a usual round or one-centred arch: a stilted arch; a usual pointed or two-centred arch; a cusped or lobed arch (trefoil, quatrefoil, cinq- foil); a horseshoe arch; a reverse-curve or ogee arch; a basket-handle arch (both three-centred). The arch is formed of voussoirs; the central one is the keystone, the lower ones are the springers. The inner side of the arch is the intrados, the outer the extrados. See Abutment; Archivolt; Spandrel.
History. — The supporting power of the arch appears to have been known to most nations of antiquity, but the power was not regarded as artistic. The Egyptians knew the round arch, but relegated it to works of engineering and pri- vate architecture; the arch never appears in their temples, tombs, or any other large monu- ments. In this they held precisely the position held later by the Greeks. The arch in the As- sembly Hall at Priene (time of Alexander), re- cently discovered, is supposed to be the only decorative Greek arch found : the few others are in fortifications, etc. But the Babylonians and Assyrians knew and used various kinds of arches in their palaces, tombs, and temples: the false arch ; the pointed and the semicircular arches. All the openings in Assyrian palaces were arched. In ancient Italy, the Pelasgic and Etruscan populations used the arch in the same way for secular and sepulchral buildings; for gates, bridges, passages. Only in temple architecture, borrowed from the Greeks of the historic age, was the architrave supreme. This custom was inherited by the Romans, most of whose secular buildings were arched, while their temples were not. But the Romans of the Early Empire did not invent the arcade — that is, an uninterrupted series of arches supported on columns or piers. This was first introduced at Diocletian's palace in Spalato, and developed in early Christian religioiis architecture. Etruscans, Romans, and early Christians knew only the semicircular arch. But the Persians and Mohammedans, beginning in the Sixth and Seventh centuries, brought into use a variety of other forms: the pointed, the horseshoe, the ovoid, the stilted arches. These forms later penetrated sporadically into Europe, especially where there were political or com- mercial relations with the Orient. The pointed arch became, in fact, the favorite Mohammedan form. It was, perhaps, a knowledge of this Oriental usage that suggested to French build- ers of the time of the First Crusade the use of this form in vaulting: and thus was laid the basis for Gothic construction, though otherwise there cannot be any connection between the pointed style of the East and Gothic architec- ture. In Europe the round-arched style of the Romanesque Period was succeeded by the more flexible pointed style of Gothic. Gothic archi- tects produced the greatest number of sub-forms and by-forms of the arch, not all of them pointed. Then the Renaissance returned to the round arch. Modern architects have no style to hamper them, and therefore use all kinds.
ARCH, Triumphal, or Memorial. Usually
a free-standing arch, spanning a road; though
sometimes city gates and monumental doorways
are turned into memorial arches. These arches
are erected to commemorate triumphs or suc-
cessful campaigns, or even great peaceful events,
or an entire reign, or even a great family. They
appear to have originated with the Romans.
Nearly one hundred and fifty such Roman arches remain wholly or in part, of which about sixty- are in North Africa. At Rome they were placed along the Triumphal Way followed by the tri- umphing general and his army from the Field of Mars to the Capitol. The custom spread from Rome elsewhere. The earliest arches mentioned at Rome are those of Stertinius (B.C. 196) and Scipio Africanus (B.C. 190). Then the Fabian gens erected one to itself (c. 120 B.C.). But it was under Augustus that the custom took root everywhere, as is shown in the Roman Forum, at Aosta, Susa, Rimini, Fano, etc. From that time until the fall of the Empire in the Fifth Century such arches followed Roman dominion throughout the civilized world, and they are found in France (Saint Remy, Orange, etc.), Spain (Caparra, Bara), North Africa (Timgad, Tebessa, Thugga, Haïdra), Syria (Palmyra, Gerasa, Baalbek), Asia Minor, etc. The early arches were of stone and without much carving, being mainly arched bases for a group of tri- umphal statuary. But under the Empire, though still crowned by the triumphal quadriga and other figures in bronze, the arches themselves became of great artistic importance, and often represent the most successful efTort of Roman genius at combining architectural and sculptural design. They were then built of marble. The number of openings varied from one to four, according as special arcades were or were not made for foot-passengers, or two main arches provided for vehicles in place of one. Still an- other favorite form was the Janus arch, or Tetrapylon, a solid cube, with arches at right angles, usually placed at the intersection of avenues, as at Philippopolis, Gerasa, and Rome. Few cities were built under the Empire without one or more of these arches, but only in Italy and South France were they profusely decorated with relief sculptures. The most perfect of all such sculptured arches is that of Trajan, at Benevento (A.D. 114); then come those of Titus (A.D. 80), Septimius Severus (A.D. 203), and Constantine (A.D. 312) at Rome, and that of Tiberius at Orange. The sculptures commemo- rated events of these emperors' reigns, and the attic contained the dedicatory inscription. One of the slenderest and most elegant is the one erected on the Mole at Ancona, to celebrate the enlargement of this port by Trajan. The Renais- sance resurrected the arch after a lapse of a thousand years (Arch of Alfonso at Naples, Fifteenth Century), and it has since the Seven- teenth Century steadily increased in popularity in Italy (Arco della Pace. Milan); France (Arc de l'Etoile, Arc du Carrousel); Germany (Brandenburger Thor, Berlin; Siegesthor, Mu- nich), and America (Washington Arch, New York; Memorial Arch, Brooklyn). Consult: Baumeister, Doikmiiler des Klassischen Alter- tuma (Munich, 1885-88) : Daremberg and Saglio, Dicfioiiitnire des antiquités grecques et ro- maines (Paris, 1881-92); Bellori, Veteres Arcus Augustorum (Rome, 1600): and Philippi, Ueber die römischen Triumphalreliefe (Leipzig, 1874).
ARCH, Joseph (1820—). An English labcu-
leader. He was born in humble circumstances;
was a farm laborer: educated himself, and be-
came a PriTuitive Methodist preacher. In 1872
he headed the movement for the betterment of
the condition of farm laborers in England, and
founded and was president of the National Agri-
