Orchestra - "A mixed body of instrumentalists for the performance of symphonic and other works" (The Concise Oxford Dictionary of Music)
The modern symphony orchestra varies in size, but typically has a strength of about 100. The largest lot of these are from the strings, which contain some 60 to 70 players. This typically comprises some 16 first and second violins, 14 violas, 14 cellos and eight to 10 doubles basses. However these numbers are sometimes reduced when playing 17th century pieces to simulate a 17th century orchestra.
Next is the woodwinds which are usually composed of two flutes, a piccolo, two oboes, one cor anglais, two clarinets, one bass clarinet, two bassoons and a double bassoon. Then there is the brass, which normally consists two trumpets, three trombones (two tenor and one bass), a tuba and four horns.
There are variations, of course. Some pieces have parts for other instruments, the most common of which are the harp and piano. Other pieces may require a larger orchestra; Wagner’s Der Ring des Nibelungen (The Ring of the Nibelung) cycle requires 15 woodwinds and 21 brass. The French composer Hector Berlioz even dreamt of having 242 strings and 30 grand pianos!
The layout of the orchestra also varies, but it generally follows a tried-and-tested format. The players are seated in a semicircle facing the conductor, with the strings right in front. The woodwinds are usually behind the strings, and behind them the brass. The percussion is normally sited right at the edge of the semicircle.
Picture: Typical layout of a modern symphony orchestra
This layout is the most commonly used, but there are many other possible ways to arrange the players, and the decision ultimately lies with the conductor. The layout may also be affected by factors such as the shape and size of the stage used.