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ARCH

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Originally appearing in Volume V02, Page 344 of the 1911 Encyclopedia Britannica.
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ARCH ,' in See also:

building, a constructional arrangement of blocks of any hard material, so disposed on the lines of some See also:curve that they give mutual support one to the other. The blocks, which are technically known as voussoirs, should be of a See also:wedge shape, the centre or See also:top See also:block (see fig. 1, A) being the See also:keystone A; the See also:lower blocks B B which See also:rest on the supporting See also:pier are the springers, the upper See also:surface of which is called the i+.. H FIG. I. skewback, C C; the See also:side blocks, as D, are termed the haunches. The lower surface or See also:soffit of the arch is the See also:intrados, E, and the upper surface the See also:extrados, F. The rise of the arch is the distance from the springing to the soffit, G, the width between the springers is called the span, H, and the See also:radius I. The triangular spaces between the See also:arches are termed spandrils, K. The arch is employed for two purposes: (1) to span an opening in a See also:wall and support the superstructure; (2) when continuous to See also:form a vault known as a See also:barrel or waggon vault. The arch has been used from See also:time immemorial by every nation, but owing to the tendency of the upper portion to sink, especially when bearing any superincumbent See also:weight, it requires strong lateral support, and it is for this See also:reason that in the earliest examples in unburnt See also:brick at See also:Nippur in See also:Chaldaea, c. 4000 B.C., and at Rakakna (Requaqna) and See also:Dendera in See also:Egypt, 3500–3000 B.C., it was employed only below the level of the ground which served as an See also:abutment on either side.

In the building of an arch, the voussoirs have to be temporarily ' The ultimate derivation of " arch " is the Latin arcus, a See also:

bow, or arch, in origin meaning something See also:bent, from which through the See also:French is also derived " arc," a curve. In French there are two words arche, one meaning a See also:chest or See also:coffer, from Latin See also:area (areere, to keep See also:close), hence the See also:English " See also:ark "; the other meaning a vaulted arch, such as that of a See also:bridge, and derived from a See also:Low Latin corruption of arcus, into area (du Cange, Glossarium, s.v.). The word " arch," prefixed to names of offices, seen in "See also:archbishop," " See also:archdeacon," " See also:archduke," &c., means " See also:principal " or " See also:chief," and comes from the See also:Greek prefix apx- or apxc- from a.pXecv, to begin, See also:lead, or See also:rule; it is also prefixed to other words, and usually with words implying hatred or detestation, such as " arch-fiend ", " arch-See also:scoundrel "; it is from an See also:adaptation of this use, as seen in such expressions as " arch-See also:rogue," extended to " arch-look," " arch-See also:face," that the word comes to mean a mischievous, roguish expression of face or demeanour. supported, until the keystone is inserted. This at the See also:present See also:day is effected by means of centreing an assemblage of timbers framed together, with its upper surface of the same form as the arch required; the voussoirs are laid on the centreing till the See also:ring of the arch is completed. In the See also:case of arches of small span, such as the See also:early examples referred to, limited to about 6 ft., such centreing might be dispensed with in various ways, but it is difficult to see how the arches of the See also:great entrance gateways, shown in the See also:Assyrian bas-reliefs, could have been built without temporary support of some See also:kind. In those days, when any amount of labour could be obtained, even the erection of a temporary wall might have been less costly than the employment of See also:timber, of which there was great scarcity. The Assyrian tradition would seem to have descended first to the See also:Parthian builders, who in the See also:palace of El Hadr built semi-circular arches with See also:regular voussoirs decoratively treated. The Sassanians who followed them employed the elliptical or See also:egg-shaped arch, of which the lower See also:part was built in See also:horizontal courses up to about one-third of the height, which lessened the span of the arched portion. In See also:Europe the earliest arches were those built by the Etruscans, either over canals (see See also:article See also:ARCHITECTURE: See also:Etruscan), or in the entrance gateways of their towns. The skew-arch in the gateway at See also:Perugia shows great knowledge in its See also:execution. From the Etruscans the See also:adoption of the arch passed to the See also:Romans, who certainly employed centreing of some kind, but always economized its use, as is clearly shown by See also:Choisy.

Al-though their walls from the Augustan See also:

age were built in See also:concrete, arches of brick were always turned over their entrance doorways, sometimes in two or three rings. The Romans utilized the arch in other ways, sometimes burying it in their concrete construction, as in their vaults, and sometimes introducing it as a See also:veneer only, as in the See also:Pantheon. In their monumental structures in See also:stone, the arch was sometimes built with regular voussoirs, i.e. with a semicircular extrados, and sometimes with the See also:joint carried far beyond. The latter was not done in the early examples of the See also:Tabularium and the See also:Theatre of See also:Marcellus, but in the Colosseum and all the arches of See also:triumph the See also:joints run through the spandrils, notwithstanding the recognition of the arch proper by its moulded See also:archivolt. Although the value of the pointed arch as a stronger constructional feature than the semicircular (owing to the tendency to sink in the keystone of the latter) had been recognized by the Assyrian builders, who employed it in their drains, it was not used systematically as an architectural feature till the 9th See also:century, in the See also:mosque of Tulun at See also:Cairo; it seems to have been regarded by the Mahommedans as an See also:emblem of their faith, and its use spread through See also:Syria to See also:Persia, was brought to See also:Sicily from Egypt, and was taken back by the Sicilian masons to See also:Palestine and employed throughout theCrusaders'churches during ther 2th century. As the pointed arch had already, for constructional reasons, been employed in See also:Perigord from the commencement of the Il th century, it does not follow that the Crusaders brought it from Palestine, but there is no doubt that its universal employment in See also:France early in the 12th century may have been partly due to its adoption in the Crusaders' churches. At first in See also:Gothic See also:work both the semicircular and pointed arches were used simultaneously in the same building, the larger arches being pointed, the smaller ones and windows being semicircular. The great value of the pointed arch in vaulting is described in the article VAULT. We have suggested that the pointed arch became an emblem of See also:Mahommedan faith, and it was introduced in See also:India but. not as a constructive feature, for the See also:Hindus objected to the arch, which they say never sleeps, meaning that it is always exerting a thrust which tends to its destruction. In India therefore it was built in horizontal courses with See also:vertical slabs leaning against one another to form the See also:apex. The See also:Moors of See also:north See also:Africa, however, never employed it, preferring the horseshoe arch which they brought into See also:Spain and See also:developed in the mosque of See also:Cordova. In the additions made to this mosque the See also:prayer chamber was enriched by the See also:caliph Mansur, who, to eke out the height, raised arch upon arch.

In the See also:

Alhambra it appears in the decorative343 See also:plaster work, and travels northwards into the See also:south of France, where at Le See also:Puy and elsewhere it is found decorating doorways and windows; in See also:England it was employed towards the end of the 12th century. About the See also:middle of the 14th century at See also:Gloucester the four-centred pointed arch was introduced, which became afterwards the leading characteristic feature of the Tudor See also:style. In France they adopted the three-centred arch in the 15th century. The See also:ogee arch was the natural result of the development of See also:tracery in the commencement of the 14th century, and in Gloucester (about 131o) the foliations were run one into the other without the enclosing circles. About the middle of the 14 th century, in the See also:arcade of the first See also:storey of the ducal palace in See also:Venice, flowing tracery is found, from which the ogee arch there was probably derived, as throughout Venice it becomes the favourite feature in domestic architecture of that and the succeeding century. The arches are of various forms as follows: 2 4 8 IO I2 14 16 2. Semicircular arch, the centre of which is in the same See also:line with its springers. 3. Segmental arch, where the centre is be-low the springing. 4. Horseshoe arch, with the centre above the springing; employed in Moorish architecture. 5.

See also:

Stilted arches, where the centre is below the springing, but the sides are carried down vertically. 6. Equilateral pointed arches, described from two centres, the radius being the whole width of the arch. 7. Drop arches, with centres within the arch. 8. See also:Lancet arches, with centres outside the arch. 9. Three centre arches, employed in French Flamboyant. lo. Four centre arches, employed in the Perpendicular and Tudor periods. 1.

Ogee arches,with curves of See also:

counter flexure, found in English Decorated and French Flamboyant. 12. Pointed See also:horse-See also:shoe arches, found in the mosque of Tulun, Cairo, 9th century. 13. Pointed foiled arches, in the arcades of See also:Beverley See also:Minster (c. 1230) and See also:Netley See also:Abbey. 14. Cusped arch ; See also:Christchurch Priory, Hants. 15. Multifoil cusped arch, invented by the Moors at Cordova in the loth century. 16. See also:Flat arch, where the soffit is horizontal and sometimes slightly cambered (dotted line).

17. Upright elliptical arch, sometimes called the egg-shaped arch, employed in See also:

Egyptian and See also:Sassanian architecture. 9 II 17 I$ 18. TheTuscanarch, where the extrados takes the form of a pointed arch. 19. The joggled arch used in See also:medieval chimneypieces and in Mahommedan architecture. 20. The discharging or relieving arch, built above the See also:architrave or See also:lintel to take off the weight of the super-structure. 21. The relieving arch as used in Egypt, in the See also:pyramid of See also:Cheops; and in Saxon architecture, where it was built with See also:Roman bricks or tiles, or consisted of two sloping slabs of stone. 2I (R. P.

End of Article: ARCH

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ARCH, JOSEPH (1826– )

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