My trusty Alain Paris "Dictionnaire des Interpretes" says [in French] that it was in Brazil on 30 June 1886 when Toscanini [19 years old & engaged to assist in rehearsals during a Brazilian tour] took the baton after the failure of several other conductors and directed Aida from memory. It was such a triumph that the impresario had him conduct the other twelve operas in the repertoire for the remainder of the tour. Regards, Bill Karzas [log in to unmask]