Arteriot´omy, the opening or cutting of an artery for the purpose of blood-letting, as, for instance, to relieve pressure of the brain in apoplexy.
Arte´sian Wells, so called from the French province of Artois, where they appear to have been first used on an extensive scale, are perpendicular borings into the ground through which water rises to the surface of the soil, producing a constant flow or stream, the ultimate sources of supply being higher than the mouth of the boring, and the water thus rising by the well-known law. They are generally sunk in valley plains and districts where the lower pervious strata are bent into basin-shaped curves. The rain falling on the outcrops of these saturates the whole porous bed, so that when the bore reaches it the water by hydraulic pressure rushes up towards the level of the highest portion of the strata. The supply is sometimes so abundant as to be used extensively as a moving power, and in arid regions for fertilizing the ground, to which purpose artesian springs have been applied from a very remote period. Thus many artesian wells have been sunk in the Algerian Sahara, which have proved an immense boon to the district. The water of most of these is potable, but a few are a little saline, though not to such an extent as to influence vegetation. The hollows in which London and Paris lie are both perforated in many places by borings of this nature. At London they were first sunk only to the sand, but afterwards into the chalk. One of the most celebrated artesian wells is that of Grenelle, near Paris, 1798 feet deep, completed in 1841, after eight years' work. Artesian wells are now common in many countries, and have been sunk to the depth of a mile or more. As the temperature of water from great depths is invariably higher than that at the surface, artesian wells have been made to supply warm water for heating manufactories, greenhouses, hospitals, fish-ponds, &c. They have also been made in the United States and Australia for the purpose of irrigation. Petroleum wells are generally of the same technical description. Artesian wells are now made with larger diameters than formerly, and altogether their construction has been rendered much more easy in modern times. See Boring.
Arteveld, or Artevelde (a˙r´te-velt, a˙r´te-vel-de), the name of two men distinguished in the history of the Low Countries.—1. Jacob van, a brewer of Ghent, born about 1300, was selected by his fellow-townsmen to lead them in their struggles against Count Louis of Flanders. In 1338 he was appointed captain of the forces of Ghent, and for several years exercised a sort of sovereign power. A proposal to make the Black Prince, son of Edward III of England, Governor of Flanders led to an insurrection in which Arteveld lost his life (1345).—2. Philip, son of the former, at the head of the forces of Ghent gained a great victory over the Count of Flanders, Louis II, and for a time assumed the state of a sovereign prince. His reign proved short-lived. The Count
of Flanders returned with a large French force, fully disciplined and skilfully commanded. Arteveld was rash enough to meet them in the open field at Roosebeke, between Courtrai and Ghent, in 1382, and fell with 25,000 Flemings.
Arthri´tis (Gr. arthron, a joint), any inflammatory distemper that affects the joints, particularly chronic rheumatism or gout.
Arthro´dia, a species of articulation, in which the head of one bone is received into a shallow socket in another; a ball-and-socket joint.
Arthrop´oda, one of the two primary divisions (Anarthropoda being the other) into which modern naturalists have divided the sub-kingdom Annulosa, having the body composed of a series of segments, some always being provided with articulated appendages. The division comprises Crustaceans, Spiders, Scorpions, Centipedes, and Insects.
Arthrozo´a, a name sometimes given to all articulated animals, including the arthropoda and worms.
Arthur, Chester Alan, twenty-first President of the United States, born 1830, died 1886, was the son of Scottish parents, his father being pastor of Baptist churches in Vermont and New York. He chose law as a profession, and practised in New York. As a politician he became a leader in the Republican party. During the civil war he was energetic as quarter-master-general of New York in getting troops raised and equipped. He was afterwards collector of customs for the port of New York. In 1880 he was elected Vice-President, succeeding as President on the death of Garfield in 1881.