Violin Sonata no. 4 in F minor op. 15

Especially attractive, this work from 1819 was the first for violin and piano by Onslow to be published with the title of Duo, the sign of an even-handed dialogue between the instruments, even more so than in the earlier Sonate de pianoforte avec accompagnement pour violon obligé. Today, it is entitled in a more conventional style for the sake of convenience. The piece awakens gradually in a gentle and expressive Largo; the Allegro vivace then engages, with its arpeggios functioning as a first subject, and a free section leading to the second subject, which combines ascending scales with falling arpeggios. The development section is devoted to the first subject. The recapitulation gives way to a concluding tonal exploration. The Minuetto consists, in the first place, of an Allegro con fuoco with an impetuous subject; the Trio section next brings calm (legato chords jointly from the piano and violin). The Andante quasi allegretto displays six variations on the folk tune, “Au clair de la lune”. After its initial statement, the melody fades away somewhat in the first and second variations, whilst it is more audible in third, surrounded by scales; it disappears once more in the fourth, Risoluto, encased in flowing curls. The slower fifth variation plays with a certain pathos, before the final variation appears in which the folk tune is skilfully distributed between the instruments atop a carpet of arpeggios. After various episodes, a culminating point and a becalmed conclusion bring the movement to an end. The Finale begins in fugato, Vivace, with a writhing subject; exercised with much ingenuity, this latter provides the occasion for a lively form of writing manifesting a marvellous contrapuntal and polyphonic mastery.