I. Dominique Francois, a French physicist and statesman, bom at Estagel, near Perpignan, Feb. 26, 1786, died in Paris, Oct. 2, 1853. After studying mathematics at the college of Perpignan, he entered in 1803 the polytechnic school. On leaving it in 1805, he was appointed secretary of the board of longitude, and in 1806 he was commissioned to finish in conjunction with Biot the measurement of an arc of the meridian in Spain, begun by Delam-bre and Mechain, as the basis of the decimal metrical system of France. He was employed in the island of Majorca on the outbreak of war, taken for a spy, saved from the mob by some months1 confinement in a fortress, afterward taken by Spanish corsairs from an Al-gerine vessel and harshly treated, enlarged on the demand of the dey, shipwrecked on the coast of Sardinia, and after new perils reached Algiers in a Bedouin disguise. Here he was treated with suspicion by a new dey, but finally reached Marseilles in a French frigate in 1809. On his arrival in Paris he was elected a member of the institute, though only 23 years old, and soon afterward appointed professor at the polytechnic school. In 1830 he became perpetual secretary of the academy of sciences, and director of the observatory, a post which he retained till his death.

He rendered special services to optics by his own experiments, and by his influence over others, and especially by directing the labors of Fresnel and Mains. He was the first to recognize the value of Young's optical papers. He investigated magnetical phenomena, and made some contributions to meteorology, especially in connection with electricity. He also successfully investigated the colors of polarized light, the application of polarization as a test of the origin of light, the experimental proof of the retardation of light in dense mediums, the apparent magnetism of copper rotating near a permanent magnet, and the influence of the aurora upon the needle. For the last three years of his life he was blind and otherwise a sufferer. He was the author of more than 6O distinct memoirs on various branches of science. He established, in concert with M. Gay-Lussac, in 1816, the Annales dechimie et de physique. The article in the "Edinburgh Encyclopa3dia" on the polarization of light is from the pen of Arago. His complete works appeared in Paris in 17 vols. (1855-60), under the direction of Barral. From the royal society of London he received in 1829 the Copley medal, an honor never before conferred upon a French man of science.

When Napoleon, after the battle of Waterloo, thought of emigrating to the United States, for the purpose of devoting the remainder of his life to scientific pursuits, he invited Arago to accompany him; and when this intention was foiled by the English, Monge endeavored in vain to prevail upon Arago to follow the ex-emperor to St. Helena. On the outbreak of the revolution of 1830, Arago espoused the cause of the people. In 1831 he was elected member of the chamber of deputies by his native department of Pyrenees-Orientales, and took his seat on the extreme left. He delivered memorable speeches in behalf of science and education, and in the political questions of the day he strenuously opposed all encroachments upon the rights of the people, and denounced the government monopoly of railways and the project of the fortifications of Paris. He was also a member of the council general of the Seine, of which he was president till 1849, and the declaration of the council in favor of the emancipation of slaves was due to him.

He took a conspicuous part in the movement which led to the overthrow of Louis Philippe, and on Feb. 24, 1848, he became a member of the provisional government, and officiated first as minister of marine, and afterward added to the functions of this office the duties of the war department. He belonged to the republican wing of Marrast and Marie, who opposed the theories of the socialists, and advocated liberal institutions, as they exist in the United States. At the same time he represented his native department in the constituent assembly. When the provisional government surrendered the reins of power, the assembly appointed him member of the executive commission. In this position he displayed great personal courage during the bloody days of June, 1848. He opposed the election of Louis Napoleon to the presidency, and gradually ceased to take part in public affairs. But to the last he proved true to his republican creed, and after the coup d'etat of December, 1851, refused to take the oath to the government of Louis Napoleon.

II. Jean, brother of the preceding, born in 1788, died in Mexico, July 9, 1836. He was a sub-treasurer in Perpignan, and, having been deprived of his appointment on a denunciation which subsequently turned out to be false, he embarked for New Orleans, and, joining the younger Mina, became a general in the Mexican service in the war of independence.

III. Jacques Etienne Victor, brother of the preceding, born at Estagel, March 10, 1790, died in Brazil in January, 1855. When only 20 years of age he made an artist's tour through various countries of the Mediterranean. In 1817 he sailed in the exploring vessel Uranie as draughtsman to the expedition. The ship was wrecked at the Moluccas, and Arago did not return to France till 1821. He afterward resided at Bordeaux and Toulouse, and lost his sight in 1837, which, however, did not prevent him from engaging in new voyages. His most interesting work is Souvenirs d'un aveugle: Voyage autour du monde (with illustrations and comments by Francois Arago, 2 vols., Paris, 1838 et seq.).

IV. Etienne, brother of the preceding, born at Perpignan, Feb. 7, 1803. He studied at Loreze, and undertook a course of chemistry at the polytechnic school, which he quitted for the purpose of joining the secret societies. He established the Lorgnette and Figaro newspapers, and was director of the Vaudeville until it was burned down. He has written upward of 100 theatrical pieces, including Les aristocraties, a five-act comedy, produced at the Theatre-Francais. In 1830 he closed his theatre to join in the popular movement, and distributed the theatrical stock of arms to the people during the three days of July. He was among the most prominent to signalize his disapproval of the shortcomings of Louis Philippe's government, which cancelled his theatrical license in 1840. The Reforme, a daily democratic journal, was founded by Etienne Arago. He was one of the prime movers in the revolution of 1848, and placed himself in the direction of the post office, which post he held till the retirement of Gen. Cavaignae. In 1849 he was expelled from France for his participation in revolutionary movements, and went to Belgium, which country he was also obliged to leave in 1851 at the request of Louis Napoleon; and after wandering about in different countries, he settled at Turin. The amnesty of 1859 enabled him to return to Paris. He attracted much public attention in 1862 by leaving the societe des gens de lettres upon the ground of its being controlled by the banker Mires and other schemers.

In 1870 he was mayor of Paris from Sept. 5 to Oct. 31, when the invasion of the hotel de ville forced him to retire. Among his later productions are a poem on Spa, the Belgian watering place (Brussels, 1851); a historical novel relating to the Vendean wars, Les Blancs et les Bleus (2 vols., Paris, 1862); and a vindication of his course in the February revolution, Les postes en 1848 (1867).

V. Emmanuel, an advocate and politician, son of Dominique Francois, born in Paris, Aug. 6, 1812. His name as well as his opinions and tendencies caused him to be retained in several political cases of importance. In 1839 he defended Barbes and Martin Bernard. He took an active part in the revolution of 1848. When the abdication of Louis Philippe was announced in the chamber, Arago, who had penetrated thither, rose and loudly proclaimed that royalty was by this act extinct, and that the people objected to a regency. Lamartine and other deputies followed, and a provisional government was organized on the spot. Lyons being in a turbulent state on account of destitution among the working class, Arago went there as commissary general, with plenary powers, and ordered 500,000 francs to be immediately applied in relief of the distress. This action was subsequently made the subject of furious party invective. He became a member of the legislative assembly for the Pyrenees-Orientales, and was envoy in Berlin from May till December, when on Louis Napoleon's election to the presidency he resigned, and strenuously opposed him after his return to Paris in the constituent and subsequently in the legislative assembly.

After the establishment of the second empire, he devoted himself almost exclusively to the law, acquiring distinction by defending in 1867 the Pole Berezowski, who attempted to murder the czar at the time of the Paris exposition, and in 1868, together with Gambetta and Cremieux, the journalist Peyrat, who had started the project of a monument in honor of Baudin. In 1869 he was put forward for the legislative assembly in two departments, but defeated by the government candidates. In 1870 he became a member of the provisional government without portfolio, resisting the aggressions of the rioters on Oct. 31. At the age of 20 Emmanuel Arago published a volume of poems, and was for five years afterward engaged in theatrical writing.