there is a list of the writings ascribed to Orpheus, of which the following are the principal.

1. 'Iepoi Xoyo (sacred legends), a complete system of Orphic theology, in twenty-four books; it is ascribed to Cercops and Diognetus, and is probably the production of several authors.

2. Teλerai (religious rites, or mysteries), directions for worshipping and appeasing the Gods; probably by Onomacritus.

3. Xohopo (prophecies). Similar works were ascribed to Musæus.

The origin of the term 'orrery' is thus given by Mr Desaguliers, in his Course of Experimental Philosophy,' 4to., London, 1734, i., p. 431. After stating his belief that Mr. George Graham, about the year 1700, first invented a movement for exhibiting the motion of the earth about the sun at the same time that the moon revolved round the earth, he remarks, This machine being in the hands of an instrument-maker to be sent with some of his own instruments to Prince Eugene, he copied it, and made the first for the late Earl of Orrery, and then several others with additions of his own. Sir Richard Steele, who knew nothing of Mr. Graham's machine, in one of his lucubrations, thinkinventor, of such a curious instrument, called it an orrery, and gave Mr. J. Rowley the praise due to Mr. Graham.'

5. 'H is Aïdov karáßaois (the descent to Hades), a poem of great antiquity, ascribed, among other authors, to Cer

cops.

6. Hymns, also of high antiquity. In the time of Plato they were recited by rhapsodists at the public games. Onomacritus appears to have been the author of many of them.

7. Of Stones, their nature, and their powers against serpents and poisons, and for appeasing the anger of the gods.

8. Argonautica, a poem on the voyage of the Argonauts to Colchis; probably by Onomacritus; at least by some one not earlier than Homer.

9. Fragments, which have been carefully collected by Gesner out of Platonic and Christian writers. Most of them are of a later date than the Christian æra.

The following are the principal editions of the Orphic poems: Orphei Argonautica, Hymni, et de Lapidibus,' Gr., in H. Stephens's Poetæ Græci Principes Heroici Carminis,' 1566, fol.; Orphei Argonautica, Hymni, et de Lapidibus, curante A. C. Eschenbachio, cum not. erudit.,' Utrecht, 1689; 'Oρpéws äñavтa, ‘Orphei Arg., Hym., de Lapid., et Fragmenta, cum notis Stephani et Eschenbachii, ex recens. et cum not. J. M. Gesneri,' Lips., 1764; Orphica," by Schaeffer, Lips., 1818; ditto, by Hermann, Lips., 1805; Argonautica,' by Schneider, Jena, 1803.

Tiedemann's Initia Philos. Græc., p. 1-100; Fabric., Bib. Græc., i., p. 140, &c.; Clinton's Fasti; Funke's Real. Schullexicon.)

ORPIMENT. [ARSENIC.]

ORPINE is a succulent herbaceous plant, the Sedum Telephium of botanists, found abundantly in some parts of England in woods and thickets. It has oval serrated leaves, erect stems, and close carpels of purple flowers; and has some reputation for its astringency: the root and stem, boiled in milk, are a popular remedy for diarrhoea.

ORRERY. There are four planetary machines to which distinct names have been given, corresponding to the phenomena they are intended to exhibit, and which, when combined so as to derive their motions from a common origin, constitute what is now generally understood by an orrery. These machines are the Planetarium, Tellurian, Lunarian, and Satellite machine. The planetarium is a mechanical representation of the orbital motions of the planets about the sun, either in circles or ellipses, and with angular velocities either uniform or variable, according to the quality of the instrument. The tellurian and lunarian, when connected in their improved form, exhibit the motion of the moon about the earth and that of the earth about the sun, and the principal phenomena which accompany the changes in their relative positions, such as the succession of day and night and the variable length of both according to the season of the year, the eclipses of the sun and moon, the variations in the moon's latitude, velocity, and distance from the earth, the progressive motion of her apogee, and the retrogradation of her nodes, &c. The satellite machine is chiefly intended to represent the motions of Jupiter's satellites about their primary, combined with the motions of the latter about the sun. Instead of attempting a particular description of any one of these machines, which could only be rendered intelligible by reference to many diagrams, while the object would be much better attained by a simple inspection of the machine itself, we shall confine ourselves to a brief notice of their history and to the explanation of the general principles upon which the construction of modern planetary machines depends, referring our readers for more ample information to the article Planetary Machines' in Brewster's Cyclopædia, contributed by the Rev. W. Pearson, formerly treasurer of the Astronomical Society.

Planetary machines were in use at a very remote period, and appear to have consisted for many centuries of moveable spheres having the earth in their centre: thus we read of the Chinese spheres said to have been made some 2000 years before the Christian æra, and more recently of the spheres of Archimedes and Posidonius, concerning which Cicero, speaking of the Epicurean philosophy, has the following remarkable passage:

If the sphere, lately made by our friend Posidonius, which marks the course of the sun and moon and the five wandering stars, were to be transported into Scythia or Britain, who, even in those barbarous countries, would doubt whether reason had presided over its construction? Yet these people (the Epicureans) doubt whether the universe, whence all things arise and are made, is not the effect of chance or of some necessity rather than of reason and a divine mind; and they regard Archimedes as more deserving of praise in imitating the changes of the sphere than nature in producing them.' (De Nat. Deor., lib. ii., cap. 34 and 35.) The earliest machine which represented the Ptolemaic system may possibly have been that possessed by Chromatus, in the construction of which no less than 200 pounds weight of gold are said to have been used. This system continued to be represented in all planetary machines till about fifteen years after the death of Copernicus, when the last of that kind of any note was erected in the library of the Pantheon at Paris by Oronce Finée.

In the latter part of the seventeenth century Huyghens and Roemer employed themselves in the construction of planetary machines in conformity with the Copernican doctrine. The one invented by Huyghens, who first introduced a systematic method of calculating with precision the necessary wheel-work for these machines, received from its author the name of the Automaton.' It derived its motion from a spring regulated by a balance, the pendulum not having been then introduced as a regulating agent, and served for many years as a pattern in the construction of orreries, as did the instrument of Roemer, called by him a Planetarium, in the construction of machines intended chiefly to exhibit the orbital motions of the planets. Roemer had also invented a satellite machine prior to the year 1679, the original or a copy of which was presented by him in that year to the English astronomer Flamsteed. Both his machines are described in his Basis Astronomiæ,' printed in 1735. The last machine we shall mention is the Planetarium of the Royal Institution of London, constructed about the year 1801, shortly after Dr. Garnett, having previsously removed his apparatus elsewhere, discontinued his astronomical lectures at that institution. For a description of this machine, the plan of which was suggested by Dr. Young and the Rev. W. Pearson, we must again refer to the paper On Planetary Machines,' by the latter gentleman.

The chief part of every orrery is the mechanism composing the planetarium, by means of which the paths of the planets about the sun and their relative periodic times are exhibited with more or less approach to truth; and this mechanism, with the method of computing it, being once understood, it will be easy to extend the same principles to the more complex cases in which the satellites revolve about their primaries at the same time that the latter rotate upon their axes and revolve about the sun, as well as to those in which the parallelism of the planets' axes and the changes in the positions of their orbits, &c. are sought to be represented. For this reason we shall confine ourselves to the method of computing the wheel-work, which will give the relative periods with any required degree of accuracy, and to the explanation of a very ingenious contrivance by means of which a true elliptic orbit may be produced. Before how

The planets Vesta and Juno had not been discovered at the time this machine was constructed.

The contrivance by means of which a true elliptic orbit may be produced is extremely simple. For this purpose all that is necessary is that the radius vector which connects the planetary ball with the superior extremity of the tube should consist of two parts or arms, the lengths of which have a determinate ratio dependent solely upon the eccen- | tricity of the orbit, and that while the larger arm revolves | about the centre of the ellipse by means of the wheel-work already described, the smaller arm be made to revolve about the extremity of the larger with the same angular velocity but in the opposite direction. This may be effected in two ways. By means of a pulley fixed to the planetary tube and connected by an endless silken cord with another pulley free to revolve about a vertical axle situated at the extremity of the larger arm. The effect of this connection will be that the latter pulley will revolve once during each revolution of the larger arm but in the opposite direction. If therefore the smaller arm be attached to this pulley it will revolve in the manner required. The same motion may be produced by employing a double pinion extending the entire length of the larger arm and communicating the rotatory motion | given to it at one extremity, to the axle of the smaller arm situated at the other. Let R and r denote the lengths of the larger and smaller arms respectively, and let the line joining the position of the sun and the centre of the concentric tubes, considered as the origin of co-ordinates, be taken for the axis of x. The aphelion of the orbit will be the point (R+r, o). Also let e denote the inclination of the larger arm to the axis of x at any moment; then since the smaller arm revolves with the same angular velocity, but in the opposite direction, its inclination to the axis of x at that moment must be denoted by-0; and the coordinates of the extremity of the smaller arm, that is, of the position of the planetary ball, will be the sum of the projections of R andr upon the axes of x and y respectively. Representing these co-ordinates by x and y, we shall therefore have

x-R cos 0+r cos 0=(R+r) cos

y=R sin -r sin 0=(R−r) sin ;

• The oversight alluded to in p. 39, that of mistaking the synodic for the sidereal period, does not appear to have been altogether avoided in the construction of the planetarium of the Royal Institution, the wheel-work of which is computed ou the supposition that the earth completes its revolution about the sun in 365 242 days. This is the length of the tropical year, or the time which elapses between the earth's leaving the vernal equinox and its arrival again at that point of the ecliptic; and is, owing to the precession of the equinoxes, less than the earth's sidereal period.

In the descriptions of the planetarium of the Royal Institution, to which

127

+

(R+r)* (R-r)

=3 1, which is the well-known equation to an ellipse referred to its centre, and whose semi-focal and non-focal axes are respectively R+r and R−r. If the excentricity e of the orbit be known the relation between R and r will therefore be determined by the equation

This method is defective in two respects. The elliptic orbits described cannot have a common focus, or else the true relative lengths of the mean distances of the planets cannot be preserved; and secondly the true angular motions of the planets about the sun are not accurately represented. Dr. Pearson corrected in some degree the latter inequality by varying the size of the teeth of the wheels and pinions employed, but for the mere purpose of illustration this appears superfluous, since, after all, the most complete mechanical representation of the solar system that has yet been invented is far inferior to that which the student may form in his own mind from an attentive perusal of a good popular treatise upon the subject.

ORRERY, EARL OF. [BOYLE.]

ORSI'NI, an old and illustrious family of Southern Italy, which has had among its members several popes, many cardinals, and other distinguished individuals. Orso Orsini, of Petigliano near the lake of Bolsena, is mentioned as senator of Rome in the years 1190-1200. His son Giovanni Orsini Gaetani, which last was his mother's family name, left two sons: 1, Napoleone Orsini, Count of Tagliacozzo in the kingdom of Naples; and 2, Matteo, styled the Great,' senator of Rome, and lord of Anagni, Marino, Galera, and other fiefs in the Campagna of Rome Matteo left several sons, one of whom, Giovanni Gaetani, became pope under the name of NICHOLAS III. A branch of the family entered the service of the Anjou kings of Naples, obtained high honours at that court, and the titles of counts of Nola and dukes of Gravina. The Orsini who remained in the Papal State were often at variance with the powerful family of COLONNA during the middle ages. The castle of Bracciano, on the lake of that name, was the chief residence of the Orsini. In January, 1505, Francis Orsini, duke of Gravina, and Paolo Orsini, were treacherously seized and strangled at Sinegaglia by Cesare Borgia, whilst the cardinal Orsini was poisoned at Rome by order of Cesare's father, Pope Alexander VI. By degrees the various branches of the Orsini became extinct, and their estates passed into other hands, with the exception of the Neapolitan branch of the dukes of Gravina, which still continues, the actual duke having married a daughter of the banker Torlonia, duke of Bracciano. The palace Orsini at Rome, a vast building, stands on the ruins of the Theatre of Marcellus. The family palace at Naples, belonging to the duke of Gravina, is one of the finest private buildings in that capital. (Imhoff, Genealogies; Moreri; Almanach de Gotha.)

ORSINI, FULVIO, said to have been an illegitimate member of the noble family of that name, was born at Rome about 1530, and became canon of St. John of Lateran. He was well versed in classical literature, both Greek and Roman, and collected a valuable library of MSS., which he bequeathed to the Vatican library. He was intimate with the cardinals Alexander and Edward Farnese, and was considered one of the first scholars of his age. He died at Rome, about the year 1600. He wrote several learned works: 1, Familiæ Romanæ quæ reperiuntur in antiquis Numismatibus, ab Urbe Condita ad tempora Divi Augusti, cum adjunctis Antonii Augustini Episcopi Ilerdensis,' fol.,

rum illustratus,' in which he points out the numerous passages in which Virgil has imitated or borrowed from the Greek poets; a very interesting commentary; 3, 'Selecta de Legationibus ex Polybio et Fragmenta ex Historiis quæ non extant Dionysii Halicarnassei, Diodori Siculi, Appiani Alexandrini, Dionis Cassii, &c.,' 4to., Antwerp, 1582, in Greek, with Latin notes, 4to.; Carmina novem illustrium Fæminarum Græcarum,' 8vo., Antwerp, 1568, and other minor publications.

ORTA LIDA. [CRACIDE, vol. vii., p. 131.] ORTE'LIUS, ABRAHAM, born at Antwerp in 1527, of a family originally from Augsburg, studied philology and mathematics, and became the first geographer of his age. After travelling through England, Germany, France, and Italy, he published his great work, 'Theatrum Orbis Terræ,' being a description of the globe, or universal geography. He was soon after appointed geographer to Philip II. of Spain. His other works are-1, Deorum Dearumque Capita ex veteribus Numismatibus;' 2, Aurei Saeculi Imago, sive Germanorum Veterum Mores, Vita, Ritus, et Religio;' 3, Itinerarium per nonnullas Galliæ Belgica Partes.' Ortelius was acquainted with most of the learned men of his age, and was particularly intimate with Justus Lipsius, who wrote his epitaph. He died in 1598. (Sweert's Vita Ortelii; Valere André, Bibliotheca Belgica.)

ORTHE'S, or ORTHEZ, a town in France, capital of an arrondissement in the department of Basses Pyrénées, 500 miles from Paris, on the road by Poitiers, Bordeaux, and Mont de Marsan to St. Jéan Pied de Port and Pamplona in Spain, and at the intersection of a cross-road from Bayonne to Pau. The town is pleasantly situated on the right bank of the Gave de Pau, which flows between steep banks of limestone. There is a suburb ou the left bank, which communicates with the town by an antient Gothic bridge. On the only pier of this bridge is a tower. The streets of the town are well laid out, and the houses tolerably well built. There are some ruins of the antient castle of Moncade, on a height commanding the town. The population of Orthès, in 1831, was 5195 for the town, or 7121 for the whole commune; in 1836, it was 7857 for the commune. The townsmen carry on trade in salt provisions, especially hams. The manufacture of linen, especially of table-linen, flourished formerly, but has much declined; that of woollen stuffs and some hardwares is carried on. There are tanyards and currying-shops. The market for cattle and corn is considerable, and there are two large yearly fairs. Slate and coal are quarried in the neighbourhood, and sulphur and petroleum are procured. Six roads converge at the town. This town was antiently subject to the viscounts of Dax, then to the princes of Béarn. Jeanne d'Albert, queen of Navarre, founded here a university for the Protestants, who then predominated in the town, and who still form a fourth or a third part of the inhabitants. They have a church; and there are a Bible Society, a high school, and several government offices.

ORTHOCE'RAS. [POLYTHALAMACEA.]

ORTHOGONAL, ORTHOGRAPHIC. The first of these terms, when not used in the same sense as the second, means simply perpendicular. Thus a curve cuts a set of curves orthogonally when it cuts them all at right angles. Orthogonal or orthographic projection is that which is made by drawing lines from every point to be projected, perpendicular to a plane of projection. Thus if a plane were horizontal, and a point were to drop from a given position upon the plane, its last position would be the orthogonal or orthographic projection of its first. [PERSPECTIVE.] ORTHOGRAPHY. When this word is looked at in its elements (two Greeks words denoting the art of writing and correctness), it would seem that there ought to be included under it whatever belongs to the art of writing a language correctly, including both what is called etymology and syntax. But the grammarians have given it a restricted sense, and it is used to denote not the writing correctly in the general, but the proper selection of literal elements of each word that is used, and the proper division of each word when one part of it is at the end of one line and another at the beginning of the line which succeeds. In the antient Hebrew manuscripts we may observe that this division of words never occurs, the scribes resorting to the expedient of widening certain of the letters, if in the ordinary form the words would not fill up the line. The lawstationers in their copies of legal documents fill up a line with a waved and unmeaning stroke, when the word which follows cannot conveniently be written in it at length. We perceive by certain grammars and dictionaries published by practical men, both at home and still more in the United States of North America, that the writers appear to suppose that their works will be resorted to even by persons of cultivation as authorities or guides to orthography. But we believe it to be the case that the number is very few of persons who actually use dictionaries for this purpose. We mean of course not mere children or persons of very imperfect education, but even of those there are very few persons who read much and write occasionally, who ever think of resorting to books of the kind we are speaking of; and persons of a better education still trust entirely to memory, and should a doubt arise, the reference would be made to some eminent author and not to the guides of which we speak. In fact, the art is acquired almost without teaching, and is maintained in vigour through a whole life by the constant practice of writing and reading. At all events there is no book, grammar, guide, or dictionary, which a scholar in England regards as in this point a book of any authority.

The arrondissement of Orthès contains 152 communes, and comprehends an area of 454 square miles; it is subdivided into seven cantons or districts, each under a justice of the peace. The population in 1831 was 84,689; in 1836, 87,459. ORTHITE. Silicate of Cerium, Iron, &c. This mineral occurs in minute, slender, columnar imbedded masses. Fracture conchoidal; hardness 6'0, 70. Colour grey, inclining to black. Streak brownish grey. Lustre vitreous. Opaque. Specific gravity 3-288.

Before the blow-pipe swells and fuses into a blackish globule; with borax it gives a transparent glass. Gelatinizes in acids and yields a solution of cerium.

it is found at Finbo, near Fahlun in Sweden, and also in Greenland, &c.

Analysis of the mineral from Finbo, by Berzelius :—
Silica

Protoxide of Cerium

36, 25

17.39

11.42

14.00

4.89

Protoxide of Iron

Alumina

Lime

Yttria

3.80

This has been the standard to which reference has always hitherto been made. Open any book printed in the reign of Queen Anne, and many words will present themselves in an orthography very different from that in which they would now be found. But we must not say that the persons who wrote them wrote incorrectly, if they wrote according to the practice of the cultivated persons of their time. If we ascend still higher and go to the reign of Elizabeth, we find the orthography still more diverse from our own; and when we reach the time of Caxton, and still more when we go back to the time of Chaucer and Wickliffe, we find many words which, though they are actually words now in use, are so disguised in their orthographical form that we can scarcely recognise them. We seem to have got among a people who spoke a different language, though they were our own forefathers, not more than ten or twelve generations above our grandfathers.

This has arisen from the want of a standard; something fixed, not varying like usage. There is an inconvenience in

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