From Academic Kids
The cor anglais or English horn is a musical instrument of the woodwind family. It is similar to both oboes and oboe d'amores but larger. If the oboe were to be regarded as a soprano in C, then the "cor anglais" would be a tenor oboe in F (that is, a transposing instrument).
The technique of playing the cor anglais is the same as playing the oboe, but it is tuned a perfect fifth lower, having a range from the E below middle C to the B flat, a thirteenth above middle C. It is perceived to have a more mellow and more plaintive tone than the oboe. Its appearance differs from the oboe in that the reed is attached to a slightly bent metal tube called the bocal and the bell has a bulbous shape.
Playing the cor anglais
The cor anglais is considered physically somewhat demanding to play. The amount of breath support needed is greater than for the oboe, as is the difficulty of maintaining a correct embouchure. One professional player has compared playing the instrument with the task of blowing up balloons for hours at a time. Players also risk tendinitis or carpal tunnel's from supporting the instrument's weight over for long periods.
Like other reed players, cor anglais players must have not only a strong instrumental technique but also good maintenance skills. The cutting of reeds from cane (arundo donax), which is generally done by the performer, is considered something of an art. While performing, cor anglais players must be vigilant to keep their reeds moist and to prevent moisture damage to their instrument by swabbing it out frequently.
"Cor anglais" is generally the name of the instrument used in Britain and culturally-affiliated countries; "English horn" is used in the United States.
Despite its name, the instrument is not thought to be English in origin. A common explanation of the name is that it is a corruption of the French cor angl駧, meaning bent horn, although there is no certainty that this is the case. This probable misunderstanding gave birth to another one, the naming of the French horn, which is as French as the cor anglais is English.
Many oboists will double on the cor anglais, just as flutists double on the piccolo. There are few solo pieces for the instrument, although the timbre of the instrument makes it well suited to the introduction of expressive, melancholic solos in orchestral works, particularly slow movements.
The instrument is also heard more frequently in film scores over the oboe, most likely because its rounder tone quality.