The Norman, Romanesque or round arch:
This type of arch has, by definition, a single centerpoint, which in normal use makes the height of the arch equal to half the span. This can lead to numerous problems particularly when it is essential for all arches to be the same height, such as when building stone vaults supported on arcading. At first, this problem was avoided by using barrel vaults with the side arches finishing below the spring of the vault, but having the end arches share the same baseline as the barrel. Later this problem was overcome by the introduction of the two-centered, pointed arch, where the only relationship between span and height is dictated by the limitations of the materials.
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The arch span/height problem also arises with arcades, such as those between a church's nave and aisles, where the plan calls for the spans to vary and the aesthetic of the elevation calls for equal heights. There is a fine example of this at Castleacre Priory Church, where the arcades begin with a shorter bay needed to support the corner turrets of the west front. The masons, confronted with this problem but not, at that time, having a solution in their structural vocabulary, decided to raise the springing point of the smaller span arch, so that it matched height with its neighbour and disguise this fact by extending the arch mouldings down the pier to make it look as if its springing point was level with the others - this is usually known as a Stilted or Horseshoe Arch
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