French horn, brass wind musical instrument. Fundamentally a metal tube of narrow conical bore, it is curved into circles because of its great length. The horn ends in a wide flare. It is a development (c.1650) of the small hunting horn. Although sometimes used in a more grandiose manner, it is still employed symphonically to produce the simple woodland sound. In modern orchestras it is usually in the key of F and is a transposing instrument. The present-day French horns normally have three valves, introduced in the 19th cent. The valves supplanted crooks that were used in the 18th cent. to reduce the horn to different keys. Hand stopping and modulation are still used to control the open tone, though mutes may also be used. The first important work to call for valved horns was Halévy's opera La Juive.
See Morley-Pegge, The French Horn (2d ed. 1973).
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