Biamonti 815 refers to an Adagio in B-flat major, a movement that may well have been conceived as an early idea for the third movement of the String Quartet in B-flat major, Op. 130. The sketch belongs to the period between February and August 1825, as Deroda notes on page 92 of his study.

Deroda points out that Beethoven labelled this sketch “Adagio in E with mute,” even though the music itself is written in E-flat. At the end of the passage Beethoven adds another intriguing note: “First part in C minor without repetition.” In his detailed analysis of the sketchbook that now bears his name, Deroda explains (pp. 92–93) that before Beethoven settled on the final form of the Andante, he explored a wide range of musical ideas. The first of these experiments—found on page 43 of the sketchbook—carries the same curious heading, “Adagio in E with mute,” again notated in E-flat, followed by the remark “First part in C minor, without repetition.”

The sketch, together with several others from this stage of Beethoven’s work, is preserved in the Beethoven-Haus in Bonn, in what is now known as the De Roda Skizzenbuch, named after its last owner.

The principal thematic idea appears on folio 22 recto, written on staves 4 and 5. Deroda associates two further fragments, on staves 7 and 8 of the same folio, with this theme; Biamonti also treats them as part of the same sketch. However, there is yet another fragment halfway across staff 6, which complicates the picture. Because Biamonti never examined the manuscript directly and instead relied on Deroda’s descriptions, he accepted these groupings at face value. A closer look at the manuscript reveals something Deroda does not emphasise: the first and third fragments are written in 2/4 time, whereas the second is cast in 4/4, suggesting they may not all belong to a single, continuous line of thought.

Sketch I is found on folio 21 recto, on staves 4 and 5. Sketches II and III appear later on the same folio, on staves 7 and 8. Biamonti notes that the music “continues for another 10 bars,” which points to all three sketches being present on the same page, even though he catalogues them separately. The first fragment clearly begins in the manner of a canon in unison, before branching out in a different direction. The second and third fragments adopt a more harmonic character, enriched with chromatic inflections, and they sit firmly in the sound world of E-flat major.