Promoting a nineteenth-century Italian technology: The crystal skies of Milan Gallery “Vittorio Emanuele II”

Abstract

The nineteenth-century technological revolution gave birth to a brand-new kind of monumental architecture—the secular “cathedrals” of the bourgeois called commercial galleries. They reached their ultimate incarnation as such in the Italian case of “Vittorio Emanuele II” counterpointing the sacred Milanese cathedral over a common square. Cathedrals were those “books of stone” that once embodied building codes of monumental architecture. Innovation became necessary with newly-developed typologies and materials. It was exactly the iron-glass covering that revolutionary element of the “gallery” typology which bridged architecture and advanced technologies. The Milanese one was a “book of bricks, metal and glass” encoding spatially genuine Italian concepts and practical knowledge on bonding traditional materials with modern ones. Demanding immediate attention is their adequate profiling and translating into practical guidelines. Even though “Vittorio Emanuele II” was thoroughly researched, its iron-glass structure offers field for further investigation on innovation. The initial aim is two-fold: first, to unveil the complex of creative ideas enclosed in the crystal skies of the Milanese gallery and the technical decisions behind them; second, to trace those which survived the numerous restorations and the adoption of advanced techniques in resolving the variety of problems verified over the years. As far as creative ideas and technical solutions are concerned, there are three main examples which could be highlighted. The first one regards the 15-m span of the coverage designed deliberately without visible reinforcing rods. The second intriguing aspect was a perspective effect in the glass cladding achieved by the glass plates’ overlapping. The third technical solution of interest concerns the glazing bars and their expediency in the effective resolving of the famous water-leakage problem. The fate of all the original design ideas and technical solutions changed on a number of occasions of ordinary and special maintenance and occasional replacements. In the rich history of interventions in the roof, its partial reconstruction after the Second World War occupies a central place. In it, the cross-like section of the glazing bars along with the spatial configuration of the glass plates were consciously observed criteria for their substitution in order to assure the fruition of the perspective effect by future generations. Another case of preservation in the post-war intervention was the profile of the new main metal arches replacing the severely destroyed original ones. Each new arch was composed by segments instead of being produced as a whole piece. Moreover, the diversity of problems began right after the completion of the cover in 1868 and continues to the present day. Multiple disciplines are involved in the search of their solution: from history of architecture for an efficient archival investigation to material chemistry and physics for preventing damages in the contact zones of bricks, iron or pig-iron and glass, caused by their different thermal expansion coefficients; from brittleness of the nineteenth-century metal structures, accompanied by severe corrosion in the metal joints, to the structural-engineering issue of instability of the lantern bodies. The very challenge before the required multidisciplinary approach is to invent advanced solutions respecting the genuine concept behind the original ones. The ultimate objective is not only to trace nineteenth-century ideas and their technical solutions but also to introduce them as future-intervention guidelines for the purposes of sustainable preservation.