A prova di bomba. Ingegneri, architetti e teorie sulle volte in un cantiere militare di metà Settecento

The article deals with an episode in the construction of the new Citadel in Alessandria, since the 1730s. This essay considers the complex debate that developed on the best form to assign to “bombproof” vaults of the buildings inside the fortified perimeter. In 1756, engineers, architects and State administrators met in a “congress” to discuss whether semi-circular or elliptical designs were to be preferred: while this meeting highlighted a situation of crisis, on the other hand it became a favourable occasion of improvement, and promotion of a truly scientific approach to construction. The need to counteract the effects of the concentrated force due to the bomb impact on the vault extrados introduced a new and never before considered factor, in a debate on vault design which was by then widespread. In respect to the theories (notably Philippe De La Hire’s) then considered as “state of the art”, the problem was approached by considering the newest theoretical developments in balistics. The problem is analyzed by a close reading of the expertises, leading to more general observations on the relationship between science, technology and the architectural professions in the 18th Century