AR´ADUS (now RUAD), an inlet about a mile in circumference lying 2 miles off the Syrian coast, 35 miles N. of Tripolis; the site of the Phoenician stronghold Arvad, a city second only to Tyre and Sidon; now occupied by about 3000 people, mainly fishermen.
ARAFAT´, or JEBEL ER RAHMEH ('Mountain of Mercy'), a hill in Arabia, about 200 feet high, with stone steps reaching to the summit, 15 miles south-east of Mecca; one of the principal objects of pilgrimage among Mahommedans, who say that it was the place where Adam first received his wife Eve after they had been expelled from Paradise and separated from each other 120 years. A sermon delivered on the mount constitutes one great ceremony of the _Hajj_; or pilgrimage to Mecca, and entitles the hearer to the name and privileges of a _Hajji_ or pilgrim.
AR´AGO, Dominique François, a French physicist, born in 1786, died at Paris in 1853. After studying in the Polytechnic School at Paris, he was appointed a secretary of the Bureau des Longitudes. In 1806 he was associated with Biot in completing in Spain the measurements of Delambre and Méchain to obtain an arc of the meridian. Before he got back to France he had been shipwrecked and narrowly escaped being enslaved at Algiers. In 1809 he was elected to the Academy of Sciences and appointed a professor at the Polytechnic School. He distinguished himself by his researches in the polarization of light, galvanism, magnetism, astronomy, &c. His discovery of the magnetic properties of substances devoid of iron, made known to the Academy of Sciences in 1824, procured him the Copley medal of the Royal Society of London in 1825. A further consideration of the same subject led to the equally remarkable discovery of the production of magnetism by electricity. He took part in the revolution of 1848, and held the office of Minister of War and Marine in the provisional Government. At the _coup d'état_ of Dec., 1852, he refused to take the oath to the Government of Louis Napoleon, but the oath was not pressed. His works, which were posthumously collected and published, consist, besides his _Astronomie Populaire_, chiefly of contributions to learned societies, and biographical notices (_éloges_) of deceased members of the Academy of Sciences.