Aunt M---- says she wishes you had been at a matinée which Baroness Nathaniel Rothschild gave this afternoon at her beautiful new palace in the Faubourg St.-Honoré. At the entrance there were ten servants in gorgeous livery, and a _huissier_ who rattled his mace down on the pavement as each guest passed. There was, besides all the élite of Paris, an Archduke of Austria. I sang the "Ave Maria" of Gounod, accompanied by Madame Norman Neruda, an Austrian violiniste, the best woman violinist in the world. Baroness Rothschild played the piano part. PARIS, _May 29, 1867._ DEAR M.,--The Metternichs' big ball last night was a splendid affair, the finest of the many fine balls. We were invited for ten o'clock, and about half-past ten every one was there. The Emperor and Empress came at eleven o'clock. Waldteufel, with full orchestra, was already playing in the ballroom of the embassy, which was beautifully decorated. At twelve o'clock the doors, or rather all the windows that had been made into doors, were opened into the new ballroom, which the Princess Metternich, with her wonderful taste and the help of Monsieur Alphand, had constructed in the garden, and which had transformed the embassy into a thousand-and-one-nights' palace. The ballroom was a marvel; the walls were hung with lilac and pink satin, and the immense chandelier was one mass of candles and flowers; from each panel in the room there were suspended baskets of flowers and plants, and between the panels were mirrors which reflected the thousands of candles. One would never have recognized the garden; it was transformed into a green glade; all the paths were covered with fresh grass sod, making it look like a vast lawn; clusters of plants and palms seemed to be growing everywhere, as if native to the soil; flower-beds by the hundreds; mysterious grottos loomed out of the background, and wonderful vistas with a cleverly painted perspective. At the same moment that their Majesties entered this wonderful ballroom, which no one had dreamed of, the famous Johann Strauss, brought from Vienna especially for this occasion, stood waiting with uplifted baton and struck up the "Blue Danube," heard for the first time in Paris. When their Majesties approached the huge plate-glass window opening into the garden a full-fledged cascade fell over the stucco rocks, and powerful Bengal lights, red and green, made a most magical effect: the water looked like a torrent of fiery lava _en miniature_. It was thrilling. No one thought of dancing; every one wanted to listen to the waltz. And how Strauss played it!... With what fire and _entrain!_ We had thought Waldteufel perfect; but when you heard Strauss you said to yourself you had never heard a waltz before. The musicians were partly hidden by gigantic palmettos, plants, and pots of flowers arranged in the most attractive way. But he!--Johann Strauss!--stood well in front, looking very handsome, very Austrian, and very pleased with himself.