Ar´butus, a genus of plants belonging to the Ericaceæ, or heath order, and comprising a number of small trees and shrubs, natives chiefly of Europe and N. America. Arbŭtus Unĕdo abounds near the lakes of Killarney, where its fine foliage adds charms to the scenery. The bright red or yellow berries, somewhat like the strawberry, have an unpleasant taste and narcotic properties. The Corsicans make wine from them. The trailing arbutus or may-flower of N. America, a plant with fragrant and beautiful blossoms, is Epigæa repens, of the same nat. ord.
Arc, a portion of a curved line, especially of a circle. It is by means of circular arcs that all angles are measured.—Electric or Voltaic arc, the luminous arc of intense brightness and excessively high temperature which is formed by an electric current in crossing over the interval of space between the carbon points of an electric lamp. See Arc-light.
Arc, Jeanne d'. See Joan of Arc.
Ar´ca, a genus of bivalve molluscs, family Arcadæ, whose shells are known as ark-shells.
Arcachon (a˙r-ka˙-shōn˙), a town of S.W. France, department Gironde, on the almost landlocked basin of Arcachon, a much-frequented bathing-place, with great oyster-breeding establishments. It is connected by railway with Bordeaux. Pop. 10,266.
Arcade, a series of arches supported on piers or pillars, used generally as a screen and support of a roof, or of the wall of a building, and having beneath the covered part an ambulatory as round a cloister, or a footpath with shops or dwellings, as frequently seen in old Italian towns. Sometimes a porch or other prominent part of an important building is treated with arcades. At the present day Bologna, Padua, and Berne have fine examples of mediæval arcaded streets, and among more modern work various streets in Turin, and the Rue de Rivoli, Paris, are lined with arcades, with shops underneath. In mediæval architecture the term arcade is also applied to a series of arches supported on pillars forming an ornamental dressing or enrichment of a wall, a mode of treatment of very frequent occurrence in the towers, apses, and other parts of churches. In modern use the name arcade is often applied to a passage or narrow street containing shops arched over and covered with glass, as for example the Burlington Arcade, London, the Royal Arcade at Newcastle, and the Gallería Vittorio Emmanuele in Milan.
Arca´dia, the central and most mountainous portion of the Peloponnesus (Morea), the inhabitants of which in ancient times were celebrated for simplicity of character and manners. Their occupation was almost entirely pastoral, and thus the country came to be regarded as typical of rural simplicity and happiness. At the present day Arcadia forms a nomarchy of the kingdom of Greece. Area, 2028 sq. miles. Pop. 162,324.
Arca´dius, born in 377, died 408; son of the Emperor Theodosius, on whose death in 395 the empire was divided, he obtaining the East, and his brother Honorius the West. He proved a feeble and pusillanimous prince.
Arcanum, The Great (meaning secret), a term applied in the Middle Ages to the highest problems of alchemy and the discovery of the supposed great secrets of nature, such as the philosopher's stone and the elixir of life. See Alchemy.