19th Century (Romantic)
The expansion and development of artistic expression that characterizes the Romantic era is reflected in the orchestra. However, it is important to bear in mind that technological advances were crucial to enabling this growth. String instruments were redesigned to a different bow pattern (Tourte) and with greater string tension. Theobald Boehm redesigned the flute, oboe and clarinet to a system that is still in common usage today. Brass instruments acquired valves, giving them chromatic capabilities. All these developments enabled a more powerful sound and more lyrical expression. However, the new instruments only gradually appeared in orchestras through the 19th Century.
Often it was opera that drove the development. Wagner included many of the new instruments, including bass tubas, bass clarinets, English horns (which made a comeback in the 19th century) and an expanded percussion section. On occasion he was obliged to invent his own instruments such as the Wagner Tuba. Meanwhile, Verdi also explored new instruments, and included cornets for the first time in the brass section. Harps appeared, often in pairs or even more, in many pieces.
The overall effect of all these developments was to produce a bigger, richer sound, with greater timbral variety. Composers exploited these possibilities and in doing so yet further developed the orchestra. In a period when creating an original sound was an important artistic goal, the orchestra provided perhaps the greatest possibility of so doing. Thus, Berlioz scored Symphonie Fantastique (1830) for the following instruments:
2 Flutes (one doubling piccolo)
2 Oboes (one doubling English Horn)
2 Clarinets (doubling on A, Bb, C, and Eb clarinets)
2 Ophicleides (obsolete bass brass instruments)
Percussion (including Bass Drum, Snare Drum, Cymbals and Bells)
And in 1895/6, Mahler composed his Symphony No. 3 for solo alto voice, female chorus, boys' chorus, and the following orchestra:
4 Flutes (two doubling piccolo)
4 Oboes (one doubling English Horn)
3 Clarinets (one doubling bass clarinet)
2 Clarinets in Eb
4 Bassoons (one doubling contrabassoon)
Percussion (including Bells, Glockenspiel, Snare drum)