Moving St. Peter's obelisk as seen in the engravings of Giovanni Guerra and Natale Bonifacio: a technological feat, or pure propaganda?

In 1586 the printer Bartolomeo Grassi published a series of engravings by Domenico Fontana (1643-1607), which showed how the Vatican obelisk was to be moved. He also published two prints of the benediction ceremony in 1587. These engravings were drawn by Giovanni Guerra of Modena and etched by Natale Bonifacio from Sibenik (Almagià 1932-33; Donati 1933; Bacotich 1933). They were printed before the obelisk was actually raised on September 10, 1586 and four years before the publication of Domenico Fontana’s volume Della Trasportatione dell’Obelisco Vaticano et delle Fabriche di Nostro Signore Papa Sisto V (printed by Domenico Basa, Rome 1590). In particular, two of the Bonifacio-Guerra engravings are "synoptic" tables that document what the construction site must have looked like in the first phase of the operation, which had been split into three stages, beginning in October 1585 and continuing until August 1586. These two images show how the obelisk was taken from its original location (beside the rotunda of Santa Maria della Febbre), lifted up from the base and lowered onto a wooden trestle, which was then used to transport the obelisk into St.Peter’s square. Details of the obelisk’s measurements (which are mistaken) and (very few) of the technical characteristics of the tools and machinery used are shown in the captions. These engravings and the volume Della Trasportatione have historically been seen as a means for spreading technical knowledge that could be re-utilised for similar enterprises. It will be interesting to study the Guerra-Bonifacio engravings, using the essays of Carugo (1979) and Curcio (2003) as a departure point, and in the light of recent research projects on the history of construction (Becchi and Cicconi 2011, in press), achieve a better understanding of the real meaning of the engravings (intentionally excluding the informations in Della Trasportatione). Did the prints have an educational purpose? Is the information they contain sufficient to pass on a very special kind of knowledge, the capacity for moving giant monoliths? Were these precious engravings merely a display of technological virtuosity (printed in limited numbers), a lavish form of transnational propaganda (since the captions are often written in Latin)? Was the intention merely to visually suggest a continuity between Imperial Rome and the Sistine Rome? The aim of this study is to clarify these and other aspects of Guerra and Bonifacio’s iconographic corpus on the Vatican obelisk. La traslazione (1586) dell’Obelisco vaticano è stata immortalata, contestualmente all’operazione, in due celebri incisioni di Giovanni Guerra e Natale Bonifacio. Quattro anni dopo, Domenico Fontana, artefice della memorabile impresa, pubblica il volume Della Trasportatione dell’Obelisco Vaticano (Roma 1590), nel quale descrive lo smontaggio del monolito dalla sede originaria, il trasporto e il successivo innalzamento in piazza San Pietro. La storiografia ha sempre interpretato questo corpus iconografico come mezzo di divulgazione di un sapere tecnico altamente specializzato, cui ricorrere per imprese analoghe. Si tratta di illustrazioni che hanno suscitato grande ammirazione, Certamente meno interesse specifico; infatti, esse attendono ancora una verifica contestuale nel dibattito, allora ancora embrionale, tra meccanica teorica e pratica. Inoltre ci si chiede se le informazioni in esse contenute siano sufficienti per trasmettere lo specialissimo “sapere”, qual’è quello dello spostamento di grandi monoliti. Il presente contributo intende riflettere sul portato tecnico e sull’efficacia divulgativa di questa iconografia.