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LEFT EWING C, Feb. 8, 1817; was graduated at the United States Military Academy in 1840; served in the cavalry on the fron- tier, and during the Mexican War with Scott from Vera Cruz to the City of Mexico; and was promoted captain for gallantry and meritorious conduct at Contreras and Churubusco. At the out- break of the Civil War he resigned his commission in the National army; joined the Confederates; and Avas actively en- gaged throughout the war. Pie took part in the Maryland campaign and in the battles of Bull Run, Gettysburg, and the Wilderness, and attained the rank of Lieutenant-General. After the war he retired to private life. He died in Springfield, Tenn., Jan. 25, 1872. EWING, JULIANA HORATIA GATTY, an English story-writer and poet; born in Ecclesfield, Yorkshire, in 1841. Her stories for children became very popular and included "Daddy Dar- win's Dovecote"; "Dandelion Clocks and Other Tales"; "A Flat-iron for a Far- thing"; "A Great Emergency and Other Tales"; and "Jackanapes." She died in Bath, England, May 13, 1885. EWING, THOMAS, an American statesman; born near West Liberty, Va., Dec. 28, 1789 ; was graduated at the Ohio University in Athens in 1815; admitted to the bar in 1816; and practiced law for 15 years. He was a United States Senator from Ohio in 1831-1837 and 1850-1851; Secretary of the Treasury under President Harrison in 1841; and Secretary of the Interior under Presi- dent Taylor in 1849. In the United States Supreme Court he ranked among the foremost lawyers of the nation. He died in Lancaster, O., Oct. 26, 1871. EXCAVATOR, an apparatus used in making docks, railway cuttings, canals, etc. Excavators are made of two kinds, each adapted for different kinds of work, though in some cases they work to- gether very effectively. In making a long "gullet" or cutting, the first to come into operation has the appearance and all the functions of the ordinary steam- crane, such as is used for loading rail- way trucks, with the exception that it is mounted on wheels to move on rails, and that, instead of the hook on the end ©f the chain, there is a large and strong iplate-iron bucket or "scoop," with a very heavy handle or lever to which a second chain is fastened. The lever is heavy enough to counterbalance the scoop when filled with clay. The machine begins by lowering the scoop, and the two chains are made to push it into the bank until it is full. The suspension chain then lifts the scoop over the wagon, while the 71 EXCHANGE chain on the handle lifting it up empties it. The machine now swings round on its center to renew the operation. The largest size can excavate two cubic yards per minute. As the excavator ad- vances over its rails, those behind are brought to the front. The cutting is made as wide as the arm or *'jib" will reach on both sides of it, which leaves sufficient room for the men to work round it freely, and for wagons to pass. When the cutting has been made the requisite distance forward, the second class of excavator is brought forward to make the cutting wider. The original conception of this is clearly derived from the dredging machine, which has long been in u.se in deepening harbors and the mouths of rivers. Its sides are made sloping to an angle of 45°, and on the top of the bank a temporary line of rails is laid a few feet from the edge. The machine is placed on the rails at the end of the cutting; the jib is lowered until the row of buckets it carries can cut into the clay; these scrape up the bank, reaching the top of it full of soil; they next pass over the machine, and are emptied into the wagons beyond it. The excavator and wagons move for- ward simultaneously, the latter receiv- ing, in the case of some excavators, a continuous stream of clay equal to about four cubic yards or two wagon loads per minute. All the movements of excavators are effected by the power of the engine, and two men manage each machine. EXCHANGE, the act of exchanging, or giving one thing for another; or that which is so given. In commerce, a place where merchants, brokers, etc., meet to transact business; generally contracted into 'Change. The institution of ex- changes dates from the 16th century. They originated in the important trading cities of Italy, Germany, and the Nether- lands, from which last-named country they were introduced into England. In some exchanges only a special class of business is transacted. Thus there ai-e stock exchanges, corn exchanges, coal exchanges, cotton exchanges, etc. For bill of exchange, see Bill. Course of exchanpre, the current price of a bill of exchange at any one place as compared with what it is at another. If for $500 at one place exactly $500 at the other must be paid, then the course of exchange between the two places is at par; if more must be paid at the second place, then it is above par at the other ; if less, it is below it. Arbi- tration of exchange, the operation of converting the currency of any country into that of a second one by means of