The Norman Arch into the Lady Chapel
The method of turned squares given by George Lesser 41 and by Colin Dudley 42 has the disadvantage that it very quickly puts a nest of lines over the diagram, few of which directly relate to architectural features of the building, which makes the geometry difficult to follow. It does however have the advantage of being a method used by masons from Norman times through to late Perpendicular. It was a secret method, but nearly given away by a boss in the south Choir aisle at Worcester bearing a design of turned squares, and by the vault under the tower at Tewkesbury, which is a diagram of turned squares carried out on the curved surface of the vault. I resist applying it automatically, for the building should be allowed to speak its geometry without preconceptions.
This method is applied in Figure 23 to the Norman arch at the east end of the presbytery that once led into an apse, and now opens onto the Lady Chapel. The largest square shown has side 18’6”, half of 37’. The inner circle in green is easy to justify. Then its raising up to become the upper red circle gives the intrados. Each circle can be justified in one way or another. The result is a tour-de-force, and shows why the arch was stilted when there was no reason such as vaulting a rectangular space for doing so.
The 19th century floor level shown in the diagram is higher than that in place when the arch was built. The black square gives the level of the top of a chamfer, at the bottom of which was the Norman floor level. The modern floor level is slightly below the top of the chamfer. The opening under the arch is therefore based on a square, as is that of the south door, but in a different sense.
There is no guarantee that the nest of squares was in this relationship to the arch, but it is clear that such a nest was used.
This method is applied in Figure 23 to the Norman arch at the east end of the presbytery that once led into an apse, and now opens onto the Lady Chapel. The largest square shown has side 18’6”, half of 37’. The inner circle in green is easy to justify. Then its raising up to become the upper red circle gives the intrados. Each circle can be justified in one way or another. The result is a tour-de-force, and shows why the arch was stilted when there was no reason such as vaulting a rectangular space for doing so.
The 19th century floor level shown in the diagram is higher than that in place when the arch was built. The black square gives the level of the top of a chamfer, at the bottom of which was the Norman floor level. The modern floor level is slightly below the top of the chamfer. The opening under the arch is therefore based on a square, as is that of the south door, but in a different sense.
There is no guarantee that the nest of squares was in this relationship to the arch, but it is clear that such a nest was used.