Nicola Zabaglia’s Scaffoldings for the maintenance of architectural space in St. Peter’s Basilica and throughout Europe in the 17th to 19th centuries

This research proposal focuses on the theme of construction and restoration scaffoldings evolution in Europe between 16th and 19th centuries, as well as on the transmission of technical building knowledge in Europe through treaties and architecture and engineering manuals. Modern technical literature on construction scaffolding has its roots in 16th century Italy. Beginning with Vitruvianism (first illustrated edition of Vitruvius, Fra’ Giocondo 1511), an increasing number of books on architecture, fortification and machinery got published. Many of these books covered technical issues and architectural topics (e.g., Lorini’s book on fortification, 1596). Such books are invaluable historic sources on transient aspects of the building process such as scaffoldings and lifting gear, and other construction site details. From the 16th to the 19th century the development building technology was driven by certain experimental model construction sites which had to overcome challenges concerning size and complexity, such as the moving of the big monoliths. In Italy, the Fabbrica of St. Peter’s (the Papal institution in charge of the new Vatican Basilica building-site administration) was one of the most influential authorities on building practice until the early 20th century. Its extraordinary efficiency in the organization of manpower and influence on the improvement of building techniques are strongly connected to the development of machinery and construction and restoration scaffoldings. The improvements in the organization of labour, procedures, and construction techniques in the Vatican building yard was due to the functional and structural optimization of machinery and scaffolding too. Their efficiency was the key to the success of all phases of construction and decoration, as well as restoration and maintenance works in the new St. Peter’s. The role played by the Fabbrica in Italian construction building industry is made clear by the constant and extensive help offered to the sites inside and outside the Vatican, which included the supply of significant amounts of material, equipment, machines, and the crucial contribution given by the highly skilled craftsmen. Traditional and innovative scaffoldings used until the beginning of the 20th century in St. Peter’s building site were celebrated in 1743 with the publication of the volume Castelli e Ponti di maestro Nicola Zabaglia. The prestigious in folio book illustrates scaffoldings invented and used in several restoration projects by the illiterate roman master carpenter Nicola Zabaglia (1667-1750), and shows how the building practices were adapted and changed and how the new breakthroughs in mechanical science were incorporated. Zabaglia improved the technique of joining wooden beams together when assembling large scaffolding and machines. He understood the specific mechanical qualities of wood, such as its elasticity and its ability to withstand traction. He knew how to make best use of the junctions of the platforms, for which he studied new systems of tying knots with cords (to keep the inner structure of the wooden beams intact) and with fittings in metal and forged iron, the use of which he always tried to limit. He also perfected new joints made only of wood, like dovetail joints, which he could do through an intuitive use of geometry and his knowledge of the properties of wood. Zabaglia’s scaffolding projects were wonderful examples of technological innovation and perfection, so much so that many of them were hired out to other building sites until the end of the 19th century. Critical and practical fortune of the Castelli and Ponti is provided by the most important European technical treatises until the end of the 19th century. Nevertheless, the leading role of Italy in innovative construction technology was gradually challenged by France during the 17th century, when technical dictionaries evolved, particularly in the French-speaking world. At the same time, practical treatises on specific crafts such as stone-cutting and carpentry started to establish themselves on the rapidly growing book market. In France, we find an increasing interest in applying the growing scientific knowledge and reasoning to real-life application problems. A scientific approach to machine design based on state-of-the-art mechanics is also reflected by Jacob Leupold’s multi-volume Theatrum Machinarum of the 1720ies. Consequently, some of the well-published Italian achievements were copied in France and Germany, whereas others were viewed more skeptically, such as the mast crane stabilized by anchoring cables (the Italian “antenna”). Yet, the integration of practical-traditional knowledge, theoretical investigation, and ad-hoc on-site experimentation was not achieved until the advent of the Polytechnical education around the turn of the 18th to the 19th century. Last not least, detailed reports on single outstanding construction achievements provide in-depth information on the technology employed. Domenico Fontana’s self-advertising book on the moving of the Vatican obelisk (1590) was probably the earliest and most successful publication of this type. The genre later reached its heyday in the French 18th century bridge building literature. Even some tables of Castelli e Ponti volume were included in the European carpentry manuals until the 19th Century. For example, the methods used by Zabaglia to assemble wooden beams and trusses was replicated by similar connection systems presented in some architectural treatises from France and Germany, as well as some of his most spectacular scaffolds. Between all, we can mention the volumes by Robert Pitrou, published in 1756 and by Johann Karl Krafft’s on l’Art de la Charpente, published in Paris in 1805. The research here proposed aims to highlight the historical development of fixed and mobile scaffoldings through a comparative study of European technical literature and to outline tools and modes of transmission of construction and restoration practices as well as main reference models reiterated by all the most important European treaties. The results achieved up until now have confirmed many important connections between Italian, French, German, Belgian and English technical treatises by 20th century. They are the evidence of the useful European comparison on results of scientific research, but also the evidence of a continuous and fruitful exchange of practical experience and theoretical knowledge, also in the field of carpentry.