ARCHITECTURE.
2i.5
breadth of the aperture should never he less than 3 feet, or 3 feetti inches. In rooms from 20 to 24 feet square, or of equal super-ficial dimensions, it may be from 4 to 4} feet broad ; in those ofa4> to 27, from 4| to j; and in such as exceed these dimen-sions, the aperture may even be extended to 5} or 6 feet. Thechimney should always be situated so as to be immediately seenby those who enter tiie room. The middle of the partition wallis the most proper place in halls, saloons, and other rooms of pas-sage; but in drawing-rooms, dressing-rooms, and the like, themiddle of the hack wall is the best situation. In bed-rooms, thechimney is always in the middle of one of the partition walls: andiii closets and other very small places, to save room, it is put in acorner. Wherever two cbimnevs are used in the same room, theyshould be plan'd either directly facing each other, if in differentwalls, or at equal distances from the centre of the wall in whichthey both are. The proportion of tiie apertures of chimney-pieces of a moderate size is generally a perfect square; in smallones it is a trifle higher; and in large ones, a tritie lower. Theornaments of chimney-pieces consist in architraves, friezes, cor-nices, columns, pilasters, termini, caryatides, consoles, and allkinds of ornaments of sculpture, representing animals and vege-tables, Ac. likewise vases, chalices, trophies of arms, &c. In de-signing them regard must be had to the nature of the place wherethey are to be employed. Such as are intended for halls, saloons,guard-rooms, galleries, and other large places, must be composedof large parts, few in number, of distinct and simple forms, and hav-ing a hold relief; but chimney-pieces for drawing-rooms, dressing-rooms, &c. may be of a more delicate and complicated nature.
Stair -cases are made for the purpose of ascending to the upperstories, and ought to be so constructed as to make the ascent safe,agreeable, and easy. To render stairs easy of ascent, the heightof a step ought not to exceed seven inches, nor in any case to beless than four, but six inches is a general height. The breadth ofthe steps should not be less than twelve inches, if it can possiblybe avoided ; nor should they ever be more than eighteen ; and torender our ascent free lrom the interruption of persons descending,their length should not exceed twelve, nor be less than four feet,except in common and small buildings, whose area will not admitof a stair-case of more than three feet. That the ascent may beboth sate and agreeable, it is requisite also to introduce some con-venient aperture for light, which ought to be as nearly opposite toour iirst entrance to the stairs, as the nature of the building willadmit of. An equal distribution of light to each flight ol stairsought to be particularly regarded ; for which reason, these aper-tures or w indows are commonly placed at the landings or halfspaces; though sometimes the whole is lighted from a dome.Stair -cases whose plans are circular, are of various kinds. Somewind round a newel or column, in the middle, and the risers ofthe steps are straight, and sometimes curved. Others form a wellor void space, in the centre. The same may be observed ofthose whose plans are elliptical: the most common, however, arethose whose jilans are a square or parallelogram, '('he ancientspaid a superstitious regard to an odd number iu their tlights ofsteps ; as 3, 5, 7, Ac. in order that in their ascent, they might lie-gin and tinish with the right foot. Palladio therefore, allows tothe stair-case of a dwelling-house, 11 or 13 steps to each flight.'When a staii-case winds round a newel, whether its plan be cir-cular or elliptical, the diameter being divided into three equalparts, two are set apart for the steps, and one for the column.But in circular or elliptical stair-cases that are open, or whichform a well in the middle, the diameter is divided into four equalaits ; two for the steps, and two lor the void space in the centre,lodern stair-cases, however, have often a kind cf well of a mixedform ; straight on each side, and circular at the returns of eachillght. The openings of_ these wells are various in wideness, butseldom exceed 18 or 20 inches.
Of Bat.jlustraiies.
Ballustradas are sometimes of real use in buildings; and at othertimes they are only ornamental. Such as are intended for use, aswhen they are employed in stair-cases, before windows, or to in-'close terraces, Ac. must always be nearly of the same height;never exceeding three feel and a half, nor ever less than three.But those that are principally designed for ornament,, as w hen theyfinish a building, should lie proportioned to the architecture theyaccompany - , and their height ought never to exceed four-fifths of
the height of the entablature on which they are placed: norshould it be ever less than two-thirds thereof, without counting thezocholo, or plinth, the height of which must be sufficient to leavethe whole ballustrade exposed to view. The best method to pro-portion ballustrades is to divide the whole given height into13 equal parts; eight of these for the height of the bailuster,three for the base, and two for the cornice or rail; or into 14 (ifit be required to make tiie bailuster less,) giving eight parts to thebailuster, four to the base, and two to the rail. The distance be-tween two ballusters should not exceed half the diameter of thebailuster measured in its thickest part, nor be less than one-thirdof it.
Of Roofs.
Before we commence the roofing, a plan of the building to becovered should be made, that we may be able to ascertain thelengths of the various timbers reouired for the whole. The par-ticular kinds of covering used in England are lead, zinc pantiles,plain tiles, and slates. Coverings of lead are doubtless the bestand most durable of any other ; but on account of their expencethey are seldom chosen, except for magnificent buildings. Leadis now most generally used on roofs nearly or perfectly fiat, whereany other sort of covering would not be safe. The pitch or per-pendicular height of such roof is about two-ninths of the width of thebuilding, or rather under what is termed pediment pitch. Pan-tile coverings may also be used on low roofs; but their generalpitch ought to be about three eighths, of the width of the building.Coverings of plain tiles and slates are generally allowed the highestpitch; because when thev are laid on low roofs, the rain willmore easily find its way between them. These ought to have apitch, the length of whose rafters is three-fourths of their girder; orat least, the sides of the roof ought to be at right angles with eachother, '['here are also various kinds of circular roofs; but thosemost generally used are formed in the manner now described,having large or oblong plans, and timber frames. Beams that ex-ceed 20 feet in extent, should lie trussed in one or more places,as may be required. Beams should never exceed 15 feet in bear-ing; nor rafters more than 10 feet; and especially in roofs of verylow pitch, whose coverings have a much greater pressure on theirrafters, than those of higher pitches, and which may therefore ex-ceed 10 feet. If the length of a beam of fir be 30* feet, its scant-lings may be 7 inches deep and 6 inches thick :
If 45,
9 inches deep and
7 inches thick.
60,
30 .
84..
75,
J0| .
10 .
90.
12* .
104- ...
the leniinches d
;th of a principal rafter be 2eep and 5 in thickness :
4 feet, its scantlings may
If 36,
7 inches deep and
6 in thickness.
41,
9 .
7 .
60,
10 .
74 .
72,
10 .
9 .
Rafters of these dimensions are generally made about one inchlarger at the bottom both in'depth ‘and thickness; whichstrengthens the roof by admitting larger tenons into the principalbeams, and bv becoming lighter at the'top. If the rafters be small,as 8 feet in length, their scantlings may be
41 inches by 3 inches thick:
If 10, 5 “ .3
12, (i . 3
O’f Cielings.
Cielings in churches and temples may be considered as the in-terior coverings of their roofs, as there is nothing between thembut the necessary framing by v Inch the whole is supported. Fordwelling houses the simplest anil most common sort are thosewhich are flat. These are generally adorned with principal com-partments, surrounded with mouldings, either let into the cielingor projecting from it. Their ornaments and mouldings do not re-quire a bold relief; but being near the eye, they must be finishedwith neatness and taste. Coved cielings are certainly much morebeautiful than flat ones; but their execution is attended with moreexpence. They are used promiscuously in large and small roomsand occupy from one fifth to one-third of the height of the room.But where the architect is at liberty to proportion the height ofthe room to its superficial diimnsions, the most eligible pro-portion ferthe cove is one-fourth of the whole height of tiie room.
The