Rossini's towering William Tell, very rarely done in these parts (and absent from the Met since 1931), arrives at the Caramoor Festival tonight for the first of two performances. There are online notes by the Rossini authority Philip Gossett and by the conductor Will Crutchfield, who is a notable scholar in his own right. Crutchfield is including music seldom presented in performance – the trio and prayer from Act IV — while omitting a good chunk of the first part of Act III. "Something has to go if the opera is to finish in four hours," Crutchfield writes. The cast is led by Michael Spyres as Arnold, Julianna Di Giacomo as Mathilde, and Daniel Mobbs in the title role. No harmonicas.