Music
Chladni invented two musical instruments, which he carried around Europe and demonstrated to far-flung audiences. The euphonium (1790) added a keyboard to the glass harmonica, which created tones by rubbing glass jars (Benjamin Franklin famously invented a version of the glass harmonica). Later Chladni developed the clavicylinder as well. After inventing the euphonium, Chladni began a peripatetic life touring Europe, lecturing on acoustics and demonstrating his inventions.
This letter is from Johann Theodor Mosewius (1788-1858), who was a singer and music director. He took Chladni home from Steffens' house on the last night of his life. This letter, addressed to the operatic singer Mathilde Hellwig, begins with sympathy with her over an illness. On 4 June 1828, in a letter enclosed in correspondence with their mutual friend Franz von Schober, Mosewius had assured Schubert of his admiration for his songs, including perhaps the first independent praise of Winterreise.