Window (properly "wind eye"), the term applied in architecture (Ital. fenestra, Fr. fenetre, Span. ventana, Ger. Fenster) to an aperture or opening in a wall for the admission of light and air to the interior of a hall or room.
The earliest windows are those which constituted the clerestory windows of the Great Hall of Columns at Karnak; they were filled with vertical slabs of masonry pierced with narrow slits. Other Egyptian temples were lighted in the same way. In one at Der el Medinet at Thebes the window was divided by miniature columns with lotus capitals. Some of the small ivory carvings found at Nimroud by Layard, now in the British Museum, are evidently of Egyptian workmanship, as they have lotus columns forming a balustrade in the lower part of the window; and such features are shown in the Assyrian bas-reliefs as windows in the towers. Dr Arthur Evans's discoveries at Cnossus have revealed, in the eastern portion of the palace, rectangular openings which were certainly windows, with raised sills and stone benches inside, and the representations of the ordinary houses at Cnossus on a series of plaques show that they were in two or three storeys with openings in the upper storeys filled with windows framed in timber with transoms and mullions. It was at one time thought that there were no windows in Greek temples, and those of the west front of the Erechtheum are known now to be later reconstructions of the Roman period, but the remains of two windows placed on either side of the as to the lighting of some of the temples in Rome, in which were placed all the magnificent statues from Greece, so as to enable them to be seen properly. The Pantheon was lighted by a circular opening in the dome 30 ft. in diameter; the rain therefore fell in at times, and consequently the pavement had a convex contour, there being also holes under the hypaethral opening in connexion with drains beneath the pavement. There was a window at the south end of the tepidarium of the Forum baths at Pompeii, said to have been filled with a bronze frame with glass in it, half an inch thick. Although no window frames have been found in Pompeii,the openings in the walls show that some of the rooms were lighted by windows; one of them in the house of Diomede takes the form of a bow window with three lights in it.
In the later styles the windows assume much greater importance, and in Gothic cathedrals almost govern the whole design. Already, however, in the earliest Byzantine church, Sta Sophia at Constantinople, the windows constituted one of the chief features of the church; the forty windows round the base of the cupola giving an exceptional lightness to the structure; besides, there are windows in. the larger and smaller apses and in the north and south walls. The windows in the latter, which are of great size, are subdivided by marble mullions with pierced lattices between of transparent marbles.
In the later Byzantine churches the windows were of smaller dimensions, but always filled with marble screens, sometimes pierced, and the grouping of two or three under a single arch is the prevailing design.
In the Romanesque styles the windows are universally roundheaded, with infinite variety of design in the mouldings and their enrichment, greater importance being sometimes given by having two or more rings of arches, the outer ones carried by small columns; this is varied in Norman work by dividing them with a shaft into two or more lights placed in shallow recesses under an arched head. Circular windows occur occasionally, as in the eastern transept of Canterbury, at Iffley church, Oxford, Barfreston and Patricksbourne in Kent. In all these early windows, which are usually small, greater light is obtained by splaying the jambs inside with a scoinson arch over them. The coupling together of two or more windows under a single arch, and the piercing of the tympanum above, led to the development of plate and rib tracery (see Tracery); also to that of the circular or rose windows, which throughout the Romanesque and Gothic periods constituted very important features in the church, being placed high up in the west front over the porch or in the transepts; sometimes, and more particularly in French churches, they occupied the whole of the upper portion of the windows, having vertical lights under them, but the junction was never quite satisfactory.
Although the employment of tracery continued long after the classic revival, the examples generally are poor in design, and even in those that are more elaborate (as those of the period of Henry II. in the church at Le Grand Andely) the introduction of classic details in the ordinary and rose windows was of too capricious a character to make them worthy of much attention. The early Renaissance architects in France in some cases, and notably in the apsidal chapels of St Pierre at Caen (1520), seemed to feel that the stained glass was too much cut up by the tracery and mullions, and omitted them altogether, trusting to the iron stanchions and cross-bars to carry their glass, so that a return was made to the simple semicircularheaded window of Roman times, retaining only the mouldings of the late Flamboyant period for the jambs and arch-moulds. Windows of this description, however, would be out of place in domestic architecture, so that the mullion window was there retained with two or three transoms, all moulded and with square heads; in the Tudor period cusping was introduced in the upper lights and occasionally in those below, and this custom lingered for a long time in the collegiate buildings of Oxford and Cambridge and in various houses throughout England. In France, square-headed windows were almost always employed, owing to the earlier introduction there of the Renaissance style, when the decoration of the mullions, generally consisting of classic pilasters, required some kind of architrave, frieze and cornice, to render the order complete; eventually the mullion and transom disappear, and in the earlier work of the Louvre the windows are simple rectangular openings, fitted with wooden framework, and, like those in Rome, Milan and Genoa, depend for their architectural effect on the moulded classic jambs, and the lintel, frieze and small cornice over; and in cases where more importance was required, with small semicircular columns or pilasters carrying the usual entablature, with small pediments sometimes angular and sometimes semicircular, repeating in fact an ancient Roman design, of which almost the only examples known are the blank windows and niches which decorated some of the enclosure walls of the Roman thermae. In Florence and Siena the early windows of the Renaissance often had semicircular heads and were coupled together, there being two lights to the window divided by shafts, thus continuing the tradition of those of the earlier Tuscan palaces; the same treatment was followed in Venice, Verona and other towns in the north-east, where the Gothic influence of the palaces in Venice created a transition; thus the mouldings of the windows of the Vendramini and Corner Spinelli palaces follow closely those of the Ducal Palace, but the arches are semicircular instead of being either pointed or ogee in form. Another type peculiar to Venice is a lofty window with semicircular head enclosed in a rectangular panel and crowned with a small entablature and pediment.
The only new combination of the 16th century in Italy, which was largely adopted in England by Inigo Jones and his followers in the 17th and 18th centuries, is the so-called Venetian or Palladian window, the finest example of which is that found in the Sala della Ragione or the basilica at Vicenza; it is true that it was here employed by Palladio to light an open gallery, but the composition was so generally approved that it led to its constant adoption for a window of more importance than the ordinary simple rectangular form. It consists of a central light with semicircular arch over, carried on an impost consisting of a small entablature, under which, and enclosing two other lights, one on each side, are pilasters. In the library at Venice, Sansovino varied the design by substituting columns for the two inner pilasters. The Palladian window was introduced by Inigo Jones in the centre of the garden front at Wilton, by Lord Burlington in the centres of the wings of the Royal Academy, and good examples exist in Holkham House, Norfolk, by Kent, and in Worcester College, Oxford. There do not seem to be any examples in either Germany, France or Spain. Circular and oval windows, lighting a mezzanine or the upper part of a hall, are found in Italy, France and England, sometimes over ordinary rectangular windows when the main front is decorated with semidetached columns as in Hampton Court Palace. (R. P. S.)
