At the funeral of the tenor Adolphe Nourrit in Paris in 1839, Chopin made a rare appearance at the organ, playing a transcription of Franz Schubert's lied Die Gestirne. On 26 July 1840 Chopin and Sand were present at the dress rehearsal of Berlioz's Grande symphonie funèbre et triomphale, composed to commemorate the tenth anniversary of the July Revolution. Chopin was reportedly unimpressed with the composition.

What event were Chopin and Sand at on 26 July 1840?