How did the symphony orchestra grow during the 19th century?

During the 19th century, the symphony orchestra underwent significant expansion in both size and tonal resources, evolving into an ensemble that often included around 100 performers.1

This growth was characterized by several key developments:

• Woodwinds and Brass: The woodwind section expanded from two to typically three or four of each instrument. The brass section was augmented by a third trumpet, third and fourth horns, and the addition of trombones.1
• Percussion: The use of percussion became more prominent and diverse. Composers increasingly utilized instruments such as the bass drum, cymbals, and snare drum, while new instruments like the celesta and tubular bells were introduced. The role of timpani was firmly established, with advancements like pedal-tuned "machine" drums appearing in the 1880s.2
• Orchestration: Composers such as Hector Berlioz, Richard Wagner, and Richard Strauss created works requiring unprecedented instrumental forces, treating the orchestra as a powerful, resourceful entity rather than mere accompaniment.13
• Leadership: The 19th century saw the rise of the specialized conductor, who assumed full control over performance and interpretation, moving away from the earlier practice of leading from a keyboard instrument.4