In 1883 Auguste Choisy published his book L=art de bâtir chez les Byzantins. In it he explained, for the first time, all the details of the geometry and construction of byzantine vaults. The main source was the direct study of the monuments, interpreting his observations in the light of traditional vaulting techniques. He is explicit about this: *ma seule ressource était d'interroger les monuments eux mêmes, ou mieux encore de rapprocher les uns des autres les faits anciens et les traditions contemporaines+ (Choisy 1883, 3). Choisy concentrated his attention on the vaults, as he was convinced that the vault governs the whole architectural system: *Toutes les circonstances de la construction découlent ainsi de la nature de la voûte byzantine; et j'ai cru qu'il convenait de ranger les faits autour de cet élément fondamental du système+ (4). The other fundamental principle is the economy of construction, as the vaults *. . .s'y subordonnent dans l'économie générale des édifices+. The observations were made during a six month mission of the Adminiatration des des Ponts et Chaussées the year 1875 (Mandoul 2008, 29). The next year he published a *Note sur la construction des voûtes sans cintrage pendant la période byzantine+ (Choisy 1876), were he resumed the main results concerning the technique of vaulting without centring.
The book had an enormous impact on contemporary historians of byzantine architecture. It was cited and praised by the new light it threw to the constructive aspects, for its clarity and rigour of exposition, and for their superb plates. Eventually, his theories were incorporated in the manuals and histories of Byzantine architecture. The book of Choisy concentrated on *l=art de bâtir+. The interest on the technical aspects of architecture almost disappeared after the First World War, maybe due to the coming of the modern architecture and the new materials (iron, steel and reinforced concrete). As a concequence Choisy=s works on *l=art de bâtir+ were almost systematically ignored. The first specifical study of Byzantine construction after the Second World Ward was written by Ward-Perkins (1958) and it has been considered, since then, the standard reference for Byzantine construction. Ward-Perkins ignore the work of Choisy making a passing criticism of his geometrical theories of Byzantine vaults. However, the detailed description of wall construction made by Ward-perkins coincides pretty well with that of Choisy (7-13). He apparently was unaware that the whole theory of Byzantine vaulting without theory centring is Choisy=s. Besides, he attributes to Giovanonni the detailed description of the use brick ribs in vaults construction. In all, it appears that Ward-Perkins did not read carefully Choisy=s book on Byzantine construction nor was familiar with the history of vault construction. The consquence was that subsequent authors didn=t take seriously Choisy=s work or simply ignored. Sanpaolesi (1971) in a work with the suggestive title *Strutture a cupola autoportanti+ simply ignore him. To Mango (1975), author of one of the standard manuals on Byzantine architecture, Choisy is superseded; Krautheimer (1984) did not consider Choisy in treating, summarily, the vaulting problems. Robert Ousterhout author of a book on the Master Builders of Byzantium (1998) considers Choisy *outdated+, being *more than a century old+. Even in detailed archeological studies of vaulted structures his work is ignored (Deichmann 1979). There are some exceptions in specialised studies on vault construction: Besenval (1984), Cejka (1978) and Storz (1994).
It must be said from the beginning, that Choisy=s L=art de bâtir chez les Byzantins is still the best source for anyone interested in understanding the geometry, construction and structural behaviour of Byzantine vaulted buildings. In what follows, we will try to demonstrate that this assertion is true
