court of his uncle in Phocis. Pylades his cousin joined with him in his efforts to avenge his father's death, the pair going secretly to Argos and killing Clytemnestra and Ęgis-thus. But realizing that he had killed his mother, Orestes became mad and fled from land to land, pursued by the Furies. Learning from Apollo that he could be cured of his madness by bringing the statue of Diana from Tauris in Scythia to Athens, he and Pylades journeyed there, but were seized to be sacrificed by the natives. The priestess Iphigenia recognized her brother in Orestes, and with her help they all escaped, carrying the statue with them. Orestes recovered his father's kingdom at Mycenę, and married Hermione. The story of Orestes is a theme for the tragedies of Euripides, Sophocles and Ęschylus.

Or'gan, one of the largest musical instruments. It is a wind-instrument having a large number of pipes, which produce the sounds on admission of air, which is carried to them by means of a bellows. It is played by keys and pedals. The most usual form of the organ is that seen in churches, which consists of four, sometimes of five, parts, each being almost a separate instrument. These are called the great organ, the swell organ, the pedal organ, the choir organ and the solo organ, when this fifth form occurs. Each has its own keyboard, but they are brought so close that one performer can reach all. The pedal organ is played with the feet, while the other keyboards are reached by the hands. There also is a system of stops, within reach of the performer's hand, which closes or opens the pipes as the keys do. Organ pipes are made of metal and of wood. The ancient organ was worked by water, and was used in the Roman theaters, Nero being one of its earliest patrons. In the reign of Honorius. 400 A. D., no nobleman's house was complete without an organ, and small ones were carried by slaves from house to house. Constantinople was the great home of organ building in the ancient world, and the first organ built in medieval Europe was patterned after one brought by Byzantine ambassadors on a mission to Charlemagne. The use of the bellows in organs dates from the time of the Emperor Julian in the 4th century, though it did not come into general use until the end of the 9th century. The smallest organs ever built were made in the monasteries; they were called régals and could be held on one's palm. The largest organs in England are those of Royal Albert Hall, Alexandra Palace, Crystal Palace, St. Paul's Cathedral, St. George's Hall, Liverpool, and Leeds town-hall. Among the largest in the world are the organs at Seville, Haarlem, Rotterdam and Utrecht. The great-organ in the music hall of Boston gave the first impulse to organ building in America. There are large ones at cathedrals in Montreal and

Boston, Music Hall, Cinwnnati, Fremont Hall, Boston, Brooklyn Tabernacle and the Auditorium in Chicago.

The American or cabinet organ is a reed organ, the outgrowth of the melodeon, in which reeds are used but not pipes, and the wind is forced in by bellows worked by the feet. The Mason and Hamlin Organ Company, founded in 1854, built the first cabinet or parlor organs, making use of an invention of Hamlin's, which consisted in so twisting and bending the reeds as greatly to improve the tone. These organs have been improved, and are made in all styles and sizes, some of the larger nearly equaling pipe organs.

Or'igen, one of the most celebrated of the Christian Fathers, was born at Alexandria, 185 A. D. His father was a Christian and a teacher of rhetoric, and he was early trained for public life. Clement of Alexandria was his especial teacher in Christianity. His father suffered martyrdom when Origen was a young man, and he then sought to support the family by opening a school himself. Bishop Demetrius appointed him master of a famous seminary for catechumens, and, having mastered Hebrew, he soon became an authority upon questions of doctrine and polity. Nevertheless, his opinions were not popular with the ecclesiastics, and he was subjected to many trials, and finally excommunicated in 231. He was received at Cęsarea, where he reopened his school with increased popularity. But the persecutions under Maximinus and Decius drove him to such extremes of suffering that he died at Tyre in 254. Origen was the first great New Testament exegete that ever lived. He devoted himself to every form of study which promised to throw the least light upon the great problems of theology and philosophy. He practiced the strictest asceticism, and voluntarily subjected himself to the most abject poverty. His work was greatly rewarded in the conversion of multitudes, among whom were many of the leading men of the east. His talents, eloquence and learning excited the praise of even the heathen writers; and while his doctrinal views have not been wholly accepted by any considerable portion of modern Christendom, his purity, unselfishness and devotion to his Master are beyond praise.

Orinoco (ō'rĭ-nō'ko), one of the great rivers of South America, rises in Venezuela. It divides into two branches near Esmeralda, one flowing south into Rio Negro ; the other branch, joined by the Guaviare, turning north and passing over the cascades of May-pures and Atures, where the river, 8,000 feet wide, narrows to 20 feet, falling over cascade after cascade, like a series of steps, and shut in by islands and rocks. The Meta and the Apuré now join the Orinoco, which flows on, four miles wide, receiving the waters of two more streams before it reaches the delta.