Sir — In a review of Ludmilla Jordanova's Defining Features: Scientific and Medical Portraits 1660–2000, Lisa Jardine describes a portrait of the astronomer William Herschel that includes the night sky1. Commenting on portraits, she writes: “As in Herschel's case, what distinguishes the scientist from other celebrities … is that, where the politician might hold a pen and the musician his instrument, the scientist's portrait is likely to allude to the scientific breakthrough itself”.
From this comment, one might not guess that, before he became a famous astronomer, Herschel was a professional musician of some distinction. He was active as an oboist, a violinist, an organist, an orchestra director and — most interestingly — a composer2. Herschel wrote symphonies, concertos, chamber music and vocal works2,3.
In June 1792, Joseph Haydn visited Herschel's observatory near Slough4. By that time, Herschel was a full-time astronomer, and it appears that Haydn's visit was motivated primarily by an interest in Herschel's astronomical activities.