Page:LA2-NSRW-3-0051.jpg



LEVANT

1059

LEVER

for work that in a few years he obtained the means to study his art in Europe. He remained abroad for 14 years, settling in New York city in 1859. His works include three scenes from the life of Columbus, several from English history and a number depicting events in the Revolutionary W"ar» of which perhaps the greatest is Washington crossing the Delaware. His Columbus in Chains procured the medal of the Brussels art exhibition. One of his latest works was the Westward Ho mural picture for the staircase of the capitol at Washington. He died at Washington, D. C., July 18, 1868.

Levant', a 'name used to designate the eastern part of the Mediterranean Sea and the coast regions of Syria, Asia Minor and Egypt. In a wider sense it is applied to all the region eastward from Italy as far as the Nile and the Euphrates.

Levee (lev'a"), the French name for embankment, specially applied to the high embankments built on either side of the Mississippi for 500 miles to prevent its overflow in times of high water. Notwithstanding the care and labor expended in the construction of the Mississippi levees, they sometimes give way under the pressure of very high water, causing the overflow of large portions of land and great destruction of property.

Lev'en, Loch, a beautiful oval lake, 23 miles northwest from Edinburgh, Scotland. It is 3 53 feet above the sea, and is surrounded by the beautiful mountains of Bernarty, West Lomond and other hills. Its outlet is the Leven, flowing 16 miles eastward to the Firth of Forth. It has a depth of from 10 to 90 feet and an area of 3,406 acres, its size having been reduced about one fourth by drainage. The two largest of its seven islands, St. Serf's Inch and Castle Island, are sandy and treeless. The first was an early seat of the Culdees, and on Castle Island Queen Mary was imprisoned for ten months. The lake abounds in trout. See Burns-Beg's History of Loch Leven Castle.

Lev'er, the simplest of all machines. It has a variety of objects. Sometimes it is employed to increase the force which one is able to apply at some particular point, as in the case of a pair of nut-crackers; sometimes one uses it to multiply the motion of a point, as in the index on the dial of a

I

or,

Ft

Fig. i

steam-gauge; sometimes, as in the case of sugar-tongs pliers and tweezers, to reach otherwise inaccessible places. The essential feature of any lever is a more or less

rigid bar capable of rotation about the edge of some body as axis. This edge is called the fulcrum of the lever, and is indicated by O in Figs, i and 2. The principle of the lever is as follows: Let Pj (in fig. i or fig. 2) be the force exerted on the end of the lever whose length is xlt and let F2 be the force exerted upon the arm whose length is x.4. We may suppose these forces to be at right angles to the arm and that the lever is rotated through an angle 0 : so that the distance through which the force Ft acts is xt 0, and the distance through which the force F2 acts is x2 0. Now, since hardly any energy is here wasted in friction, we may, according to the principle of the conservation of energy, say that the work done by these two forces is the same, and hence

F, /   _

/ PI""

/  xs,

which means that the force one can obtain by use of a lever is to the force which he applies to the lever inversely as the lengths

F   / of the arms. The ratio   3/p   is sometimes

called the mechanical advantage of the lever.

5

--J

Fig. 2

Great care must always be observed in estimating the length of the arms. The fulcrum at O is the axis of rotation; and the distance from this axis to the point where the one force is applied is one arm, xx; the distance from the axis to the point where the other force is applied is the other arm, xs. These definitions are illustrated in each of Figs, i and 2. The theory of the lever was fiist correctly enunciated by Archimedes (287-212 B. C.) The pulley, the windlass, the chemical balance, the ordinary pin, the button etq. are merely special cases of the lever.

Le'ver, Charles James, a popular novelist, chiefly noted for the rollicking fun of his Irish stories, was born at Dublin, Aug. 31, 1806, and graduated at Trinity College in that city in 1827. His most popular work, Charles O'Malley\ is a reflex of his own college life at Dublin, and many of the incidents in this novel are no doubt drawn from his own experience in the world. His other notable novels include Harry Lor-requer, Con Cregan, Roland Cashel, Lord Kilgobbin and Tom Burke of Ours. He died at Trieste, France, June i, 1872.