work is ('(DisiJcratiuns iiiilitaircs ct poUtifjucs t»c Us fiirlificntionK (Paris, 1795).
ARCO'NA. Spf Arkona.
ARCOS DE LA FRONTERA, iir'kos ilA lu fiuii-tri'ia iSji., Buw of the Frontier, alhuling to its being built in bow-sliape and to its position on the frontier). A town on the ri{.'ht bank of the Guadalete, in the province of Cadiz, Spain (Map: Spain, C 4). It is situated on a conical height ,i44 feet above sea-level, and is a remarka- bly picturesque city with steep, crooked streets. Above the city stands the old castle of the dukes of Arcos. now in ruins. Beyond apjiear the Ronda ^Mountains. There are seven mon- asteries, two parish churches, with the main church of Gothic style, interesting among its buildings. The manufactures include leather, mats, thread, and rope. There is considerable trade in oil. wine, and fruit. Pop. 1900, 14,393. Arcos is the Arcohriga (Celt, briya, town) of the Roi7ians. It was wrested from the Moors by Alfonso the Wise, and strongly fortified as a frontier town, in 1204.
AR'COSO'LIUM (Lat. arcus, arch + solium, seat, chair of state). A name given to the niches, surmounted by an arch, that were used, for example, in the early Christian catacombs, for the burial of the more illustrious dead. They usually contained a carved marble sarcophagus, and were ornamented with frescoes.
ARCOT, iirkot' (Tamil Arkat, Si.x Woods). A city in the presidency of Jladras, India, the capital of the district of North Arcot, on the right bank of the Palar River, 65 miles west of Madras (Map: India, 6). It is a railway junction, has a military cantonment, contains some mosques in a tolerable state of repair, and the ruins of the Nawab's palace. Of great an- tiquity and mentioned by Ptolemy, it is note- worthy because of its history, the most brilliant incident of which was its capture and defense by Clive (q.v.), in 1751. The walls of the famous fort now serve as a dyke which protects the city against periodical inundations. Pop. 11,000.
ARCTIC (Gk. apuriKoc, nrktikos, northern, from Gk. aparoc, urktos, bear, north). A term meaning "lying near the constellation of the Bear." The Arctic Circle is a circle drawn round the Xorth Pole, at a distance from it equal to the obliquity of the ecliptic, or 23%°. The corresponding circle round the South Pole is the Antarctic Circle. Within each of these circles there is a period of the year when the sun does not set, and another when it is never seen, this period increasinE; as we approach the pole itself. At the pole it is six months in length, if we neglect the effects of refraction (q.v.).
ARCTIC CUR'RENT, HIGH'LANDS. See Arctic Rriiiox
ARCTIC DISCOVERY. See Polar Research.
ARCTIC O'CEAN. See Arctic Region.
ARCTIC PLANTS. See Arctic Reoiox.
ARCTIC RE'GION. Broadly speaking, that portion of tlie surface of our globe which sur- rounds the Xorth Pole within the limits of the Arctic Circle, and thus, extending twenty-three and one-half degrees in every direction from the pole, covers an area of 8,2()0.OO0 square miles. It includes the northern coast-lands of Europe, North America, and Asia, ancj the outlying islands to the luirth of these continents, as well as the middle and northern parts of Greenland, the northern part of the Atlantic Ocean, and the whole of the Arctic Ocean. The northern islands comprise the great archijielago north of the continent of North America, including the Parry Islands, BatKn Land, Prince Albert Land, Banks Land, Prince of Wales Land. North Somerset, Grinnell Land, etc.. and the islands north of Eu- rope and .sia : the S])itzbcrgen group, Nova Zem- bla, the Franz-. loscf group, and the New Siberian group. It is a region of snow and ice ; for months in the winter the sun is below the horizon, and though for other months in summer it never sets, its heat is not strong enough in most quarters to reduce the quantity of snow and ice which forms in the cold season. The longest day and the longest night at latitude 70° are about two months each ; ten degrees farther north they are about tliree months each; at the pole they divide the year almost equally.
Topography. The land surface of the Arctic region has been as yet but incompletely explored, although the unremitting interest in Arctic exploration is gradually adding to our knowledge of its extent and details. The loftiest region is Greenland, along the east and west coasts of which there are mountains rising from 3000 to 8000 feet above sea level, culminating in Petermann Peak, with an estimated altitude of 11,000 feet. The name "Arctic Highlands" was given to that portion of the American Continent which lies between Hudson's Bay and the mouth of the Mackenzie River, reaching far below the Arctic Circle. The district lies partly within and partly without tlie barren or treeless stretches of northern North America. The southern portion has elevations of 1700 to 2000 feet above sea level. The portion north of Great Slave, Great Bear, and Athabasca Lakes has a gentle and regular slope toward the Arctic Ocean. The usage of the term "Arctic Highlands" may, perhaps, be extended so as to include the highlands west of Smith Sound. The name was also applied by Ross in 1818 to the region around Cape York (latitude 76° to 78°, longitivde 67° W.), in Greenland; and the most northern Eskimos, who live on the seacoast at the foot of these mountains, have until recently borne the name of "Arctic Higlilanders," given to them by Ross. The northern part of Seward Peninsula is characterized also by a broken topography, with mountains rising 5000 feet or more above sea level. Banks Land and other large islands oiT the coast of the North American Continent, including Bafiin, Ellesmere, Grinnell, and Grant Lands, are comparatively low, with rounded mountains in the interior. In Baffin Land the central iilateau is from 000 feet to 800 feet above the sea, and isolated mountains attain a height of 2000 feet. In the eastern part of Siberia the surface is broken by low mountain ranges and by wide river valleys! The portion of Siberia lying west of the Yenisei River, however, is a low, almost unbroken plain, covered with a dense growth of moss, and containing numerous and extensive swamps, features that are comprehended under the general term of tuiidra (q.v.). Portions of Franz-Josef Land and Crown-Prince Rudolf Land (latitude 80° to 83°) are elevated, the mountains and plateaus rising 2000 feet or more aboie the sea. Upon these plateaus, and that of Spitzbergen, and particularly upon that
