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opposite the entrance, and the side through which theentrance is made ; but neither of these is supposed to havebeen in the original edifice, but to have been introduced atsome later period.- The large niches on the exterior sidewithin the portico are cylindro-spherical, without any dress-ings. In the remains of the piazza of Nerva (see Desgodetz ’sAntiquities of Rome) a niche is exhibited upon a circularplan, with a rectangular front and cylindrical head in themiddle of the attic, over the intercolumns ; the axis of thecylinder, forming the head of the niche, is horizontal, andparallel to the nahed of the wall. This niche is surroundedwith an architrave, standing upon the base of the attic, whichprojects to receive it, and the head of the architrave supportsthe crowning of the attic.

The Ruins of Palmyra, by Wood , exhibit niches of varioushinds, some of which are very fantastically dressed. Theinside of the portico of the temple of the sun has two niches,one on each side of the doorway, with cylindrical backs,terminated at the head with spheroidal tops, which show anellipsis on the face with its greater axis horizontal. Theseniches are decorated with four attached columns, whoseaxes are placed in the surface of a C3'linder : the entablatureover the columns terminates under the spheroidal head ; thehead is decorated with a shell, and surrounded on the frontwith an elliptic archivolt upon the face of the wall. SeePlates VI. and IX. of the Ruins of Palmyra .

The inside of the portico of the court of the same edifice,shown in Plate XI. exhibits two niches on each side of thedoorway, which terminate on the front in parallel lines, andwith a semicircle at the head ; they finish with a pilaster oneach side : the capital, which is Corinthian , serving as animpost to the archivolt surrounding the head. Besides thisdressing, a column is placed on each side, attached to thewall, so that the distance between the insides of the columnsis greater than that between the outsides of the pilasters ;the architrave of the entablature rests upon the archivolt ofthe head of the niche.

The inside of the court of the great temple of Balbec exhibits niches dressed in the most whimsical manner ; thesides of the niches terminate with the wall in vertical lines,and the head with the said wall in a semicircle.

The sides finish with Corinthian pilasters; the entablatureis horizontal over the pilasters ; hut the architrave and cor-nice are carried round the semicircular head of the niche,which appears to be spherical within, being decorated witha shell resting upon an impost, and corresponding in itssituation to the height of the capital on each side. Theinside of the temple of Jupiter, at Spalatra, is decorated withniches, one between every two columns; the one oppositethe entrance, and those on each of the two sides, are rect-angular below, but finish with cylindric heads : the axis of thecylinder, which forms the head, is parallel to the horizon,and in the direction of radii which belong to the cylindricwall, in which these niches are placed.

The other four niches are cylindro-spherical ; that is, theyhave cylindrical backs, and are terminated with sphericalheads. All these niches are decorated with an impost, con-tinued from side to side, and the heads are furnished witharchivolts.

In the pointed style of architecture, niches are sometimeshighly decorated. The back very frequently consists ofthree sides of a hexagon, and the head is terminated with arich canopy, forming a complete hexagon with the interior ;the under part of each of the three projecting sides of thecanopy has a Gothic arch, and the soffit represents a groinedvault, decorated with tracery and ribs in the most beautifulmanner.

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The bottoms of these niches are formed by a table 0 0 f .same shape as the head, and terminate below in the t ,

a pendent. . O fof ;

The ceiling of the canopy represents the groined jjyan hexagonal building in miniature, as some of the ^° 0 py <decorated chapter-houses exhibit; the top of the 'finishes with battlements ; and the vertical angles are ^ te itimes finished with pendent buttresses, which are surffl 0 | :with pinnacles elaborately finished with crockets. ^ for 1Niche, in carpentry, the wood-work to be lathed o'plastering. _ 1 -

The most usual construction of niches in carpem ,

those with cylindrical backs and spherical heads, up 011 1cylindro-sphertc niches; the execution of which dep eDthe principles of spheric sections. g p a sS' ■

As all the sections of a sphere are circles, and tho 30 ^ cf ,ji ■ing through its centre are equal, and the greatest tl' e

be formed by cutting the sphere ; it is evident, that tl) ehead of a niche is intended to form a spherical surnribs may be all formed by one mould, whose curvatu* 0l) ebe equal to that of a great circle of the sphere, ' : 1

passing through its centre: but the same spheuo* 1 (jo# 8 : ,

may be formed by ribs of wood moulded from the - ^jbleof lesser circles, in a variety of ways ; though not 8 °^ eC ,i 0 i

an 1

for the purpose as those formed of great circlestheir disposition for sustaining the lath is not so gthe trouble of moulding them to different circl e9 >forming the edges according to different bevels, >•’ olD pa> e<1range them in the spherical surface, is very great, cwith those made from great circles. _ at -e

The regular dispositions for the head of a me* 1following: _ ve rti c ."

The ribs of niches are generally disposed ' n . a 0 th e1 '’I*plane, parallel to each other, or intersecting eac 1 ( j ir ouSa vertical line. When the line of intersection P aS f®'^ e3 ; * ,U j.the centre of the sphere, all the ribs are great 0110 en ti' e 0

if the line of intersection do not pass through the c

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the sphere, the circles which form the -

all of different radii. ne3) tl'® 1 j |

When the ribs are fixed in parallel vertical P. a Ql . par® , e :disposition is either parallel to the face of the ' va ’ | je spb 8 ^to a vertical plane passing through the centre o* . g (V iM, :perpendicular to the surface of the wall; anc. ^fa c ^ 1 " !■understood whether the surface be a plane, or thader, or that of a cylindroid. an d t 110 f !

Though these dispositions are the most comm® 1 ’‘ j t io»fit for the purpose, there is still another regular, P ra ct*^|| ;the ribs of a niche, which is easily constructed th , ’° U ® 1 is 1viz. by making all the ribs intersect in a line P a3SI ,p aC e ofthe centre of the sphere perpendicular to the g ? l a .\ I pot 1,wall ; but this method is not so eligible for lal ;" i

Another method is by making the planes gt

parallel to the horizon : this is not only attende ^ j a tl jl 0 |labour in workmanship, but is incommodious ;

upon. 0 f a 8 it |

The number of positions in which themay be placed are almost infinite ; as the nb g ittt®^ a eScommon intersection in a line or axis obli<l ue P.^a,

the horizon, or their position may be in P 81 ^ posi* 1 ^.obliquely situated to the horizon : but the th® 1

already enumerated, ought to be those to " {e

penter should direct his attention. n j C be> 'qjiig [

Plate I. Figure 1, No. 2, the elevation of 8all the ribs intersect each other in a vertical 11 ’] a n, 'Ljd 8 ,with the inside of the front rib, as shown by t 1 (he 1 m .

To describe any one of the ribs, aamn

contn 1

circle of the plan round beyond the wall, as

far

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may’