'Such scientific and profound harmonies': The Italian Opera Orchestra and Early Performances of Mozart's Don Giovanni in London

The Orchestra in the Theatre – Composers, Works, and Performance is part two of the publication The Opera Orchestra in 18th- and 19th- Century Europe. It deals with the opera orchestra in the theatre and opera house, that is to say, as an institution within an institution; it sheds light on the encounters of different orchestras with certain innovative and demanding operas; and it studies the interrelation between orchestras and operas by analysing what happened to an opera when it was played by an orchestra that differed substantially from the one for which the opera was conceived – or to put it another way, what happened to the structure of an orchestra when it performed an opera with an atypical or unusually large instrumentation. Thanks to their circulation and performance (i.e. representation) on stages all across Europe, such operas made an important impact on the opera orchestras that had to perform them and that were challenged by their demands. These operas sometimes served as the stimulus for the renewal of an opera orchestra, because of the necessary changes – most often increases – in instrumental resources; but case studies will also show that such changes did not always have a lasting impact on orchestral practices or the constitution of an opera orchestra, but that they sometimes were only temporary, for the duration of a particular production. However, all this testifies to the fact that apparently stable orchestral institutions underwent internal changes caused by musical transfer and musical representation. The institutionalization of opera orchestras involves the concepts and terms of 'stability' and 'discipline'. It would seem that this transformation depended on that of the opera house, but, even though the orchestra was an essential partner in the performance of operas, there were cases in which the institutional stability of theatres did not imply that of the orchestra. The theatre might be seen as an indispensable entity within a court, a state or a town, but its orchestra could nevertheless be considered a mere component of the operatic production that was hired like singers, scores or even scenery, on a seasonal basis; this was still usual in Italy during the first decades of the 20th century. In most places, however, this precarious condition of opera orchestras changed during the 19th century; the institutionalization and stability of orchestras were conditions which instrumentalists aspired to and were ready to struggle for