A Dictionary of Music and Musicians/Posthorn
POSTHORN. A small straight brass or copper instrument, varying in length from two to four feet, of a bore usually resembling the conical bugle more than the trumpet, played by means of a small and shallow-cupped mouthpiece. Originally intended as a signal for stage-coaches carrying mails, it has to a limited extent been adopted into light music for the production of occasional effects by exceptional players.
Its pitch varies according to length from the four-foot C to its two-foot octave. The scale consists of the ordinary open notes, commencing with the first harmonic. The fundamental sound cannot be obtained with the mouthpiece used. Five, or at most six, sounds, forming a common chord, are available, but no means exist for bridging over the gaps between them. In a four-foot instrument such as was commonly used by mail guards, the sequence would be as follows
[ W. H. S. ]