The prevalence of the Lind fever, which seemed to know no abatement, however, made a London engagement at this period not highly flattering to other singers, and Mlle. Cruvelli beat a retreat to Germany, where she made a musical tour. She was compelled to leave Berlin by the breaking out of the Revolution, and she made, an engagement for the Carnival season at Trieste, during which time she gave performances in "Attila," "Norma," "Don Pasquale," and "Macbeth," and other operas of minor importance, covering a wide field of characters, serious and comic. In 1850 we hear of Mlle. Cruvelli creating a very great sensation at Milan at La Scala. Genoa was no less enthusiastic in its welcome of the young singer, who had left Italy only two years before, and returned a great artist. No stall could be obtained without an order at least a week in advance. In April, 1850, she made her first Parisian appearance at the Theatre Italien in Paris, under Mr. Lumley's management, as _Elvira_ to Mr. Sims Reeves's _Ernani_, and the French critics were highly eulogistic over this fresh candidate for lyric honors. She did not highly strike the perfect key-note of her genius till she appeared as _Leonora_ in "Fidelio," at Her Majesty's Theatre, in London, on May 20, 1851, Sims Reeves being the _Florestan_. Her improvement since her first London engagement had been marvelous. Though scarcely twenty, Mlle. Cruvelli had become a great actress, and her physical beauty had flowered into striking loveliness, though of a lofty and antique type. Her sculpturesque face and figure, her great dramatic passion, and the brilliancy of her voice produced a profound sensation in London. Her _Leonora_ was a symmetrical and noble performance, raised to tragic heights by dramatic genius, and elaborated with a vocal excellence which would bear comparison with the most notable representations of that great _role_: "From the shuddering expression given to the words, 'How cold it is in this subterranean vault!' spoken on entering _Florestan's_ dungeon," said one critic, "to the joyous and energetic duet, in which the reunited pair gave vent to their rapturous feelings, all was inimitable. Each transition of feeling was faithfully conveyed, and the suspicion, growing by degrees into certainty, that the wretched prisoner is _Florestan_, was depicted with heart-searching truth. The internal struggle was perfectly expressed."