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DALHOUSIE  where he soon showed his lifelong passion for mathematical studies. His first distinction was admission at 23 to the Academy of Sciences. Two years later appeared his “Treatise on Dynamics,” which reduces all the laws of motion to the consideration of equilibrium, thereby marking an epoch in mechanical philosophy. Later works were: “General Cause of Winds,” which gained the prize of the Academy of Berlin, 1746, and which contains the first conception and use of the Calculus of Partial Differences; “Equilibrium and Movement of Fluids” (1744); “Precession of the Equinoxes and Change of the Axis of the Earth” (1749); and “The Several Important Points in the System of the World” (1754). His “Mathematical Works” (8 vols. 1761-1780) contain an immense number of memoirs, some on new subjects, some containing developments of his previous works.

D'Alembert did not confine himself to physical science. For the great “Encyclopédia” planned by Diderot he wrote the famous “Preliminary Discourse,” a noble tribute to literature and philosophy. Besides numerous articles in the “Encyclopédia” (the mathematical portion of which he edited), he published books on philosophy, literary criticism, the theory of music, and a treatise “On the Destruction of the Jesuits” (1765), which involved him in controversy. He became secretary to the Academy in 1772, and thereafter he wrote the lives of all the members deceased between 1700 and that year—one of the most pleasing of his works. His literary works have been published by Bossange (5 vols., 1821). He died Oct. 29, 1783.  DALHOUSIE, JAMES ANDREW BROWN RAMSAY, 10th EARL and 1st MARQUIS OF, a British statesman; born in 1812; was educated at Harrow and at Christchurch, Oxford. After filling the offices of vice-president (1843) and president of the board of trade (1844), he was appointed governor-general of India (1847). In this post he showed high administrative talent, establishing railway lines, telegraphs, irrigation works, etc., on a vast scale. He greatly extended the British empire in India, annexing the Punjab, Oude, Berar, and other native states, as well as Pegu in Burma. In 1849 he was made a marquis, and obtained the thanks of both Houses of Parliament. He outstayed his term of office to give the government the aid of his experience in the annexation of Oude; and when he returned to Europe in 1856 it was with a constitution so completely shattered that he was never

able to appear again in public life, and died Dec. 19, 1860.  DALLAS, a city and county-seat of Dallas co., Tex.; on the Trinity River, and the Gulf, Colorado and Santa Fé, the Houston and Texas Central, the Missouri, Kansas and Texas, the Texas and Pacific, Chicago, Rock Island and Gulf, the St. Louis Southwestern, the St. Louis and San Francisco, and other railroads; 32 miles E. of Fort Worth. It is the metropolis of N. Texas, and although comparatively a young city, is well laid out and substantially built. Area, 19 square miles.

Business Interests.—Dallas is in the great grain belt of the State, and has large cotton, mining, manufacturing, and commerical interests. It is the leading manufacturing city of the State, and it is also the largest inland cotton market in the United States, handling over 1,500 bales of spot cotton yearly. The principal articles were cotton machinery, leather goods, shoes, dressed meat, cotton goods, foundry and machine-shop products, cement and clothing. There were in 1920 5 National banks, and several private banking houses. The assessed real and personal property valuation in 1919 was $103,587,650.

Public Interests.—In 1919 the city had 342 miles of streets, of which 152 miles were paved; 218 miles of water mains; and electric light and water plants, the latter owned by the city. Among the prominent buildings are the Catholic and Episcopal churches, the United States Court-house, the Texas State Fair and Dallas Exposition buildings. Cathedral of the Sacred Heart (R. C.), Cathedral of St. Matthew (P. E.), Ursuline Convent, St. Mary's Orphanage, St, Paul's Sanitarium (all R. C.), and St. Mary's College (P. E.). Dallas is the seat of the Southern Methodist University, and has hospitals, and a park system of nearly 800 acres. There is a boulevard system of over 60 miles. There are over 25,000 pupils in the public schools, and the annual cost of maintaining the school system is about $850,000. Pop. (1910) 92,104; (1920) 158,976.  DALLAS, GEORGE MIFFLIN, an American diplomatist; born in Philadelphia, Pa., July 10, 1792. He was graduated at Princeton College in 1810. In 1813 he was admitted to the bar, and soon after entered the diplomatic service. In 1831 he was elected a United States Senator from Pennsylvania. He was United States minister to Russia from 1837 to 1839, and in 1844 was elected Vice-President of the United States. In 1846 his casting-vote as President of the Senate repealed the protective tariff of