Geometric Constructive Traces in Drawings by Francesco Borromini

Abstract

Here some results are presented from the ongoing research of the analysis of the drawings by Francesco Borromini, preserved at the Albertina in Vienna, relating to designs of cupolas, in order to highlight the geometric constructions and the proportional relationships in function of the realization of the projects. In fact, besides the symbolic geometries traceable especially in the most famous buildings, such as the San Carlo alle Quattro Fontane or Sant’Ivo alla Sapienza, evidenced even by Borromini himself, other and more decisive geometries are revealed by carefully observing the signed drawings. The research methodology adopted is based on comparing what emerged from the analysis of the drawings, the study of the treatises concerning the construction methods of the cupolas and the results obtained from the survey by means of a 3D laser scanner. The survey, in fact, becomes the tool to ascertain the correspondence between the theoretical form underlying the drawings, and the realized form, including the provisional works that determine the geometric conformation, verifying the link between the geometric-graphic reasoning related to the load distribution and the consequent dimension of the components.