Duplex instruments

Duplex instruments (It.: gemelli, twins), brass instrs. that can either produce 2 different tone qualities at the same pitch, being provided with 2 separate bells for this purpose, or play in 2 different tonalities without change of mouthpiece. Or, to put it differently, a combination of 2 dissimilar instrs. at the same pitch, or of 2 similar ones at different pitches. Prototype of the first variety is Charles Claggett's *chromatic trumpet and French horn of 1788. Experiments designed to…