ther, money paid or property transferred under the mistaken impression that a legal obligation existed could not be recovered if a natural obligation existed. In many cases, moreover, a natural obligation was a sufficient basis for suretyship or for a new promise, and in a few cases such an obligation could be used as a set-off against a legal obligation. Modern legislators do not regard the conception with favor, but the courts have not been able to dispense with it. Consult the authorities referred to under CIVIL LAW. OBLIQUE MOTION. See MOTION. OBOE (It. oboe, from Fr. hautbois, Eng. hautboy, high wood, so called from the high notes of the instrument, from haut, high + bois, wood). The oldest and most important wood-wind instrument. It is of great antiquity and is traced in the sculpture of Egypt and Greece. The oboe is the most elaborate and difficult of reed instruments. It is made of wood, generally of box, ebony, cocoa, or rosewood, and is constructed in three pieces, or joints, forming a continuous tapering tube, about 21 inches long, the bore of which is narrow at the small end, and widens into a bell-shaped opening, one and one-half inches in diameter at the mouth. In the upper and middle piece there are holes, by stopping or opening which with the fingers the player forms the notes of the natural scale, the intermediate semitones being formed by the keys. The reed is fixed upon the end of a small brass tube which fits, socket-like, into the small end of the upper piece. The sound of the oboe is reedy and penetrating, though mild, and from its great power in swelling or diminishing the sound, it is capable of every variety of expression. In the modern orchestra two oboes are employed, the treble oboe, a non-transposing instrument, the music for which is written in the G clef, and the alto-oboe or cor anglais (q.v.), a transposing instrument. The principal solo compositions for the oboe are: Handel's six concertos; Mozart's quintet for oboe and strings; Beethoven's trio for two treble oboes and cor anglais; Hummel's variations, with orchestra; and Kalliwoda's concertino in F, with orchestra. The oboe d'amore, in use in the eighteenth century, became obsolete, but was reconstructed by M. Mahillon, of Brussels, at the order of M. Gevaert, in order to perform correctly the works of Bach. See MUSICAL IN STRUMENTS. OBOK, ō-bŏk'. A seaport of French Somaliland (q.v.), situated at the western end of the Gulf of Aden (Map: Africa, J 3). It was acquired by France in 1855, and with the surrounding district formed the colony of Obok, which became the nucleus of the French possessions in Somaliland. Population, about 1000. OB'OLEL'LA (Neo-Lat., diminutive of Lat. obolus, from Gk. ßoλós, small coin). A small fossil brachiopod of oval or rounded outline common in and very characteristic of Cambrian rocks of North America and Europe. OB'OLUS (Lat., from Gk. ßoλós). The name of a Greek measure of weight and a Greek coin. Six of these oboli made a drachma. DRACHMA. See OBRADOVIČ. ô-brä'dó-vich, DOSITHEUS (1739-1811). A Servian author, the father of modern Servian literature. He was born at Coákovár, Hungary, and at the age of fifteen entered the Monastery of Oprovo in Syrmia. He afterwards traveled in the East and in Italy; and in 1783 he published Zivot i priklučenija, or “Life and Adventures," partly autobiographic and partly fantastic. This was the first book written in the popular speech of the Servians, and made it a literary language. In Belgrade, where he settled in 1807, he was made Senator and Minister of Public Education. Besides many translations, especially of Esop's Fables (1788), he wrote Sověti zdravago razuma, or "Wise Counsel" (1784), and a work on morals, Sobranie nravouA complete čitelnych veščej (1793 and 1818). edition of his works in ten volumes appeared at Belgrade (1833-45). Consult Sevic, Dositheus Obradovič (Neusatz, 1889). OBRENOVITCH, đ-brěnô-vich. A ruling family of Servia which attained power in 1817, when Milosh Obrenovitch (q.v.) was chosen Prince by the nobility and the clergy. Milosh was compelled to abdicate in 1839 and was followed by his sons, Milan, who ruled only for a few weeks, and Michael Obrenovitch (q.v.), who in turn was deposed in 1842, the power passing to the rival house of Karageorgevitch. Alexander Karageorgevitch fell in 1858 and was succeeded by the old Prince Milosh, who died in 1860 and made way a second time for his son Michael. The latter was assassinated in 1868 and Milan I. (q.v.), a grandson of Jefrem, the younger brother of Milosh Obrenovitch, was 1882, but in 1889 was forced to abdicate in favor chosen Prince. He attained the kingly title in of his son, Alexander I. (q.v.), who was assassinated in 1903, leaving no heirs. Peter Karageorgevitch was chosen King by the Skuptchina. See SERVIA. O'BRIEN, FITZJAMES (1828-62). An IrishAmerican poet, story-teller, and journalist, born in Limerick. He was educated at the University of Dublin, served for a time, as is supposed, in the British Army, and squandered a considerable inheritance in London, editing a periodical in aid of the first World's Fair (1851). The next year he came to the United States. His most striking work appeared in the Atlantic Monthly-two short stories hardly surpassed for creative imagination in American literature. These are The Diamond Lens and The Wondersmith. He supplied the stage also with many ephemeral dramas, and with one, A Gentleman from Ireland, that held the boards for a generation. In the Civil War he served in the Seventh Regiment, was severely wounded, and after a lingering illness died, in Cumberland, Md. (April 6, 1862). was a distinguished figure in the Bohemian New York of his day, and witness to the impression that he made in that sprightly circle is preserved in a sheaf of personal recollections prefixed to The Poems and Stories of Fitzjames O'Brien, edited by his friend William Winter (1881). O'Brien has never received full praise for his unique, if bizarre, talents, which are most clearly displayed in his stories, but are also visible in a number of poems, such as "The Skaters" and "The Wharf-Rat." Hc O'BRIEN, JEREMIAH (1744-1818). An American patriot, born probably at Kittery, Maine. In 1775 the captain of the British armed vessel Margaretta threatened to bombard the town of Machias, where O'Brien then lived, unless the liberty pole were removed. On June 12th O'Brien and his five brothers, accompanied by about thirty-five of their townsmen, many of them armed only with pitchforks, manned a little sloop in the harbor, attacked the Margaretta and after a brief engagement captured her. After the battle Captain O'Brien transferred the Margaretta's cannon to his own vessel, which he rechristened the Machias Liberty, and used as a coast patrol. Later he became a privateer captain sailing under letters of marque from the colony, and while commanding the Hannibal, 20 guns, was captured by two British frigates and sent to England, where he was confined in the Mill Prison. After the close of the war he was appointed the first collector of the port of Machias. A O'BRIEN, LUCIUS RICHARD (1832-). Canadian painter, born at Shanty Bay, Ontario, and educated at Upper Canada College, Toronto, where he studied architecture and civil engineering. He came to be considered the best painter in water colors that Canada has produced. As first president of the Royal Canadian Society of Artists, he furthered the interests of other artists, and Canadian art in general. His best paintings are descriptive of scenery upon the Lower Saint Lawrence. O'BRIEN, WILLIAM (1852-). An Irish journalist and Parliamentary leader. He was educated at Cloyne Diocesan College and at Queen's College in Cork. In 1869 he became a reporter on the Cork Daily Herald, in 1875 he joined the staff of the Freeman's Journal, and in 1880 founded the United Ireland. Because of his political activity, he was nine times prosecuted by the law officers of the Crown and was imprisoned for more than two years. He represented the Nationalists in Parliament almost continuously from 1883 until 1895, when he retired because of dissensions in the party. In 1890 he visited the United States and collected considerable funds for the benefit of the Irish cause, and after Parnell's conviction he became one of the leaders of the anti-Parnell faction. In 1898 he originated a new agrarian movement under the name of the United Irish League, and founded the Irish People, as its organ. He published several books, among them When We Were Boys (1890) and Irish Ideas (1894). O'BRIEN, WILLIAM SMITH (1803-64). An Irish politician. He was educated at Harrow School, whence he passed to Trinity College, Cambridge. He entered Parliament for the Borough of Ennis in 1828. In 1835 he was returned for the County of Limerick, and for several years strongly advocated the claims of Ireland to a strictly equal justice with England, in legislative as well as executive measures. Professing his inability to effect this in the United Legislature, and having been committed to prison in the House of Commons by the Speaker's orders for refusing to serve on committees, he withdrew from attendance in Parliament in 1841, and joined actively with Daniel O'Connell (q.v.) in the agitation for a repeal of the legislative union between England and Ireland. In the progress of that agitation, O'Brien sided with the party known as 'Young Ireland,' and when the political crisis of 1848 resulted in a recourse to arms, he took part in an attempt at rebellion in the south of Ireland. He was arrested, convicted, and sentenced to death. The sentence, however, was commuted to transportation for life. He was transported to Tasmania, but in 1856, in common with the other political exiles, he was permitted to return to his native country. He published The Principles of Government (1855). Consult: Sullivan, New Ireland (London, 1877); Duffy, Young Ireland (2d ed., ib., 1883). OBSERVATORY (from Lat. observare, to observe, from ob, before + servare, to keep; connected with Skt. sar, Av. har, to protect). An regular observation of astronomical, meteorologiinstitution supplied with instruments for the cal, or magnetic phenomena. In some observa tories all three classes of observation are carried on, but in most cases special attention is paid to astronomy alone, and only such meteorological observations are taken as are required for the calculation of the effect of atmospheric refraction on the position of a heavenly body; there are, however, a few observatories which are devoted solely to meteorological or magnetical observations. In While observation of the heavenly bodies dates from prehistoric times and individuals at intervals made their crude observations of the heavens, the first observatory, in our modern sense of the word, was that of Alexandria, founded about B.C. 300. It continued in activity till A.D. 200; and it was here that Hipparchus discovered the precession of the equinoxes and fixed the positions of the sun, moon, and planets by means of armillary spheres (q.v.) and astrolabes, having graduated circles on which celestial latitudes and longitudes could be read off, when a pair of sights was pointed to the heavenly body. Ptolemy used a quadrant, with which he measured zenith distances on the meridian. the ninth and tenth centuries the Arabs founded observatories at Bagdad, Damascus, and Mokattam, near Cairo. In the latter place the Hakimite tables were constructed. In the thirteenth century the splendid observatory at Meragha, Persia, and in the fifteenth century that of Samarkand were founded by Mongol Khans. Here planetary tables and star catalogues were constructed. The first observatory in Europe was that of Nuremberg, erected in 1472, and the revival of astronomical observations in Europe dates from its foundation. In 1576 Tycho Brahe began the erection of his famous observatory on Hven, an island in the Sound. He converted the quadrant used by Ptolemy into an altazimuth by mounting it on a vertical axis in connection with a horizontal or azimuth circle. It was not till the middle of the eighteenth century that the improvement of time measurement with pendulum clocks enabled astronomers to rely for the determination of right ascensions on the times of passage across the meridian, instead of measurements with a graduated circle. The quadrant was then fixed in the meridian, and being attached to a massive wall, its dimensions were increased, and greater accuracy thereby secured in the determination of meridian zenith distances. Neither the quadrant nor the mural circle (q.v.) which succeeded it, however, could be relied upon for accurate motion in the plane of the meridian, but Römer remedied this defect by inventing the transit instrument (q.v.), which enabled astronomers to observe the times of meridian passage or transit with great accuracy, and thus to determine the right ascension of the heavenly bodies by means of the apparent but sometimes has a green, red, or brown color, diurnal movement. With the transit and quad- is striped or spotted, and even chatoyant or rant Bradley commenced that series of observa- aventurine. It occurs in volcanic regions, in It tions of the positions of the sun, moon, planets, round compact pieces, granular or fibrous. and stars, which have continued ever since at is often found in association with pumice, which Greenwich, and on which, in combination with is identical with it in chemical composition, but less extensive series at Paris, Königsberg, and different in structure. Pitchstone is also of elsewhere, all our tables of the motions of the similar composition, but contains a larger perheavenly bodies are founded. In modern observa- centage of water and is without lustre. Obsidian tories the transit and mural circle have been is found principally in the volcanic regions of combined into one instrument, the meridian cir- Iceland, Italy, Hungary, Spain, New Zealand, cle (q.v.), which determines both right ascen- Siberia, Mexico, Peru, and the western parts of sions and declensions at a single observation. the United States, especially in Georgetown, In planning observatories a very usual mistake Col., and at the Obsidian Cliff in the Yellowstone is an over-supply of instruments and too few Park, where it occurs in massive form. astronomers. A large telescope really needs six famous locality in Mexico is the Cerro de Navajas, persons to keep it busy: two astronomers, two or 'Hill of Knives,' in the State of Michoacan. assistants, and two computers. Moreover, the Obsidian takes a high polish, but is very brittle. 'life' of a telescope is very short. Every few Nevertheless, it was extensively used among years new instruments are invented, and unless primitive peoples for arrowheads and spearheads, these are supplied to the observatory its astron- for knives, mirrors, polished figures, and ornaomers will work at a disadvantage, and its astro- ments, the best specimens of which have been nomical output will be diminished in quantity found in Mexico. The early Romans obtained and value. obsidian mirrors from Ethiopia. The mineral is still sometimes employed as material for ornamental boxes, buttons, and other articles. The great observatories of the world may be divided into several classes. In the first place, we have the great Government institutions occupied with continuous observations such as are needed to strengthen our knowledge of the fundamental parts of astronomy. The Royal Observatory at Greenwich, England, is perhaps the most important of this class. It was founded by Charles II. Similar institutions are established at Paris, Berlin, Pulkova (q.v.), near Saint Petersburg, and Washington. At the last-named place the observatory is called the United States Naval Observatory (see NAVAL OBSERVATORY), and the astronomers are professors of mathematics in the United States Navy. Another class of observatories are maintained by universities and other educational institutions. These are intended to combine instruction with research, and in them an effort is usually made to extend the science of special investigations rather than by long continued routine observation. In the United States the principal observatories of this class are the Harvard University Observatory, the Lick Observatory (q.v.) of the University of California, and the Yerkes Observatory (q.v.), belonging to Chicago University. Finally, we have the very important class of astrophysical observatories, which are occupied with a study of the physics of the heavenly bodies. Probably the most important of these is at Potsdam, Germany. Much astrophysical work is also done at the university observatories of Harvard and Chicago. See TELESCOPE; MERIDIAN CIRCLE. For the lately established observatories for the observation of the variations of latitude, see LATITUDE, VARIA TIONS OF. OBSIDIAN (from Lat. obsidiana, false reading for obsiana, a sort of mineral, probably obsidian, from Obsidius, false reading for Obsius, name of a man who is said to have discovered it in Ethiopia). A volcanic glass consisting of silica in combination with aluminum, calcium, iron, potassium, and sodium. It is hard and brittle, with a remarkable vitreous lustre, and a perfect conchoidal fracture, the edges of the fracture, which are semi-transparent or translucent, being very sharp and cutting like glass. Obsidian is generally black or very dark gray, The OBSTETRICAL TOAD. See MIDWife Frog. OBSTETRICS (from Lat. obstetricius, relating to a midwife, from obstetrix, midwife, form obstare, to stand before, from ob, before, toward + stare, to stand), MIDWIFERY, or ToKOLOGY. That branch of medicine which is concerned with the care of women during pregnancy, and during and after labor, whether natural or irregular, with the diseases peculiar to the puerperal state, and with the care of the It also embraces a knowledge new-born child. of the anatomy of the female generative organs and the physiology of reproduction in the human species. While among savages little or no assistance is given to the parturient woman, and the process is left to unaided nature, among civilized peoples from the earliest times there has been a class of persons-usually womenwho have attended women during this trying period. The Jews had women (called mejelledeth) who acted as midwives, as did the Egyptians; and among the Greeks there was a corresponding class of women known as mœeutriæ. Phanarete, the mother of Socrates, was a midwife; and Plato explains the duties undertaken by these women. Hippocrates gave considerable attention to midwifery, and describes the operation of turning the child in abnormal labors. Among the Romans both physicians and midwives (obstetrices) attended confinements. Cæsarian section was performed after the death of the mother, and Pliny mentions that Scipio Africanus and Manlius were born in this way. There was a royal law (rex legia) providing for the performance of this operation when necessary. Celsus and Paulus of Ephesus wrote of obstetrics during the first century, and a gradual increase in the knowledge of the physiology and mechanism of labor can be traced in the writings of Galen (second century), Actius (fifth century), and Paulus Ægineta (seventh century). The latter advocated the operation of craniotomy in suitable cases. During the Middle Ages there was little progress in obstetric science in Europe, but the Arabian and Persian schools made many improvements in this branch of medicine as well |