OATS

where the witne is about to give his evidence viva voce; and by competent authority, where the evidence is reduced into writing, the attestation of the witne being termed his "affidavit." Any believer in a definite form of religion can be a witne , and the oath may be administered " according to such forms and ceremonies as he may declare to be binding." (1 & 2 Vic. c. 108.) But persons who cannot take an oath are incapable of being witne es; such, therefore, as will not declare their belief in God, in a future state of rewards and punishments, and that perjury will be punished by the Deity, are excluded; as well as those who, from their years or ignorance, are incapable of comprehending the nature of an oath. Oaths are still required by law on many occasions besides the giving evidence m judicial proceedings, and were formerly in a still greater number, until the 5 & 6 W.4. c.fi2., which substituted declarations in a great variety of cases, especially relating to the customs, excises, and post-office. Besides the Quakers and Moravians, several small sects of Christians profe conscientious objections to oaths, grounded on the expre language of the scriptures. The church of England, in common with the Catholic church in all ages, and with most varieties of Christians, considers judicial oaths lawful, and declares them so by her 39th article. They have also been held mischievous or unnece ary by some philosojphical writers, especially Bentham, in his Rationale qf Evidence. The only answer to his reasoning appears to be, that however unreasonable the belief that the duty of truth is rendered more imperative by the formality of an oath, still, while such belief is a prevalent one, or while the imagination of witne es in general is impre ed by its solemnity, the convenience of retaining the practice overbalances the disadvantages. OATS. See Avena. OBE'DIENCE, PASSIVE, in Politics, signifies the unqualiiied obedience which, according to some political philosophers, is due from subjects to the supreme power m the state; insomuch that not only its lawful, but its unlawful commands, may not be forcibly resisted without sin. The doctrine of pa ive obedience or non-resistance was strongly profe ed by the church of England in the time of King James I.; much commented on by writers, both for and against it, under Charles and James II.; and condemned at the Revolution. 5ee Non-resistance, and Divine Right. O'BELISK. (Gr. e^airxof, dim. from effao;, Lat. obelus, a needle, or dart.) A lofty quadrangular monolithic column, " diminishing upwards, with the sides gently inclined, but not so as to terminate in an apex at the top; neither is it truncated or cut off at the summit, but the sides are sloped off so as to form a flattish pyramidal figure, by which the whole is suitably finished off and brought to a point, without the upper part being so contracted as to appear insignificant." Egypt w^s, properly speaking, the land of obelisks; and they are unquestionably to be reckoned among the most ancient monuments of that extraordinary people. Much learning and ingenuity has been expended in endeavouring to ascertain their origin, and the purposes for which they were erected; but it does not appear that any satisfactory solution of the problem has hitherto been given. It has been frequently a erted that obelisks were originally erected in honour of the sun, of which they were said to be symbolical, and that they served the purposes of a gnome or sun-dial; but this opinion is now almost totally rejected, and it is generally believed that obelisks were nothing more than monumental structures, serving as ornaments to the open squares in which they were generally built, or intended to celebrate some important event and to perpetuate its remembrance. They were usually adorned with hieroglyphics; and we learn from the testimony of Diodorus and Strabo that the inscriptions with wliich they were charged. declared the amount of gold and silver, the number of troops, and the quantity of ivory, perfumes, and corn which all the countries subject to Egypt were required to furnish. The two largest obelisks were erected by Sesostris in Helio polis. They were formed of a single block of granite, and measured 180 feet in height. When Egypt became a Roman province, August us removed these obelisks to his own capital; and this practice found numerous imitators both m some of his succe ors to the imperial throne, and, at a much later period, in many of the Roman pontiffs from the 16th century down to the present times. Of these obelisks that of the Later an, which is the largest now known, being 105 feet in height exclusive of the pedestal, and weighing 440 tons, was brought by Const an tine from Helio polis to Alexandria, and thence by Constant i us his son to Rome, where it was.erected in the Circus Maxim us. The obelisk next in size to that of the Later an was placed originally in the Vatican circus by Caligula, but it now standfr in the piazza of St. Peter's; its entire height is 132 feet, including the pedestal, . The obelisks most generally known, at least in name, are the Luxor, which was removed to Paris in 1833; and the two 837 OBJECT-GLASS. monoliths called Cleopatra's Needles, of which one it I standing, and the other on the ground; but these are smaller than those we have adverted to, the Luxor being 76 feet in height, and the Needle of Cleopatra which still stands being about 63 feet in height, exclusive of the pedestal, . A full consideration of the Egyptian obelisks would involve us in the discu ion of several most important questions, on which our limits preclude us from entering. Of these perhaps the most extraordinary is the wonderful knowledge of mechanical power which the Egyptians evinced in erecting and removing such gigantic Btructures,_a feat which it would require the greatest skill and ingenuity of modern engineers, even in the present comparatively perfect state of mechanical science, to accomplish. ( See the learned treatise of Zoega on Obelisks; see also SirG. Wilkinson's Egyptians, vol. iii., pa im, which contains some excellent illustrations of the different methods adopted by that people for removing their huge structures from place to place.) O'BELUS. In Diplomatics, a mark soralled from its resemblance to a needle (Gr.sgaof); usually thus — orthus -7- in ancient MSS. It was used by Origen, in his Ilezapla, to mark the pa ages where something is found in the Septuagint which is not in the Hebrew. The common use of the line— in modern writing is to mark the place of a break in the sense, where it is suspended, or where there is an ungrammatical transition; but a paragraph introduced where the sense is suspended is more properly marked by the sign of a parenthesis. O'BERON. In Mediaeval Mythology, tlie King of the Fairies. Wiel and's beautiful poem, and "Weber's romantic opera of this name, the Midsummer Night's Bream, and innumerable other poems and tales of which he is the hero, have made the name of Oberon so familiar that it will be unnece ary to do more in this place than to state the origin of the fable. The name Oberon first appears in the old French fabliaux of Huon of Bordeaux; it is identical with Auberon, or Alberon, the first syllable of which is nothing more than the old German word Alb, elf or fairy, which, in the HeldenBuch and other old German poems, is expre ed variously by Alberich or Alban. (See Grimm's Deutsche My tho logie, p. 256. ) He was represented as endowed with magic powers, and with the qualities of a good and upright monarch, rewarding those who practised truth and honesty, and punishing those who acted otherwise. His wife's name was Titania, or Mab, whose powers have been so beautifully depicted in Romeo and Jtdict. OBE'SITY. (Lat. obes us,/fl7.) Unhealthy fatne . The tendency to the formation of fat is often so exce ive as to constitute a disease, and it occasionally prevails in particular habits, so as to cause a most unsightly bulk of body, and to be independent of diet. The celebrated Lambert, who exhibited himself some years ago, was a remarkable specimen of this disease. He died in the fortieth year of his age, and weighed, a little before his death, 739 pounds. There is an account, in the PhilosO' phical Transactions for 1813, of a girl, only four years old, who weighed 256 pounds from accumulation of fat. When obesity is limited to the abdomen, arising from exce ive deposition of fat in the omentum, and producing what is called a pot belly, or where it is the result of indolence and indulgence in luxurious diet, a slow and prudent change from a full to a spare diet, and the judicious use of purgatives and of appropriate modes of exercise, have occasionally effected remarkable cures. O'BIT. (Lat. obit us, death.) In the Roman Catholic liturgy, a service performed for the repose of a departed soul. OBI'TUARY. (Lat. obitarium.) A register in which are enrolled the names of deceased persons for whom obits are to be performed, and the days of their funeral. It is also used for the book containing the foundation or institution of the several obits in a church or monastery. In the former sense it is synonymous with necrology, in the latter with martyrology. OBJECT-GLASS (of a refracting telescope or microscope). The lens which first receives the rays of light coming directly from the object, and collects them into a focus, where they form an image which is viewed through the eye-gla . The excellence of an object-gla depends on the distinctne of the image which it forms. On account of the unequal refrangibility of the rays of light, it is nece ary, in order to procure a distinct image, to employ an achromatic combination of lenses, formed of substances having different dispersive powers, and of such figures that the aberration of the one may be corrected by that of the other. The substances chiefly used are crown gla and flint-gla ; the dispersive powers of which are respectively as 3 to 5. By combining a convex lens of crown-gla with a concave lens of flint-gla , havinK their focal distances in that proportion, an image would be formed free from colour, but it would not be free from aberration. The determination of the form of the compound lens which shall give the least po ible aberration for parallel rays is a problem which admits of exact 3 H 3 Page 851