Obscurantists.

O'BOE. See HAUTBOY.

OB'OLUS (Gr. obolos or obelos, a spit), the smallest of the four common Greek coins and weights, was originally, as is generally supposed, a small piece of iron or copper, similar in form to the head of a spit, or spear head, whence its name. In this form it was used as a coin, and a handful of "oboli" was equivalent to a drachma (q.v.). It was subsequently coined of silver, and in the ordinary round form, but still retained its original name; its value, both as a coin and a weight, was now fixed as the part of a drachma so that in the Attic system it was equivalent to 1§d. and 15 Troy grains respectively; while the Eginetan obolus was worth 24d. as a coin, and 25 Troy grains as a weight. Multiples and submultiples of this coin were also used, and pieces of the value of 5, 4, 3, 2, 14 oboli, and of §, 1, 1, and † of an obolus respectively, are to be found in collections of coins.

OB'OLUS, in natural history. See INVERTEBRATE ANIMALS, sub-kingdom mollusca, division A; class III. family 10.

OBOOKI'AH, HENRY, b. in the island of Hawaii, about 1795. In his childhood in a civil war his parents were killed before his eyes. Taking his infant brother upon his back, and attempting to escape, his brother was pierced through with a spear, and he was made prisoner and taken to the house of the man who had killed his parents. His uncle, the high priest of the island, found him here and took him home. He was kindly treated by his uncle, but he was unhappy, often weeping day and night. He gladly in 1805 embarked to come to the United States with capt. Brintnal of New Haven, Conn., and for a while resided with the captain. He attended church, and showed a great desire for instruction, lingering about the college buildings. Finding the desire unattained, and thinking of the students there who were enriching their minds with the treasures which were inaccessible to him, he sat down weeping on the threshold. The Rev. Edwin W. Dwight, a resident graduate, found him there, and taking him to his house, gave him instruction. Samuel J. Mills visiting New Haven soon became acquainted with him, and Henry expressed a desire to "learn to read the Bible, and go back to his native islands and tell the people of God." Mills took Henry to his father's house in Torring ford, where he rapidly improved in religious and secular knowledge. Afterward he accompanied Mr. Mills to Andover, where he spent two years. By invitation of James Morris, he spent the winter of 1813 at the Litchfield grammar school. In the autumn of 1814 by advice of friends he placed himself under the care of the North consociation (Congregational) of Litchfield co., for the direction of his studies; and Nov. 15, 1815, he was received under the care of the American board. A foreign mission school having been established at Cornwall, Conn., Obookiah was placed there to be educated. But on Feb. 17, 1818, he was stricken with fever, and soon died. But he had not lived in vain. His earnest desire for an education, shown in New Haven, led to the establishment of the Cornwall school, and the education of several of his countrymen, and to the awakening of the Christian community to a deep interest for the Sandwich islands; to which a mission was commenced soon after his death.

O'BRIEN, a co. in n.w Iowa, drained by Little Sioux river, and Willow creek; on the Chicago, Milwaukee, and St. Paul railroad; 576 sq.m.; pop. '80, 4,155-3,626 of Ameri can birth. The surface is mostly prairie, and the soil fertile. The principal productions are corn, wheat, oats, and barley. Co. seat, Primgar.

O'BRIEN, FITZ-JAMES, 1829-62; b. Ireland; emigrated to America in 1850, and, in April 1861, joined the New York 7th regiment. In the following January he was placed on the staff of gen. F. W. Lander, was wounded in a skirmish Feb. 16, 1862, and died from the effects of a surgical operation. He was a contributor in prose and verse to the Atlantic Monthly. He was happy in his choice of themes, especially for his poetical work, and he gave them noble treatment, vigorous but refined. He was a brave soldier. He is called the ablest of those of the New York Bohemians, from 1850 to 1863, who are now dead. He was a member of that literary coterie to which Charles G. Halpine, E. C. Stedman, Walt Whitman, and T. B. Aldrich belonged, and in a publication of the present year entitled Life, Poems, and Stories of Fitz-James O'Brien, edited by William Winter, who knew him well, are included his stories, most distinguished for imaginative ability and literary art, The Diamond Lens and the Golden Ingot.

O'BRIEN, JEREMIAH, 1740-1818; b. Ireland; came to this country and settled in Maine; in 1775, with only a few assistants, struck the first hostile blow in the American waters, capturing the Margaretta, a British armed vessel, for which act he was appointed capt. of privateers. Soon afterwards ne captured other English vessels, and was com missioned capt. in the state navy, but finally was made prisoner, and confined in the prison-ship Jersey for six months, then sent to England and placed in Mill prison, but a year later escaped, and returned to Maine. He held the office of collector at Machias, at which place he died.

O'BRIEN, WILLIAM SMITH, b. in 1803, was the second son of the late sir Edward O'Brien, bart. of Dromoland, in the county of Clare, Ireland, and uncle of the present lord Inchiquin; that ancient barony having recently passed to the Dromoland O'Briens on the failure of the elder branch. William S. O'Brien was educated at Harrow school,

whence he passed to Trinity college, Cambridge. He entered parliament for the borough of Ennis in 1826, and was a warm supporter of Catholic emancipation. In 1835 he was returned on advanced liberal principles 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 embroiled himself with the speaker by refusing to serve on committees (for which refusal he was committed to prison in the house by the speaker's order), 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, a division having arisen on the question of moral as against physical force between O'Connell and the party known as young Ireland," O'Brien sided with the latter; and when the political crisis of 1848 eventuated in a recourse to arms, he took part in an attempt at rebellion in the s. of Ireland, which in a few days came to an almost ludicrous conclusion. He was in consequence arrested, and, having been convicted, was sentenced to death. The sentence, however, was commuted to transportation for life; and after the restoration of tranquillity in the public mind in Ireland, he, in common with the other political exiles, was permitted to return to his native country. From that date (1856) he spent much of his time in foreign travel; and although he wrote more than once in terms of strong disapproval of the existing state of things, he invariably abstained from all active share in the political proceedings of any party. He died June, 1864.

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OBSCENE PRINTS, BOOKS, or PICTURES, exhibited in public render the person so doing liable to be indicted for a misdemeanor. Persons exposing them in streets, roads, or public places, are also liable to be punished as rogues and vagabonds with hard labor. An important change in the law was effected by lord Campbell's act (20 and 21 Vict. c. 83), which was passed to suppress the traffic in obscene books, pictures, prints, and other articles. Any two justices of the peace, or any police magistrate, upon complaint made before him on oath that such books, etc., are kept in any house, shop, room, or other place, for the purpose of sale, or distribution, or exhibition for gain or on hire, and that such things have been sold, etc., may authorize a constable to enter in the day-time, and, if necessary, use force by breaking open doors, or otherwise to search for and seize such books, etc., and carry them before the magistrate or justices, who may, after giving due notice to the occupier of the house, and being satisfied as to the nature and object of keeping the articles, cause them to be destroyed.

OBSCENE PRINTS, BOOKS, or PICTURES (ante). By U. S. revised statutes, sec. 2,491, all persons are prohibited from importing into the United States from any foreign country any obscene book, pamphlet, paper, writing, advertisement, circular, print, picture, drawing, or other representation, figure, or image, on or of paper or other material, or any instrument or drug for any immoral purpose. No invoice or package containing such articles shall be admitted at the custom house. Any judge of any U. S. district or circuit court, before whom complaint in writing is made upon knowledge or belief, and if upon belief, setting forth the grounds of such belief, supported by complainants' oath, may issue a warrant to any marshal or deputy marshal to search for and seize such immoral articles, and to make return so that they may be condemned and destroyed. The proceedings, as in other cases of municipal seizure, are subject to appeal or writ of error. It was held in The U. S. vs. One case of Stereoscopic Slides, Sprague, 407, that where an invoice contains any immoral articles, the whole is forfeited. By sec. 3,878, obscene publications, etc., are excluded from the mails. By sec. 3,893 any person who shall knowingly deposit in or take out from the mails such things for the purpose of circulation or distribution, shall be guilty of a misdemeanor, and for each offense be fined not less than $100 or more than $5,000, or imprisoned not less than one year or more than 10 years, or both at the discretion of the court. The prohibition of these statutes is against every article or thing intended or adapted to any obscene, indecent, or immoral use. By sec. 5,389, every person in the district of Columbia, or any of the territories, or elsewhere within the United States jurisdiction, who sells, lends or gives away, or in any manner exhibits or publishes or offers to publish any obscene publication etc., shall be punished with hard labor in the penitentiary for not less than 6 months, or more than 5 years for each offense, or shall be fined not less than $100 or more than $2,000 with costs. By sec. 1785, any officer, agent, or employee of the United States who violates laws against obscene literature etc., is guilty of misdemeanor, and for each offense, shall be fined not less than $100, nor more than $5,000, or shall be imprisoned at hard labor for not less than one year, nor more than 10 years or both. See VICE, SOCIETY FOR THE SUPPRESSION of.

OBSCURAN'TISTS, the name given, originally in derision, to a party who are supposed to look with dislike and apprehension on the progress of knowledge, and to regard its general diffusion among men, taken as they are ordinarily found, as prejudicial to their religious welfare, and possibly injurious to their material interests. Of those who avow such a doctrine, and have written to explain and defend it, it is only just to say that they profess earnestly to desire the progress of all true knowledge as a thing good in itself; but they regard the attempt to diffuse it among men, indiscriminately, as perilous,

Observatory.

and often hurtful, by producing presumption and discontent. They profess but to reduce to practice the motto

A little learning is a dangerous thing.

It cannot be doubted, however, that there are fanatics of ignorance as well as fanatics of science.

OBSERVANTISTS, or OBSERVANT FRANCISCANS. Under the head FRANCISCANS (q.v.) has been detailed the earlier history of the controversies in that order on the inter pretation of the original rule and practice established by St. Francis for the brethren, and of the separate organization of the two parties at the time of Leo X. The advocates of the primitive rigor were called Observantes, or Strictioris Observantiæ, but both bodies were still reputed subject, although each free to practice its own rule in its own separate houses, to the general administrator of the order, who, as the rigorists were by far the more numerous, was a member of that school. By degrees, a second reform arose among a party in the order, whose zeal the rigor of the observantists was insufficient to satisfy, and Clement VII. permitted two Spanish friars, Stephen Molena and Martin Guzman, to carry out in Spain these views in a distinct branch of the order, who take the name of reformati, or reformed. This body has in later times been incorporated with the observantists under one head. Before the French revolution, they are said to have numbered above 70,000, distributed over more than 3,000 convents. Since that time, their number has, of course, been much diminished; but they still are a very numerous and widespread body, as well in Europe as in the new world, and in the missionary districts of the east. In Ireland and England, and for a considerable time in Scotland, they maintained themselves throughout all the rigor of the penal times. Several communities are still found in the two first-named kingdoms.

OBSERVATION AND EXPERIMENT are the leading features of modern science, as contrasted with the philosphy of the ancients. They are indispensable as the bases of all human knowledge, and no true philosophy has ever made progress without them, either consciously or unconsciously exercised. Thus, by Socrates, Plato, and Aristotle, no less than by Archimedes and the ancient astronomers, observation and experiment are extensively though not prominently or always obviously employed; and it was by losing this clue to the spirit of their master's teaching, that the later disciples in these schools of philosophy missed the path of real progress in the advancement of knowledge. It was in the latter half of the 16th c. that the minds of philosophers were first consciously awakened to the importance of observation and experiment, as opposed to authority and abstract reasoning. This result was first occasioned by the discoveries and controversies of Galileo in Florence; and to the same end were contributed the simultaneous offorts of a number of philosophers whose minds were turned in the same direction-Tycho Brahe in Holland, Kepler in Germany, William Gilbert in England, who were shortly after wards followed by a crowd of kindred spirits. The powerful mind of Francis Bacon lent itself to describe the newly awakened spirit of scientific investigation, and though hỏ ignored or affected to despise the results achieved by the great philosophers just mentioned, he learned from them enough to lay the foundation of a philosophy of inductive science, which, if we look at the course of scientific progress since his day, seems to have been almost prophetic. The difference between observation and experiment may be said to consist in this, that by observation we note and record the phenomena of nature as they are presented to us in her ordinary course; whereas by experiment we note phe nomena presented under circumstances artificially arranged for the purpose. Experiment is thus the more powerful engine for discovery, since one judiciously conducted experi ment may provide the data which could only result from a long course of observations.

OBSERVATORY, an institution supplied with instruments for the regular observation of natural phenomena, whether astronomical, meteorological, or magnetical. In some observatories 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 meteorologieal or magnetical observations. Confining our attention to astronomical observatories, it will be convenient to divide them into two classes-public and private observatories-the former being devoted to those observations which from their nature require to be continued on the same system for long periods of time, whilst the latter are usually founded for some special object, which may be attained with a comparatively small expenditure of time and labor,

The most important work which is carried out in public observatories is the deter mination of the movements of the sun, moon, and planets among the stars; and as a corollary to this, the relative positions of the stars to which the other heavenly bodies are referred. In early times the Greek astronomers fixed these positions by means of armil lary spheres and astrolabes, having concentric graduated circles, on which the latitudes and longitudes could be read off, when a pair of sights was pointed to the heavenly body. Ptolemy made use of a quadrant, with which he measured zenith distances on the meridian; and many centuries after, Tycho Brahe converted this form of instrument

into an altazimuth by mounting it on a vertical axis in connection with a horizontal or azimuth circle. With this instrument Tycho Brahé made a long series of observations of the altitudes and azimuths of the heavenly bodies at the observatory which the king of Denmark erected for him, and he also measured with great assiduity their angular distances from each other by means of a sextant, a method of observation which Flamsteed afterward employed with a much improved form of the instrument, and which is now extensively used with the reflecting sextant, for finding the longitude at sea. It was not till the middle of the last c., that the improvement of the clock by Graham enabled astronomers to rely on it for the determination of right ascensions by the times of passage across the meridian, instead of by measuring them 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. Two such instruments pointing respectively n. and s. were erected at the royal observatory, Greenwich, and used by Bradley and his successors from 1750 till they were displaced by the mural circle (see CIRCLE, MURAL), an instrument vastly superior in principle, since the troublesome errors of centering of the quadrant were got rid of by combining the readings of opposite parts of a graduated circle, whilst the effect of division errors was much reduced by taking the mean of the readings at 6 or 8 equidistant points of the circle. At the same time, the accuracy of the readings was greatly increased by the invention of the micrometer-microscope, which made it possible to measure spaces to Too of an inch. Neither the quadrant nor the mural circle, however, could be relied upon for accurate motion in the plane of the meridian, but Römer remedied this defect by inventing a separate instrument, the transit (q. v), which enabled astronomers to observe the times of meridian passage or transit with great accuracy, and thus to determine the differences of right ascension of the heavenly bodies by means of the apparent diurnal movement. With the transit and quadrant Bradley commenced that series of observations of the positions of the sun, moon, and planets, and of stars for reference, which have been continued ever since at Greenwich, and on which, in combination with less extensive series at Paris and Königsberg, all our tables of the motions of the heavenly bodies are founded. In modern observatories, the transit and mural circle are combined into one instrument, the transit-circle, a change which has been rendered possible chiefly by the improvement in graduated circles since the invention of Troughton's dividing engine, the unwieldy size of the old quadrants and mural circles necessitating an attachment to a massive wall. Although Reichenbach made transit-circles at the beginning of this c. for several foreign observatories, including that of Dorpat, the lightness of their structure and their want of stability prevented their being introduced generally, and the mural circle held its place in the principal observatories till sir George Airy designed the Greenwich transit-circle in 1851, an instrument of a most massive character, which has served as model for nearly all that have been constructed in recent years. The main features of the modern transit-circle are: (1) that it is not reversible, its collimation error being determined by means of two collimators, or reversed telescopes pointing at each other and at the transit telescope, n. and s. respectively; (2) that a spirit-level is not used, the level error being found by means of the reflection of the wires from the horizontal surface of mercury. These two negative characteristics, while admitting of great massiveness in construction (the Greenwich instrument weighs more than a ton), have removed three troublesome sources of error-inequality in the pivots, lateral flexure of the telescope in the process of reversion, and the effect of currents of heated air on a spirit-level. An important auxilliary to the transit-circle is the chronograph, an American invention, which, in various forms, is now found in all well-equipped observatories, the principle in all cases being the same-viz., the registration on a revolving cylinder of paper of the times of transit across the system of spider-lines of the transit-circle, as well as of the seconds of the sidereal clock, by means of electric currents, which pass through electro-magnets, when the circuit is closed either by the observer or the clock, thus causing a momentary attraction of a piece of soft iron, and producing a corresponding mark on the paper either with a pen or a steel point. This system, while improving somewhat the accuracy of the individual observations, admits of a large number being made at intervals of two or three seconds, and leaves the observer free to make several observations of zenith distance during the passage of a star across the field of view. Allusion has been made to the importance of the sidereal clock in modern astronomy. Considerable improvements have been made in its construction since Graham's time, the original gridiron pendulum having been replaced successively by the mercurial and the zinc and steel, and the dead-beat escapement by Dennison's gravity and Airy's detached escapement. Recently an apparatus depending on the attraction of a movable magnet connected with a float in a siphon barometer has been applied by sir George Airy to the sidereal clock at Greenwich, to correct for the effect of variations in the atmospheric pressure on the motion of the pendulum. This clock is placed in a basement which is kept at a nearly uniform temperature, an important condition, which has contributed to make its peformance very far superior to that of any other clock hitherto constructed, and fully equal to the requirements of the methods of observation now in use. With instruments such as have just been described, regular observations of the sun, moon, and planets, and of fundamental stars, are made at Greenwich, Paris, Washington and Oxford, supplemented at the first-named observatory by extra-meridian observations of the moon with a massive altazimuth, which can be employed when the moon is too near

new moon to be seen on the meridian in full daylight, and which is in fact used to secure an observation on every night when the moon is visible.

The observations of stars at these four observatories are directed to the most accurate determination of the places of a limited number, and the deduction of their proper motions by comparison with the results obtained by Bradley, Piazzi (with an altazimuth by Ramsden at Palermo), and Groombridge; but at other observatories differential or zone observations of large numbers of stars have been made, with the object of making a complete and tolerably accurate survey of the heavens, the rhomb or ring micrometer being used for this purpose. Among those who have devoted themselves to this work may be mentioned Lacaille at the cape of Good Hope, Lalande at Paris, Bessel at Königsberg, and Argelander at Bonn. These zone-observations are now being repeated with the transit-circle at a number of observatories, associated together for the purpose of getting far more accurate places than was possible with the equatorial. A large number of observatories, chiefly in Germany and America, are devoted to a very different class of observations-viz., differential observations with the equatorial (q.v.) of comets and small planets as referred to comparison-stars, and the search for such objects; whilst at other observatories, among which that of Pulkowa may be mentioned, the measurement of double stars with the micrometer is laid down as the chief object. Of late years two new subjects have been introduced in the routine of observatory work-photography and spectroscopy. The former was carried on for many years at Kew observatory under Mr. de la Rue's auspices, and at his private observatory at Cranford, and the work is now being continued at Greenwich: the latter has been taken up at a number of Italian observatories, and particularly at Rome by P. Secchi, and it now forms part of the regular system at Greenwich; whilst the observatories at Paris, Berlin, and Vienna are equipped for these physical observations, and in America and Australia they are vigorously carried on at several observatories-Melbourne, in particular, being provided with a four-feet equatorial reflector for this purpose, as well as for the examination of nebulæ. The most important work of an observatory, however, consists, not in making observations, which are easily multiplied, but in reducing and publishing them-a task of far greater labor, and requiring far higher qualifications. However various may be the observations, the method of eliminating their errors is the same in all cases, and similar mathematical considerations apply to their reduction, whether they be meridian observations, micrometer measures, measures of photographs, or spectroscopic observations; and it is when such treatment is required in any inquiry that it should be undertaken at a publi observatory, where this rigorous method will be applied. See illus., TELESCOPES AND OBSERVATORIES, vol. XIV., p. 270.

The work of private observatories hardly admits of being specified, though its general character has already been indicated; it may suffice to mention the observations of double stars and nebula by the two Herschels, Groombridge's catalogue of circumpolar stars, Smyth's double-star measures, Carrington's Redhill catalogue and solar observations, the nebular observations of Lord Rosse and Mr. Lassell, De la Rue's long series of photographs, and the spectroscopic observations of Huggin's and Lockyer.

In addition to regular astronomical observations of all kinds, national observatories are usually charged with the distribution of time signals, and the rating of chronometers for the navy-matters of great practical importance, especially in this country, where Greenwich time is communicated directly by telegraph to more than six hundred towns.

OBSIDIAN, a mineral accurately described by Pliny under the name which it still bears. It is a true kind of native glass, composed of silica (from 70 to 80 per cent), alumina, lime, soda, potash, and oxide of iron. It is hard and brittle, with remarkably vitreous luster, and perfectly conchoidal fracture, the edges of the fractures very sharp and cutting like glass. It varies from semi-transparency to translucency only on the edges. It is often black, or very dark gray; sometimes green, red, brown, striped, or spotted; and sometimes chatoyant or avanturine. It occurs in volcanic situations, and often in close connection with pumice, in roundish compact pieces, in grains, and in fibers. It is capable of being polished, but is apt to break in the process. It is made into boxes, buttons, ear-drops, and other ornamental articles; and before the uses of the metals were well known, it was employed in different parts of the world for making arrow and spear heads, knives, etc. It is found in Iceland, the Lipari isles, Vesuvius, Sardinia, Hungary, Spain, Teneriffe, Mexico, South America, Madagascar, Siberia, etc. Black obsidian was used by the ancients for making mirrors, and for this purpose was brought to Rome from Ethiopia. It was used for the same purpose in Peru and Mexico. Mirrors of black obsidian are indeed still employed by artists. Chatoyant or avanturine obsidian is very beautiful when cut and polished, and ornaments made of it are sold at a comparatively high price.

OBSTETRICS. See MIDWIFERY.

OBVERSE, or FACE, the side of a coin or medal which contains the principal device or inscription, the other side being in contradistinction called the reverse. See NUMISMATICS O'CALLAGHAN, EDMUND BAYLEY, LL.D., b. Ireland. After studying two years at Paris he went in 1823 to Quebec; commenced the practice of medicine in 1827; became in 1836 a prominent member of the provincial parliament; in 1834-37 was editor of the Vindicator, the national organ at Montreal. In 1837 he removed to New York. O'C. published several works, among which the following are the most important: History of