Until Beethoven, the piano sonata was not composed as a vehicle for virtuoso technique -- that was the domain of the concerto -- but as entertainment for amateurs in the privacy of their homes. Many such pieces were written for students, often as something of an exercise. Haydn had a number of students for whom he composed piano sonatas, and the wide range of ability among his students accounts for the disparate levels of sophistication we find among the over 50 surviving sonatas. Some of these works have been lost because Haydn gave the manuscripts to his students without making copies.
Two of Haydn's sonatas, the Sonatas in C major and E flat major (Hoboken XVI: 50 and 52), were not written for students, but for Therese Jansen, a leading pianist in London who had studied with Clementi. Haydn composed them in 1794-1795, during his second visit to the English capital. The two sonatas give evidence not only of Jansen's formidable technique, but of the more powerful sonority of the English piano in comparison to its German and Austrian counterparts. The C major sonata, in particular, betrays its temporal proximity to Haydn's unpredictable "London" Symphonies and their frequent eccentricities. The "additive" process at the opening of the first movement is only one example.
The first Allegro is one of the most impressive monothematic sonata-form movements in Haydn's output. The first theme is a sparse articulation of the tonic triad that pauses in its sixth measure. After a transition that is significantly longer than the first theme, Haydn arrives at the dominant, G major, restating the theme, this time in double notes and accompanied by rising scales in the left hand. More scales and variations close the exposition. In the development section, the material passes through numerous harmonies while the theme is reduced to only one of its fragments -- a falling octave that changes to different intervals. The recapitulation is highly modified and contains some new material. Because the secondary theme is the same as the first, there is no need to "resolve" it to the tonic, so Haydn skips ahead to the ensuing passages.
Highly expressive and technically demanding, the Adagio was clearly written for an accomplished musician. Set in the subdominant, F major, the movement is in sonata form with a brief development section. The brilliant right-hand octave passages in the second theme group contrast with the delicate, arched opening theme and attest to Ms. Jansen's technique.
Much as in the Rondo finale of Haydn's Symphony No. 88, the recurrent theme in the Allegro finale of the C major sonata serves as variation fodder for the intervening episodes. There are teasing moments when only part of the rondo theme returns while frequent pauses heighten the listeners' anticipation.