Hello everybody, I found an odd feature in a small French pipe organ:
polyphonic organ pipes that can produce more then one note while using
only one pipe! I thought that this technology may be useful on small
street and fair organs, so I am writing this to share this discovery
with you all.

Generally, this feature is only used for the lowest few notes of each
register. Usually each pipe can only play two or three notes, because
only one of the notes can be played at a time. However, this would not
be an issue for the bass section of a mechanical organ.

To provide a general summary of how these polyphonic pipes work, the
pipe has one toe per note it can produce. Each toe has a one-way valve
to prevent air backflow. For the fundamental tone, the pipe works as
a regular organ pipe. For the added tones, a small part of the wind is
routed out of the toe and though either a channel in the pipe wall or
an external tube to a pneumatic located somewhere up the length of the
pipe.

The inflation of this pneumatic lifts open a key that is usually held
closed by a spring. This makes the pipes speaking length shorter,
making a different note. The fundamental is tuned by a tuning slide at
the top of the pipe, the alternate notes by small slides under the keys.

I thought this nifty little contraption would be useful for squeezing
a few more bass notes out of a small organ, but it could also be used
on larger organs to save space that would be taken up by larger pipes.
I should mention however I have only seen this on labial pipes, not
reeds.

I'm also not a organ builder so I can't provide overly detailed
information, but I will make a few sketches over the weekend that I can
share if anybody would be interested.

Thanks for your time,
Christian Tedesco
cmt0817@gmail.com.geentroep [delete ".geentroep" to reply]

 [ Found at http://orguedebierre.free.fr/le_maitre.htm (my translation):
 [ Louis Debierre, organ builder. In August 1882 he filed patent for
 [ multiple-tone organ pipes "to produce alternately several notes of
 [ the scale and thus obtain the same sound effect as with the system
 [ of one pipe per note."
 [
 [ Debierre's pipes are not a polyphonic instrument like a guitar.
 [ They are monophonus, because they play only one note at a time, like
 [ a flute. Schirmer's "Dictionary of Musical Terms" of 1895 defines
 [ polyphonic as:
 [
 [ "Polyphonic. 1. Consisting of 2 or more independently treated parts
 [ ;-- contrapuntal ;-- concerted ; opp. to homophonic and harmonic.--
 [ 2. Capable of producing 2 or more tones simultaniously, as the
 [ pianoforte, harp, or organ ; opp. to monophonus, and equivalent to
 [ polyphonous." Ref. A Dictionary of Musical Terms, (C) G. Schirmer
 [ 1895. Oxford Dictionaries adds: "polyphonic (of an instrument):
 [ capable of producing more than one note at a time."
 [
 [ See and hear Debierre's pipes in the video at
 [ https://www.dailymotion.com/video/xfpv7f -- Robbie