ORCHESTRA (Gr. orchestra., from orcheomai, I dance), in the Greek theaters, the place allotted to the chorus of dancers; in modern theaters, the part of the building assigned to the instrumentalists; and in the modern concert-room, the place occupied by the instrumental and vocal performers. The word orchestra is also used to denote the musicians collectively.
A complete orchestra consists of stringed and wind instruments, and instruments of percussion. The employment of stringed and wind instruments together was long deemed a barbarism. Gluck was among the first composers who showed that they could be effectively combined, and his ideas were more fully developed by succeeding com posers The perfecting of the old instruments, and the introduction of new ones, for merlyconfined to military bands, have added immensely to the power and resources of the modern orchestra, whose capacities, however, have sometimes been misused.
The proper strength of an orchestra must depend on considerations connected with the locality. The stringed instruments should in all cases greatly outnumber the wind instruments; and those latter, the instruments of percussion. The stringed instruments in general use are the violin, viola, violoncello, and double-bass, and their force often amounts to as many as fifty, while even in a large orchestra there are seldom more flutes, hautboys, or bassoons than two of each. The horn trumpet, and ophicleide or serpent, the other wind instruments admitted into the orchestra, are used as sparingly; and of instruments of percussion, a pair of kettle-drums is often considered sufficient, though cymbals and triangles are occasionally added. In a small orchestra, trumpets, trom bones, the serpent, and the kettle-drum shout(' be avoided as being too noisy.. By far
the greatest part of the work falls to the share of the stringed instruments, the parts for which form a complete quartet for first violin, second violin, viola and violoncello, which should be perfect within itself, independently of the.parts for the wind instruments. The object of the double-bass is to enforce the violoncello part. This full quartet is occasion ally interrupted by harmony in two or three parts, or passages in unisons or octaves. The success of the combination of wind and stringed instruments depends on the skill and judgment of the composer. The bassoon, horn, or flute may double any given part of the stringed instrument quartet, so as to produce an effect of re-enforcement, or it may have its owu distinctive melody. An occasional variety is produced by the entire cessa tion of stringed instruments for a short period, letting the wind instruments be heard alone.
The orchestra of a concert-room should be so arranged that the front is about five ft. above the level of the floor, and it should rise gradually in steps towards the end wall, whose angles ought to be rounded off so as to enable the whole body of sound to be reflected. Reverberation is essential to the proper effect of music. From the exigences of dramatic representation, a theatrical orchestra must necessarily be much inferior to a concert orchestra; the instrumentalists, brought together in the lowest part of a theater on a horizontal plane between the spectators and the stage, are deprived of most of the advantages arising from a proper arrangement.