Complex sentence: A growing number of engagements saw an increase in the size of the orchestra, and when Johan Gottlieb Naumann carried out his reforms in the 1780s, the ensemble numbered 46 members.
Split into simpler sentences: A growing number of engagements saw an increase in the size of the orchestra. When Johan Gottlieb Naumann carried out his reforms in the 1780s, the ensemble numbered 46 members.