no more than a shrub, sometimes rises 60 feet. It is a wide-spreading tree, the bark brown and deeply furrowed, the leaves dark-green, small and glossy. The yellow wood is strong but difficult to work, and takes a fine polish; it is valued in shipbuilding, and the bark yields considerable tannin. See Mathews : Familiar Trees and Lounsberry : A Guide to the Trees.

Oak-Apples, called also nutgalls and gall-nuts, are round balls about as large as an apple, found on the leaves and stems of oaks and produced by the action of insects. The insect pierces the plant and places an egg with a small quantity of poisonous fluid in the opening. The gall or apple grows rapidly and is fully formed before the egg hatches. The insect remains in the apple during its second stage, and finally as a gallfly eats its way into the world. The nuts are used in making inls and tannin.

Oak'land, Cal., a city of Alameda County is on the eastern side of San Francisco Bay, four and one half miles from San Francisco. It is a beautiful city, well-shaded and watered, with many fine residences — many of them the homes of the business men of San Francisco. Oakland has an excellent public school system, many school buildings and a parochial system (R. C.) kept in perfect gradation with the public schools. Among the higher educational institutions are California College (Baptist), St. Mary's College (R. C), two academies (R. C.) and, connected with the public high-school, a well-equipped observatory. Pacific Theological Seminary (Congregational) and a Catholic college are established here, and at Berkeley, adjoining Oakland on the north, is the University of California. Among the noteworthy buildings are the postoffice, hospitals, Home for the Blind, St Joseph's Home for Deaf-Mutes, the Y. M. C. A. and the Y. W. C. A. The city manufactures cotton and woolen goods, jute, iron, nails, shoes and pottery, has large canning factories, planing and lumber mills; and shipbuilding is carried on. Population 150,174.

Oasis (ō'-sĭs), a fertile spot in the desert, due to the presence of wells or underground springs. The French have made oases in the Algerian deserts by sinking artesian wells. Some African oases are large enough to be inhabited, and grow crops of rice and millet, and are shaded with palms.

Oats, species of the genus Avena, belonging to the grass family. The common cultivated oat is A. sativa which is native to the eastern hemisphere. The genus contains about 50 species, which are widespread in the north temperate regions. In the United States three species occur, the purple oat (^4. striata), Smith's oat {A. Smithii) and the common wild oat (^4. fatua). The oat is hardy, thrives best in a cool, moist climate, and is extensively grown in the United States, Canada and northern Europe. Rus-

sia and the United States rank first as oat-producing countries. The grain is of great importance as food for man and beast, the plant is valued for forage, hay and straw. It has few insect enemies, but is injured by rust and smut.

Oaxaca (w-hā'kă), a state of Mexico, near the isthmus, is bounded on the north by Puebla and Vera Cruz, east by Vera Cruz and Chiapas, south by the Pacific and west by Guerrero. It contains 35,382 square miles and the population is esti mated at 943,633, of whom the much larger part are civilized Indians. The greater portion of the area is mountainous, the Sierra Madre del Sur rising to a height of 12,000 feet, and running across the whole width of the state from east to west. The capital, of the same name, 210 miles southeast of Mexico City, has a population of 35,049. The resources are among the best in Mexico, its elevation giving it a considerable rainfall and a less oppressive climate than that found in several of the states of that country. Its soil is good, and wheat, coffee, sugar, cotton, cocoa, plantains, and fruits of all kinds are exported.

Ob'elisk, a memorial monument of stone with a pointed top. It usually has four faces, and is broadest at the base. These monuments were used by the Egyptians at the entrances of their temples, probably to record the honors and triumphs of their kings. They are .covered with inscriptions in Egyptian hieroglyphics or picture writing. They are very ancient, going back to the 4th dynasty in Egypt, though the larger part date from the 18th and 19th dynasties. Two large ones, which stood at Heliopolis, were carried by Rameses II to Alexandria, and have been called Cleopatra's Needles. One of these was erected on the Thames embankment in London in 1878, and the other, presented by the khdive of Egypt to the United States, is in Central Park, Ne^ York City. There are others at Rome, Florence. Berlin and Paris. Washington Monument, finished in 1885 in the city of Washington, is the largest obelisk in the world. It is 55 square feet at the base, and 555 feet in height. See Egyptian Obelisks by Gorringe.

Oberammergau (ō'br-ăm'mr-goi'), a village in Bavaria, 43 miles southwest of Munich. It is celebrated as the place where the famous miracle-play representing the Passion of our Savior is played once in ten years. It is the only survival of the o'd miracle-plays, being excepted from the order abolishing them in Europe in 1779. Ir 1633, in gratitude for an escape from the plague which devastated the surrounding country, the people of the village vowed to perform this play once in ten years. The actors, in number 350 and the chorus of 80 members, are all taken from the villagers. It is played for twelve Sundays, in a large theater holding 5,000 spectators, many of whom are