Page:Encyclopædia Britannica, first edition - Volume I, A-B.pdf/422

 35^ A R C H I T breadth of the whole joint may be from one fourth to one third of the height of the fiat furface of the ruftic. Inftead of a fecond order, it is fometimes ufual to crov/n the firfl: with an Attic Story: Thefe Attics fhould never exceed in height one third of the height of the order on which they are placed, nor be lefs than one quarter of it. Their figure is that of a pedeftal: The bafe, dye, and cornice, jof which they are compofed, may bear the fame proportions to each other as thofe of pedeftals do; and the bafe and cornice may be compofed of the fame mouldings as thofe of pedeftals. Sometimes the Attic is continued throughout; at others, it projects, and forms a pilafter over each column of the order. The breadth of this pilafter is feldom made narrower than the upper diameter of the column below it, and never broader. Its proje&ion may be equal to one quarter of its breadth. OF PEDIMENTS. Pediments moft probably owe their origin to the inclined roofs of the primitive huts. Among the Romans, they were ufed only as coverings to their facred buildings, till Caefar obtained leave to cover his houfe with a pointed roof, after the manner of temples. In the remains of antiquity we meet with two kinds of pediments, the triangular and circular. The former of thefe are promifcuoufly applied to cover fmall or large bodies: But the latter being of a heavier figure, are never ufed but as coverings to doors, niches, windows, or gates. As a pediment reprefents the roof, it fliould never be employed but as a finiftiing to the whole compofition. The ancients introduced but few pediments into their buildings, ufually contenting themfelves with a lingle one to adorn the middle or principal part. But fome of the moderns, and particularly the Italians, have been fo immoderately fond of them, that their buildings frequently confift of almoft nothing elfe. The girder being a necefiary part in the conftru<5tion of a roof, it is an impropriety to intermit the horizontal entablature of a pediment, by which it is reprefented, to make room for a niche, an arch, or a window'. In regular architetfure, no other form of pediments can be admitted, befides the triangular and circular. Both of them are beautiful: and when a confiderable number of pediments are introduced, as when a range of windows are adorned with them, thefe two figures may be ufed alternately, as in the niches of the Panthaeon, and in thofe of the temple of Diana at Nifmes. The proportion of pediments depends upon their fize ; for the fame proportions will not do in all cafes. When the bale of the pediment is fliort, its height muft be increafed; and w hen the pediment is long, the height muft be diminifhed The beft proportion for the height is from one fifth to one fourth of the bafe, according to the extent of the pediment, and the chara&er of the body it covers. The materials of the roof muft alfo be attended to ; for if it be covered with tyles, it will be necefiary to raife it more than one quarter of the bafe,. as was the cuftom of the ancients in their Tufcan temples..

E C T U R E. The tympan is always on a line with the front of the frize; and, when large, admits of various ornaments. OF BALLUSTRADES. Ballustrades are fometimes of real ufe in buildings ; and at other times they are only ornamental. Such as are intended for ufe, as when they are employed in ftair-cafes, before windows, or to inclofe terrafles, ire. muft always be nearly of the fame height; never exceeding three feet and a half, nor ever lefs than three. But thofe that are principally defigned for ornament, as when they finifti a building, Ihould be proportioned to the architecture they accompany; and their height ought never to exceed four fifths of the height of the entablature on which they are placed; nor ftiould it ever be lefs than two thirds thereof, without counting the zocholo, or plinth, the height of which muft: be fuflicient to leave the whole balluftrade expofed to view. The beft proportion for balluftrades is to^divide the whole given height into thirteen equal parts; eight of thefe for the height of the ballufter, three for the bafe, and two for the cornice or rail; or into fourteen, (if it be required to make the ballufter lefs), giving eight parts to the ballufter, four to the bafe, and two to the rail. One of thefe parts may be called a module; and, being divided into nine minutes, may ferve to determine the di-! menfions of the particular members. In balluftrades,. the diftance between two ballufters Ihould not exceed half the diameter of the ballufter meafured in its thickeft part, nor be lefs than one third of it. The breadth of the pedeftals, when they are placed on columns or pilafters, is regulated by them; the dye never being made broader than the top of the fliaft, nor much narrower : and when there are neither columns nor pilafters in the front, the dye Ihould not be much lower than a fquare, and feldom higher. On ftairs, or any other inclined planes, the fame proportions are to be. obferved as on horizontal ones. OF GATES, DOORS, AND PIERS. There are two kinds of entrances, viz. doors, and gates. The former ferve only for the paflage of perfons on foot; but the latter likewife admit horfemen and carriages. Doors are ufed as entrances to churches, and other public buildings, to common dwelling-houfes, and apartments: And gates ferve for inlets to cities, fortrefles, parks, gardens, palaces, The apertures of gates being always wide, they are generally made in the form of an arch, that figure being the ftrongeft. But doors, which are generally of fmall dimenfions, are commonly parallelograms., and clofed horizontally. The general proportion for the apertures, both of gates and doors, whether arched or fquare, is, that the height be about double the breadth. The ufual ornaments of gates confift of columns, pilafters, entablatures, pediments, ruftics of different kinds, imports, archivolts, he.; and the moft common method of adorning doors is with an architrave, for rounding the