Page:The American Cyclopædia (1879) Volume I.djvu/676

640 ARC a plant of the same order, but of a different genus. It takes its generic name (Gr. eiri and , upon the ground) from its trailing lowly habit, and its common name Mayflower from Trailing Arbutus (Epigtea repens). the season of its blossoming. The leaves are alternate, coriaceous, and evergreen ; the stems and other portions of the plant are covered with reddish, bristling hairs; and the cluster of very fragrant white or pink flowers appears in the axils of last year's leaves. It is found throughout New England, especially near the coast, on the edges of pine forests, and it also grows in great perfection in the valley of the Connecticut. It is also called ground laurel. ARC (Lat. arczw, a bow), the name of any portion of a curved line; thus, an arc of a circle is a portion of the circumference. To rectify an arc is to give the length of the straight line to which it would be equal if it were made to have the same length in a right direction which it now has in a curved. Two arcs are said to be equal when, being rectified, they have the same length ; and similar when, being taken from different circles, they have the same number of degrees that is, are equal fractions of their respective circumferences. The arcs of a circle serve to measure the angles (see ANGLE) ; if from the vertex of the angle as a centre, with whatever radius, a circum- ference be described, the number of degrees of the arc intercepted between the two lines which form the angle will be ihe measure of the angle. Thus, for instance, as the arc of 90 corresponds to a right angle, if we find that the intercepted arc contains 15, we con- clude that the angle is to a right angle in the ratio of 15 to 90, or that it is the sixth furi of a right angle. The chord of an arc is the right line which joins its extremities; a seg- ment is the area included between an arc and its chord; and a sector is the area included between an arc and the two radii going from its extremities to the centre of the circle. ARCADIA ABC, Joan of. See JOAN OF ARC. ARCACHON, a village of France, in the depart- ment of Gironde, 35 m. by railway "W. S. W. of Bordeaux ; pop. about 2,000. It is situated on a landlocked bay or lake (bassin d'Arcachon), about 60 m. in circumference, connected with the gulf of Gascony by a narrow strait. Since 1854 the village has been converted into a watering place by the P6reire family, who bought the surrounding woods and swamps, and drained part of the bay. Previous to the Franco-German war the visitors annually aver- aged 5,000. Persons suffering from diseased lungs are much benefited in winter by the mildness of the climate. The beach is very fine, and sea bathing attracts in summer many visitors. The pine woods extend almost as far as Bayonne, and abound with game. ARCADIA, the central and, next to Laconia, largest of the ancient divisions of the Pelopon- nesus ; area about 1,700 sq. m. It included the most picturesque and beautiful portion of Greece. The country embraced by its ancient boundaries is mountainous, with many forests, but it contains also rich meadow lands, and rivers and brooks abound. Mount Cyllene in the northeast, Erymanthus in the northwest, and Lycfflus in the southwest, are some of its mountains most frequently mentioned by the an- cients. The Alpheus was its principal stream, and Stymphalis its largest lake. It had neither seaports nor navigable rivers. Pausanias says its name was derived from that of Areas, son of Callisto. In the most ancient times its inhabitants, of Pelasgic origin, were hunters and rough shepherds; but they gradually turned their attention to agriculture and to raising cattle. Their habits were simple, and the quiet and happiness of their life among the mountains, their fondness for music and danc- ing, their hospitality and pastoral customs, made the Arcadians pass among the ancients for favorites of the gods. Pan and Diana were their principal deities. The poets have chosen Arcadia for the scene of many idyls, until its name has become the synonyme for a land of peace, simple pleasures, and untroubled quiet. In spite of this the Arcadians were, like nearly all mountain races, a brave and martial people, and, though they produced no great military leaders, were almost constantly engaged in war, either on their own account or as the mercenaries of others, fighting brave- ly even against their own countrymen for those who hired them. They fought in the ranks of both contending parties in the Peloponnesian. war, and at the battle of Issus thousands of them were slain in the army of Darius, by Alexander. The principal cities of Arcadia Mantinea, Tegea, and Orchomenus engaged in frequent and injurious disputes among them- selves. Against the Spartens the Arcadians (about 370 B. C.) built the city of Megalopolis, and organized a general assembly. They sub- sequently became confederates in the Achroan league, and on its final defeat in 146 B. C. fell