What are the origins of the french horn; how does it work and how was it developed?
THE HORN BEGAN LIFE as a long, fairly thin piece of tubing with a mouthpiece at one end down which air was blown by the player, and a bell at the other end. The only notes it could play were ones that were part of the harmonic series derived from the bass fundamental (lowest note). The harmonic series is the sequence of overtones that is available from a given fundamental note, and which appears in nature as part of what constitutes a particular note. From a particular fundamental the horn’s effective range is from the 2nd harmonic to the 16th. Here is an example of the harmonic series.
The player of a horn obtains these notes by the way he shapes his lips.
The notes available were thus limited in the earliest horn to those available from a particular fundamental (bass note), so as time went by horn-players and instrument-makers devised different methods of getting the full range of notes.
The end result was the valves, which effectively allow the horn to have sufficient fundamentals to make all notes of the chromatic scale possible (sometimes twice over). It’s as though several natural horns were combined in one instrument.
Stretched out the horn was a very long instrument and completely unwieldy in an orchestra or for any other practical purposes. So as time went by the tubes became wound into a circle with the bell sticking out one end and the mouthpiece the other. Steve Bell gives a short illustrated tour of the instrument as it is today.