In December 1787, Mozart finally obtained a steady post under aristocratic patronage. Emperor Joseph II appointed him as his "chamber composer", a post that had fallen vacant the previous month on the death of Gluck. It was a part-time appointment, paying just 800 florins per year, and required Mozart only to compose dances for the annual balls in the Redoutensaal (see "Mozart and dance"). This modest income became important to Mozart when hard times arrived. Court records show that Joseph aimed to keep the esteemed composer from leaving Vienna in pursuit of better prospects.