, not in the character of public prosecutors, but on application from the plaintiff or accuser, in which case their province was somewhat similar to that of an English grand jury in finding and ignoring bills. Sometimes, perhaps, the application to the archon was a form of little more importance as to the responsibility of the archon than that in English law of suing out a writ. To each of the first three archons, and collectively to the six thesmothetæ, a distinct province and peculiar duties were assigned. Incidental notices of these are to be found scattered over the Greek classics, especially in the Attic orators; more systematic accounts occur in the earlier lexicographers and antiquarians, among whom Julius Pollux may be particularly distinguished, whose authority would have more weight if we were better acquainted with the sources from which their information was derived and the times to which their accounts refer. Copious collections have been made from them by modern compilers, of whom, perhaps, the most popular in our language is that of Archbishop Potter. We shall present our readers with only a brief outline, sufficient to convey a general view of the separate jurisdiction of these magistrates in the later times of the Athenian republic. It seems to have been the duty of the chief archon, or epónymus, to throw his official protection around those whose interests were most liable to be overlooked in the ordinary execution of the law. Hence he was the appointed guardian of orphans and minors. He was also charged with a more general superintendence in matters which concerned the safety and good order of the state than was committed to his colleagues. The king archon was more especially concerned with religious matters. He was required to preside at the performance of the most solemn sacrifices. He had a certain control over the ministers of religion, and either himself tried offenders, or originated trials, in cases of impiety. It is hardly necessary to observe, that in the early periods of regal government kings were almost universally the chief ministers of religion. It is commonly supposed that the title of this archon was intended to denote the transfer of an important part of the king's prerogative to the magistrate who, in the department of religion, supplied his place. The office of the polemarch was doubtless in its first institution that which the name implies, to command in war; and even as late as the battle of Marathon, we find the polemarch Callimachus acting an important part in the council of war which preceded it, and commanding in virtue of his office the right wing of the Athenians in the engagement; but in later times, when the generals of the republic were immediately chosen by the people, the polemarch was confined to the discharge of civil duties, and particularly had cognisance of matters which concerned the strangers and metics (resident aliens) at Athens, exercising a jurisdiction in this respect not unlike that of the prætor peregrinus at Rome. The thesmothetæ should, according to the meaning of their title, have been legislators, or propounders of laws. It was not however their office to introduce laws, but rather to watch over the conduct of those who put themselves forward as legislators, and also annually to examine the existing laws for the purpose of removing contradictory and superfluous enactments-to keep, as it were, the statute-book in a pure and consistent state. (Dem. contra Lacr.' p. 940, 10, and 12; contra Zenoth.' p. 890, 10; Lys. 'contra Andoc.' p. 104, 15; Herod. 6, 109, 111; Lys. contra Panc.' p. 166, 32, and 40.) It appears that the whole college of archons was sometimes assembled in council (Dem. 'contra Meid.' p. 542, 2); but we have no information respecting the authority which they collectively exercised. A U n Fig. 2. H L in different positions on the second figure, the following will appear, on a little consideration : For further information on the various and important duties assigned to the different archons, in addition to this brief and general notice, the reader is referred to the authorities mentioned above; but we would remind the young student, in his inquiries, that the reliance to be placed on the accuracy of even a credible and well-informed author must depend in some measure on the circumstances under which his information is given; and this should especially be kept in mind when, as in the subject of the present article, all our information, so far as it is supplied by the Greek classics, is obtained, not from regular essays, but from incidental notices. Our meaning in this caution will be best explained by an instance. The subject of inquiry may be the manner in which certain officers were appointed; and this, as in the case of the archons, may have varied at different times. The mode of appointment may, according to a common practice with the Athenians, be implied by an epithet familiarly joined with the title of the office. Now, it is possible that an author, who when writing professedly on the subject would have given minutely accurate information, may use this epithet, familiar to him, inaccurately with reference to the times of which he is (v moves from A to U), at every moment some circle above M N emerges 3. During the passage from the equinox to the summer solstice speaking, if the circumstance indicated by it is of no importance to the entirely into light, and an opposite circle below m n begins to be entirely subject immediately before him. Evidence drawn from a casual expres-covered by darkness: and both states remain until the return of the sion must often be taken into account, but then it should be carefully circle ov in the next quarter of the year. And vice verså for the rated at its proper value. passage from the equinox to the winter solstice (when v moves from a to w). ARCOGRAPH. [CYCLOGRAPH.] ARCTIC CIRCLE. The term arctic is derived from the Greek, and signifies literally of or belonging to the bear, meaning the constellation of that name. Arctic circle had formerly a different signification from that which it now has. Among the Greeks it meant the parallel to the equator which just touches the horizon, being entirely above it, and which therefore separates those parallels which are always above, from those which are partly above and partly below, the horizon. (See Strabo, Casaub. p. 95.) Similarly the antarctic circle (if the phrase were used) would be a parallel to the equator which touches the horizon, being entirely below it, and which therefore separates those parallels which never rise above, from those which are partly below and partly above, Thus every different latitude had a different arctic circle; and in the latitude in which astronomy was first cultivated, the great bear just swept the sea, and did not set, whence the boundary circle obtained its name. the horizon. In the modern sense of the term, it is one fixed circle, or very nearly so; and the first use of it as such is found in the celebrated treatise on the sphere, by Holywood, better known by the name of Sacrobosco, published in the twelfth century. For the complete meaning of the term, we refer to DAY. We can only here briefly remind the reader that at the equator all days are equal; that in going northwards from the equator, the day of the summer solstice lengthens as the latitude increases, until we reach the pole, where there is but one day and night in the year, of six months each. There must therefore be some circle of the globe, in the northern hemisphere, at which the longest or summer solstice day is just twenty-four hours; and an opposite circle in the southern hemisphere, at which the sun does not appear for twenty-four hours. The first is the arctic, the second the antarctic, circle of the earth. We need hardly say, that at the day of the winter solstice in the northern hemisphere, there is a day of twenty-four hours in length at the antarctic circle. V Fig. 1. P and p (fig. 2.) are the north and south poles of the earth, the lines through which serve to remind us of the earth's axis. AB is the equator, and OH and OL are the directions in which the sun is seen at the northern summer and winter solstices, that is, the line which points to the sun rises and falls between Hо and OL twice in a year. We do not consider the apparent motion of the sun round the earth, because, as the sun is always on the meridian of some place, and any conclusion respecting day and night drawn from one meridian holds good for any other, we may conceive the meridian PBPA to move round with the sun. Or, to consider it in another point of view, instead of supposing the sun to appear to move round, let it remain in the fixed meridian, PBPA, and increase the daily rotation of the earth by a quantity equal to the daily motion of the sun on the equator, which will preserve the relative rotations, leaving us only to take notice of the rise and fall of the sun in the ecliptic; which is the cause of the peculiar phenomena of the arctic circle. The semicircle o v, in the first figure, is supposed to be cut out and applied to the right hand figure, o to o, in such manner that the needle, v, shall always be directly opposite to the sun. In the figure (2.) are given the extreme positions of o v; namely, м Um, at the northern summer, N wn, at the northern winter, solstice. The semicircle o v covers all those parts of the earth which do not see the sun, and the rotation round the axis, PP, brings every part of the earth under o v when its night begins. MN and m n are the arctic and ant be in light for twenty-four hours, and all below mn in darkness: and hours, and the same time in darkness. 4. No circle lying between M N and mn is ever entirely in light or entirely in darkness. circle, that is, to find during what part of the year the sun performs Hence, to find the duration of light at any place above the arctic his daily rotation entirely above the horizon, look in an almanac for the times before and after the summer solstice, at which the declination of the sun is equal to the polar distance (or latitude subtracted from 90°) of the place. Between those two times there is perpetual light. For example, the north point of Nova Zembla (latitude 75°, polar distance 15°) will have perpetual light between May 1 and August 12, 1859. For the time of perpetual darkness do the same with the winter solstice: thus there will be perpetual darkness at the above-mentioned place from November 3, 1859, to February 9, 1860. The north polar distance of the arctic circle is equal to the angle HOB, the greatest declination of the sun, or the OBLIQUITY of the ecliptic. The south polar distance of the antarctic circle is the same. This quantity changes very slightly from year to year. It is as follows: January 1, 1858, 23° 27′ 28′′-29 decreasing at present by about half a second yearly. The arctic and antarctic circles are the boundaries which separate the frigid from the temperate zones, as they are called. The part of the earth included within each of the two is about 4 per cent. of the whole surface of the globe. The best known points through or near which the arctic circle passes are Cape North in Iceland, the Maelstrom whirlpool, the mouth of the Oby, Behring's Straits, and the south of Melville Island. For discoveries of land within the antarctic circle, see ANTARCTIC OCEAN, in GEOG. DIV. of ENG. CYC. The arctic and antarctic circles of the heavens occupy positions with respect to the celestial poles similar to those occupied by the same circles on the earth. Thus a traveller going round the arctic circle would always have some point of the celestial arctic circle directly over head, or in his zenith. But the term is hardly ever employed by astronomers. In all that precedes we have taken no notice of REFRACTION, the effect of which is to raise the sun a little towards the nearest pole at every point of the globe, thus lengthening the day and diminishing the night. In some latitudes the effect would be very considerable, and would increase the duration of light by as much as a day. ARCTURIN. [ARBUTIN.] ARCTURUS, or a Boötis, a star of the first magnitude in the constellation Bootes. It derives its name from two Greek words, signifying the tail of the bear, and, though not in the latter constellation, it is very nearly in a right line drawn through the two hinder stars of the tail (and n). It rises N.E. by E. at Greenwich, and is on the meridian in about 72 hours after rising; which takes place at half-past seven A.M. on the 1st of January, and about two hours later for the first of every succeeding month. Its mean places are as follows: rounding stars), the value of which is thus given in the catalogue of from the opposite side; for a rectangle, multiply together adjoining stars published by the British Association in 1845. sides, P Q and PR; for a four-sided figure, in which RT and s v are The hectare is generally used in describing a quantity of land. It is 2:4711695 English acres, or 404 hectares make 1000 acres, which disagrees with the first result by less than 1 part out of 50,000. AREA. This term is a Latin word, and means the same thing as superficies, or quantity of surface, but is applied exclusively to plane figures. Thus we say, "the surface of a sphere, the area of a triangle," and "the surface of a cube is six times the area of one of its faces." The word is also applied to signify any large open space, or the ground upon which a building is erected; whence, in modern built houses, the portion of the site which is not built upon is commonly called the area. Returning to the mathematical meaning of the term, the measuring unit of every area is the square described upon the measuring unit of length: thus, we talk of the square inches, square feet, square yards, or square miles, which an area contains. And two figures which are similar, as it is called in geometry,- that is, which are perfect copies one of the other on different scales, have their areas proportional to the squares of their linear dimensions. That is, suppose a plan of the front of a house to be drawn so that a length of 500 feet would be represented in the picture by one of 3 feet. Then the area in the real front is to the area of the front in the picture in the proportion of 500 times 500 to 3 times 3, or of 250,000 to 9. Similarly, if the real height were 20 times as great as the height in the picture, or in the proportion of 20 to 1, the real area would be to that of the picture as 20 times 20 to once one, or as 400 to 1; that is, the first would be 400 times as great as the second. Any figure which is entirely bounded by straight lines may be divided into triangles, as in the adjoining diagram. The area of every triangle may be measured separately by either of the following rules, in which the word in italics may mean inches, yards, miles, or any other unit, provided only that it stands for the same throughout. 1. Measure a side, A B, of the triangle A B C, and the perpendicular CD which is let fall upon it from the opposite vertex, both in units. Half the product of A B and C D is the number of square units in the triangle ABC. Thus, if AB be 30 yards, and CD 16 yards, the triangle contains 240 square yards. 2. Measure the three sides, A C, CB, BA, in units; take the half sum of the three, from it subtract each of the sides, multiply the four results together, and extract the square root of the product; this gives the number of square units in the triangle. For instance, let the three sides be 5, 6, and 7 inches; the half sum is 9, which, diminished by the three sides respectively, gives 4, 3, and 2. 9, 4, 3, 2, multiplied together, give 216, the square root of which is 147, 147 very nearly. The triangle therefore contains about 14 square inches, The following rules may be applied in the following cases :-for a parallelogram, multiply AB, a side, by CD, its perpendicular distance parallel, but T V and R S converge, multiply RS, one of the converging sides, by Y Z, its perpendicular distance from the middle point of the other. When R T and S v are perpendicular to R 8, then Y Z is half the sum of R T and s v. To find the area of a circle, multiply the radius o A by itself and the result by 355; then divide by 113. To find the area of the sector OAD B, see ANGLE. To find the area of the portion A B D, find those of the sector o A D B, and the triangle O A B separately, and subtract the second from the first. In all these cases, the result is in the square units corresponding to the linear units in which the measurements were made. The area of a curvilinear figure can only be strictly found by mathematical processes too difficult to be here described, but the following method will give an idea of the principles employed. Let A CDB be a curvilinear figure bounded by the curve CD and the lines CA, A B, B D, of which the first and third are perpendicular to the second. Divide AB into any number of equal parts (eight is here supposed) by the points 1, 2, 3, &c., and construct the accompanying obvious figure by making A p, 1 q, &c., parallelograms. It is plain that the area sought, A C D B, is greater than the sum of the inscribed rectangles, denoted by the letters or numbers at opposite corners, E A 1 2 3 4 5 6 7 B 10, 2p, 3 q, 4 r, 58, 6 t, 7 u, B v; and that it is less than the sum of the circumscribing rectangles Ap, 1q, 2r, 38, 4t, 5u, 6 v, 7 D. Therefore the area sought does not differ from either of these sums by so much as they differ from one another; but the sums differ from one another by the sum of the rectangles cp, pq, qr, rs, st, tu, uv, v D, which, placed under one another, give the rectangle DE, which is less than D7: consequently neither sum differs from the area sought by so much as D 7. But by carrying the division of A B, with which we set out, to a sufficient degree, the area of D 7 might have been reduced to any extent which might have been thought necessary; that is, name any fraction of a square inch, however small, and A B can be divided into such a number of equal parts that D7 shall be smaller than that fraction of a square inch. Hence the sum of the inscribed or circumscribed parallelograms may, by dividing the line AB sufficiently, be made as nearly equal to the area as any practical purpose can require. The accuracy of the preceding process will be increased by summing, not the parallelograms, but the figures Acp1, 1pq2, 2 qr 3, &c., considering cp, pq, qr, &c., as straight lines. This will be equivalent to adding half the rectangle D E to the sum of the rectangles aforesaid. The practical rule is-Add all the intermediate ordinates, 1 p, 2q, &c., to the half sum of the extreme ordinates a C and BD: multiply the total by the common value of a 1, or 12, &c. This approximation is the first step of the method of QUADRATURES, which see. approximation one step further, and finds what is the limit to which The mathematical process of finding the area carries the preceding the sum of the inscribed parallelograms approaches nearer and nearer, show, is an exact expression for the area required. If a represent one as the number of divisions of A B is increased. This limit, it is easy to of the lines A 1, A 2, &c., and y the corresponding line 1 p, 2 q, &c., the area of the curve is found by the process of the integral calculus thus represented: Syd x, |