BUTTRESS

An external support to a wall, so arranged as to counteract the lateral thrust of roofs and vaulting. The buttre is not used in Cla ic architecture, where the thrust is always vertical; and in Romanesque it is hardly developed. It is, in fact, a correlative of the pointed arch, especially when used in vaulting, and so first attains considerable depth in the Lancet period. In the Tudor period, when it had to support fan vaulting of vast expanse and weight, its depth or projection was proportionably increased. The flying buttre , arch-buttre , or cro -springer , is an arch delivering the weight to be supported at a distance, as of a spire at the angle of the tower, of a clerestory at the aisle buttre , or of the chapter-house roof at Lincoln, to the heavy ma es of masonry prepared at a distance to receive it. The pinnacles which frequently terminate buttre es are intended to add to the weight of the supporting ma . (See Bay .)