Three technical reports of R.G. Boscovich on the statics of domes, in: Further Studies in the History of Construction

The paper presents a comparative analysis of three reports written by Ruggiero Giuseppe Boscovich (1711–1787) on the occasion of the debates which developed, during the eighteenth century, on famous structural disputes: we are referring to Parere for the dome of St. Peter (1742), Scrittura for the Imperial Library of Vienna (1763), and Sentimento for the Cathedral of Milan (1765). In Parere Boscovich proposes the first application of the principle of virtual works (formulated just a few decades earlier by Johann Bernoulli) to the analysis of the stability of a damaged structure with the aim to assess its safety margins and, if the case, define an improvement intervention. A further application is in Sentimento where, however, the purpose is not to analyze a damage state but rather to assess the structural response to a new load condition. Besides the contribution that such an analysis can constitute for the history of mechanics, the importance of the three reports – even though characterized by significant differences, related not only to the specific problems but also to the scientific growth of Boscovich – is that, for the first time in the history of architecture, we are in the presence of a systematic treatment of mechanical problems aimed at a rational justification of architectural interventions. Therefore, in addition to their scientific value, which can be summed up in the methodological cogency and the thorough discussion of mechanical issues, the three reports allow reflecting, even though marginally, on the complex relationship between science and architecture which, just in the eighteenth century, shows a growing involvement of knowledge of statics in building design.