Geometric Rules used in the Construction of Late Gothic Vaults: Case Study of St. Zygmunt’s Church in Szydłowiec

Abstract This paper examines the geometric principles which governs the construction of late Gothic vaults, by using the example of the vault in the chancel of St. Zygmunt’s Church in Szydłowiec (Poland). Scientific studies concerning the Szydłowiec temple and similar European construction were analyzed. On this basis, the geometrical rules for the construction of the vault, which is unique in Poland, were established. The initial figure was a regular octagon, the side of which determined the length of the spans. The radius of the two-bend prinzipalbogen, inscribed in the octagon, defines the curvature of all ribs. The research used measurements of the vault and the original plan from the time of construction. As a result of the analysis, the use of a two-bend prinzipalbogen was confirmed. Axial symmetry, parallel lines, and collinearity of nodal points are other geometric principles that builders followed.