GEOMETRIC PROGRESSIONS AND THE CONCEPTUAL DESIGN ON FORTIFICATION ARCHITECTURE IN THE TREATISE ON FORTIFICATION BY GALASSO ALGHISI

摘要

This article presents an application of geometry in architecture. It aims to investigate the geometric pattern underlying the conceptual design of the model of Renaissance fortification proposed by Galasso Alghisi in the treatise Delle Fortificationi (Venice 1570). The study focuses on the geometrical analysis of the generative dynamic of the tested form which is illustrated here by means of detailed engravings. Within the well-established tradition of Renaissance treatises on the subject, it is argued here that Galasso Alghisi's treatise is of particularly interest for several reasons: the presence in the fortification drawing of the geometric layout that underpins the finished form; the concept of the fortification design interpreted as an evolutionary process; the identification of several geometric parameters with respect to which it is possible to obtain a (theoretically infinite) number of formal variables, all derived from the same circular origin; the absence of radial geometry. More specifically, the following aspects will be examined: the method of the geometric-configuration of the fortification type proposed by Galasso Alghisi, together with the identification of the related formal matrices; the functioning of the Istromento (instrument) described by Galasso Alghisi and advised in order to 《proportion the sites to be built upon and transform the drawings of the fortresses into structures following the proportions》.