Magnetograph
an instrument for recording the fluctuation of the magnetic field of the earth. The variations in strength only are recorded-the exact value at any given time is usually obtained by use of a magnetometer. The principle of operation most commonly used is the reflection of ray of a light from a mirror attached to a suspended or freely moving magnetic needle to a recording sheet of photographic paper which is attached to a drum actuated at a uniform speed by clockwork. When the instrument is to be used for recording the magnetic declination, the magnetic needle is usually suspended by a quartz fiber. When used to measure the vertical component, the needle is mounted on a knife edge so that its axis about which it may move is horizontal. Any movements of the needle, which should be of light weight in order that the inertia may be of a minimum, will cause a movement of the image reflected upon the recording paper, and a curve representing the relative changes of the magnetic is obtained.
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Magnetometer
an instrument for measuring any of the magnetic elements, as the dip, inclination, and intensity.
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Magnets
this term, which was originally applied only to loadstone, or magnetite (Fe3O4), has come to include the various substances which have magnetic properties. A magnet in the form of a needle (compass) or bar, when so suspended that it is free to move about a vertical axis, places itself in an approximately N. and S. direction. Portions of a magnet have the property of attracting iron, nickel, cobalt, and a few other substances, while some substances are repelled. The substances which are attracted by a magnet are called magnetic substances. Those portions of the magnet which have the property of attracting or repelling are called the poles, and, in the case of a bar magnet, are usually located near the ends. Opposite magnet poles have the power of attracting each other; the like poles repel each other. A piece of iron or steel which has been stroked laterally with a magnet becomes magnetized, an and forms a typical example of ferromagnetism. If a core of iron is wound with insulated and an electric current passed through the wire, the core takes on magnetic properties and becomes an electro-magnet, the direction of the electric current determining the polarity of the magnet. The latter method has by far the greater commercial application.
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Magnificat
the song of the Virgin Mary, which, in the Vulgate, begins with "Magnificat." See BREVIARY. MAGNOLIA [named after Pierre Magnol (1638-1715), Professor of Medicine at Montpellier, and author of several botanical works], the typical genus of the tribe Magnolicæ and the order Magnoliaceæ. Sepals three, deciduous; petals, six to nine; stamens and pistils many; carpels compacted in spikes or cones; seeds baccate, somewhat cordate, pendulous, with a long white umbilical thread. The species are trees or shrubs, with alternate leaves and large, terminal, odoriferous flowers. They are found in North America and Asia. M. grandiflora, the great-flowered magnolia, or laurel bay, is a fine evergreen tree, 70 feet high in America, and from 20 to 30 in foreign gardens. The species have large, beautiful, fragrant flowers.
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Magnolia
a genus of trees and shrubs characterized by thick, often evergreen, leaves and showy terminal flowers. Named for Pierre Magnol (1638-1715), a French botanist. There are fifteen species in all, confined to eastern North American and subtropical Asia. Some are only shrubs. Magnolia wood is white and is considered desirable for cabinet work. The Japanese use the wood of a native variety for lacquered work. The common American magnolia is a stately tree with broad evergreen leaves from one to three feet long. It bears fragrant white flowers, four to twelve inches in diameter, in full bloom from early May until the end of June.
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Magruder
JOHN BANKHEAD, an American military officer; born in Winchester co., Va., Aug. 15 1810. He was graduated at the United States Military Academy; served in the Mexican War; at the outbreak of the Civil War entered the Confederate army; took part in the battle of Malvern Hill, July 1, 1862, being in command as Major-General; was appointed commander of the Department of Texas, Oct. 16, 1862; afterward served under the Emperor Maximilian, of Mexico; and died in Houston, Tex., Feb. 19, 1871.
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Maguey
the Agave Americana, from which PULQUE (q. v.), pita flax, etc., are made. MAGYARS. See HUNGARY.
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Mahaffy
SIR JOHN PENTLAND, C. V. O., an Irish educator; born in Switzerland, in 1839. He was educated in Germany and at Trinity College, Dublin, being graduated in 1859, and winning a fellowship in 1864. He was made Professor of Ancient History there in 1869; was Donnellan lecturer 1873-1874. He was noted for a wide range of scholarship, and was a frequent contributor to periodicals and published books on many subjects. Among these are "Lectures on Primitive Civilization" (1868); "Prolegomena to Ancient History" (1871), treating of Egyptian antiquities; "Rambles and Studies in Greece" Greece" (1876); "History of Greek Classical Literature" (1880); "Empire of the Ptolemies" (1896); "The Silver Age of the Greek World" (1906); "What Have the Greeks Done for Civilization?" ("Lowell Lectures," 1909). He died in 1919.
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Mahanoy City
a borough in Schuylkill co., Pa., on Mahanoy Creek and on the Lehigh Valley and the Philadelphia and Reading railroads; 13 miles N. E. of Pottsville. It contains a public library, electric lights, National banks, daily and weekly newspapers, and churches of the leading denominations. It is located in a rich anthracite coal region, from which it gains much of its prosperity. It has colleries, several potteries, iron foundries, etc. Pop. (1910) 15,936; (1920) 15,599. MAHARAJAH (literally, a great king), a title applied in courtesy to every Indian rajah, or to any person of high rankor deemed holy
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Mahler
GUSTAV, a German musical composer; born in Bohemia 1860 and died in Vienna 1911. From 1884 to 1900 he conducted orchestras in various cities of the Continent, Prague, Leipzig, and Budapest. In 1897 he became director of the Court opera at Vienna and retained this position until 1907. During the season 1907-1908 he conducted German operas at the Metropolitan Opera House, New York, and in 1909 he reorganized the New York Philharmonic Orchestra and made it one of the best in America. He achieved more success as a conductor than as a composer, and is ranked as one of the greatest masters of his profession.
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