l cortile della Dogana in Palazzo Vecchio: il dettaglio che illumina la regola

The present paper describes a new hypothesis on the Old Palace in Florence, that develops and modifies some statements of my Musso e non quadro, la strana forma di Palazzo Vecchio dal suo rilievo, 2007. The new hypothesis resulted from a specific research on the Dogana courtyard, carried out in 2008, through the analysis of the surveying of the courtyard. Such outcomes have been found thanks to computer aided drawings. It would be impossible to reach the same results with analogical drawings, because they come from some formal characteristics resulting from mathematical calculations, and not from graphical procedures. It is therefore likely that tradition has forgotten the practices that I am going to describe, when the architectural culture has lost interest in them, due to the prevalence of drawn design on mental and mnemonic design. Thanks to computerized representation, crucial steps of architectural design are recognizable, and compose a more complete picture of the strategies used to define the artifacts that continue to receive the urban life and to satisfy the needs for identity symbols. The analysis of the Dogana surveying highlights an unexpected requirement: the apparent disorder of the courtyard hides an order real, but not easy to understand. If we measure the irregular trapezoidal areas of its strips in succession, we find that their measures, compared with Gothic units of squared measure in Florence, the staioro, are expressed by easy proportioned numbers: 1,5 - 1 – 1- 0,3 staiora. The Dogana courtyard is a problematic issue, traditionally considered as a functional part of the Palace, not a representative one. The discovered proportions of the square measures of its parts, on the other hand, lead us to presume that it could offer a symbolic meaning too. A very strict logic drew the plan of the Dogana, as consequence of the design of the Priori palace. The ratio was shown to me by a young mathematician, Filippo Callegaro, researcher of the Scuola Normale at Pisa, whom I asked how could the Gothic architects have calculated linear measurements of trapeziums of known areas and prefixed angles. Through a sketch and a description of the Palace, the answer was simple and enlightening: it was necessary and sufficient to know the triangle which the trapezium belonged to. With this key I changed my tale of the Gothic design of the palace, while the hypothesis of the influence of the areas on the Gothic design is unchanged.