Tradition and technological innovation on roman building sites from the 16th to the 18th century: construction machines, building practice and the diffusion of technical knowledge.

The triumphant raising of the Vatican obelisk, conducted by Domenico Fontana under Sixtus V between April and September 1586, had a knock-on effect in the building industry: it unleashed a process of innovation and development in building technology. The heir of Roman imperial mechanics, this technology would reach a level of efficiency and functionality between the sixteenth and eighteenth century not to be surpassed for a long time. It was favoured, on the one hand, by the new impulse registered in Roman building practice from the fifteenth century on and, on the other, by the renewed interest in mechanics, aimed at the invention of new and more functional apparatus for the building industry. But alongside these mechanical supports, a decisive role was also played by the development of a quite extraordinary organizational, managerial and technical apparatus that had its main organ of propulsion in the Reverenda Fabbrica di San Pietro, at once an experimental laboratory and an unrivalled reservoir of resources, both technical and professional. In this system, the sector of building machinery assumed a major role. It became an integral and indispensable part of architectural practice. This was not only thanks to the progress of the theory of machinatio, but above all thanks to the gradual advancement of the apparatus developed to support the building industry by technical experts in the field. The provisional apparatus, the machines and operational procedure developed by Fontana are an integral part of a wider operational programme, inspired by flexibility in the use of machines and equipment and their adaptation to the ordinary practice of building. The huge financial investment implied by such a programme was one that only the Fabbrica di San Pietro could afford. The investment, however, could be recouped by the hiring out of machinery to other Roman building sites. This practice continued and is still documented in the nineteenth century, for instance in the restoration of the portico of San Paolo fuori le Mura or in the raising of dedicatory columns and obelisks. The prolonged use of this building apparatus is proof of the traditional and pragmatic character that informed executive practice and building technology right down to the introduction of construction in reinforced concrete. Until then, wood, iron and rope would remain the main constituents not only of such basic building apparatus as winches, windlasses, capstans, scaffolding, trestles and derricks, but also of hoisting gear such as traglie and girelle (pulleys). Each modification or innovation could be tested, and finally adopted, only by use and direct practice. In this situation of marked traditionalism, the diffusion of technical know-how, almost exclusively of empirical and pragmatic character, remained in the hands of the master builders and sampietrini (maintenance men) of the Fabbrica di San Pietro, such as the unlettered expert (“homo sanza Lettere”) Nicola Zabaglia, or technical experts of various origin and training. The frequent consultations between experts, the technical advice sought from the most skilled building foremen (capomastri), and the fruitful exchange of craftsmen between various building sites in Rome, generated a spontaneous and immediate transmission of know-how in the technical and mechanical field. Only rarely did this know-how avail itself of the nascent science of mechanics, from which it long remained separated. To the precepts of theoretical mechanics it seemed to prefer the more reassuring precedent set by the well-tried building practices of antiquity and the Renaissance