In this article, Carl Czerny's "Letters to a Young Lady on the Art of Playing the Pianoforte" (1837) is studied as a machine manual within the cybernetic economy of James Watt's governor. It is argued that while the young pupil is encouraged to subject herself to a strict discipline of physical deportment at the piano, this activity is in conflict with her own desire to become a self-regulated learner. The key claim made is that although Czerny's surveillance strategy prevents Miss Cecilia from breaking with the cybernetic ideal and appropriating the pianistic technology for purposes of virtuosic self-expression, she becomes aware of her latent agency and its potentially subversive implications for gendered music making. As such, Czerny's piano manual addressed to the stereotypical nineteenth-century piano girl anticipates the pianistic discourse associated with the invention of the player piano at the turn of the twentieth century.