MOO

210

MOO

it was named by the Mohammedans, the sacred arch, willtend to corroborate this statement. The shape was firstintroduced into architecture by Muavia, the first of theOmmiad dynasty, who adopted it in all the buildings heerected, and it afterwards became common in all countries intowhich the Moors had penetrated. The same outline is foundin the bulbous dome, which is so peculiar a feature of theMohammedan mosque; and there can be no doubt but thatthis dome was suggested by the cresent arch, no more indeedthan that the semicircular or segmental domes were derivedfrom the corresponding arches. We might say that the pro-bability in the former case is the stronger, in as much as thatform of dome is scarcely natural, and not to be accounted forby requirements of construction. The profile of the bulbousdome is precisely that of the horse-shoe arch. Anotherinstance in which the crecent-shape appears,-is the cuspingor scalloping of the soffit, or sometimes of both outlines ofthe arch, which is a common practice, and may have givenrise to the use of cusps in Gothic architecture.

The profile of the horse-shoe arch is that of a segment ofa circle greater than a semicircle, or, in other words, it is acircular segmental arch, which is struck from a centre abovethe springing line. A modification of the same form is used,which may be termed the pointed-crescent or horse-shoe arch.This form consists of two segments meeting in a point atthe apex, and is struck from two centres, both, as before,above the springing line.

The semicircular arch was borrowed by them, and usedoccasionally in conjunction with the others. The pointedarch is by some supposed to be invented by the Arabians,and to have been copied from them by the Gothic architects;be this, however, as it may, it is certain that it was exten-sively in use amongst them, ami is found in Persia, Egypt ,and Arabia, but was most prevalent at Bagdad and in the East.It is said to have been introduced by the house of El Abbas,who adopted it in opposition to the crescent form which hadbeen employed by the rival house of the Ommiades ; buteven by them the old form was not entirely discarded,being retained in the principal entrances, and also in theform of the domes.

Another variety of arch is the stilted, which is of semi-circular form, the centre from which it is struck being taken,as in the case of the horse-shoe arch, somewhat above thespringing line ; but instead of the circle being continueddownwards, and contracted in width towards the impost line,the ends of the semicircle are carried down straight or per-pendicularly, so as to give an appearance of elevation andlightness to the arch, which it Would not otherwise possess.

The last form which we shall notice is the cusped or scal-loped arch, the outline of which is similar to the polyfoil-beaded compartments in Gothic apertures, being producedby three or more intersecting semicircles. There is thisdifference, however, that whereas the Gothic examples aremerely ornamental accessories, the Moorish form main partsof the construction ; the scallops are large, and form theoutline of their main arches, the extrados as well as theintrados following the same profile.

All the above forms of arches are treated in various ways,both as to their impost and decoration. Sometimes the archsprings directly from the solid wall, at other times it is madeto rest upon columns. In the case of the horse-shoe arch,when the former arrangement takes place, the whole of thearch rests upon the wall, or, in other words, the wall projectsas far as the most prominent part of the arch, so that thearch does not overhang the impost; but in the other arrange-ment, the columns are recessed back so as to range with theextremity of the diameter with which the arch is struck,

the

space between the columns as wide as

the capital ot ‘JJ

thus leaving a

diameter or extreme width of the arch . .

column, or an impost moulding above it, projects forvvai

_x„ ii.„ x_ :4.:„^ l' ii.„ „i.

Sometinie s > ,corl» e fTin 3

the walls, and serving as imposts. |

as to sustain the extremities of the archmore especially when stilted, the arch is supported byprojecting from

practice of corbelling is very prevalent. In someface of the arch, thattrados,stops

cases

a

is, the width between the intrudesextrados, is continued down the impost-jambs, but in 0 ,

it stops at the springing. This face again varies ^sideraiily in breadth, and sometimes is not shown at a* ^the face of the wall; it is generally, however, a wide bit* 1archivolt following the outline of the arch, sometimes P ,showing only the joints, sometimes plain with the ad< ( |,of a moulding round the extrados, and at others ^moulded and otherwise decorated. The decoration is u3U t j,ein compartments formed by the joints, and frequemv^.alternate-voussoirs are contrasted by a difference of orn a jtation. The depth of the archivolt was sometimes so Sas to equal the radius. Cusping in the direction of tbeline of the arch is a common mode of decoration, being s ° ( j 0 s,times applied in the shape of a moulding round the ex tr ’ 1 ofami sometimes the intrados or soffit only being so c oserrated. Occasionally the arches of apertures are leftbeing filled up with walling, and having a square- 11 ‘ ( | J0aperture underneath : this is especially the case w> ^crescent arch. Arches of whatever kind are generally P ^ e .within a square-headed panel or compartment, which 1 .quently surrounded by a border or plat-band, somsimilar to the square hood-mould of the perpendiculat P^pof Gothic architecture.

This band, as well as the sp a ^intercepted between it and the arch, are usually covere t ,ornamentation of various descriptions. Sometimes tvV . 0 . ( |j, i 3bands are introduced, with a space between them, ' v t ioH-commonly filled up with inscriptions or other dec 0 ^This last method, however, is not common except i napertures, or in principal entrances. ,k 11 ^ 6

The columns are of slender proportions, and reim r ^ g \rfor extraordinary lightness and variety of form-

but often ornamente

larg 0

shafts are sometimes plain,carving, being sometimes surrounded with

g r oO' ,e

a spira 1 .

twisting round the shaft, at others grooved perpend’

The capitals are of various forms, usually carved 0l .Jef 3 ’tered foliage, being sometimes imitations of the classic ^and sometimes designs of their own ; the cap is c0 . v<S | j yriil) 11111a plain abacus. Columns were very frequent m )e"j,

edifices, disposed in clusters or rows, and supp°* 0arcades ; they add considerably to the light app u11their buildings. . t0 „eS °\

Corbelling, which consists in the projection ot ^ts 11

bricks at regular distances from the main wall, is jutr' 1

sive use in Arabian architecture, and was proba pH ' .duced into Europe by them. The practice seem 8 .^.s ^originated in the East, for it is seen in Eastern e ^al 1 '

very early date, and prevails to a great extent . ...

tecture both of India and China . The Arabians u ill** 1

lecially 1,1

■tlSi

corbels in all their structures, but more especmfortresses, to throw out the parapets for machic<d a JAmongst the many peculiarities of Arabian » l ’^none is more worthy of mention than that metim ^. ( | ementation which has been designated under tarabesques, although the term, as applied by 111 ^jeddoes not exactly describe the peculiar ornamentwith us, the term includes a wider range of deed*law of the Mohammedan faith prohibited all 1 g e ly 011 -a 3of human or animal figures, as bordering too c °..^cep 1 "practices of Christianity and paganism, and this P