THOUGH made up of different instruments, the orchestra may be regarded as a unit from the point of view of composer, conductor, and audience. The conductor's share in the matter will be treated in a special chapter, but it has seemed worth while to explain here a part of the composer's work, and certain points that the audience may look for when hearing orchestral music.
The orchestra of Bach, although it had many instruments now obsolete, did not give quite the effect of the full modern orchestra, as it lacked many of the deeper instruments, such as the tubas, contrabassoons, and so on. Bach's music, therefore, is not overpowering in effect, but flows along naturally and smoothly. The contrapuntal character of his music (written as if in parts instead of chords) makes this fluent quality particularly noticeable. In some cases the modern instruments replace the obsolete ones.
Handel's and Bach's scores were often merely outlined, or only partially filled out. In this music the composer was often the leader, and sat at the harpsichord, or organ, where he could arrange his own harmonies to suit himself. For modern purposes, some of the old scores have bad to be "filled in" by more recent composers.
Thus in the case of the oratorio "The Messiah," which is given widely even to-day, there are two such refurbishings, as already stated, -- one by Mozart and one by Robert Franz.
The scores of classical and modern times are complete, having been wholly finished by their composers; and from them the student can trace the growth of the orchestra.
The symphonies of Haydn and Mozart led to those of Beethoven, who is the great representative of the classical period. The classical orchestra consisted of first and second violins, violas, 'cellos, contrabasses, flutes, sometimes a piccolo, oboes, clarinets, bassoons, horns, trumpets, sometimes trombones, and kettledrums. With these the composer could give all the effects he desired.