MAXOMETRIC FLAME

Il62

MANUAL TRAINING

device consists of a flattened and curved metallic tube which changes shape as the difference of pressure between the inside and outside is changed. It was invented by Bourdon, and is frequently called a Bourdon gauge. (See Barometer.) One end of this gauge is fixed, while the other is free to move an index which shows the pressure on a graduated dial.

Manometric (măn'-mĕt'rĭk) Flame, an instrument for exhibiting to the eye the disturbances wh ich a sound produces in the air, was invented and perfected by Rudolph Knig of Paris. In the figure, R and S represent two blocks of wood which have been bored out. A diaphragm of goldbeater's skin is clamped between these two blocks and divides the apparatus into parts. Illuminating gas is admitted to the left-hand side of the apparatus, as indicated by the arrows, and burns with a quiet flame so long as the diaphragm is undisturbed. If, however, the air on the right of the diaphragm is suddenly compressed, the flame will flare; and if this air is suddenly rarefied, the flame will for an instant burn low. The effect of a sound-wave striking this diaphragm is then to drive it alternately forward and backward, making the flame pulsate These acoustical disturbances are, however, so rapid that the changes in the height of the flame are not easily seen. Accordingly, the flame is generally observed in a rotating mirror, which serves to separate the images of the flame at successive instants. In practice the block, S, is generally provided with a mouthpiece or with a tube to lead the sound up to the diaphragm, M. This instrument is used to exhibit, in the most beautiful manner, the qualities of various sounds, as, for instance, the difference in the various vowels pronounced by the same voice.

Mans'field, a city, county-seat of Richland County, in the central part of Ohio, 65 miles northeast of Columbus. It is situated in the midst of a fine farming-country, on an elevated site. It has a large trade, and manufactures threshing machines, steel harrows, electrical supplies, stoves, brass goods, pumps, agricultural machinery, wagons, webbings, suspenders, cigars, boilers, carriages and flour. It was the home of Senator Sherman. The chief buildings are the Public Library, Children's Home, Y. M. C. A. and Ohio Reformatory. Mansfield has many churches, several public-school buildings and two business-colleges, and is justly proud of her school-system Population 20,768.

Mansfield, Richard, an actor, was born on Heligoland, May 24, 1857. He first ap-

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MANOMETRIC FLAME

peared as a musician in Liverpool in 1877, and for some years after that was seen only in small parts in comic operas. His first marked success was achieved in New York at the Union Square theater in January, 1883, as the Baron de Chevreul in a Parisian romance. Three years later he appeared as a star in Prince Karl. Later he gained a high position as an actor, managing a company of his own and appearing in a wide variety of plays. Among his successful rles were Dr. Jekyll and Mr. Hyde, Cyrano de Bergerac, Shylock, Henry V and Brutus. He died on Aug. 30, 1907.

Manteuffel (man'toif-jel), Edwin Hans Karl, Freiherr von, a Prussian general, was born at Dresden, Feb. 24,1809. He entered the army in 1827 and became head of the military bureau at Berlinin 1857. As commander of the first army he fought successfully at Amiens and other places in the Franco-Prussian War. In 18 71 Manteuffel attacked the French near Belfort and drove 80,000 men across the frontier into Switzerland. In 1879 he was made viceroy of the conquered provinces of Alsace and Lorraine. He died at Karlsbad, Bohemia, June 17,1885.

Mantua (mn't-ă), a fortified city of northern Italy, formerly the capital of the duchy, is on two islands formed by the Min-cio. The surrounding marshy district and its fortifications perhaps make it the strongest fortress in Italy. It has broad streets and many open squares. The fortress of the Gon-zagas, adorned with paintings by Mantegna, the cathedral of San Pietro and the church of San Andrea are its chief buildings of interest. Vergil was born at a suburb of Mantua. Mantua first was an Etruscan town, then it belonged to the Romans, Ostrogoths and Lombards. The Gonzaga family became its rulers in 1328, and raised the city to its height of splendor and renown. Mantua became a part of Austria in 1708, which held it till 18Ŏ6, except for two short periods when it was in the possession of France. In the latter year it was ceded to Italy. The city has had three great sieges —by Emperor Ferdinand II in 1630, the French in 1797 and the Austrians in 1799. Population 29,-142.

Man'ual Training in Public Schools. In 1868 Victor Delia Vos, director of the Imperial Technical School for government engineers at St. Petersburg, conceived the plan of teaching certain kinds of tool-work by means of models and drawings and practice exercises, before any attempt should be made at the execution of trade-work. The exhibition made by his school at the Centennial Exposition in Philadelphia (1876) directed the attention of American educators to a system which, it was felt, could be made of inestimable value to the young, many of whom remained in school only long enough to conceive a distaste for manual labor, but not long enough to acquire professional culture.