BUTTRESS, an erection serving to support a wall or other building, which is either too high otherwise to main tain its position. or is pressed against from the other side by an adventitious force.
Buttresses are so frequent in Gothic architecture as to become a marked and principal feature in buildings of that style ; they are placed around the exterior sides of the edifice, usually one between every two windows, and one or two at each of the angles of the building. In the earlier erections, each angle was supported by two buttresses, dis posed so as to leave their sides parallel to the planes of the walls; but in later examples, for the sake of giving a lighter appearance to the building, as well as fur economizing materials, only one buttress was used. situate in such a manner as to receive the direct drift of the vaulting, having its sides parallel to the vertical diagonal plane which bisects the angle formed by the two planes of the adjoining farces of the building. The use of these projections is not so much to support the weight of the walls, as to resist the outward thrust of the roof, more especially when vaulted.
There are two kinds of buttresses used in Gothic build ings ; those that are formed of vertical planes, and attached to the walls, are called pillared buttresses ; those which rise from the pillared buttresses upon the sides of the aisles, with an arch-formed intrados, and sloping extrados or top, are called flying buttresses, arc boutants, or arch buttresses.
In few instances perhaps have the medituval architects shown greater constructive skill than in the erection of buttresses, as is more especially evidenced in their larger structures, such as cathedrals, where by means of them the active force ofthe vaulting, which would otherwise overthrow the walls, is borne down harmless outside the building into the earth. By the are-boutants the drift is parried over the
aisles to the upper part of the main buttresses, where, by the gravity of the super-imposed pinnacles, the direction of the three is changed, so that from an horizontal thrust, it becomes or at least approaches to a vertical pressure, which again is carried through the mass of the buttress to the ground at its base. No material is thrown away, all is pressed into active service, what does not answer a useful end is removed, and nothing, added merely for ornament; an instance of the latter has been shown in the case of the surmounting pinnacle; which, although by a superficial observer it might he considered as mere ornament, is in reality of the utmost importance in the construction ; as an example of the previous statement, may be produced the buttresses at Westminster llall, from which a considerable portion near the ground and adjoining the walls, being of no service, has been entirely cut away.
Pillared buttresses are enriched with pinnacles, niches, statues, and other ornaments. Flying buttresses are often perforated, particularly in the later examples, in which the perforations assume the form of polyfoils, flambeaux, and other beautiful devices. A rich specimen is to be Ibund in Henry the Seventh's chapel at Westminster, where the buttresses are of a wonderfully light and gorgeous appear ance; the main buttresses also in this instance are of a very elaborate description.