Dimrs. Doors are apertures in exterior walls, used for passage into public and private buildings ; and in the interior, for communication from one apartment to another. In the fourth book of Vitrnvius rules are laid down for Doric, Ionic, and Attie doors, all of which have apertures narrower at the top than at the bottom. These trapazoidal closures of apertures have the property of shutting themselves, 1%-laich, perhaps, might have occasioned the introduction of this form, and are use ful in modern times for raising the door above the floor in the act of opening, in order to keep it clear of the carpet. Ex amples of them are to be found among, the ruins of ancient edifices ; they have also been introduced by a few modern architects. The apertures of doors of small dimensions are most commonly closed with lintels. Doors, in general, are regulated in their apertures by the size of a man, so as never to be smaller than that he might pass freely through them ; they are seldom less than two feet nine incliesin width, by six feet six inchcs in height, except in confined situations, and where utility is beyond any other con sideration.
Doors of entrance vary in their dimen sions, according to the height of the story, or magnitude of the building, in which they are placed. In small private houses Cott. feet may be the g-reatest width, and in most eases three feet six inches will be sufficient. Tbe lintels of doors should. range with those of the windows ; and the \ width of their aperture should not be less than that of the windows. A good pro portion of doors is, that where its dimen sions has the ratio of three to_seven ; their height should never be less than twice, nor more than twice and a half, their breadth. In the entrance doors of piiblic edifices, where there is a frequent Ingress and eg-ress of people, and often crowded, their width may- be from six to ten feet Inside doors, or doors of com munication, should be in some measure proportioned to the height of the stories ; however, there is a certain limit for the dimensions of their apertures, which they should not exceed ; for the difficulty of shutting- the door will be increased by its magnitude ; therefore the apertures of doors, which are intended to shut in one breadth, should never exceed three feet six inches. In palaces and in noblemen's houses, where much company resort, and in state apartments, all the doors are fre quently- thrown open ; they are made much larger than other docirs, being. from four to scr feet in width, with folding leaves. The proportion of the apertures of such doors will often be of a less height than that of twice the breadth, a.s all the rooms in the same story have a communi cation with one another, tbe whole of the doors in that story will have one common height.
The apertures of exterior doors placed in blank arcades are regulated bv the imposts, the top of the aperture being generally made level with the springing of the arch ; or if the door has dressings which include a cornice, the top of the cornice ought to be on the same level with the springing of the arch. With re gard to the situation of the principal en trance, it is evident that the door should be in the middle, as it is not only more symmetrical, but will communicate more easily with all the parts of the building. In principal rooms, doors of communica tion should at least be two feet distant from the walls, if possible, that furniture may be placed close to the door-side of the room. The most common method of adorning doors is with an architrave sur rounding the sides of the aperture, or with the architrave surmounted with a cornice, forming an architrave cornice, or with the architrave frize and cornice form ing a complete entablature. Sometimes the ends of the cornice are supported with consoles, placed one on each side of the architrave ; and each console is most commonly attached to the head of a pi laster ; sometimes the surrounding archi trave is flanked with pilasters of the or ders, or of some other analogical form. In this case, the projections of their bases and capitals are always within that of the architrave : the architrave over the capi tals of the pilasters is the same as that of the head of the door, and the parts ex actly of the same height, and projections profiling upon the sides of the surround ing architrave. Sometimes, either with or without these dressings, the door is also adorned with one of the five orders, or with columns supporting a regular en tablature, frequently surmounted with a pediment. Doors are also sometimes adorned with rustics, which may either be smooth, hatched, frosted, or vermicti lated ; but their outline must be sharp. The rustics are disposed in contiguity with each other, or are repeated by equal in tervals : as to the shafts of columns, the rustic cinctures may either be cylindrical or with rectangular faces. In doors with rectangular apertures and rusticated heads, the rustics are drawn from the vertex of an equilateral triangle within the aperture. The entrance doors of grand are often adorned with por ticos, frequently in the manner of Grecian temples; sometimes the plan of the por tico may be circular, which should never have less than three intercolumniations, as the entablature would appear to over hang its base, in such a degree as to of fend the eye of a beholder.