PEN

273

PEN

rer *iai n in

and Pk • vanous parts of Greece , in Boeotia, Attica, Argolis,pv°t} v , 0CIS } also at Julis and Delphi ; but the above will^ S' y e a sufficiently explicit idea of their general

•4525s**. (from the Greek ntXsKvc, a.hatehet, and6 C a figure in the form of a hatchet. Such is the figure

A „ n ’ conta i ne d under the inverted quadrantal arcs A b andThe^ t ' ie sem 'eircle bob.

the sq. area °fi the pelecoides is demonstrated to-be equal toe< Dalt Fe Ac ’ an fi that, again, to the rectangle eb. It isthe lefw tke S( l u are A c, because it wants, of the square-ont® th e t nan< T the two segments a® and ad, which are equaltight hand Se ^ ments B c anc t c D > hy which it exceeds on the

TENiY^ 1 vav fited roof without groining..

8u Pport he or E hii -osophical Bridge, a wooden bridge>hent s nf posts and pillars, and sustained only by but-Terdk 6 en ^ s ' See Bridge.

®f th e 1 NT ’ an °rnament not uncommon in the vaulted roofsf insist 6 ° r P er P en( hc u lar period of Gothic architecture,h'oiti the * ° Pa h° 8s of foliage, or other ornament, suspendedtonvef-- SUtnm it of the vaulting at the end of ribs, which,' v hich fg 11 ® Prom the soffit of the roof, meet at a point below.P^3 ex - , C0Vere d with the boss alluded to. Beautiful exam-Orn artl at Henry VII. ’s chapel, "Westminster.

of tf 11 * 8 a 8 ' m >lar description occur also in the timber‘hgi. tue same _ 1 : 1 . ;— .i.- _c

0f»

h arrim e sanie date, as likewise attached to the ends ofr-ben ra8j or tethe extremities of-the ridge-pieces

P ENrvr'\T 6ceive th® en ds of the barge-boards.

^Ult, S() h'NTlVE, in architecture, the whole body of a^rin e s P e /*ded out of the perpendicular of the walls, and

of^iler dBfi St the arc - boutants -

a dom uelInes it a portion of a.vault between the arches

pin of th’ Usua % enriched with sculpture. Eelibien, the0rr oi nrr e vault contained between the double arches, the

' rhe °Pen& and the ogives,rrujgt Y ent ' v es are usually of brick, or soft stone-; .andlev»i 6 *?hen that the joints of the masonry be always

'aid

joints of the masonry be always«tice fi! aa<1 ™ right lines proceeding from the sweepth joint FlSe 18 taken -

hscessit S ’ t0 °’ must be ma de as small as possible, to save' a g in u „v T °f filling them up with slips of wood, or ofn mortar.

*C eVe !> and

e .jh the r "' vi5 Jacketing, a cove bracketing, springingc 0 * ' n 8> so ectan gular walls of an apartment upwards to the'J’Plete pf 8 , to fi >r ® the horizontal part-of the ceiling into aW e Pron 6 ’ ° r elli P 8 *s-

8 are c ^ 1 , or ' tei 'i on for such bracketing is, that if thetb e Sectip„_T horizontal planes through the coved p

parts,

s i<)p° r|; 'onJof S j brou gh such parts will be portions of circles,p 0 8 of mhpses, having their axes proportional to the

figure. apartment ’ '

so that each section will be a com-■“esides having four curvilinear parts, it will.. Parts, which are portions of the sides of the

lC ea ch ,;/ ait „ men ‘; and the axis of the ellipsis will

c<, ;

, (II c on Ce iy 9 Radi - ing > The surface to be formed mayc 1-e 0ce 0 f tn ’ k et a square be inscribed within the cirP«nd' V

S a ! Cul ar t„ R«nes througW<.,Sain 0 p ] ane ofthe

\r° f th

four ft 1 ' )ase °f a hemisphere, and let the hemispherePlanes through the sides of the square, per-base ; then let this hemisphere

"Ut h — WU8C , men 1C4. inis ucuiispucic

touch the anot . ker plane parallel to the plane of the

section of the four parts ent off; the sur-

isph er ain >ng solid will then consist of a portion ofn J.Y fight n ’ one ent ire circle, and four equal semicircles,s be to the entire great circle. Therefore, if

e d in planes passing through the axis of the

sphere, then the two ribs, which stand-upon the diagonals,will be entire semicircles; or, if a dome be perforated by acylindric surface, of which the axis is that of the dome, theribs will still have-the same position.at any springing, whichis one of the semicircular arches.

Plate 1. Figure 1.—The representation of the pendentivecradling of a dome. No. 1, Abcd, the plan ; bec thespringing-line of a semicircular form, described on the diame-ter, bo, The shaded parts, at i, k, l,m,n, mark the placesfor the feet of the ribs to stand upon. G. h, sections of thecurb, No. 2. The elevation, o p and Q R, the shortest ribsused ; of these there are four each, standing in the middle.

Figure 2. No. 1, 2.—Plan and elevation, representing thependentive cradling of a dome.

Figure 3.—The geometrical construction of the pendentivecradling of a segment dome. This figure shows the portionsof the ribs that-must be used in the construction of the car-pentry : thus, c m, av, cw, c x, are the ribs which everyeighth-part of the plan requires.

Figured No. 1, 2.—The plan and elevation of the pen-dentive cradling of a cone.

Plate 2. Figure L-«-Plans, sections, and ribs of pendentivecradling.

To. construct this cradling, let a.b c d, No. 1, be the plan,which is an oblong figure. We must find the circumscribingplan of the spheroid, so that the length and breadth shall bein the same ratio ns the two dimensions of the plan. Forthis purpose, draw the diagonals, A c and b d, cutting eachother in e. Through the centre, e, draw m i parallel to b c,or A d, cutting the plan at x and h ; also, through e drawk l parallel to ba, ore d, cutting the side, b c, at f. Fromthe centre, E, describe a quadrant, to touch the side of theplan at f, so that the portion of the circumference may becontained between k e and i e ; bisect the arc, and throughthe point of bisection draw a line parallel to bc, or any ofits parallels, cutting the diagonal, A C, in g ; join f g and G h,and draw c K and c i respectively parallel to G f and G h ;make e l equal to e k, and ,e m equal to.E i ; then about thetwo axes, .mi and el, describe an ellipsis, which will be thebase of the spheroid that will form the surface for the ribs.

When the plan- of the figure to be covered is square, drawthe seats of the ribs as in preceding examples. Also, drawthe kirb for the skylight in the same proportion as the sidesof the plan.; then the rib which stands upon f u will be theportion of the quadrant of a circle, described with the radiuse k, as at No. 4, where e k, No. 4, answers to e k, No. 1 ;Jtf to KF ; and f u to fu ; then, by drawing the perpen-dicular, fl and u n, No. 4, to cut the quadrant, km, at l andn, In will show the portion of the curve which will form thecomplete edge of the rib to cover the part f u.

Take half the transverse axis, m e, No. 1, and apply it inthe straight line, m e, the left-hand figure at the bottom ;draw e o perpendicular to m e, and make e o equal e k, No. 1 ;describe the quadrant of an ellipsis, onlm.; make m x, x w,respectively, equal to M x, x w, No. 1, draw the perpendicu-lars, w n and x l, then the portion of the ellipsis, intersectedat n and l, will be the edge of the rib to cover x w on theplan.

In like manner b n, No. 5, is the edge of the ribs to coverthe half of either diagonal, a c or b d.

No. 2. the transverse section and elevation.

No. 3, the longitudinal section and elevation, showing howthe ribs are to be fixed.

PENETRATE, the most sacred chamber of a heathentemple.

PENETRALIA, chapels in Roman houses, in which thefemale or household gods were placed.

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